Thursday Abstract Podium Presentations
July 07, 2016—8:30 AM to 10:30 AM—Strand 11
Thursday, July 07, 2016, 8:30 AM–8:45 AM
Changes in Markers of Stress, Recovery, and Training Load During a Women's Division I Field Hockey Season
S. Conway, A. Walker, M. Hofacker, M. Rabideau, O. Tok, B. McFadden, D. Sanders, C. Ordway, and S. Arent
Rutgers Center for Health and Human Performance
Maintenance of athlete health and performance is critical to overall success. The use of physical monitoring and biomarkers may provide a more comprehensive approach to player management. Purpose: To evaluate the physiological changes that occur over the course of a woxmen's Division I field hockey season using biomarkers associated with breakdown and recovery. Methods: Blood samples were obtained from women's Division I field hockey players (N = 24; Mage = 19 ± 1.09 years; Mweight = 64.49 ± 7.39 kg; Mheight = 166.05 ± 3.33 cm; M%BF = 26.14 ± 6.52%) at the start of preseason (T1), at week 4 (T2), week 8 (T3), and the end of the season (T4). Athletes arrived fasted and euhydrated 36 hours after a game. Hemoglobin (Hb), Iron (Fe), creatine kinase (CK), total cortisol (CORT), free cortisol (FCORT), T3 and prolactin (PRL) were analyzed. All players were monitored for training load (TL) and calorie expenditure standardized for body weight (Kcal) using the Polar Team2 System throughout the season. Results: There were significant changes in Hb, Fe, CK, CORT, FCORT, T3, TL and Kcal (p ≤ 0.05) over the course of the season. Hb, Fe and CORT each changed significantly between T1 and T2 (ΔHb = −0.567 ± 0.161 g·dl−1; ΔFe = −54.5 ± 8.87 mcg·dl−1; ΔCORT = 2.87 ± 1.24 mcg·dl−1, p ≤ 0.05) and remained significantly different from T1 at T3 and T4 (p ≤ 0.05). CK rose significantly between T1 and T2 (ΔCK = 54.14 ± 9.08 U·L−1, p ≤ 0.05) and remained significantly higher than T1 at T3 (p ≤ 0.05) before returning towards baseline at T4. There was a significant rise in FCORT from T1 to T2 (ΔFCORT = 0.172 ± 0.061 mcg·dl−1, p ≤ 0.05) which persisted through T3 (p ≤ 0.05) before rising again from T3 to T4 (ΔFCORT = 0.129 ± 0.056 mcg·dl−1, p ≤ 0.05). There was a significant rise in T3 between T1 and T2 (ΔT3 = 18.09 ± 5.94 ng·dl−1, p ≤ 0.05) before returning to baseline at T3 (ΔT3 = 18.41 ± 5.52 ng·dl−1, p ≤ 0.05) with no further change at T4. There was no significant change in PRL between time points; however, there was a trend toward significance from T2 to T3 (ΔPRL = 2.91 ± 1.65 ng·dl−1, p < 0.1) with continued elevation at T4. Both TL and Kcal were at their highest in preseason before a continued decline throughout the season (p ≤ 0.05). Conclusions: These results show significant changes in Hb, Fe, CK, CORT and FCORT between T1 and T2 indicative of significant homeostatic disruption that is sustained throughout the season despite a decrease in physical workload. This demonstrates that the increased demand and physical breakdown that accompanies a short, but intense, preseason persists throughout the competitive season without significant opportunity to recover. Despite monitoring training load and calorie expenditure, biomarkers provide a more comprehensive assessment of systemic stress and recovery. Practical Applications: Integrating a testing system that uses periodic blood draws to analyze biomarkers in order to understand how they are changing in response to practices, games and travel may help teams avoid non-functional overreaching. Biomarkers have the potential to help coaches construct and modify a team's in-season periodization program to optimize athlete recovery and performance over long competitive seasons. Acknowledgments: Special thanks to Quest Diagnostics and the Rutgers Women's Field Hockey Team.
Thursday, July 07, 2016, 8:45 AM–9:00 AM
Effect of Acute Alcohol Ingestion on Resistance Exercise Induced mTOR Signaling in Men
D. Levitt,1 A. Duplanty,2 H. Luk,1 R. Budnar,1 A. Fernandez,3 D. Hill,4 B. McFarlin,1 and J. Vingren1
1Applied Physiology Laboratory, University of North Texas; 2Louisiana State University Health Science Center; 3Institute for Exercise and Environmental Medicine; and 4University of North Texas
Purpose: The purpose of this study was to investigate the effect of consuming alcohol after heavy resistance exercise (RE) on mTOR signaling in men. Methods: Ten resistance-trained men (mean ± SD: 25 ± 3 years, 83.8 ± 15.7 kg, 177 ± 7 cm, 14.8 ± 8.5% body fat) completed 2 identical acute heavy resistance exercise trials followed by ingestion of either an alcoholic beverage (alcohol condition; 1.09 g ethanol·kg−1 lean mass−1, diluted to 15% vol/vol) or an isovolumetric placebo beverage (placebo condition). A within-subjects, crossover design was employed. Condition assignment was counterbalanced and assigned using randomization. Prior to exercise (PRE) and 3 (+3 hours) and 5 (+5 hours) hours post-exercise, muscle tissue samples were obtained from the vastus lateralis by microbiopsy. Muscle samples were analyzed for phosphorylated mTOR, S6K1, and 4E-BP1 using Western blotting. A 2 (condition) × 3 (time) ANOVA with repeated measures on both factors was used to analyze results. Results: A significant (p ≤ 0.05) condition × time interaction effect was found for mTOR and S6K1 phosphorylation. At +3 hours, mTOR and S6K1 phosphorylation was higher for placebo than for alcohol. No significant differences between conditions or over time were found for 4E-BP1 phosphorylation. Conclusions: The major finding of this study was that post-exercise alcohol ingestion attenuated RE-induced mTOR and S6K1 phosphorylation 3 hours after a bout of RE in resistance-trained men, indicating decreased activity of these protein kinases within the mTOR signaling pathway. Practical Applications: The results of this study indicate that consuming alcohol after heavy resistance exercise attenuates mTOR signal transduction in the post-exercise recovery period, and as a result, could attenuate RE-induced protein synthesis and thus training adaptations. Although more research is needed to determine the downstream effects of this attenuation in mTOR signal transduction, male athletes should limit the consumption of alcohol after performing heavy resistance exercise. Acknowledgments: This study was funded by a grant from the National Strength and Conditioning Association.
Thursday, July 07, 2016, 9:00 AM–9:15 AM
The Role of Forskolin Supplementation on Resting Skeletal Muscle Cyclic-AMP Concentration in Humans
J. Nicoll, A. Sterczala, A. Bryce, and A. Fry
University of Kansas
Resistance exercise overtraining induces a downregulation of β2-adrenergic receptors (β2-AR) in skeletal muscle. Consequently, cyclic adenosine monophosphate (cAMP) signaling via the β2-AR may be attenuated in an overtrained state. Forskolin (FSK) is a potent stimulator of cAMP in vitro, and is a common ingredient in nutritional supplements where it has been shown to increase fat loss. If FSK supplementation could increase skeletal muscle cAMP concentrations, it may help attenuate the detrimental performance effect of overtraining. Purpose: The purpose of this investigation was to determine if FSK supplementation increases skeletal muscle cAMP concentrations in humans. Methods: In a within-subject, crossover investigation muscle biopsies were collected from 10 college aged women (mean ± SD; age = 20 ± 0.94 years; height = 169 ± 7 cm; body mass = 67.09 ± 8.70 kg) following supplementation with a placebo (PL) or 50 mg FSK in a randomized, single-blinded, repeated measures, counter-balanced design. Resting muscle biopsies were collected from the vastus lateralis prior to (PRE), and 45 minutes after supplementation (POST), and was immediately frozen in liquid nitrogen. Frozen tissue samples were homogenized, centrifuged, and the resultant supernatant was collected for subsequent analysis. Skeletal muscle cAMP concentrations were measured via commercially available ELISA (Arbor Assays). Data were analyzed using a mixed methods repeated measures analysis of variance (treatment × time) with pairwise comparisons made using Fisher's LSD. Results are reported as mean ± SE. Significance was determined at alpha-level p ≤ 0.05. Results: There was no significant treatment × time interaction (p = 0.738). A significant main effect for time was observed, such that POST biopsies demonstrated significantly lower cAMP concentrations than PRE biopsies when data were collapsed across groups (3.80 ± 0.77 vs 1.44 ± 0.54 pM·ml−1; F(1,9) = 9.16, p = 0.014). Conclusions: The results of the present investigation suggest, at least acutely, 50 mg of FSK does not influence resting cAMP concentration in human skeletal muscle. Future research should investigate the potential synergistic influence of exercise and FSK on cellular signaling in muscle. Furthermore, it may be necessary to apply a period of FSK loading or increase supplement dosage. Practical Applications: Resistance exercise overtraining reduces β2-AR, and therefore may alter signal-transduction proteins related to adaptation in muscle. While preliminary, it does not appear FSK supplementation influences cAMP in intact resting human skeletal muscle. Coaches and strength and conditioning professionals should be aware acute supplementation does not alter muscle cAMP within 45 minutes. More research is warranted prior to consideration of FSK as an ergogenic aid. Acknowledgments: This study was supported by the NSCA GNC Nutritional Research Award.
Thursday, July 07, 2016, 9:15 AM–9:30 AM
The Effect of Short-Term High Intensity Training on Accident of Myocardial Ischemia in Rats
A. Li,1 C. Tsai,2 S. Fu,2 J. Zhang,3 C. Yu,2 and K. Tseng2
1Department of Exercise and Health Sciences, University of Taipei; 2Department of Exercise and Health Sciences, University of Taipei, Taiwan; and 3Department of Exercise and Health Science, University of Taipei, Taiwan
Due to modern lifestyle changing, cardiovascular diseases have become a major cause of death. Myocardial ischemia was the most cause of heart disease. Usually, myocardial infarction results from ischemia. Regular exercise could enhance physical activity and cardiopulmonary fitness, but not clear for myocardial infarction. Purpose: This study wanted to explore the effect of short-term high intensity training on ischemic accident of myocardium in rats. Methods: 15 Sprague-Dawley rats were divided into control (CON) group, ischemic precondition (IPC) group and high intensity exercise (EXC) group. EXC group received a-week adaptive swimming training when the rats were 3 week old, and high intensity swimming training for 3 hours per day when them were 4–7 week old. IPC group received couple cycles of coronary artery left anterior descending (LAD) occlusion for 10 minutes and reperfusion for 10 minutes before coronary artery occlusion (CAO). Each group underwent CAO that included LAD occlusion for 40 minutes and reperfusion for 180 minutes. In order to compare the difference of intervention, the heart was cut to stain and blood sample was collected after reperfusion. Results: Morphological staining found that infarct sizes was lower in EXC (14.7 ± 0.3%) and IPC's (17.6 ± 0.5%) than CON (26.2 ± 0.6%). CPK concentration in cardiac, kidney in EXC (0.80), IPC (0.92) were lower than CON (4.03) in blood exam. This result indicated there was lower cellular damage in EXC and IPC. Conclusions: The study showed that myocardium of ischemic damage could be decreased after high intensity exercise. It confirmed that exercise has preconditioning effect to prevent damage of myocardial infarction. It could change the intensity, duration or periodization of exercise prescription to investigate the amount of exercise intervention in future studies. Practical Applicationcs: The high intensity training could be applied to preventing myocardial ischemia. There are different effects with various training intensity. The short-term high intensity training is suggested to be the strategy for accident of myocardial ischemia.
Thursday, July 07, 2016, 9:30 AM–9:45 AM
A Comparison of Countermovement Jump Force-Time Curve Phase Characteristics Between Athletes Stratified by Maximal Isometric Strength
C. Sole,1 S. Mizuguchi,2 K. Sato,2 G. Moir,3 and M. Stone2
1The Citadel–The Military College of South Carolina; 2East Tennessee State University; and 3East Stroudsburg University
The countermovement vertical jump (CMJ) is commonly used to monitor an athlete's explosive strength. However, little agreement exists as to which CMJ variables are the most important when evaluating performance. One potential source of meaningful information is through an analysis of the characteristics (size and shape) of the individual phases of the CMJ force-time (F-t) curve. Purpose: To compare the phase characteristics of the CMJ F-t curve between athletes stratified by maximal isometric strength. Methods: Data from 144 NCAA Division I athletes (male, n = 72, age = 20.5 ± 1.5 years, body mass = 82.4 ± 11.4 kg, height = 182.4 ± 7.8 cm; female, n = 72, age = 20.1 ± 1.0 years, body mass = 67.8 ± 11.4 kg, height = 168.6 ± 7.0 cm) were included in this study. On the basis of allometrically scaled isometric mid-thigh pull peak force (IPFa), the top (HPGS), middle (MPGS), and lower (LPGS) 20 male and 20 female athletes from the sample were selected for analysis. Additionally, athletes were further stratified by jump height within each strength group to form jump performance sub-groups. Athlete's CMJ F-t curves were analyzed and the following characteristics were calculated for 6 common phases (unweighted, stretching, net impulse, acceleration-propulsion I, acceleration-propulsion II, and propulsion-deceleration): phase duration, magnitude, area (impulse), and shape. A series of 3-way mixed ANOVAs were used to examine the differences in F-t curve phase characteristics between strength groups and jump performance sub-groups in males and females. Results: A significant phase × strength effect was found for unweighted phase duration (p = 0.010) for males. Phase × jump sub-group effects were found for phase magnitude (p < 0.001) and impulse (p < 0.001) in males and phase magnitude (p = 0.008), impulse (p < 0.001), and shape factor (p = 0.042) for females. Male athletes with the greatest IPFa exhibited shorter unweighted phase durations (HPGS = 332 ± 36 milliseconds; MPGS = 372 ± 45 milliseconds; MPGS = 373 ± 61 milliseconds) while proficient jumpers exhibited greater phase magnitude and impulse throughout the phases of the CMJ F-t curve that constitute positive impulse. Additionally, more proficient jumpers were associated with a greater shape factor in the stretching (eccentric) phase of the CMJ F-t curve. Conclusions: The results of this study suggest stronger athletes exhibit shorter unweighted phase durations as compared to their less-strong counterparts. Additionally, the CMJ F-t curve phase characteristics common among proficient jumpers may exist irrespectively of maximal isometric strength. Practical Applications: Monitoring the duration of the unweighted phase may provide information regarding an athlete's strength level throughout a training process. Practitioners seeking to improve jump height should consider training methods focused on increasing both the magnitude and impulse of the F-t curve phases contained within positive impulse.
Thursday, July 07, 2016, 9:45 AM–10:00 AM
Twitch Potentiation of the First Dorsal Interosseous Muscle in Young and Old
University of Kansas
The first dorsal interosseous (FDI) muscle is used frequently for everyday activities regardless of age. Thus, it can provide insight on the effects of aging on muscular performance. Purpose: To determine the effects of aging on twitch potentiation in a small hand muscle (FDI) in younger (YG) and older (OG) individuals and to determine if muscle cross-sectional area (CSA) or echo intensity (EI) via ultrasonography can explain potential differences between the YG and OG. Methods: 16 healthy young (mean ± SD: age = 22 ± 2 years; mass = 77 ± 18 kg) and 11 healthy older (age = 62 ± 5 years; mass = 84 ± 14 kg) men and women participated in this study. Participants completed 3 maximal voluntary contractions (MVCs) of the FDI (abduction of the index finger) with the highest 0.25 seconds of force used to determine the target forces for the 10% and 50% MVCs. The submaximal contractions were held for 12 seconds at the targeted force. A resting twitch was evoked prior to and following the 10% and 50% MVCs. Pre-10 and -50% MVC peak twitch forces (highest 0.005 seconds) were averaged and absolute difference scores were calculated between these averaged twitch forces and the post-10% (ΔTF10) and post-50% (ΔTF50) MVC peak twitch forces. EI and CSA were measured from a cross-sectional ultrasound scan at 50% of the length of the FDI. Independent samples t-tests between groups were performed on peak MVC force, EI, CSA, and a 2-way mixed factorial ANOVA (group [YG vs. OG] × contraction intensity [10% vs. 50% MVC]) was used to examine possible differences in ΔTF10 and ΔTF50. Results: There were no significant differences between peak MVC force (p = 0.505) or CSA (p = 0.706), however, there was a significant difference (p = 0.043) for EI between groups (YG = 45.7 ± 7.95 AU; OG = 52.2 ± 7.34 AU). For the ΔTF, there was no significant 2-way interaction (p = 0.256) for group × contraction intensity. However, there were main effects for contraction intensity (p < 0.001) and group (p = 0.007). ΔTF was greater following the 50% MVC (ΔTF50 = 0.47 ± 0.25 N) than 10% MVC (ΔTF10 = −0.002 ± 0.17 N) and was greater for YG (0.31 ± 0.34 N) than OG (0.13 ± 0.27 N). Of note, ΔTF10 was slightly negative in the OG (−3.2 ± 11.7%), whereas, slightly positive for the YG (+3.6 ± 15.9%). In addition, ΔTF50 in the OG (28.4 ± 12.6%) was smaller in comparison to YG (57.4 ± 32.8%) (Figure 1). Conclusions: The OG had lower twitch potentiation than the YG, which may be the result of a greater amount of non-contractile tissues and muscle fiber atrophy within the CSA as evident with greater EI in the OG than the YG despite similar CSAs. Practical Applications: Healthy aging lead to a decrease in twitch potentiation in a muscle that is typically used in a similar manner to younger individuals. Age-related inactivity of a large limb muscle would likely further impair twitch potentiation and muscle performance. Furthermore, resistance training should be examined as a modality to minimize the influence of age-related declines in twitch potentiation.
Thursday, July 07, 2016, 10:00 AM–10:15 AM
A Noninvasive Test for Estimating Type I Myosin Heavy Chain of the Vastus Lateralis With Electromyographic Signal Decomposition and Mechanomyography
M. Trevino,1 J. Miller,1 A. Fry,1 P. Gallagher,1 J. Vardiman,2 and T. Herda1
1University of Kansas; and 2Kansas State University
Purpose: The purpose of this study was to determine if a combination of motor unit (MU) firing rate parameters and the mechanomyographic amplitude (MMGRMS)-force relationships could be used to estimate type I percent myosin heavy chain (%MHC) expression for the vastus lateralis (VL) during a 40% maximal voluntary contraction (MVC). Methods: Twelve individuals (age = 20.91 ± 2.30 years, weight = 70.76 ± 14.47 kg) volunteered for this investigation. Participants performed 3 isometric maximal voluntary contractions of the leg extensors on an isokinetic dynamometer followed by an isometric trapezoid muscle action at 40% MVC. Electromyographic (EMG) and MMG sensors were placed over the VL. EMG signals were decomposed (dEMG) to extract action potentials and firing events of single MUs. Only MUs decomposed with accuracies >90% were included for analysis. Recruitment (REC) and derecruitment (DEREC) thresholds, firing rates at REC (FR-REC) and derecruitment (FR-DEREC), and mean firing rates (MFR) at the target force level were calculated for each MU. Linear regressions were performed to determine the slopes and y-intercepts of the FR-REC and MFR vs. REC, and FR-DEREC vs. DEREC relationships. For the linearly increasing and decreasing muscle actions, linear regression models were fit to the log-transformed MMGRMS-force relationships and the slope (b term) was calculated. In addition, MMGRMS was averaged during a steady force epoch at the target force value. Subjects gave a muscle biopsy of the VL and type I MHC expression was determined by SDS-PAGE. Pearson's product moment correlation coefficients were used to determine the relationships among type I %MHC expression and each dEMG and MMG variable. Sequential multiple-regression procedures were used to determine if a predictive model for type I MHC expression of the VL could be developed with variables that were significantly correlated with type I MHC expression. Alpha was set at 0.05. Results: Multiple variables were correlated with type I MHC expression. The b terms for the linearly increasing segment had the highest correlation (R2 = 0.73) with type I MHC expression. The addition of the slopes for the FR-DEREC vs DEREC relationships to the regression model significantly accounted (p = 0.028) for a greater percentage of the variance (R2 = 0.849) than the b terms for the linearly increasing segment alone (Table 1). Conclusions: There were multiple relationships among type I MHC expression and the electrical (dEMG) and mechanical (MMG) behavior of the muscle. The b terms during the linearly increasing segment and the slopes for the FR-DEREC vs. DEREC relationships accounted for 85% of the variance for type I% MHC expression. Practical Applications: The combination of dEMG and MMG parameters recorded during a moderate intensity contraction may provide a noninvasive test for estimating and/or quantifying changes in type I %MHC expression of the VL due to exercise training interventions. Acknowledgments: This study was supported by the General Research Fund from The University of Kansas, Lawrence, KS.
Thursday, July 07, 2016, 10:15 AM–10:30 AM
Neuromuscular Responses During Fatiguing Intermittent Isometric Muscle Actions
C. Smith, T. Housh, E. Hill, K. Cochrane, N. Jenkins, A. Miramonti, R. Schmidt, and G. Johnson
University of Nebraska—Lincoln
Purpose: The purpose of the present study was to examine the time course of changes in neuromuscular responses during a fatiguing, intermittent isometric workbout. Methods: Eleven men (mean ± SD age 22 ± 3 years) performed 50, 6-s intermittent isometric muscle actions of the leg extensors each separated by 2-s of rest at 60% maximal voluntary isometric contraction (MVIC). Electromyographic (EMG) and mechanomyographic (MMG) amplitude (root mean square; RMS) and frequency (mean power frequency; MPF) were obtained from the vastus lateralis (VL) every 10% of the time to exhaustion and normalized as a % of the initial repetition (Figure 1). Polynomial regression analyses were used to determine the model of best fit for the normalized EMG RMS, EMG MPF, MMG RMS, and MMG MPF vs. repetition relationship and one-way repeated measures ANOVAs with post-hoc Student Newman-Keuls were used to identify when these neuromuscular parameters were different than the initial value. Results: Figure 1 shows the results of the polynomial regression analyses and one-way repeated measure ANOVAs for the EMG RMS, EMG MPF, MMG RMS, and MMG MPF vs. repetition relationships. Conclusions: The findings of the present study indicated 3 unique patterns of neuromuscular responses (repetitions 1–20, 20–40, and 40–50) during the fatiguing workbout. The increase in EMG RMS and MMG RMS, but no change in EMG MPF and MMG MPF during the first phase (repetitions 1–20) of the fatiguing workbout were not consistent with Muscle Wisdom motor unit activation theory, and were better explained by the Onion Skin Scheme. During the middle phase (repetitions 20–40) there were increases in EMG RMS and MMG RMS accompanied by decreases in EMG MPF and MMG MPF that could be explained by Muscle Wisdom or the Onion Skin Scheme. In addition, there were increases in MMG RMS, decreases in MMG MPF, and a plateau in EMG RMS during the final phase (Repetitions 40–50) that may also be explained by either Muscle Wisdom or the Onion Skin Scheme. The current study suggested that both Muscle Wisdom and the Onion Skin Scheme can explain the maintenance of torque production during different phases of a fatiguing workbout. Thus, the evaluation of the time course of neuromuscular changes during a fatiguing workbout better describes the process of fatigue compared to the more commonly used pretest vs. posttest measurements. Practical Applications: These findings have application to fields including strength training, supplementation, and clinical practices. Identification of the time course of changes in neuromuscular responses can be used to quantify and interpret training-induced adaptations that affect the process of fatigue. Furthermore, the current study begins the process of developing training programs that utilize the time course of changes in neuromuscular responses and motor unit activation strategies to affect the sport-specific processes of fatigue and performance.
Thursday Abstract Poster Presentations—Session A
July 07, 2016—11:30 AM–1:00 PM—Celestin ABC
Thursday, July 07, 2016, 11:30 AM–1:00 PM
Knee Extension Strength and Muscle Fiber Type Composition in Resistance-Trained Men
J. Arevalo,1 R. McManus,2 J. Rosengarten,1 S. Lynn,1 J. Spencer,1 L. Brown,1 J. Bagley,3 P. Costa,1 and A. Galpin1
1Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California; 2Biochemistry and Molecular Exercise Physiology Laboratory, Department of Kinesiology, California State University, Fullerton, California; and 3Muscle Physiology Laboratory, Department of Kinesiology, San Francisco State University
Chronic resistance training increases the prevalence of myosin heavy chain (MHC) IIa (fast-twitch) fibers. Consequently, resistance-trained individuals have lower proportions of MHC I (slow-twitch), I/IIa (hybrid), IIa/IIx (hybrid), and IIx (fast-twitch) fibers. Most research on muscle fiber type composition and knee extensor strength has studied untrained or recreationally trained participants. While a few studies have examined fiber type in resistance-trained participants, surprisingly little is known about the direct relationship between muscle strength, leg dominance, and fiber type in resistance-trained men. Purpose: To compare strength, leg dominance, and fiber type in the quadriceps of resistance-trained men. Methods: Six resistance-trained men (age = 23.3 ± 3.3 years; height = 179.3 ± 8.5 cm; mass = 86.0 ± 13.7 kg, mean ± SD) were asked to perform a one-repetition maximum (1RM) knee extension per leg on a plate-loaded knee extension machine. Leg dominance was categorized as “the preferred kicking leg.” Participants also underwent muscle biopsies of their left and right vastus lateralis. MHC isoform composition was determined via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) in 134.6 ± 34.4 muscle fibers, per leg. Results: No significant differences were found in fiber type or knee extension 1RM between dominant and non-dominant legs (p > 0.05). Thus, these data were collapsed across legs. A significant positive correlation was shown between strength (64.5 ± 9.9 kg) and MHC IIa/IIx composition (3.52 ± 3.95%, p = 0.017, r = 0.616). No significant correlations existed between strength and MHCI (29.4 ± 11.9%, p = 0.017, r = −0.326), MHC IIa (65.5 ± 10.8%, p = 0.267, r = 0.200), or MHCIIx (0.1 ± 0.3%, p = 0.464, r = −0.030) composition. However, a trend toward a negative correlation was seen between strength and MHC I/IIa (1.5 ± 1.6%, p = 0.075, r = −0.442) composition. In addition, after combining MHCI and MHC I/IIa fibers, no significant correlation was identified between strength and fiber type (p = 0.19, r = −0.442). After combining MHC IIa and MHC IIa/IIx fibers, no significant correlation was identified between strength and fiber type (p = 0.24, r = −0.362). Conclusions: Previous studies show significant relationships between muscle fiber type and whole muscle performance. Specifically, we anticipated identifying a correlation between strength and MHC IIa abundance. However, our data suggest a limited ability of fiber type composition to predict leg extension strength in trained men. Our other findings, that resistance-trained men possess large amounts of MHC IIa fibers, minimal hybrid fibers (MHC I/IIa and IIa/IIx), and virtually no pure MHC IIx fibers, are in accordance with previous literature. Practical Applications: The relationship between MHC IIa/IIx composition and strength, while statistically significant, likely plays only a marginal role in whole muscle performance as the absolute number of fibers (∼3.5%) is low. However, the positive correlation with fast-twitch hybrids, combined with the negative correlation with slow-twitch hybrids, supports the traditionally described relationship between fiber type and performance. These unique findings support the need for further study of single muscle fiber characteristics of the strength-trained.
Cluster and Traditional Set Configurations Elicit Similar Myokine Responses
J. Mata,1 A. Kreutzer,1 S. Jenke,1 J. Stone,1 A. Jagim,2 M. Jones,3 and J. Oliver1
1Texas Christian University; 2University of Wisconsin—La Crosse; and 3George Mason University
Myokines, expressed and released by muscle fibers, play an important role in the metabolic and immunological response to resistance exercise. Traditionally, IL-6 has been regarded as a pro-inflammatory marker. However, more recently it has been purported that IL-6 released from the contracting muscle has anti-inflammatory effects, inhibiting increased levels of TNF-α and stimulating the production of anti-inflammatory cytokines. Further, it has been proposed that IL-15 released by the contracting muscle may lead to increased lean body mass, reduced trunk fat mass, and increased bone mineral content. Both myokines have been shown to be upregulated following a variety of resistance exercise protocols. However, no investigations into the effects of cluster set (CS) configurations (i.e., the inclusion of brief [15–30 seconds] intraset rest) on IL-6 and IL-15 have been reported. Purpose: Therefore, this study examined the effects of CS and traditional sets (TS) on IL-6 and IL-15 during the parallel back squat exercise (BS) in resistance-trained men. Methods: Ten highly resistance-trained men (mean ± SD; 26.6 ± 4.2 years; 179.2 ± 6.5 cm; 82.6 ± 6.7 kg; 16.3 ± 6.7% body fat; 2.0 ± 0.03 BS: body mass ratio) participated in this repeated measures crossover study. Subjects performed TS (4 sets × 10 REPs at 70% 1RM with 120 seconds interset rest) and CS (4 × (2 × 5) at 70% 1RM with 30 seconds intraset rest and 90 seconds interset rest). Blood samples were obtained prior to (PRE) and immediately following (IPE) each exercise bout, as well as 30 minutes (30 P), 60 minutes (60 P), 24 hours (24 P), and 48 hours (48 P) after cessation of exercise. A 2 factor (PROTOCOL, TIME) repeated measures ANOVA was used to determine differences in myokine response. Bonferroni post hoc analysis was performed when a significant finding (p ≤ 0.05) was identified. Results: No significant PROTOCOL (IL-6: p = 0.996; IL-15: p = 0.468) or PROTOCOL by TIME interaction (IL-6 p = 0.103; IL-15: p = 0.204) was observed for either myokine. However, a main effect for TIME was observed for both IL-6 (p < 0.001) and IL-15 (p = 0.046). When compared to PRE (0.454 ± 0.123 pg·mL−1), IL-6 increased in all subjects IPE (0.454 ± 0.123 pg·mL−1; p = 0.024), peaking at 30 P (0.712 ± 0.248 pg·mL−1; p = 0.043), and remaining elevated at 60 P (0.685 ± 0.218 pg·mL−1; p = 0.033) before returning to baseline levels 24 P (0.528 ± 0.279 pg·mL−1; p = 1.0). IL-15 increased in all subjects from PRE (1.198 ± 0.424 pg·mL−1) to POST (1.410 ± 0.441 pg·mL−1; p = 0.011) before returning to baseline levels at 30 P (1.235 ± 0.454 pg·mL−1; p = 1.0). Conclusions: Similar responses in IL-6 and IL-15 following CS and TS suggest that both protocols elicit comparable myokine-triggered anti-inflammatory effects. The modest increases in both myokines when compared to prior studies might be due to the relatively small total volume load in the current protocol. Practical Applications: We have previously reported that a 12-week periodized hypertrophic CS protocol allows for greater adaptations in power output and similar gains in lean mass compared to a TS protocol of equal volume. The similar myokine response observed in the current study may, in part, explain the similar gains in lean mass previously reported. Thus, CS offer the strength and conditioning practitioner a valuable training tool to promote greater power adaptations, while eliciting similar metabolic and immunological responses, which may explain the comparable lean mass gains.
Physical Characteristics Predictive of Changes in Biomarkers Related to Stress and Recovery During Preseason in Women's Division I Field Hockey Players
A. Walker, S. Conway, M. Rabideau, B. McFadden, M. Hofacker, C. Ordway, D. Sanders, and S. Arent
Rutgers Center for Health and Human Performance
Blood-based biomarkers provide unique insight into the physiological changes athletes experience during training and competition. Along with physical assessments, these markers may be useful for maximizing outcomes and minimizing non-functional overreaching. Purpose: To identify physical and performance characteristics of female field hockey players that best predict changes in hormonal and biochemical markers related to stress and recovery during a 4-week preseason period. Methods: Women's Division I field hockey players (N = 22; Mage = 19.7 ± 1.1 years; Mweight = 64.3 ± 7.4 kg; Mheight = 166.3 ± 3.4 cm; M%BF = 26.1 ± 6.7%) where monitored from the start of preseason (T1) through the first 2 weeks of the competitive season (T2). At T1, all athletes reported for performance testing which included body composition (%BF), vertical jump (VJ), and a maximal graded exercise test to assess V[Combining Dot Above]O2max via direct gas exchange. On a separate day, athletes arrived fasted and euhydrated the morning before preseason practices started for blood-draws. Creatine kinase (CK), iron (Fe), total cortisol (TCORT), free cortisol (FCORT), sex-hormone binding globulin (SHBG), and T3 were assessed. Blood draws were repeated 4 weeks later (T2). Caloric expenditure (standardized for bodyweight) was monitored throughout training and games using the Polar Team2 System. Results: There were significant changes in CK (ΔCK = 54.13 + 9.1 U·L−1, p ≤ 0.05), Fe (ΔFe = −52.05 + 8.1 mcg·dl−1, p ≤ 0.05), and SHBG (ΔSHBG = 7.36 + 3.1 nmol·L−1, p ≤ 0.05) from T1 to T2. V[Combining Dot Above]O2 accounted for 16.3% of the variance in SHBG, which approached significance (β = −0.40, p = 0.063). TCORT significantly increased from T1 to T2 (ΔTCORT = 2.9 + 1.2 mcg·dl−1, p ≤ 0.05) with V[Combining Dot Above]O2 accounting for 31% (β = 0.56, p ≤ 0.05) of the variance and %BF accounting for an additional 20.1% (β = −0.71, p ≤ 0.05). FCORT significantly increased from T1 to T2 (ΔFCORT = 0.17 + 0.061 mcg·dl−1, p ≤ 0.05) with V[Combining Dot Above]O2 accounting for 32.7% (β = 0.57, p ≤ 0.05) of the variance. T3 significantly increased from T1 to T2 (Δ T3 = 18.9 + 5.9 mg·dl−1, p ≤ 0.05) with %BF accounting for 48.9% (β = −1.11, p ≤ 0.05) of the variance. Kcals expended in preseason were positively correlated with V[Combining Dot Above]O2 (r = 0.76, p ≤ 0.05) and negatively correlated with %BF (r = −0.48, p ≤ 0.05). Conclusions: V[Combining Dot Above]O2 and %BF were predictive of changes in SHBG, TCORT, FCORT, and T3, biomarkers which have been associated with overreaching. These finding show that players with a higher V[Combining Dot Above]O2 and lower %BF are more likely to experience elevated physical stress during periods of intense training. While this is contrary to most coaches' concerns regarding low-fit players reporting for camp, it appears that the more physically fit individuals perform at a higher work output which may produce even greater physiological disruption. The changes seen for all of the biomarkers measured illustrate the overall physical strain that is put on all players throughout preseason training. The capacity of these higher level athletes to perform at an increased level coupled with less rest during preseason increases the potential for breakdown. Practical Applications: The use of blood biomarkers as well as performance and body composition measurements can be tools for proper player management during the preseason period for female athletes. Though it may seem counter-intuitive, players with a greater fitness should be monitored during strenuous preseason training due to their propensity to overwork in preparation for the competitive season. Acknowledgments: Supported by Quest Diagnostics and a special thanks to the Rutgers Field Hockey Team.
Effects of 10-Week Taekwondo Training on Metabolic Profiles and Aerobic Capacity
C. Chen,1 Y. Sung,2 C. Chou,3 and Y. Liao4
1Department of Exercise and Health Science, University of Taipei; 2Department of Chinese Martial Arts, Chinese Culture University; 3Physical Education Office, National Taipei University of Technology; and 4Department of Exercise and Health Science, National Taipei University of Nursing and Health Sciences
Taekwondo is a popular combat sport and has been introduced into Olympic game. However, the responses of metabolic profiles and aerobic capacity to intensive Taekwondo training have not been fully investigated. Purpose: The main purpose of this study was to examine the effects of 10-week intensified Taekwondo training on metabolic profiles and aerobic capacity. Methods: Seventeen male elite Taekwondo athletes (age: 19.8 ± 0.3 years, height: 175.4 ± 1.5 cm, weight: 69.7 ± 2.2 kg) who compete at the national or international level were participated in this investigation. Blood samples were collected to determine the level of fasting blood glucose, insulin, HOMA-IR, lipid profiles (CHOL, TG, HDL-C, and LDL-C), cortisol, and DHEAS, as well as muscle mass, body fat percentage, V[Combining Dot Above]O2 max, before and following the 10-week intervention. The Taekwondo training program (10 h·wk−1) included warm up, Taekwondo skill training, weight training, flexibility training, aerobic training, and cool down. Results: Ten-week Taekwondo training significantly reduced the levels of fasting blood glucose, insulin, CHOL, LDL-C, DHEA-S, and HOMA-IR value. Moreover, training induced significant increases in body weight, muscle mass and decreases in body fat percentage. Level of blood cortisol was significant increased after 10-week exercise training and represented the lower D/C (DHEA-S/cortisol) ratio as well. The V[Combining Dot Above]O2 max value showed significantly enhanced after Taekwondo training. Conclusions: Ten weeks Taekwondo training improved the insulin sensitivity, lipid profiles and aerobic capacity, despite intensified training resulted in greater physiological stress reflected by low D/C ratio. These benefits seem to be associated with increased muscle mass and reduced body fat percentage after training. Practical Applications: To monitor the changes of health status and speed up the recovery in athletes during the training season is quiet important works for couch and training team. The current study provides the fundamental information to strength and conditioning professionals, sports nutritionists, and sports scientists to design strength and conditioning program to improve the exercise performance in Taekwondo athletes. Acknowledgments: This study was partly supported by MOST 104-2410-H-845-006-MY2.
Acute Hormone Response to Slow Velocity and Traditional Velocity Resistance Exercise
P. Dietz,1 A. Fry,2 J. Nicoll,2 A. Sterczala,2 A. Bryce,2 A. Carbuhn,2 and T. Herda2
1Upper Iowa University; and 2University of Kansas
Resistance exercise elicits acute physiological responses essential for increasing strength, power, and hypertrophy. Testosterone, cortisol and growth hormone concentrations have been shown to increase acutely after resistance exercise. The magnitude of increase for these hormones depends on numerous factors, including muscle mass involvement, total work performed, rest intervals, and rate of work performed to mention a few. Various methods of resistance training have gained in popularity such as super-slow resistance exercise (i.e., 10 seconds concentric and eccentric phases) where movement velocity is purposely slow. Because of the slow movement, there are limitations to the loads that can be lifted (e.g., <50% 1 RM). Although advocates of slow velocity resistance exercise suggest its superiority for hypertrophy and strength development, research conducted on acute endocrine responses to one variation of slow velocity resistance exercise (Goto et al. 2008) suggests it produces acute hormonal concentrations comparable to traditional resistance exercise. Purpose: The purpose of this study was to measure the acute hormonal & lactate responses to traditional (TRAD) vs. super-slow velocity (SLOW) resistance exercise in healthy resistance trained men. Methods: Healthy resistance-trained men (n = 10; X ± SD; age = 24.7 ± 4.4 years) performed 2 testing sessions in random-order; a SLOW session (1 set × 10 repetitions at 28% 1RM; 10 seconds eccentric and 10 seconds concentric), and a TRAD session (3 × 10 at 70% 1RM; maximal velocity). Both sessions included the barbell parallel back squat and bench press exercises. A position transducer was used to verify barbell velocities for every repetition of both protocols. Blood was sampled via venipuncture pre and post exercise and analyzed via ELISA. Results: The table below lists the changes for several hormone variables from pre and post values (X ± SD) for both protocols (TRAD and SLOW) squat and bench press exercises (*diff. from pre; †diff. from SLOW; p ≤ 0.05). Conclusions: Slow velocity resistance exercise did not exhibit a greater acute increase for each of the hormones and metabolites measured when compared to TRAD. Both TRAD and SLOW protocols produced similar changes in circulating concentrations of cortisol and growth hormone, however, only the TRAD induced a significant increase in testosterone and a greater lactate response post resistance exercise. Practical Applications: Super-slow velocity resistance exercise did not produce an enhanced hormonal environment for hypertrophy and strength/power adaptations to resistance exercise when compared to TRAD resistance exercise.
The Effect of Ibuprofen on Pro-Inflammatory Cytokines in Response to Ultra-Endurance Cycling in the Heat
M. South,1 H. Luk,2 D. Levitt,2 B. Kupchak,3 M. Ganio,4 B. McDermott,4 L. Kunces,5 C. Munoz,6 E. Lee,6 L. Armstrong,6 B. McFarlin,2 D. Hill,1 and J. Vingren2
1University of North Texas; 2Applied Physiology Laboratory, University of North Texas; 3Uniformed Services University; 4University of Arkansas; 5EXOS; and 6University of Connecticut
Purpose: The purpose of this study was to examine the effect of ibuprofen ingestion prior to a 164-km cycling event in the heat on circulating pro-inflammatory cytokines. Methods: Thirty-one recreational cyclists (age = 51 ± 9 years, height = 171 ± 20 cm, body mass = 81.2 ± 15 kg, body fat = 22 ± 6%) were recruited and were randomly assigned to ingest either ibuprofen (600 mg; n = 17) or placebo capsules (rice flour; n = 14) in the 2015 Hotter'N Hell Hundred ride in Wichita Falls, TX. Wet bulb globe temperature during the ride ranged from 23.7 to 32.8° C. Blood samples were collected within 2 hours prior to the ride (PRE, 0500–0700 hours) and immediately after the ride (POST). Serum was analyzed for pro-inflammatory cytokines: interleukin (IL)-2, IL-6, IL-8, and IL-12, granulocyte macrophage colony-stimulating factor (GM-CSF), interferon gamma (IFN-γ), and tumor necrosis factor-alpha (TNF-α). Results: No significant time × condition interaction effect was found, although there was a trend (p = 0.052) for a greater increase in IL-6 concentration from PRE to POST in the placebo condition compared to the ibuprofen condition. Pro-inflammatory cytokines IL-6, IL-8, and TNF-α were significantly (p ≤ 0.05) increased from PRE to POST. No change was observed for IL-2, IL-12, IFN-γ, and GM-CSF from PRE to POST. Conclusions: A dose of ibuprofen prior to the 164-km cycling event in the heat did not affect the concentration of circulating pro-inflammatory cytokines. However, ride completion induced a substantial increase in the circulating IL-6, IL-8, and TNF-α concentrations. Practical Applications: In recreational cyclists, acute ingestion of 600 mg ibuprofen before the event does not alter the circulating pro-inflammatory cytokines in response to 164-km cycling event in the heat. It is possible that higher or repeated doses of ibuprofen would result in suppression of pro-inflammatory cytokines.
Effect of Ethanol Ingestion on the Androgen Receptor Response to Heavy Resistance Exercise
J. Vingren,1 A. Duplanty,2 R. Budnar,1 D. Levitt,1 H. Luk,1 A. Fernandez,1 B. McFarlin,1 and D. Hill3
1Applied Physiology Laboratory, University of North Texas; 2Louisiana State University Health Science Center; and 3University of North Texas
Purpose: Athletes and others who engage in regular exercise drink more ethanol (alcohol) and report a greater number of binge drinking episodes than their non-athlete peers. Ethanol consumption might interfere with resistance training adaptations (and subsequently athletic performance). It has been found that acute ethanol ingestion alters the acute testosterone response to heavy resistance exercise, a response that is most pronounced in men. The underlying mechanism for this altered testosterone response mechanism remains unknown. Independently, resistance exercise and ethanol can alter muscle protein expression of the androgen receptor (AR), the receptor through which testosterone induces its physiological effects, during recovery; however, the combined effect of ethanol ingestion and resistance exercise on AR content has not been investigated. Therefore, the purpose of this study was to examine the effect of ethanol ingestion on the acute AR response to a bout of heavy resistance exercise. Methods: Eighteen resistance trained men (n = 10) and women (n = 8) (24 ± 3 years; 170 ± 5 cm; 73.0 ± 10.9 kg) completed 2 identical acute heavy resistance exercise tests (AHRET: 6 sets of 10 repetitions of Smith machine squats) in the mid-morning (∼10:00–11:00) separated by approximately 28 days (to allow for standardization of menstrual phase for the women). From 10 to 20 minutes post-AHRET, participants consumed either grain ethanol (EtOH condition, 1.09 g·kg−1 lean mass) or no ethanol (placebo condition) diluted in an artificially sweetened and calorie free beverage. Muscle samples were obtained by biopsy before (PRE) and 3 (+3 h) and 5 (+5 hour) hours after the AHRET and analyzed for AR content using Western blot analysis. Results: In men, ethanol ingestion significantly (p ≤ 0.05) reduced AR content during recovery from exercise and prevented a transient resistance exercise-induced increase in AR at +3 hour. In women, there was a trend (p = 0.062) towards a resistance exercise-induced increase in AR content during recovery but there was no apparent effect of ethanol ingestion on AR content. Conclusions: Consuming a moderate-high dose of ethanol after exercise reduced AR content in men but not in women. A gender difference has previously been found for the testosterone response to ethanol ingestion after resistance exercise; ethanol was found to augment the testosterone response during recovery in men but not in women. Thus, the present findings of a reduction in AR content, and thus fewer receptors for testosterone to bind, might, at least in part, explain the previously observed augmented testosterone response. Practical Applications: In resistance trained men, ethanol ingestion appears to interfere with the acute testosterone signaling response to resistance exercise. Thus, male athletes and clients should not ingest alcohol after resistance exercise. Although no effect was found for ethanol ingestion on AR in women, practitioners should emphasize caution to their female clients and athletes that choose to consume alcohol following resistance exercise sessions as other physiological aspects might be affected. Acknowledgments: This project was funded in part by a grant from the National Strength and Conditioning Association.
Kinetic and Lower Extremity Kinematic Differences Between American and Russian-Style Kettlebell Swings
W. Barker, P. Fullmer, K. Hall, A. Steakley, and W. Amonette
University of Houston—Clear Lake
Purpose: The purpose of this study was to determine lower extremity kinematic differences and quantify ground reaction forces (GRF) in 2-handed kettlebell (KB) swings utilizing American and Russian styles. Methods: Twenty subjects (25.1 ± 3.2 years; 165.0 ± 8.2 cm; 72.5 ± 9.7 kg) with >6 months of KB training volunteered. Subjects participated in one testing session after providing informed consent. Anthropometric measurements were completed prior to a 5-minute bike warmup. After executing practice repetitions, subjects performed 1 set of 5 swings with 16 and 24 kg loads utilizing the American and Russian styles. Initial swing style was presented in a randomized and balanced order; all repetitions with each load were completed with one style before changing styles. Synchronous data were collected with a 3D motion capture system and a force plate at 200 Hz. The third repetition of each set was used to compute the following peak values: body and KB weight adjusted GRF (GRF-adj), hip extension, flexion, and range of motion (ROM), knee extension, flexion, and ROM, ankle plantar and dorsiflexion, and hip angular velocity. Kinetic and kinematic data were compared using 2-way ANOVAs (style × load) with Tukey's HSD; alpha was set at p ≤ 0.05. Results: GRF-adj differed by style (p < 0.01) and load (p < 0.01). Peak GRF-adj in the American-style swing for 16 and 24 kg loads was 677.2 ± 67.4 N and 767.9 ± 65.8 N, respectively. For the Russian-style swing, peak GRF-adj using 16 and 24 kg loads was 588.6 ± 56.5 N and 697.2 ± 55.3 N, respectively. Total hip ROM did not differ by style (p = 0.67) or load (p = 0.79). There were no style (p = 0.20) or load (p = 0.33) differences in peak hip flexion. However, there was a difference in both style (p < 0.01) and load (p = 0.04) for hip extension. American-style swings (7.1 ± 2.2°) resulted in greater peak hip extension compared to Russian (10.3 ± 2.5°). The 24 kg load (7.9 ± 2.3°) resulted in greater peak hip extension compared to the 16 kg load (9.5 ± 2.4°). Angular velocity of the hip differed by style (p = 0.04), but not load (p = 0.13). Peak angular velocity of the hip was greater in American (197.0 ± 11.1°·s−1) compared to Russian-style swings (185.0 ± 10.9·s−1). Total knee ROM differed by style (p ≤ 0.05), but not load (p = 0.12). Total knee ROM was greater in American (64.3 ± 3.4°) compared to Russian-style swings (61.2 ± 4.0°). There were no style (p = 0.87) or load (p = 0.76) differences for knee flexion, but both style (p < 0.01) and load (p < 0.01) differed significantly for knee extension. Peak knee extension was greater in American (7.6 ± 2.0°) compared to Russian-style swings (10.5 ± 2.3°). The 24 kg load (9.7 ± 2.2°) resulted in greater knee extension than the 16 kg (8.4 ± 2.1°). There were no differences in peak dorsiflexion by style (p = 0.77) or load (p = 0.39); plantar flexion did not differ by style (p = 0.88) but there was a difference in load (p < 0.01). Greater plantar flexion was achieved with the 24 kg (−4.3 ± 1.7°) compared to the 16 kg load (−2.2 ± 1.5°). Conclusions: We conclude that American-style swings create larger GRF, more complete hip and knee extension, and faster hip velocities compared to Russian-style swings. Regardless of style, 24 kg swings resulted in more hip and knee extension and greater elevation of the heel compared to a 16 kg load. Practical Applications: Strength and conditioning professionals desiring to achieve greater GRF and more complete extension using KB training should prescribe American-style swings, and to the extent it is safely possible, use heavier loads.
Gender Comparison of American and Russian Style Kettlebell Swings
P. Fullmer, W. Barker, D. Bauer, J. Grant, M. Watts, and W. Amonette
University of Houston—Clear Lake
Kettlebells (KB) are popular resistance training tools utilized to improve neuromuscular performance and to stimulate metabolic responses. One of the simplest and most popular KB exercises is the 2-handed swing which is commonly completed utilizing 2 styles: American or Russian. In the American style, the KB is swung such that the KB finishes over the head; in the Russian style, the KB is swung to chest level. Purpose: To compare and evaluate the ground reaction forces (GRF) and hip kinematics of American and Russian style swings and to quantify any potential gender differences. Methods: Ten men (25.2 ± 2.5 years; 176.7 ± 7.3 cm; 87.3 ± 10.8 kg) and 10 women (24.9 ± 3.8 years; 165.0 ± 8.2 cm; 72.5 ± 9.7 kg) with >6 months experience with KB training volunteered. Height was measured with a stadiometer, body weight (BW) with a digital scale, and lean body mass (LBM) using air displacement plethysmography. During a single session, they completed 1 set of 5 repetitions with both swing styles at 3 loads: men (16, 24, and 32 kg) and women (12, 16, and 24 kg). All American or Russian style swings were completed before changing styles. The initial starting style was randomized within subjects. Motion capture data were collected at 200 Hz using a 16 marker lower body model. GRF data were collected simultaneously with a force plate at 1,000 Hz. The peak resultant force; peak adjusted vertical GRF (FZ—body and KB weight); peak adjusted vertical GRF normalized to BW and LBM; and hip and knee angular velocities were compared on the third repetition of the 16 kg KB swing. A 2-way ANOVA with repeated measures was used to determine main effect differences and interactions in gender and swing style with an alpha of p ≤ 0.05. Results: There was a significant effect for both gender (p < 0.001) and swing style (p < 0.001) in the peak resultant force. Men (1,850.4 ± 89.7 N) generated more force than women (1,396.1 ± 45.5 N); and more force was generated with the American (1,674.1 ± 95.3 N) swing style compared to the Russian (1,572.4 ± 79.3 N). There was a significant main effect for gender (p = 0.02) and swing style (p = 0.01) for the adjusted vertical GRF. Men (766.5 ± 74.5 N) generated more force than women (499.3 ± 22.0 N) and a greater vertical GRF was generated in the American (677.2 ± 67.4 N) style compared to the Russian (588.6 ± 56.5 N). There was a significant main effect for swing style for both vertical GRF normalized to BW (p = 0.02) and LBM (p = 0.01), but no main effect was evident for gender (p > 0.05). Vertical GRF normalized to BW was greater with the American (0.85 ± 0.06 N/N) compared to Russian (0.74 ± 0.06 N/N) swing style. Likewise, vertical GRF normalized to LBM was greater with the American (1.09 ± 0.07 N/N) compared to Russian (0.95 ± 0.06 N/N) swing style. Peak hip and knee angular velocities were similar between genders (p > 0.05) and there were no differences between swing styles (p > 0.05). Peak hip angular velocities were similar in American (200.1 ± 11.2°·s−1) and Russian (188.2 ± 10.9°·s−1) swing styles. Likewise, knee angular velocities were similar in American (162.1 ± 11.1°·s−1) compared to Russian (158.3 ± 11.9°·s−1) swing styles. Conclusions: There appears to be no significant difference between men and women within either swing style, but greater GRFs are generated in the American compared to Russian style swings. Practical Applications: If strength and conditioning coaches desire to maximize GRF during KB swings, the American style may be more advantageous for a given mass regardless of gender.
Asymmetries in Knee Extension Strength Do Not Correlate With Sagittal Plane Knee Landing Mechanics in Resistance Trained Men
J. Rosengarten, J. Arevalo, S. Lynn, J. Spencer, L. Brown, P. Costa, and A. Galpin
Center for Sport Performance, Department of Kinesiology, California State University, Fullerton, California
Poor landing mechanics are often a result of weak lower body musculature. Yet, no study has compared knee-landing mechanics from a drop vertical jump to knee extension strength. In addition, no study has examined these variables in relation to leg dominance. Purpose: To examine the relationship between landing mechanics, knee extension strength, and leg dominance in resistance-trained men. Methods: Sixteen resistance-trained men (age = 23.94 ± 2.9 years; height = 180.19 ± 6.4 cm; mass = 85.23 ± 10.7 kg; mean ± SD) volunteered. The men were asked to perform 6 drop vertical jumps (i.e., step off of a 31 cm box, land, and perform a vertical jump as quickly as possible) onto 2 side-by-side force plates embedded into the ground. In random order, participants were instructed to step-off the box with either the right foot first (3 trials) or the left foot first (3 trials), land, and jump using both feet. The dominant leg was categorized as the preferred “kicking leg.” Peak sagittal knee moment and peak vertical ground reaction force (VGRF) was measured for each leg. Maximal jump height was measured bilaterally using Visual 3D biomechanical program (C-Motion). Following the jumps, participants were asked to perform a one-repetition maximum (1RM) knee extension for each leg. Results: Paired Samples T-Tests showed a significant difference in knee extension strength between the dominant (64.2 ± 11.0 kg) and non-dominant (61.1 ± 9.1 kg) legs (p = 0.036). However, asymmetries did not exist between legs sagittal knee moment (p > 0.05) or VGRF (p > 0.05). Moreover, no significant correlations were found between bilateral vertical jump height (49.6 ± 9.9 cm), knee extension strength (for dominant r = −0.013 or non-dominant r = −0.067), sagittal knee moment (for dominant r = 0.301 or non-dominant r = 0.211), and VGRF (for dominant r = 0.067 or non-dominant r = −0.064). Thus, we combined values for the left and right leg for VGRF and sagittal knee moment. No correlation was observed between jump height and combined VGRF (1.91 ± 0.4 × BW, r = −0.005), and combined sagittal knee moment (2.22 ± 0.4 N·m−1·kg−1; r = 0.265). Furthermore, no correlation was observed between bilateral sum strength (left + right leg 1RM) (125.3 ± 21.3 kg), jump height (r = −0.039), VGRF (r = 0.286), and sagittal knee moment (r = −0.019). Conclusions: Asymmetries in strength between limbs is not uncommon, particularly in untrained populations. Surprisingly, we report differences in maximal strength between limbs in previously leg strength trained men. The “preferred kicking leg” functioned as an appropriate question for the establishment of leg dominance (strength) among this cohort. We hypothesized these functional differences among limbs would yield asymmetries in drop jump performance. However, our data indicate strength differences cannot predict landing mechanics or leg dominance among strength-trained men. The differences in muscle action between the 1RM test (single-joint, concentric only) and the drop jump (multi-joint, eccentric followed by concentric) may explain our findings. Future investigations should examine more similar strength tests such as a 1RM squat. Practical Applications: Significant differences in single joint strength may not necessarily predict movement mechanics during complex, multi-joint activities in trained men. Injury screening tests and tools should understand this limitation when implementing. The use of such a test to predict asymmetries in jump performance (and therefore, predict the likelihood of future injury) is questionable in this group of participants.
Investigation of the Corollary Discharge Mechanism Using Electromyographic Signals From the First Dorsal Interosseous Muscle During Pinching Exercises
N. Wages,1 T. Beck,1 X. Ye,1 J. Carr,2 and H. Tharp2
1The University of Oklahoma; and 2University of Oklahoma
Perception is the conscious recognition of internal/external sensory stimuli and is not only dependent upon the evaluation of sensory stimuli, but also on the interpretation of those same stimuli. This means that our sensory system not only responds to stimuli from the internal/external environment, but also to cues generated by our own mental states during the process of receiving sensory input. Purpose: The purpose of the present investigation was to investigate, using surface electromyography (sEMG), whether the corollary discharge mechanism is dependent primarily on visual stimuli, auditory stimuli or tactile stimuli. Methods: Ten healthy, college-aged men (mean ± SD age = 26.5 ± 3.5 years; height = 178 ± 3.5 cm; weight = 88 ± 10.8 kg; BMI = 27.7 ± 2.7 kg·m−2; FDI skinfold thickness = 3 ± 0.7 mm) were measured (using EMG amplitude) during one bout of pinching exercises. After 2 familiarization visits, subjects were asked to come into the lab for their first exercise visit to perform a maximum voluntary contraction (MVC) for the first dorsal interosseous (FDI) muscle. Following this MVC, the subjects were asked to pinch (using only thumb and index finger) a predetermined randomized dumbbell weight sequence (between 1 and 5 lbs) using a predetermined randomized sensory stimuli sequence (visual, auditory, or tactile) and in a randomized hand order (dominant or non-dominant). Results: The results indicated (from 1 lb to 5 lb dumbbells) that there was a significant decrease in sEMG amplitude of 6.7, 10.9, 10.2, 12.4, and 12.4 μV, from the visual cue to the auditory cue; a significant increase of 0.97, 1.4, 1.7, 1.5, and 1.8 μV, from the visual cue to the tactile cue; and a significant increase of 7.8, 12.3, 11.9, 13.9, and 14.3 μV, from the auditory cue to the tactile cue, respectively. Conclusions: The sEMG amplitude responses from the FDI muscles appeared to support the role of corollary discharge as being primary dependent on auditory cues, followed by visual cues, and finally tactile cues (when performing the appropriate force output for pinching a particular weight). Furthermore, when compared to the dominant FDI muscle, the non-dominant FDI muscle appeared to have significantly lower fine-tuned motor control strategies (during all pinching measurements, as well as across all sensory stimuli). Practical Applications: Since many activities of daily living require the fingers and thumb to function together in a coordinated manner during the act of picking up or manipulating an object, the functionality of pinching has implications for a variety of populations. Specifically, rehabilitation specialists are encouraged to emphasize auditory stimuli, before visual stimuli, when attempting to improve hand muscle functionality after an injury, with the intent to develop more adept, fine-tune motor control strategies within those weakened hand muscles.
Effects of Isolated Core Stability Training on Standing Static Postural Control, Recovery of Standing Postural Control and Kicking Velocity in Soccer Athletes
A. El-Kerdi,1 L. Cabell,2 G. Zipp,2 and F. Battaglia2
1Philadelphia University; and 2Seton Hall University
The ability of the trunk to maintain the position and motion of the trunk over the pelvis and lower extremities (LEs) is predominantly accomplished via quick postural responses to internal and external forces. These pre-programmed postural responses are integrated within the neuromuscular system. It is theorized that poor core stability is a result of a failure in the neuromuscular system to support the trunk and pelvis over the LE's. This could result in poor performance and higher risk of injury. Purpose: To examine the effects of an 8-week isolated core stabilization program on static postural control, recovery of postural control and kicking velocity in soccer athletes. A secondary aim was to evaluation the short-term reliability of the measurements. Methods: Twenty collegiate division II and III soccer athletes (n = 10 male, n = 10 female) participated in a quasi-experimental randomized pre-post training study (n = 10 control, n = 10 experimental). Subjects were randomized into a control or an experimental group stratified based on gender. The experimental group performed core stabilization exercises in 4 positions (supine, quadruped, side-lying, prone) 3× per week (twice under direct supervision). The exercises were organized in 4 phases which were progressively more challenging with specific advancement criteria. Testing consisted of repeated then averaged trials for all tests. Center of pressure (CoP) derivatives (MAXx, MAXy, RMSx, RMSy, PATH) and normalized muscle EMG (%MVC) of 6 trunk muscle groups (transversus abdominus/internal obliques, external obliques, rectus adbominus, multifidi, lumbar and thoracic erector spinae) were obtained to quantify static standing postural control using single limb stance (SLS) and tandem stance (TS) for both right (R) and left (L) LEs. Recovery of control was measured using a jump land protocol to quantify time to stabilization (TTS) both in the M/L and A/P (TTSx and TTSy) directions for both LE's. Kicking velocity was used as a measure of soccer performance. The first 10 subjects were recruited to repeat baseline testing 4 hours later to examine the short-term reliability of the measurements. Results: There was good (>0.75) but mostly excellent ICC's (>0.9) with relatively small MDC and SEM's for all variables. Following training, the experimental group demonstrated a significant reduction in CoP deviation of all derivatives and decreased normalized trunk muscle activation of 4/6 muscle groups during SLS and TS under both EO and EC conditions (p ≤ 0.05). Although there were some improvements in %MVC muscle activation of the external obliques and the thoracic erector spinae, said improvements did not reach statistical significance. The experimental group also showed significant improvements in TTS (RTTx by 0.45 seconds, RTTSy by 0.55 seconds, LTTSx by 0.7 seconds, LTTSy by 0.8 seconds, p ≤ 0.05) and increased kicking velocity (by 6 km·h−1) following training. There were also significant improvements in all but 2 variables (the external obliques and thoracic erector spinae) as compared to controls following training (p ≤ 0.05). Conclusions: Completion of an 8-week isolated core stabilization program resulted in improved static and dynamic standing postural control and kicking velocity in division II and III soccer athletes. These results begin to elucidate to role of the core and the effects of core stabilization training on standing postural control and performance in soccer players. Practical Applications: These results have direct implications on clinical intervention for healthy and injured soccer athletes. Training the core in isolation may have benefits for soccer performance other than what was reported in this study. Improving balance and postural control has been shown to reduce incidences of LE injuries in athletes. There is evidence that poor trunk control may be related in incidences of LE injuries. Further, this program may be used to achieve early trunk control for later stages of rehab when more dynamic/integrated exercises are performed or when weight-bearing exercises are contra-indicated.
Associations Between Performance Measures of Vertical Jumping and Bat Swing Mechanics
J. Batcher, N. Raszeja, T. Embry, and C. Bailey
Introduction: Recently, inertial measurement units (IMU) have been affixed to baseball bats for the purpose of analyzing 3 dimensional bat swing mechanics. While weekly jump performance monitoring is somewhat frequently utilized in sports, monitoring swing mechanics appears to be rare. Furthermore, associations between vertical jumping performance and bat swing mechanics have not been completed. Purpose: The purpose of this study was to evaluate the relationship between bat swing analysis variables as measured by an IMU and jump performance characteristics as measured on a force plate in collegiate softball players. Methods: Twenty collegiate softball players participated in this study which was completed in one session. Following a dynamic warm up, all subjects performed 2 maximum effort squat jumps (SJ) and 2 maximum effort counter-movement jumps (CMJ). Jump performance variables of interest included jump height (JH), peak velocity (PV), peak power (PP), and PP scaled by body mass (PP per killogram). After jump testing, athletes participated in bat swing analysis with an IMU attached to the knob of a bat and each subject completed 3 maximal effort swings. Variables collected from each swing included the bat velocity at impact (PV at Con), peak hand velocity (PV), time to contact (TtoCon), bat vertical angle at contact (Vert θ), and attack angle (Attack θ). Relative reliability was evaluated with Intraclass Correlation Coefficients (ICC) and associations between jump and bat swing performance variables were evaluated with Pearson's zero order, product-moment correlations. Interpretation of correlation results was completed with the scale provided by Hopkins (2013). Results: Acceptable reliability was observed for all variables accept CMJ PV and the bat swing vertical angle (ICC = 0.48 and 0.63 respectively). The only statistically significant relationships observed were between SJ JH and PV at Con (r = 0.42), CMJ PP and Vert θ (r = 0.46), SJ PP and PV at Con (r = 0.56), SJ PP and Vert θ (r = 0.68), CMJ PP and PV at Con (r = 0.50). Conclusions: The largest r values observed were between SJ PP and PV at Con, SJ PP and Vert θ, CMJ PP and PV at Con. This appears to indicate that jumping PP is the best predictor of batting performance of the variables tested, but the relationship with PP was not present with all bat swing performance variables. Furthermore, the strength of other relationships fell within the trivial to moderate range. It should be noted that 2 outliers based on body mass were found that skewed the data distribution in SJ PP and CMJ PP, which inflated the strength of the relationships. This is evident as the relationship strength decreases between form variables with PP to variables with PP per killogram. Practical Applications: Data from this study analyzing the relationship between vertical jumping and swing mechanics indicates that it would not be appropriate to replace jump monitoring with bat swing performance monitoring in an athlete monitoring protocol as a trend of large relationships between both assessments was not present. Instead, it appears that both need to be monitored and the results are independent of one another. Future investigators may wish to evaluate the influence of ground reaction forces during a swing on the swing analysis variables measured by an IMU.
Mechanomyographic Response for the Biceps Brachii During a Sustained Maximal Voluntary Contraction
J. Carr,1 T. Beck,2 X. Ye,2 and N. Wages2
1University of Oklahoma; and 2The University of Oklahoma
The surface mechanomyographic (MMG) signal corresponds to the mechanical properties of skeletal muscle function. In addition, there is evidence that suggests a relationship exists between the MMG signal and global motor unit activity (i.e., motor unit recruitment and firing rate). Therefore, by examining the MMG response to a sustained maximal effort force task, valuable information regarding muscle fatigue and motor control may be considered. Purpose: To examine the linearity of the MMG amplitude and frequency responses for the biceps brachii during a sustained maximal isometric contraction. Methods: Twelve habitually active males (mean ± SD: age = 24.8 ± 3.1 years; height = 180.2 ± 4.4 cm; mass = 91.0 ± 14.0 kg) volunteered for this study and were familiarized with the testing procedures prior to testing. Before the fatigue test, the subjects performed 3 maximal voluntary contractions (MVC) of the dominant forearm flexors, the highest force value from the 3 trials was designated as the baseline MVC (MVCb). The subjects then sustained a maximal voluntary isometric contraction of the forearm flexors until force output could not be maintained above 50% MVCb. MMG activity was detected from the biceps brachii with a piezoelectric accelerometer. The linearity of the MMG amplitude and MMG mean frequency vs. time relationships were examined with linear regression models. Results: The results indicated significant linear relationships for MMG amplitude across time for 8 of the 12 subjects: (mean ± SD: slope = −48.1 ± 47.6 microvolts per seconds; y-intercept = 2,772.3 ± 1,920.1 microvolts; r2 = 0.37 ± 0.28). Additionally, 5 of the 12 subjects displayed significant linear relationships for MMG mean frequency across time: (mean ± SD: slope = −0.27 ± 0.42 Hz·s−1; y-intercept = 48.2 ± 20.5 Hz; r2 = 0.18 ± 0.19). Conclusions: These results demonstrate that the MMG signal can be used to monitor fatigue-induced changes in muscle function. There was a tendency for both the MMG amplitude and the MMG mean frequency to decrease across time. However, the divergent patterns of response between individuals may be due to unique motor control strategies related to the demands of the fatigue task.
Isokinetic Knee Strength Is Associated With Knee Flexion Range of Motion Kinematics in the Vertical Jump
J. Bores, C. Vernon, D. Ridings, J. Champion, and W. Amonette
University of Houston—Clear Lake
Proper and safe landing from a jump requires the knee to flex over a generous range of motion (ROM) to theoretically increase the time at which forces are absorbed and transferred up the leg, and valgus ROM should be limited to protect ligamentous structures of the knee. Purpose: The purpose of this study was to identify associations between height (Ht), weight (Wt), lean body mass (LBM), leg length (LL), isokinetic strength at 2 speeds in the quadriceps and hamstrings and right knee flexion-extension ROM and varus-valgus kinematics during landing. We hypothesized that those with more hamstring and quadriceps strength would have a larger ROM in flexion and less valgus movement. Methods: After each of 18 volunteers (8 f, 10 m; 24.4 ± 8.7 years; 68.3 ± 18.3 kg; 166.5 ± 15.3 cm) signed an informed consent or adolescent assent approved by an institutional review board, measurements of Ht, Wt, LBM and LL were performed followed by a cycle warm-up. Next, a lower-body marker set was applied to participants and 3D motion capture data were collected during 2 countermovement vertical jumps (VJ) and depth jumps (DJ) from a 46-cm box. Isokinetic flexion-extension torques were then collected at 60 and 240° s−1. Pearson correlation coefficients were computed between Ht, Wt, LBM, LL, peak isokinetic torques at both speeds and right knee flexion and valgus ROM kinematics. Alpha was set at p ≤ 0.05. Results: Knee flexion ROM in the VJ was correlated with knee extension (r = 0.50; p = 0.034) and flexion strength and 60°·s−1 (r = 0.52; p = 0.026). Although there were trends towards an association of knee flexion ROM with LBM (r = 0.41), isokinetic extension (r = 0.41) and flexion (r = 0.42) strength at 240°·s−1 the correlations were not significant. No associations were found between knee flexion ROM in landing from a VJ and any other measured variable: Ht (r = 0.24), Wt (r = 0.38), LL (r = 0.22). No associations were evident between knee varus-valgus movement upon landing from a VJ and Ht (r = 0.11), Wt (r = 0.17), LBM (r = 0.13), LL (r = 0.20), extension (r = 0.26) and flexion (r = 0.10) strength at 60°·s−1 or extension (r = 0.06) and flexion (r = 0.16) strength at 240°·s−1. Knee flexion ROM upon landing from the DJ was not associated with Ht (r = 0.16), Wt (r = 0.26), LBM (r = 0.36), LL (r = 0.05), extension (r = 0.24) and flexion (r = 0.26) strength at 60°·s−1 or extension (r = 0.26) and flexion (r = 0.27) strength at 240°·s−1. No correlations were present between knee varus-valgus ROM upon landing from the DJ and Ht (r = −0.06), Wt (r = −0.20), LBM (r = −0.06), LL (r = −0.04), extension (r = −0.09) and flexion (r = −0.02) strength at 60°·s−1 or extension (r = −0.12) and flexion (r = −0.01) strength at 240°·s−1. Conclusions: No associations between ROM in knee flexion or knee varus-valgus and Ht, Wt, LBM, LL and knee flexion-extension strength at 60 and 240°·s−1 were shown in the DJ. This may be indicative of the novelty of DJs to participants without rehearsed motor coordination. There was an association between VJ knee flexion ROM in landing and hamstrings and quadriceps strength at 60°·s−1, meaning those with more quadriceps and hamstrings strength at slower speeds tend to absorb forces over a greater knee flexion ROM. Practical Applications: Strength and conditioning professionals should prescribe exercise regimens to improve quadriceps and hamstrings strength as this may facilitate the distribution of forces in the knee over a greater ROM during landing. Also, DJs may not be appropriate predictors of habitual jumping mechanics for those new to the skill.
The Relationship Between Rapid and Maximal Strength, and Functional Balance Performance in Career Firefighters
T. Barnette,1 E. Ryan,2 G. Gerstner,1 A. Tweedell,3 C. Kleinberg,4 H. Guiliani,1 and N. Shea1
1University of North Carolina Chapel Hill; 2University of North Carolina at Chapel Hill; 3Department of Defense; and 4Under Armour
The fire service has one of the highest rates of occupational injuries, with an estimated national cost between $2.8–$7.8 billion dollars. One of the most common injuries firefighters face are related to slips, trips, and falls (STFs). We are aware of no laboratory based studies that have specifically examined the influence of neuromuscular function on STF-related injuries. Purpose: The purpose of this study was to examine the relationship between lower extremity rapid and maximal strength, and functional balance performance during a simulated firefighting activity. Methods: Forty-two career firefighters (age = 34.7 ± 7.2 years; stature = 178.9 ± 8.2 cm; body mass = 94.4 ± 23.0 kg) volunteered for this investigation. Participants visited the lab on separate occasions for the strength and functional balance testing. The participants were asked to refrain from exercise for 24 hours prior to each visit and refrain from caffeine ingestion 4 hours prior to testing. Isometric leg flexion strength of the right leg was assessed using a calibrated isokinetic dynamometer at 60° below full extension. Following a submaximal warm up, 3 leg flexion maximal voluntary isometric contractions (MVCs) were performed with 2 minutes of rest between each effort. Maximal strength was determined as the highest 500 milliseconds peak torque (PT) value during the MVC, whereas rapid strength was determined as the peak rate of torque development (RTDpeak) determined from the peak derivative of the time-torque curve. Peak torque and RTDpeak were then normalized to body mass. The functional balance test consisted of a balance beam (4 m [L], 15 cm [W], 5 cm [H]) with raised platforms (20 cm [H]) at each end and an overhead obstacle placed midway across the beam and set at 75 percent of the subject's height. Firefighters were instructed to step down from the first raised platform, walk along the beam, pass under the overhead obstacle, step up to the second platform, and repeat this going backward as fast as possible while wearing their standard personal protective equipment and self-contained breathing apparatus. Each participant performed 5 trials accounting for minor (i.e., foot contacted the ground) and major errors (i.e., overhead obstacle falls) with a minute rest between each to create a performance index. Minor and major errors resulted in one and 2 second penalties, respectively, and the best performance index was used for analysis. The relationships between normalized PT and RTDpeak, and the functional balance performance index scores were examined using Pearson's correlation coefficients (r) with an alpha level set a priori at p ≤ 0.05. Results: The functional balance performance index (mean ± SD: 11.20 ± 2.99 s) was not significantly related to normalized PT (r = −0.218; p = 0.165); however, there was a significant negative relationship with normalized RTDpeak (r = −0.410; p = 0.007). Conclusions: These findings indicated that functional balance performance was related to rapid strength, but not maximal strength of the leg flexor muscles. Practical Applications: These data may suggest that early rapid strength production vs. maximal strength may play an important role in recovery from a STF. Training designed to improve rapid strength development of the leg flexor muscles may be an attractive strategy to reduce STF injuries in the fire service. Acknowledgments: Sponsored by National Institute of Occupational Safety and Health (T42OH008673).
Mechanical Efficiency in Running Is Decreased after 40-km of Cycling in Trained Triathletes
J. Stewart, K. Zwetsloot, P. Rice, V. Georgescu, D. Lidstone, R. Gurchiek, C. Capps, and J. McBride
Appalachian State University
Triathletes are required to alter movement patterns while maintaining intensity during the swim, cycle, and run phases of competition. For many triathletes, the run phase after cycling is characterized by decreased performance, compared to running alone. Purpose: To examine whether a 40-km cycling bout alters running economy (RE) and mechanical efficiency of running (ME) in trained triathletes. Methods: Eight competitive triathletes (7 males, 1 female; 21.0 ± 1.5 years; Height 1.8 ± 0.1 m; Weight 73.9 ± 8.2 kg; V[Combining Dot Above]O2max 59.2 ± 7.6 ml·kg−1·min−1) with a minimum of one-year experience competing in triathlon distances ranging from Olympic to Ironman participated in this study. Subjects reported to the lab for 3 separate visits (separated by ≥ 48 hours). At visit one, subjects completed the informed consent, a V[Combining Dot Above]O2max test, anthropometric measures, and baseline performance testing [isometric squat maximal voluntary contraction (MVC) and countermovement jump (CMJ)]. During the second visit, RE and ME were measured during running after subjects completed a 5-km treadmill run (R5K). For visit 3, RE and ME were measured during running after subjects completed 40-km of cycling (C40K) using a Computrainer. MVC, CMJ, and muscle glycogen values were measured before and after the exercise bout on visit 2 and 3. Results: ME during running after 40-km of cycling (C40K) was significantly lower than ME during running after completing a 5-km treadmill run (R5K) (C40K: 48.4 ± 5.7%, R5K: 53.7 ± 3.5%; p = 0.004). RE, as a percentage of V[Combining Dot Above]O2max (C40K: 74.8 ± 9.3%, R5K: 74.1 ± 7.8%; p = 0.771) or as absolute V[Combining Dot Above]O2 (C40K: 6.5 ± 1.3 L·min−1, R5K, 6.4 ± 1.2 L·min−1; p = 0.804), was not significantly different between C40K and R5K. Blood lactate (C40K: 5.5 ± 1.2 mmol·L−1, R5K: 4.2 ± 1.3 mmol·L−1; p = 0.055), respiratory exchange ratio (RER; C40K: 0.93 ± 0.11, R5K: 0.88 ± 0.05; p = 0.260), and work (C40K: 61,380 ± 6,176 joules, R5K: 64,094 ± 5,554 joules; p = 0.137) were not significantly different between C40K and R5K. Also, there were no significant differences in the percent decrease in glycogen (C40K: 14.3 ± 10.1%, R5K: 15.0 ± 8.0%; p = 0.879), percent decrease in CMJ (C40K: 10.9 ± 9.2%, R5K: 10.1 ± 12.9%; p = 0.885), or percent decrease in MVC (C40K: 15.3 ± 9.8%, R5K: 15.9 ± 16.9%; p = 0.923). Conclusions: The lower value for ME in running observed following cycling in this study might be due to the combined effect of slightly higher blood lactate values, slightly higher RER, and slightly lower external mechanical work performed. Practical Applications: A lower value of ME after cycling may hinder run performance and thereby increase time to completion. However, the exact mechanisms for the observed lower value of ME after C40K are unclear. Future investigations should examine additional physiological and biomechanical variables that might impact ME, such as variations in running form after cycling. Acknowledgments: Partially funded by the Appalachian State University Office of Student Research.
Influence of Elevated Heel Heights During Low Effort Lifting
H. Lu, B. Romer, and J. Trammell
Louisiana Tech University
Footwear is a necessary equipment item for any strength and conditioning program. While many sport oriented footwear are designed with similar aesthetic components, there are often considerable variations in the geometry and mechanical components within a footwear brand and between brands. A common component of recent research interest is the elevated heel height commonly found in most daily living and sport oriented footwear. Purpose: The purpose of the present study was to examine the influence of elevated heel heights on lower extremity coordination during the execution of a low effort barbell back squat. Methods: Twelve (age = 23.3 ± 3.3 years) resistance trained participants (males, n = 6; females, n = 6) took part in a randomized protocol of 3 repetitions at 25% of their maximal effort barbell squat at a 0, 5, 10, or 15° incline. Participants performed 3 consecutive repetitions during each condition, followed by 5 minutes of rest. Heel height was adjusted to the designated heel height through custom-made wooden-lifting platforms set to specific incline levels (0, 5, 10, and 15%). Sagittal plane kinematics were collected through a single Basler Scout camera recording at 100 Hz and processed through MaxTRAQ2D (Innovision Systems, Inc., Columbiaville, MI, USA). A custom Matlab program (The Mathworks, Inc., Natick, MA, USA) was utilized to determine the continuous relative phase (CRP) ratios of the thigh-shank during each condition, with sagittal plane joint angles and velocities calculated for 3 squat gait cycles to determine CRP mean and the deviation phase (DP) of the thigh-shank. Separate repeated measures ANOVA's were completed, with dependence on the CRP mean and DP. Results: Results indicated that there were no significant differences found in the CRP mean or DP of the thigh-shank during lifting gradients. Descriptive statics indicate that individuals tend to display a more out-of-phase coordination pattern (Average Eccentric CRP: −472.1°; Average Concentric CRP: −609.6°) during concentric motions as opposed to eccentric motions. Conclusions: The results of the present study suggest that elevated heel heights have no significant effects on coordination patterns or coordination variability; however, descriptive statistics indicated that differences may exist when examining the muscular contraction patterns. Elevated heel heights have been shown to alter peak lower extremity kinematics and maximum acceptable weight of lifts (MAWOL). The differences in concentric and eccentric coordination patterns may have important implications for understanding the effects of training induced strength gains as well as the development of cumulative trauma disorders. Expansion of the study population is warranted to examine the effects of muscle contractions on lower extremity coordination patterns. Practical Applications: Squatting, and squat derivatives, are involved in activities of daily living, rehabilitation protocols, and performance enhancement programs. Furthermore, this weight bearing movement involves a large number of muscles at the ankle, knee, and hip joints. The present study suggests that the heel heights commonly found in many commercially available footwear do not significantly alter lower extremity coordination patterns, though the type of muscular contraction is worthy of consideration in future research.
Relationships of Selected Anthropometric Measures to Handgrip Strength in Active Adults
C. Henson,1 M. Leatherwood,1 G. Ryan,2 R. Brannan,3 and R. Herron1
1University of Alabama; 2Catawba College; and 3Life University and Auburn University Montgomery
Many coaches and strength practitioners believe that those with larger hand surfaces or body weights present higher absolute handgrip strength. As such, many perceive those with large hands of possessing a possible performance or strength advantage. However, research investigating the relationships between common anthropometric measures and handgrip is inadequate. Purpose: This study aimed to investigate the relationship between common anthropometric measures and handgrip strength in active adults. Methods: Eleven participants (4 female, mean ± SD, age = 27 ± 4 years) completed a battery of anthropometric and handgrip measures. Anthropometric measures included height (m), weight (kg), body composition via multi-frequency bioelectrical impedance (MF-BIA), forearm circumference (cm), hand length (cm), hand width (cm), and body mass index (BMI = wt [kg]·ht−2 [m]). Handgrip was recorded as the sum of the max score achieved on a handgrip dynamometer by the left and right hands. The highest of 3 attempts was recorded in an upright position with arms and hands by their side. Results: Pearson-product moment correlations revealed weak correlation between handgrip strength and ht (r = 0.31), wt (r = 0.39), body fat percentage (r = −0.18), hand length (r = 0.27), hand width (r = 0.37). However, BMI, lean body mass, and forearm circumference were moderately related to handgrip strength (r = 0.41, r = 0.56, and r = 0.58 respectively). Conclusions: These data indicated that lean body mass and forearm circumference are more strongly related to handgrip strength than hand size. Practical Applications: Although a biomechanical advantage could exist due to hand size, muscle mass and the diameter of the forearm are higher correlates of handgrip strength. This underscores the importance of muscular hypertrophy and, in particular, cross-sectional area of the active muscle when maximizing one's ability to develop force.
Association of Vertical Jump Displacement With Laterality-Based Foot Moment Arms
L. Weiss,1 J. Caia,1 B. Schilling,1 L. Chiu,2 and M. Paquette1
1The University of Memphis; and 2University of Alberta
Considering the talocrural and metatarsophalangeal joints, the foot includes both first- and second-class levers that contribute to jumping performance. Reliable and precise measures of the respective static moment arms have been obtained when grouped for laterality (foot dominance). Unilateral grouping (right and left sides) has been shown to explain 20–28% of shared variance with restricted vertical jumps (RVJ). However, it remains to be seen how much variance can be explained using laterality-grouped output. Purpose: To determine the association of vertical jump displacement with 2 moment arm lengths of the foot grouped for laterality under 3 different loading conditions. Methods: Longitudinal foot dimensions were obtained in 27 men and 27 women, 18–39 years of age, including the anterior-posterior distance between the posterior calcaneus and: (a) talocrural (TALO) and (b) metatarsophalangeal (META) joints. Dominance was based on the preferred kicking foot. Bilateral measurements were obtained using a digital sliding caliper on stationary subjects under the following loading conditions: (a) seated, (b) bilaterally-standing, and (c) unilaterally-standing. Associations between RVJ and the various moment arms were determined by bivariate correlation for the entire sample (n = 54). Results: Average RVJ displacement was 32.1 + 9.1 cm. Longitudinal foot dimensions (mean +SD for both dominant and non-dominant sides) ranged from 5.1 + 0.5 cm to 5.2 + 0.4 cm for TALO, and 16.9 + 1.2 cm and 17.3 + 1.1 cm for META. Bivariate correlations for RVJ displacement with foot moment arms are found in table 1. It is noteworthy that only 4 of 54 subjects (7.4%) were left-foot dominant. Conclusions: 10–26% of RVJ displacement was explained by laterality-based TALO dimensions while 20–27% was explained by laterality-based META dimensions. The bilateral- and unilateral-standing loading conditions appeared to result in moment arms that generally explained slightly more variability in RVJ than when subjects were seated. Practical Applications: Laterality-grouped foot moment arms explain some variance in RVJ performance, but do not appear to enhance the explained variance when measurements are grouped for right and left sides. It is unclear if the proportional representation of foot sidedness seen in the current investigation was an aberration.
The Influence of bar Diameter on EMG Activity of Hand Flexors During an Isometric Contraction
V. Hanson,1 M. Leatherwood,1 T. Williams,1 R. Brannan,2 R. Herron,1 and P. Bishop1
1University of Alabama; and 2Life University and Auburn University Montgomery
Handgrip strength is rarely prioritized although it can be a limiting factor in upper-body pulling exercise and dynamic Olympic lifts. Purpose: The purpose of this study was to determine if large-diameter bars elicit greater hand flexor EMG activation compared to a standard bar during isometric dumbbell holds at various elbow positions. Methods: Eleven participants (4 female, mean ± SD, age = 27 ± 4 years) completed 3 visits to the lab. During the first visit, participants completed a multi-repetition max of a single-arm, dumbbell biceps curl used to estimate a 1-RM. Each participant was then scheduled to return to the lab 2 more times separated by 48–96 hours to complete isometric dumbbell exercises at varying forearm positions and elbow flexion angles with a large diameter dumbbell (LD = 5.72 cm diameter) or normal diameter dumbbell (CON = 2.54 cm diameter) in a repeated-measures, counter-balanced, cross-over design. Results: A 2-way, repeated measures ANOVA (diameter × forearm position) was used to investigate mean differences within each degree of elbow flexion, 0, 45, and 90°. At 0° elbow flexion, there was no interaction (p = 0.07), however main effects were discovered for diameter and forearm positions. LD bar diameter elicited lower EMG activity compared to control (LD = 0.84 ± 0.06, CON = 1.1 ± 0.06, p < 0.001). Furthermore, pair-wise comparisons saw differences between supinated (1.13 ± 0.07) grip vs. both pronated (0.93 ± 0.04, p = 0.002) and neutral grips (0.91 ± 0.07, p = 0.005) with no difference between the latter (p = 0.73). At 45° elbow flexion, there was no interaction (p = 0.63) nor main effect of diameter (p = 0.72). However, a significant main effect of forearm positions (p < 0.001) and subsequent pair-wise comparisons elucidated differences between supinated (1.68 ± 0.09) grip vs. both pronated (1.25 ± 0.05, p < 0.001) and neutral grips (1.27 ± 0.06, p < 0.001) with no difference between the latter (p = 0.69). Finally, at 90° elbow flexion, there was no interaction (p = 0.48), however main effects were discovered for diameter and forearm positions. LD bar diameter elicited lower EMG activity compared to control (LD = 1.33 ± 0.05, CON = 1.55 ± 0.07, p = 0.002). Furthermore, pair-wise comparisons saw differences between supinated (1.82 ± 0.09) grip vs. both pronated (1.23 ± 0.06, p < 0.001) and neutral grips (1.27 ± 0.05, p = 0.001) with no difference between the latter (p = 0.56). Conclusions: Contrary to popular opinion, these raw RMG data indicated LD bar elicited activation in the hand flexors at the end point range of motion. Additionally, Supinated forearm positions was most effective in eliciting high EMG activity when compared to other forearm positions. Practical Applications: LD bar training during accessory lifts may not provide enough stimuli to improve grip strength. Further research is needed to investigate LD's influence on forearm activity during heavy Olympic lifting.
Joint Kinetics of Three Variations of the Clean Exercise
T. Daehlin,1 T. Krosshaug,1 and L. Chiu2
1Norwegian School of Sport Sciences; and 2University of Alberta
In the pulling phase of the clean, the ankle plantar flexors, knee extensors, knee flexors and hip extensors perform work on the athlete's body and barbell. In other multi-joint tasks, joint kinetics do not scale linearly with changes in effort. Therefore, performing the clean with varying effort may influence training adaptions and inter-muscular coordination. Purpose: This investigation compared the work performed by lower extremity net joint moments (NJM) during 3 variations of the clean. Methods: Six males and 2 females (age: 26 ± 6 height: 1.76 ± 0.09 m, mass: 93.6 ± 19.5 kg) with a minimum of 3 years experience performing the clean volunteered to participate. In the first of 2 sessions, participants' one repetition maximum (1RM) clean was determined. Attempts were recorded on digital video to verify that all participants demonstrated the towards-away-towards barbell trajectory. In the second session, participants performed 4 repetitions each of cleans performed with sufficient effort to lift the bar to the minimum height required to receive it in a full squat (minimal height clean); or with maximum effort to elevate the barbell as high as possible and receiving it in a full (maximal effort clean) or partial (power clean) squat. Each repetition was performed with 80% 1 RM in a randomized order. The lower extremity was modelled based on 25 reflective markers attached to the feet, legs, thighs and pelvis. Marker trajectories and ground reaction forces were measured using 7 optoelectronic cameras and 2 force platforms. Work generated at the ankle, knee and hip were calculated and compared between the 3 test conditions using multivariate repeated measures ANOVA and post hoc t-tests with Bonferroni correction (α = 0.05). Results: Total lower extremity NJM work, knee extensor work and knee flexor work were greater in maximal effort and power cleans compared to the minimal height clean (p ≤ 0.05; Figure 1). Furthermore, ankle plantar flexor work was greater in the power clean compared to the minimal height clean (p ≤ 0.05; Figure 1). Conclusions: Total lower extremity NJM work is greater when maximal effort is exerted to lift the barbell as high as possible. The increased total NJM work is primarily accounted for by increased knee extensor and flexor work. Practical Applications: Greater knee extensor and flexor work is performed when exerting maximal effort to elevate the barbell as high as possible compared to lifting the barbell to the minimum height required. Therefore, how the clean is executed may influence the muscles trained and the development of inter-muscular coordination. As the minimal height clean requires the least work to be performed, this variation may be optimal for the purpose of training a weightlifting technique that allows heavier loads to be lifted.
The Relationship Between Sway Medicals Concussion Management System Application and Biodex Balance System SD During the Balance Error Scoring System Test in Female Athletes
C. Cooper, C. Perez, H. Velasquez, N. Sauls, and N. Dabbs
California State University, San Bernardino, California
Introduction: In recent years, postural stability assessments have become widely used in the evaluation of sport-related concussions for athletes. Concussion testing has become a crucial factor in an athlete's return-to-play-safety. The objective measures from balance testing can provide trainers and coaches' with more quantitative data to evaluate the severity of an athlete's injury. Purpose: The purpose of this investigation is to determine the relationship between SwayMedical's Concussion Management System Application and Biodex Balance System SD during the Balance Error Scoring System (BESS) test. Methods: Ninety-three Division II female athletes (age 19.45 ± 1.37 years; height 168.79 ± 8.90 cm; weight 68.37 ± 10.85 kg) from the following teams, soccer, volleyball, basketball, and softball, all completed a single session balance test. All participants read and signed an informed consent followed by obtaining age, height, and weight. Prior to any testing, all participants were familiarized with the BESS protocol. Participants completed SwayMedical's baseline balance test with an iPod strapped via chest harness, while completing the BESS protocol on the Biodex Balance System concurrently. The BESS protocols consisted of 5 conditions: Double Stance (DS), Tandem Left (TL), Tandem Right (TR), Single Left (SL), and Single Right (SR). Each condition was performed for 10 seconds with eyes closed with 10 seconds rest between conditions. Pearsons r correlations were conducted to analyze the relationship between the 2 systems for all 5 conditions and an overall condition. Results: There was a significant (p < 0.01), negative, correlation between the Biodex System and the Sway Application in BESS test conditions, DS (r = −0.33), TL (r = −0.39), SR (r = −0.61), SL (r = −0.70), and overall (r = −0.70). There was no significant (p > 0.05) correlation between the Biodex System and the Sway Application for TR condition. Conclusions: There is an overall significant relationship between the Biodex Balance System and SwayMedical's Concussion Management System Application. The negative correlations are indicative of each method using an opposite scoring system. The findings of this study show SwayMedical's application is a valid tool that can be used by practitioners and clinicians to assess concussions. Practical Applications: Practitioners assessing concussions using the BESS test can comfortably and confidently use the Sway Application to determine an athlete's return to play. In clinical settings as well as in the field, the Concussion Application Management System may be more convenient, affordable, and adaptable compared to the Biodex Balance System.
Compare Physiological Responses of Elliptical Trainer With Treadmills
K. Su,1 W. Tseng,2 J. Zhang,3 S. Fu,1 C. Yu,1 and K. Tseng1
1Department of Exercise and Health Sciences, University of Taipei, Taiwan; 2Department of Sports, Taipei City Government, Taipei, Taiwan; and 3Department of Exercise and Health Science, University of Taipei, Taiwan
Few studies focused on the comparison between treadmills (TM) and elliptical trainer (ET), especially in cardiopulmonary fitness. These devices have own particularities and training effects. Purpose: To investigate the physiological responses differences of lower limb's in electromyography (EMG) and total oxygen uptake (V[Combining Dot Above]O2) with 40, 60 and 80% of the maximum heart rate (HRmax) between elliptical trainer (ET) and treadmills (TM). Methods: Thirteen healthy college students (10 male, 3 female; mean age = 21 ± 2 years) received ET and TM with randomly sequence. All subjects underwent ET and TM maximal exercise test (CPET, bruce protocol) and accepted 40, 60, and 80% of the HRmax after 48 hours. The Zero Wire EMG (sampling rate 2,000 Hz) combined with Cosmed Quark CPET were used to record muscle activation and collect oxygen consumption during the process. Results: The signal of Gastrocnemius (GN), Tibialis Anterior (TA) in low intensity (40% HRmax) on TM was higher than ET (p ≤ 0.05). In high intensity (80% HRmax), the signal of GN, TA and Biceps (BF) on TM was higher than ET, but Gluteus maximus (GM) was smaller (p ≤ 0.05). There were no significant differences in V[Combining Dot Above]O2max between TM and ET (HRmax 40, 80, and 60%). Conclusions: In different intensities, the muscular total work of GN, GM, BF, and Rectus Femoris (RF) in ET were more dominant, and GN, TA, and BF in TM were more obvious. The training effect of cardiopulmonary fitness in ET was similar to TM during the same intensity. Practical Applications: The elliptical trainer is a suitable exercise device for simulating walking or running and with lower impact. It had a well effect in cardiopulmonary fitness and decreasing the impact to the joint which related to the risk of lower limbs. Exercise on elliptical trainer may concern for elderly, who have suffered from osteoarthritis and overweight to avoid the shock force to the joint.
The Effect of Leg Dominance on the Kinematics of a 180° Pivot Maneuver in Female Soccer Players at Three Different Stages of Physical Maturation
V. Smykalski, D. Kivi, P. Sanzo, and G. Paterson
Purpose: The purpose of this study was to evaluate the effect of leg dominance on lower limb kinematics during a 180° pivot maneuver in healthy female soccer players at 3 different stages of maturation: pre-pubertal, pubertal, and post-pubertal. Methods: Twenty-seven athletes of 4 female soccer teams (Under 10, 12, 14, and 18 year old teams) were recruited to participate. The modified Pubertal Maturation Observation Scale (PMOS) was used to classify 9 participants into each maturational group: pre-pubertal (10.3 ± 1.1 years), pubertal (12 ± 1.4 years), and post-pubertal (14.8 ± 2.0 years). Testing involved the completion of a short maximal effort sprint coupled with a pivoting turn. This included a 3.5 m acceleration starting from a stationary position, immediately followed by a 180° pivot maneuver with either their dominant or non-dominant leg, and another 3.5 m acceleration towards and through the starting position. Trials were recorded using 2 Basler high-speed digital video cameras and timed using a wireless timing gate system. The angles of knee flexion, hip flexion, thigh and shank rotations, and hip abduction/adduction were evaluated at initial contact (IC), maximum knee flexion (MKF), and toe-off (TO) during the 180° pivot maneuver. To assess the interaction effects for each of the dependent variables, 2 (leg dominance) × 3 (maturation stage) × 3 (instants) factorial ANOVAs were used. Results: Two significant interaction effects were observed between the post-pubertal and the pubertal groups for shank rotation angle. The post-pubertal group had a greater shank internal rotation angle with the non-dominant leg at both MKF and TO. In addition, there were significant main effects for knee and hip flexion angles, hip adduction/abduction angle, and thigh and shank rotation angles among instants. Although not statistically significant, there were noteworthy, practically important trends observed in the data. The dominant leg had smaller knee flexion angles at each event within each group, smaller hip flexion angles within the post-pubertal group at IC and MKF and within the pubertal group, as well as larger adduction angles at MKF and TO within each group. Furthermore, the post-pubertal group had the largest peak hip abduction angles and hip flexion angles at IC when isolating on the dominant leg. Conclusions: The results of this study suggest that post-pubertal females pivoting with their dominant leg perform kinematic patterns that may lead to a greater risk for an ACL in jury during a 180° pivot maneuver as compared to less mature players on the non-dominant leg. Practical Applications: The use of the FIFA 11+ Warm-up Manual Part 1: Running Exercises by all participants in this study may have implications for the training of these female soccer players, as statistically significant maturational differences were not seen. Coaches should conduct individual evaluations of their players during the warm-up exercises to ensure proper technique is observed and also to identify high-risk athletes. Focus should be directed towards initial contact, based on the findings of more at risk kinematic positions seen in the current study. Although there is a greater potential ACL injury risk for females, this research should also be carried out in males.
Effect of Center of Pressure on Sagittal Plane Form at Maximum Depth of Bodyweight and Weighted Back Squats
R. Hale, J. Hausselle, R. Gonzalez, and S. Dorgo
The University of Texas at El Paso
The back squat is a fundamental exercise, commonly used to target major lower extremity muscle groups. Proper back squat form is continually under debate but is most often determined by visual kinematics rather than quantitative measurements. Purpose: The goal of this study was to determine how proper sagittal plane form affected the center of pressure (COP) location below the foot during a bodyweight back squat (BWS) and a weighted back squat (WBS). Methods: Sixty recreationally active males (18–25 year old) performed 3 BWS and 3 WBS with 70% of the subjects' body weight. Subjects wore the same neutral full support sport shorts, and were equipped with an electric goniometer on their right knee while standing with each foot on a force plate. Subjects stood with feet shoulder-width apart, toes facing forward, and heels horizontally lined up with one another. COP location was measured at maximum squat depth and normalized to shoe size, with the heel being 0% and the toe 100% (Figure 1). Following a post-assessment video analysis, data were categorized as either Expert (n = 23) or Beginner (n = 37). Experts demonstrated proper execution of a back squat and Beginners demonstrated improper execution of head, thoracic, trunk position, or tibial progression. BWS and WBS COP location values for the Expert and Beginner groups were analyzed by an independent samples t-test. Results: Significant COP location differences were observed between groups for BWS (p < 0.001) and for WBS (p < 0.001). Expert average COP location was 26 ± 6% under both feet during the BWS and 38 ± 10% during WBS. Beginner left foot COP was 41 ± 23% during BWS and 57 ± 30% during WBS, while right foot COPs were 36 ± 10% and 48 ± 7%, respectively. Conclusions: Results demonstrated that proper squat form affects COP location. Findings suggest a relationship between the visual criteria of squatting and COP location as a quantitative outcome measure. Added weight results in greater anterior COP location for both Experts and Beginners. Improper form during a BWS is visually exaggerated when performing a squat with weight and correlates to the anterior shift in COP location. Practical Applications: Proper development of a squat form is an essential component for athletic preparatory training, strengthening the hip, knee, ankle, and back musculature. Subjects who possess good squat form visually appear to push their buttocks out and keep their heels on the ground. Our findings confirm that proper squat form requires a shift of weight posteriorly, firmly planting the heels, and unloading the toes and balls of the feet. Acknowledgments: Authors acknowledge the Interdisciplinary Research grant #19507766.
Kinetic Contributions of Upper Limbs During Eccentric and Concentric Phases of Counter-Movement Vertical Jumps With and Without Arm Swing
E. Mosier,1 A. Fry,1 M. Lane,2 P. Moodie,3 and R. Moodie3
1University of Kansas; 2Eastern Kentucky University; and 3Dynamic Athletics Research Institute
The vertical jump is a complex multi-joint action where muscles of the lower and upper extremities collectively summate forces to produce movement. What is not clear is the portion of the resulting ground reaction forces (GRF) that is due to the arm swing action during eccentric and concentric phases. Purpose: The purpose of this study was to determine the kinetic contributions of the upper extremities through the eccentric and concentric phases during counter-movement vertical jumps (CMJ) while using arm swing (AS) or no-arm swing (NAS) conditions. Methods: Fourteen healthy, recreationally active men (X ± SD; age = 24.1 ± 3.9 years, height = 1.76 ± 0.05 m, weight = 82.6 ± 10.6 kg) performed in random order a total of 6 jumps consisting of 3 AS and 3 NAS CMJ. The AS began with the participant standing upright with arms fully raised above the head. The NAS began with the dominant upper limb fully raised overhead, while the non-dominant hand remained on the iliac crest during the entire CMJ. All jumps were performed by descending to an internal knee angle of 90° using maximal effort and reaching for a target suspended from the ceiling. A 3 dimensional (3-D) markerless motion capture system (MCS; DARI, Lenexa, KS, USA) was used to analyze the kinetic and kinematic data. Body segmental masses were determined from DEXA scans. Relative contributions (%) of the upper limbs to the mean and peak GRFs [(arm GRF/total GRF) per time point] were expressed for both the concentric and eccentric phases. T-tests and ANOVAs (*ECC vs. CON, †AS vs. NAS; p ≤ 0.05) were performed on mean values from all 3 jumps for AS and NAS for each subject. Results: Results for the relative contributions of the upper limbs for the AS and NAS CMJ are shown in the table. AS CMJ mean forces were 903.44 ± 130.24 N† (eccentric) and 1,583.68 ± 231.73 N*† (concentric). NAS CMJ mean forces were 857.75 ± 109.41*†N (eccentric) and 1,521.69 ± 201.62 N*† (concentric). AS arm GRF mean forces were 265.01 ± 83.94 N† (eccentric) and 496.84 ± 155.155.39 N*† (concentric). NAS arm GRF mean forces were 79.16 ± 18.09 N*† (eccentric) and 166.76 ± 27.81 N*† (concentric). Conclusions: The enhancement of performance when jumping using an AS resulted in a 13% increase in jump height. The contribution of the arms averaged 33% during the eccentric phase and 29% during the concentric phase. The contributions of an arm swing during a CMJ results in different GRF characteristics when comparing eccentric and concentric phases with and without the use of the upper limbs. Practical Applications: The upper extremities can greatly influence vertical jump performances and the accompanying kinetics. When analyzing jump GRFs, strength and conditioning professionals must be aware of how much the upper limbs contribute to these forces during different CMJ phases. Additionally, proper arm swing mechanics must be emphasized when instructing correct jump technique.
Rapid Velocity and Rate of Activation Characteristics of the Knee Extensors in Young and Old Males
M. Magrini, G. Hester, Z. Pope, R. Colquhoun, C. Estrada, and J. DeFreitas
Oklahoma State University
The age-related loss of muscle power is associated with a decrease in physical functioning in older adults. Velocity is an important component of power, thus it is important to identify velocity-related measures that may be affected by aging. Furthermore, the neuromuscular factors that contribute to the age-related decrement in maximal velocity capacity are not clear. Purpose: To examine the rapid velocity and muscle activation characteristics of the knee extensors in young and old males. Methods: Healthy, young (YG; n = 15, age = 21 ± 1.95 years, body mass = 69.55 ± 13.93 kg) and old (OG; n = 15, age = 65.07 ± 9.05 years, body mass = 89.97 ± 13.20 kg) untrained males volunteered for this study. After being familiarized and performing several practice contractions, each participant performed 2–3 maximal concentric isokinetic contractions of the knee extensors at 500°·s−1 (IsoK500) using a 70° range of motion (ROM). Participants were instructed to “kick out as fast as possible throughout the entire ROM.” There was no resistance during IsoK500, with the exception of lever arm mass, as this velocity was above all subjects' maximum velocity. The highest velocity attained (PV; degree per second) and the linear slope of the velocity-time curve from the onset of contraction to PV (RVD; degree per·second square) were recorded for each IsoK500. Surface electromyography (sEMG) of the vastus lateralis was recorded and the peak EMG (PEMG; mV) amplitude was obtained for each contraction. The sEMG signal was normalized to PEMG and the rate of activation (RA; %PEMG per second) was calculated as the linear slope of the rectified EMG-time curve for a 50 milliseconds period after the onset of contraction. The contraction producing the highest PV was used for subsequent analysis of all dependent variables (DVs). Independent samples t-tests were performed for each DV to determine if differences existed between the YG and OG. A Pearson correlation coefficient was used to determine the relationship among PV, RVD, and RA in all participants regardless of age. Results: The OG demonstrated a reduced PV (−12.45%; p < 0.001) and RVD (−26.48%; p < 0.001) compared to the YG. However, there was no difference between the YG and the OG for RA (p = 0.226). Surprisingly, there was no relationship between RA and PV (r = −0.074, p = 0.699) or RA and RVD (r = −0.073, p = 0.702). Conclusions: These findings reveal that older adults had lower PV and RVD of the leg extensors when compared to young adults. Results suggest that RA does not considerably contribute to the performance differences; therefore, other mechanical or neurological components may contribute to performance. Practical Applications: These outcomes highlight the age-related differences in peak velocity, rate of velocity development, and rate of activation during a maximal velocity contraction. Because velocity is a pivotal part of power production deficits in velocity of the knee extensors may affect performance of functional tasks. When examining rapid force characteristics, future researchers should take caution to include the rate of activation since it was not significantly related.
The Effects of Various Weighted Implements on Baseball Swing Kinematics in Collegiate Baseball Players
C. Williams,1 N. Dabbs,2 J. Gdovin,1 S. Wilson,1 V. Moreno,1 D. Eason,1 E. Hoke,1 Y. Fu,1 C. Wade,1 and J. Garner1
1University of Mississippi; and 2California State University
Baseball players have a variety of warm-up implements available to use prior to an at bat. Previous research has examined bat velocities of different warm-up implements through a speed gate at the point of bat contact with a ball. To our knowledge, this is the first study that has examined 3D kinematics of a collegiate baseball swing. Purpose: The purpose of this study was to investigate the effects of different warm-up (WU) devices on maximal resultant velocity (MRV), resultant velocity at ball contact (RVBC), and time between MRV and RVBCin collegiate baseball players. Methods: Eight current varsity baseball players (age: 20.1 ± 1.2 years, mass: 87.5 ± 10.2 kg, height: 183.8 ± 5.9 cm) completed all experimental sessions during fall training. Retro-reflective markers were placed on the bat and tee to measure basic bat kinematics during the swing. Participants completed a general calisthenics WU before being counter-balanced into one of 4 WU conditions: standard bat (SB) (33 in/30 oz), fungo (FG) (10.6 oz), weighted gloves with standard bat (WG) (55.6 oz) and donut with standard bat (DN) (55.6 oz). Each participant was asked to perform their normal on deck routine, finishing with 5 maximal swings with the designated condition. After completion of the warm-up a one minute rest period (simulating normal game conditions) was given to allow each participant to get set to perform 5 maximal, game-speed, swings with a standard baseball bat. The participant chose his preferred batting stance and was instructed to hit a ball placed on a tee at a position comfortable for each participant. Each maximal swing attempt was separated by a period of 20 seconds to mimic the time difference between pitches. A ten minute wash-out period was given for each participant at the conclusion of the fifth experimental swing. Upon completion of the wash-out period, athletes repeated similar protocols for each condition. Results: Three 1 × 4 (group × condition) RMANOVA revealed no significant differences in MRV (SB 72.8 ± 4.5 mph, FG 72.6 ± 4.6 mph, WG 74.8 ± 4.4 mph, DN 73.8 ± 4.4 mph) or RVBC (SB 71.3.8 mph, FG 71.3 ± 2.6 mph, WG 72.6 ± 3.4 mph, DN 71.8 ± 3.8 mph) or time difference between MRV and RVBC between all WU conditions (SB 0.011 ± 0.011 seconds, FG 0.009 ± 0.008, WG 0.011 ± 0.009 seconds, DN 0.011 ± 0.009 seconds). Conclusions: Results of this study showed no significant differences in MRV, RVBC or time between MRV and RVBC for any WU implements as resultant of all 3 planes of motion. Future research should further examine the influence of different warm-up implements on body and swing kinematics. Practical Applications: If presented with the current options, athletes should chose the warm-up implement with which they are most comfortable.
Acute Caffeine Ingestion Does Not Affect Motor Unit Behavior During Submaximal Isometric Contractions
A. Sterczala, J. Nicoll, M. Trevino, J. Miller, A. Fry, and T. Herda
University of Kansas
The ergogenic effect of caffeine has been reported to increase muscular power, local muscular endurance and time to exhaustion. Research suggests that the performance enhancing effects of caffeine may be induced through increased calcium release from the sarcoplasmic reticulum or via increase excitatory neurotransmitter activity. As such, caffeine supplementation may affect motor unit (MU) behavior. Purpose: The purpose of this investigation was to determine the effects of caffeine on MU behavior of the first dorsal interosseous (FDI) during isometric trapezoidal muscle actions at 20% maximal voluntary contraction (MVC). Methods: In a crossover design, 10 healthy, college-aged men and women (23.2 ± 4.4 years, 173.4 ± 9.3 cm, 71.1 ± 11.7 kg) completed both caffeine and placebo trials on separate days. An electromyographic (EMG) sensor was placed over the FDI. Prior to caffeine or placebo ingestion, subjects performed 3 index finger abduction MVCs, followed by an isometric trapezoid muscle action at 20% MVC calculated from the highest MVC. For the isometric trapezoid muscle action, the force was increased at a rate of 10% MVC/s to the deserved force level for 30 seconds followed by a decrease of 10% MVC/s to baseline. A computer monitor provided subjects with a force trajectory and real-time feedback of their force output. After completion of the MVCs and the initial 20% isometric trapezoid muscle action, subjects ingested caffeine or the placebo. At 30 and 60 minutes post-ingestion subjects performed 2 additional MVCs followed by a 20% isometric trapezoid muscle action. Decomposition techniques were applied to the EMG data to extract action potentials and firing events of single MUs. Mean firing rates (MFR) during the contraction plateau were determined for each motor unit. The absolute change in EMG amplitude (EMGRMS) and MFR average from the second second to the 19th second for each 20% MVC was used for statistical analysis. Data were analyzed by two 2 × 3 repeated measures ANOVAs. Alpha level was set at p = 0.05. Results: No significant treatment × time interaction (p = 0.809) or main effects for treatment (p = 0.153) or time (p = 0.207) were observed for the changes in average MFR. Similarly, no significant treatment × time interaction (p = 0.828) or main effects for treatment (p = 0.975) or time (p = 0.229) were observed for the change in average EMGRMS. Data are presented in Table 1. Conclusions: Caffeine had no effect changes in average MU MFR or EMGRMS during the steady force portion for the isometric trapezoidal muscle actions at 20% MVC. The results of this investigation suggest that caffeine's ergogenic effect is not mediated by changes in MU behavior. Practical Applications: The reported performance enhancing effects of caffeine such as increases in muscular power, local muscular endurance and time to exhaustion are not likely due to changes in MU behavior.
Effect of Hip Constraints on Latissimus Dorsi Activation During Sprint Acceleration Mechanics
C. Greenleaf,1 W. Weimar,2 and J. Patel1
1Palmetto Health Orthopedics; and 2Auburn University
Bipedal sprint acceleration initiation is a ballistic movement, which is characterized by a forceful arm and leg motions. The Latissimus Dorsi (LD) has been shown to assist the pelvic girdle and trunk motion and possibly affect the techniques of the upper extremity in the performance of athletes. Meaning, that the arm swing is the opposition of the leg swing, and aids an individual in remaining upright during a demanding balance tasks. Hence, if hip motion is constrained then an associated change should be noted in the upper extremity to compensate for the reduction in hip motion. Purpose: The purpose of this study was to investigate Latissimus Dorsi LD muscle activity in response to hip motion constraints during sprint acceleration. Methods: Fifteen club-level male rugby students (22 ± 2.85 years, 182 ± 6.4 cm, 77.95 ± 10 kg) volunteered. Participants performed twelve bouts of a 10-m sprint for 4 different conditions. The conditions were randomized: (N) normal; (CUA) constrained upper arm; (CFA) constrained full arm; (CH) constrained hip. Each of the participants completed 3; 10-m sprints for each of the 4 conditions and surface electromyography (sEMG) of the ipsilateral and contralateral LD muscles at toe off (ILLDTO and CLLDTO) were recorded. Results: Two, 1 (side) × 4 (constrained condition) repeated measures ANOVA was conducted with a p value set apriori at <0.05. The results yielded a significant main effect for the constrained condition on the % Maximal Volitional Isometric Contraction (MVIC) of the ILLD at toe off (N = 1.94%±, and CH = 3.21%±). Additionally, a non-significant main effect was noted for %MVIC of CLLD at toe off (N = 0.68%±, and CH = 0.91%±) between the N and the CH conditions. Conclusions: The results of the present investigation suggest that the constrained hip conditions did yield increases in Latissimus Dorsi activity, with the significant difference yielding from the ILLD result. Meaning, the arm motion and corresponding upper body activity may contribute more than simply to balance and conserve angular movement. Practical Applications: The development of trunk and upper body musculature, specifically the LD, may enhance the overall performance of sprint mechanics during athletic competition. Additionally, understanding the dynamic relationship between the hip motion and the corresponding trunk motion may allow practitioners to devise specific, and potentially more efficient strength and conditioning programs for athletes who require sprint mechanics as a part of their athletic performance.
The Effect of Low Level Laser Therapy on Delayed Onset Muscle Soreness of the Biceps Brachii
M. Miller,1 T. Boike,1 C. Mass,1 W. Holcomb,2 N. Hanson,1 and T. Michael1
1Western Michigan University; and 2University of Southern Mississippi
Low level laser therapy (LLLT) is often used as a therapeutic modality to alleviate delayed onset muscle soreness (DOMS) associated with exercise. The majority of research utilized a range of 30–40 Joules of energy delivery, eliciting inconsistent results, with speculation that higher energy delivery, around 50 Joules, would produce improved results. Purpose: The purpose of this study was to determine if greater energy delivery during a LLLT treatment would be more effective in alleviating DOMS. Methods: The study took place in a human performance research laboratory. Twenty-three healthy subjects, 10 females, and 13 males (age = 26.0 ± 8.6 years, height = 175 ± 9.1 cm, weight = 79.7 ± 14.1 kg) volunteered to participate. Subjects completed 6 sessions each separated by 24 hours, one orientation session, 4 treatment sessions, and one post non-treatment assessment session. The orientation session consisted of obtaining demographic variables and determining peak concentric force of the left biceps brachii. The first treatment session included a DOMS protocol on an isokinetic dynamometer that consisted of 15 sets of 15 concentric and eccentric bicep brachii contractions at a speed of 90°·s−1 with one minute rest between sets. The DOMS inducing exercise bout was followed by a LLLT treatment. Soreness was measured before the DOMS protocol and during each consecutive treatment session before LLLT delivery, except during the last post session where only soreness was measured. Soreness was assessed using a 100 mm visual analogue scale (VAS) for perceived muscle pain, an algometer measurement for pressure tolerance, and an isometric hold test to measure strength loss as a result of soreness. A between groups design with repeated measures, utilizing one of 3 LLLT conditions (0 J applied to 8 subjects, 40.5 J applied to 8 subjects, and 50.9 J applied to 7 subjects) was delivered at 3 locations on the left bicep brachii (mid-point and 2 inches above and below). A Chattanooga Vectra Genisys Laser was used to deliver LLLT treatments. The investigator applying the LLLT and all subjects were blinded to the treatment condition. All conditions were randomized. Results: A 3 × 5 Repeated Measures ANOVA was used to determine differences between the energy groups and the soreness variables over time. The RMANOVA revealed no significant condition by time interactions for energy groups with VAS, algometer, and isometric hold tests (p > 0.05). Conclusions: The results indicate that LLLT, regardless of the Joules of energy used in this study, did not alleviate DOMS as tested. Practical Applications: During normal strength and conditioning workouts, muscle soreness can occur. However, LLLT used to alleviate this soreness is speculative at best. The strength and conditioning specialist and medical staff should use alternative treatment strategies to alleviate muscles soreness after exercise. More research is needed by the medical staff and strength training professionals to determine if greater Joules of energy may be more favorable for decreasing DOMS associated with exercise.
Have the Mechanical Demands of Lower Body Non-Ballistic Resistance Exercise Been Underestimated?
J. Lake and K. Austin
University of Chichester
The propulsion phase of ballistic (B) and non-ballistic (NB) resistance exercise has traditionally been identified as starting at the lowest displacement of the mass of interest to its peak displacement. Research shows that this can overestimate differences in the mechanical demands made during B and NB resistance exercise, leading to B typically been used for power development. Conversely, identifying the propulsion phase from the positive acceleration of the mass of interest has been shown to reduce differences in the mechanical demands made during B and NB. However, research comparing lower-body B and NB is limited to one load (45% of back squat one repetition maximum [1RM]). Purpose: The aim of this study was to compare differences between B (jump squat, JS) and NB (back squat, BS) mean force, velocity, power and time across a range of loads when the propulsion phase was identified using the traditional (peak displacement, PD) and alternative (positive acceleration, PA) methods. Methods: Twelve men performed 4 BS and JS repetitions with 30, 45, 60 and 75% of their BS 1RM on a Kistler 9281B force plate recording vertical force at 1,000 Hz. System weight was calculated by averaging 1 second of quiet standing force and was subtracted from force to obtain net force; this was divided by mass to obtain acceleration, which was integrated with respect to time to obtain velocity. Force was multiplied by velocity to obtain power. Displacement was obtained by integrating velocity with respect to time. Force, velocity and power were averaged over propulsion phases identified as starting from the lowest displacement to either PD or peak velocity (PA). Results: Descriptive statistics and results of repeated measures analysis of variance are presented in Table 1. JS mean force was significantly larger than BS mean force when the PA method was used (p < 0.001, d = 1.21). Differences were significantly, though not meaningfully, larger with 60% 1RM (p < 0.001, d = 1.26). JS mean velocity was significantly greater than BS mean velocity with all loads when both methods were used (p < 0.01, d = 3.12). Differences were significantly larger when the PD method was used (p < 0.001, d = 4.22). JS mean power was significantly greater than BS mean power with all loads when both methods were used (p < 0.001, d = 2.21). Differences were significantly larger when the PA method was used (p < 0.001, d = 2.39). JS time was significantly less than BS time with 45% (p = 0.001, d = 1.38), 60% (p < 0.001, d = 2.22) and 75% (p < 0.001, d = 2.61) 1RM when both methods were used; the 60% and 75% differences were significantly larger, as were differences when the PD method was used (45%: p = 0.01, d = 1.49; 60%: p < 0.001, d = 2.34; 75%: p < 0.001, d = 2.75). Conclusions: Results demonstrate that significantly greater mechanical demands are made by the JS over a shorter propulsion phase. However, the results also show that the importance placed on the method that is used to identify the propulsion phase of B and NB upper-body resistance exercise does not apply to B and NB lower-body resistance exercise. Practical Applications: The JS should be used when the desired training stimuli requires significantly more mean force and power to be applied at a faster velocity over a shorter propulsion phase. Furthermore, the PA method should be used when the mechanical demands of the active phase of resistance exercise are of interest, while using both provides a way of assessing time spent decelerating the mass of interest.
Decreased Percent Body Fat but Not Body Mass Is Associated With Better Performance on Combat Fitness Test in Male and Female Marines
E. Pletcher, M. Lovalekar, M. Frame, Y. Kido, K. Beals, B. Nindl, and K. Allison
University of Pittsburgh
Higher percent body fat (BF%) has been reported as a predictor of reduced running performance and muscular strength. The Marine Corps designed the Combat Fitness Test (CFT) to emphasize functional fitness related to operational demands. Three, equally weighted, components include an 880 yd endurance course (movement to contact: MTC), a 30 pound ammunition lift (AL) and a 300 yd shuttle run that includes combat related tasks (maneuver under fire: MANUF). Purpose: To investigate the association between body mass (BM), fat free mass (FFM), and BF% with CFT performance in male and female Marines. Methods: 210 male (22.4 ± 2.6 years) and 84 female (22.6 ± 2.8 years) Marines were categorized separately and grouped into quintiles according to BM (kg), FFM (kg) and BF%. Kruskal Wallis test or one-way ANOVA, as appropriate, were used to determine if significant differences in CFT total and component scores existed between groups of subjects classified into quintiles of BM, FFM and BF% (0.05, 2-sided). If required, post hoc analysis was conducted using a Bonferroni correction. Results: No significant differences in CFT scores were observed between BM quintile, in either men or women. No significant differences in CFT scores were observed between FFM quintiles in men. Total CFT score (p = 0.002), MTC (p = 0.014), MANUF (p = 0.008) and AL (p = 0.014) were all significantly different among FFM quintiles in women, with significant differences observed between the lowest and highest quintile for all variables, as well as between the lowest and third for Total CFT, MANUF and AL (Table 1). Total CFT score (p = 0.007), MTC (p = 0.001) and MANUF (p = 0.022) were significantly different among BF% quintiles in men, with significant differences observed between the lowest and highest quintiles for Total CFT and MANUF, as well as the lowest and third quintiles and the lowest and highest quintiles for MTC (Table 1). Total CFT score (p = 0.008), MTC (p = 0.033) and AL (p = 0.016) were significantly different among BF% quintiles in women with significant differences observed between the lowest and highest quintile for Total CFT score and the second and highest quintiles for MTC (Table 1). Conclusions: No significant relationship was observed between BM classification and CFT performance. In female Marines, a significant relationship existed between FFM classification and CFT performance. For both male and female Marines, a significant relationship existed between BF% classification and CFT performance. Male and female Marines in the lowest BF% quintile had better CFT scores than those in higher quintiles. Practical Applications: Results indicated that increased BF% in men and women might be detrimental to performance on total CFT score and its components, while increased FFM mass in women might be beneficial. Percent body fat may be a better indicator of predicting performance on CFT than BM. Acknowledgments: ONR Award #N00014-14-1-0021.
Time Course Toward Baseline of Hand-to-Foot BIA Body Fat Percentage Following an Acute Bout of Aerobic Exercise
K. Pezzuti, B. Nickerson, B. Welborn, M. Richardson, and M. Esco
University of Alabama
Bioelectrical impedance analysis (BIA) is a common field method used to measure body fat percentage (BF%) in sport and health and fitness settings. Though a bout of exercise may influence the reliability of BIA, limited research exists to examine this possibility. Purpose: The purpose of this investigation was to examine the influence of an acute bout of aerobic exercise followed by a 1-hour recovery period on predicted BF% via BIA. Methods: Fifteen college-aged adult males volunteered to participate in this study (age = 23.73 ± 3.7 years, height = 176.6 ± 6.8 cm, weight = 81.1 ± 10.3). A urine specific gravity (USG) < 1.020 was required by all participants prior to testing to ensure hydration status. Following USG measurements, each participant completed a 30-minute steady state treadmill bout of exercise at an intensity of 60% estimated heart rate reserve. BIA was measured before exercise (PRE), immediately post-exercise (IP), and at 10, 20, 30, 40, 50, and 60-minutes post-exercise. Results: The estimated BF% value via BIA at PRE was 22.35 ± 3.56%. The post-exercise measures were as follows: IP = 20.05 ± 3.49%; 10-minute post = 20.32 ± 3.36%; 20-minute post = 20.97 ± 3.57%; 30-minute post = 21.43 ± 3.68%; 40-minute post = 22.09 ± 3.71%; 50-minute post = 22.31 ± 3.68%; 60-minute post = 22.52 ± 3.63%. Compared to PRE, BIA measures at IP, (p < 0.001, Cohen's d = 0.65), 10-minute post (p < 0.001, Cohen's d = 0.58), 20-minute post (p < 0.001, Cohen's d = 0.38), and 30-minute post (p = 0.002, Cohen's d = 0.25) were significantly different. However, the remaining post-exercise measures were not significantly different than PRE (p values ranged from 0.34 to 0.91). Intraclass correlations showed that the post-exercise measures provided very large (ICC = 0.89 for IP) to near perfect (ICC = 0.91 to 0.98 for 10–60-minute post values) relationships with PRE. Conclusions: The findings from this study suggest that when compared to PRE, BIA estimates of BF% were significantly lower up to 30 minutes following exercise before approaching baseline values thereafter. The very large to near perfect ICCs suggested similar patterns of variation in estimated BF% at each post-exercise time point when compared to PRE. Practical Applications: Practitioners should consider the results of this study before estimating BF% with BIA within a health and fitness setting. When a bout of exercise was recently completed, a time period of least 40 minutes may be required to produce a value that is similar to pre-exercise levels. Though further research is needed, the time requirement following exercise may be less than what manufactures currently recommend for reliable estimates of BF% via BIA.
Fat-Free Mass Index in NCAA Division I College Football Players
E. Trexler,1 M. Blue,1 J. Mann,2 J. Mayhew,3 K. Hirsch,1 M. Mock,1 and A. Smith-Ryan1
1University of North Carolina at Chapel Hill; 2University of Missouri; and 3Truman State University
Many athletes seek to optimize body composition to fit the demands of their sport. American football requires a unique combination of power, speed, and body mass, with demands that vary widely between position groups. Fat-free mass index (FFMI) may be a valuable metric for strength and conditioning professionals to evaluate an athlete's capacity for gaining lean mass, or suitability for a given position. Normative values and upper limits for FFMI have previously been explored in resistance-trained males, but have not been evaluated in American football players. Purpose: To examine normative values and position-based differences in FFMI in Division I college football players. Methods: The current study consisted of a cross-sectional body composition analysis of 147 college football players (mean ± SD; age = 19.8 ± 1.2 years; height = 186.6 ± 6.5 cm, weight = 106.9 ± 20.0 kg), using dual-energy x-ray absorptiometry. Participants were instructed to abstain from eating and exercising 2 hours prior to the assessment. Body composition was measured in the pre-season period to estimate lean mass (LM), fat mass, and bone mineral content (BMC). FFMI was calculated using the following formula: FFMI = (LM + BMC)·(Height)−2, where LM and BMC were measured in kilograms, and height was measured in meters. Linear regression was used to normalize FFMI values for height; adjusted values were used for analysis. Results: Height-adjusted FFMI values ranged from 19.2 to 31.9 kg·m−2 (mean = 24.3 ± 2.0 kg·m−2, interquartile range [IQR] = 23.1–25.5). Using the height adjustment equation derived from the current sample, 47 athletes (32%) had values above 25 kg·m−2, which has previously been identified as a theoretical upper limit for male nonusers of anabolic steroids. Using the previously published equation for adjustment, 38 (26%) were above 25 kg·m−2. FFMI differed between positions (p < 0.001). Offensive linemen (25.2 ± 2.2 kg·m−2, IQR = 23.8–26.7), defensive linemen (DL; 25.9 ± 2.3 kg·m−2, IQR = 24.6–26.9), linebackers (24.6 ± 1.2 kg·m−2, IQR = 23.4–25.6), and running backs (RB; 25.7 ± 0.9 kg·m−2, IQR = 25.6–26.2) were all significantly greater than quarterbacks (22.9 ± 1.2 kg·m−2, IQR = 22.3–23.4), wide receivers (22.6 ± 1.5 kg·m−2, IQR = 22.2–23.8), defensive backs (DB; 23.6 ± 1.2 kg·m−2, IQR = 22.8–24.3), and special teams (22.6 ± 1.8 kg·m−2, IQR = 21.9–23.7; all p ≤ 0.05). Tight ends (23.8 ± 1.5 kg·m−2, IQR = 23.5–24.7) and LBs were both lower than RBs and DLs (p ≤ 0.05), and DBs were greater than WRs (p ≤ 0.05). Height adjustment had a minimal impact when compared to raw FFMI values (mean difference <0.001 kg·m−2, R = 0.996). Conclusions: FFMI differed significantly between position groups, indicating that FFMI may provide valuable information for football strength and conditioning practitioners. The previously suggested upper limit of 25 kg·m−2 appears to underestimate the upper limit for FFMI in Division I football players. Practical Applications: FFMI may help practitioners determine a player's potential for adding lean mass, and a player's suitability for a particular position group. Players can use position-based normative values to identify ideal FFMI goals, and athletes seeking to gain lean mass may realistically strive for FFMI values as high as the upper 20 s. FFMI can be calculated from any 2-compartment body composition estimate and does not appear to require height normalization in this population, thereby enhancing its potential for widespread application in strength and conditioning.
Validity of Selected Bioimpedance Equations for Estimating Body Fat Percentage: a Four-Compartment Model Comparison
B. Nickerson, B. Welborn, K. Pezzuti, P. Bishop, and M. Esco
University of Alabama
The assessment of body fat percentage (BF%) with bioelectrical impedance analysis (BIA) is advantageous in field settings due to its non-invasive nature, quick administration, and relatively low cost. Numerous BIA equations have been developed and are available for practitioners. However, the validity of each when compared to a 4-compartment model (4-C) model is unknown. Purpose: The purpose of this study was to compare BF% values derived from published BIA equations to the 4-C model. Methods: Eighty-two adults (42 men and 40 women) volunteered to participate (age = 22.6 ± 4.9 years). The impedance measurements (i.e., resistance and reactance) were determined with a hand-to-foot BIA (single-frequency), which was then used to calculate BF% from previously developed equations by Chumlea et al. (BIA-NHANES III), Deurenberg et al. (BIA-Deurenberg), Kyle et al. (BIA-Kyle), and Sun et al. (BIA-Sun). Criterion BF% was calculated with the 4-C model from body mass, body volume (BV), total body water (TBW), and bone mineral content (BMC). Underwater weighing with simultaneous residual volume was used to determine BV, bioimpedance spectrscopy for TBW, and dual energy x-ray absorptiometry for BMC. Results: No significant difference (p = 0.70) in mean BF% was seen for BIA-Sun (21.7 ± 7.3%) vs. the 4-C model (21.8 ± 7.8%), while BIA-NHANES III (24.9 ± 7.6%), BIA-Deurenberg (25.5 ± 6.9%) and BIA-Kyle (24.1 ± 7.2%), were significantly higher (p ≤ 0.05) compared to the criterion. The standard error of estimate for BIA-NHANES III, BIA-Deurenberg, BIA-Kyle, and BIA-Sun were 3.0, 3.8, 3.4, and 3.3% with a 95% limits of agreement of (±5.9%), (±7.4%), (±6.6%), and (±6.4%), respectively. Conclusions: The BIA-NHANES III, BIA-Deurenberg, and BIA-Kyle do not appear to be acceptably valid with the 4-C model. However, the non-significant mean difference, low standard error of estimate and narrow limits of agreement found in the BIA-Sun equation suggests it is valid, when compared to the 4-C model, for estimating BF% in adult males and females. Practical Applications: The Sun et al. equation is recommended when estimating BF% with hand-to-foot BIA. However, caution should be used when predicting BF% with BIA using the Chumlea et al., Deurenberg et al., and Kyle et al. equations.
Comparison of Lean Soft Tissue Measures From Hand-to-Foot, Single-Frequency Bioimpedance and Dual-Energy X-Ray Absorptiometry
B. Welborn, B. Nickerson, K. Pezzuti, and M. Esco
University of Alabama
Lean soft tissue (LST) is an important parameter of body composition assessment, especially as it relates to strength and conditioning. Dual-energy x-ray absorptiometry (DXA) is an accurate laboratory method of measuring LST. However, DXA measures are costly, time consuming, and not readily available. Some hand-to-foot bioelectrical impedance (BIA) devices provide a measurement of LST, yet little evidence is available to support their level of agreement with criterion measures. Purpose: The purpose of this study was to compare LST measures from hand-to-foot, single frequency BIA to DXA in a sample of healthy men and women. Methods: One-hundred and eighteen participants (male = 50.8%, age = 21.7 ± 4.6 years, height = 171.9 ± 9.7 cm, weight = 72.6 ± 16.5 kg) volunteered for this study. LST was measured via the BIA and DXA devices on the same day. Statistics included comparing mean values, correlation coefficients (r), and standard error of estimate (SEE). Results: The mean ± SD LST measures from BIA was 51.26 ± 13.30 kg and from DXA was 53.04 ± 13.78 kg, which was significantly different (p = 0.001, Cohen's d = 0.14). The LST measures from BIA were strongly and significantly correlated with DXA (r = 0.91, p < 0.001), with a standard error of estimate of 5.86 kg. Conclusions: The LST measurements from BIA was significantly lower compared to DXA, yet the difference was trivial. Significant and strong correlation existed between the 2 measures, and the BIA provided a range of individual error compared to DXA. Practical Applications: Practitioners should be aware of the study's results before utilizing hand-to-foot single-frequency BIA as a surrogate for DXA when measuring LST. The BIA measures could provide LST values that are slightly less than DXA.
Case Study: Longitudinal Effects of Contest Preparation on Psychological, Physiological, and Performance Attributes on a Drug-Free Bodybuilder
A. Pardue,1 L. Sprod,1 E. Trexler,2 W. Tseh,1 and A. Smith-Ryan2
1University of North Carolina—Wilmington; and 2University of North Carolina at Chapel Hill
Purpose: This case study assessed the effects of a 21 year old, male, amateur natural bodybuilder's contest preparation diet and exercise on various psychological, physiological, and performance parameters over a 12-month period. Methods: Hormonal analyses of serum testosterone, T3, T4, ghrelin and cortisol were taken every 3 months, with the exception of ghrelin, which was tested twice during the study: at baseline and again at month 8. Anaerobic power, sleep quality, resting metabolic rate, profile of mood states (POMS), resting blood pressure and heart rate, and body composition via BOD POD were assessed monthly. Body composition analyses via dual-energy x-ray absorptiometry were taken 3 times throughout the 12-month period: at baseline, month 8 and month 13. Results: Seven months prior to the beginning of the competitive season, serum testosterone, T3 and T4 gradually declined from 623 to 173 ng·dl−1, 123–40 ng·dl−1, and 5.8–4.1 ng·dl−1, respectively, while cortisol and ghrelin progressively increased from 25.2 to 26.5 μg·dl−1 and 383 pg·mL−1–822 pg·mL−1, respectively. Serum leptin remained within the <0.5 ng·mL−1 measurement range. Peak anaerobic power measured via Wingate Anaerobic Test declined from 752.96 to 536.48 watts while percent body fat and total body mass declined from 13.84% to 5.14% and 85.0 kg–76.3 kg, respectively, via DXA. Resting metabolic rate declined from 2,275.42 kcal·d−1 to 1,910.11 kcal·d−1. Total mood disturbance increased from 69 points to 114 points, peaking at 161 points reached at month 6 of the diet. Sleep efficiency, measured via Actigraph, increased from 74.5 to 81.5%. During the 5 months following the conclusion of the competitive season, total caloric intake systematically increased from 1,724 calories to 2,950 calories whereas aerobic activity decreased toward baseline values. Conclusions: This study supports the small but growing body of research on the transient, albeit negative effects that pre-contest diet and training strategies may invoke on drug-free bodybuilders preparing for competition. Practical Applications: Results gleaned from these data may be used to educate clinicians and coaches about the acute, deleterious effects of contest preparation upon the athlete's body and psychological state. Future research should focus upon minimizing these detrimental effects in order to maintain healthier endocrine levels and mitigate reductions in training performance, while striving for the low body fat percentage necessary for competitive success. Acknowledgments: This study was supported by funds acquired from The BioLayne Foundation and UNC Wilmington CSURF program.
Dual-Energy X-Ray Absorptiometry and B-Mode Ultrasound Estimation of Visceral Adiposity: Associations With Total Body Composition and Metabolic Risk
M. Mock, K. Hirsch, E. Trexler, M. Blue, and A. Smith-Ryan
University of North Carolina at Chapel Hill
The regional location and type of adipose tissue have both been demonstrated as stronger prognostics of metabolic disorder than conventional anthropomorphic measures, such as body mass index. Visceral adiposity has been associated with increased health risk, prompting exploration into means of quantifying adipose tissue type. However, visceral adipose estimation techniques need to be evaluated against known risk factors and refined in order to broaden their practicality. Purpose: To evaluate dual-energy x-ray absorptiometry (DEXA) and B-mode ultrasound (US) as methods of visceral adipose tissue estimation in relation to total body composition and metabolic blood markers. Methods: Forty-five volunteers (Males: n = 23, Females: n = 22; Mean ± SD; Age = 35.0 ± 8.9 years; Height = 171.1 ± 10.1 cm; Weight = 98.1 ± 18.3 kg, BMI = 33.4 ± 5.5 kg·m−2) underwent a body composition assessment and fasted blood draw. Fat mass (FM), fat-free mass (FFM), and body fat percentage (%fat) were determined from ADP (BodPod). Estimates of visceral adipose mass from DEXA (VATDEXA) were determined from the software-selected android region of a whole-body DEXA scan (GE iDEXA), while visceral adipose tissue thickness (VATUS) was measured from a B-mode ultrasound (GE logiq-e) image of the abdomen ∼5 cm proximal to the umbilicus. Fasted blood samples were analyzed for total cholesterol (TC), high-density lipoproteins (HDL), low-density lipoproteins (LDL), triglycerides (TRG), and insulin (INS). Pearson's correlation coefficients were determined to assess the strength of association between visceral adipose measures and FM, FFM, %fat, TC, HDL, LDL, TRG and INS. Correlations were also determined independently in males and females to evaluate potential sex differences. Results: When evaluating associations between VATDEXA and total body composition, significant positive correlations were found with both FM (p = 0.003, r = 0.435) and FFM (p = 0.015, r = 0.362). VATDEXA was also positively correlated with TRG (p = 0.021, r = 0.344) and INS (p = 0.002, r = 0.455), and negatively correlated with HDL (p = 0.024, r = −0.336). Despite exhibiting a significant positive correlation with VATDEXA (p < 0.001, r = 0.516), VATUS was not significantly associated with other body composition measures or blood markers. When stratified by sex, VATDEXA in males was strongly correlated with FM (p = 0.009, r = 0.534) but not FFM (p = 0.633, r = 0.104), while both FM and FMM correlations were significant in females (p = 0.001, r = 0.684; p = 0.013, r = 0.519). Conclusions: As a pro-inflammatory, metabolically active organ, visceral adipose tissue accumulation may have more severe health implications than other forms of excess fat. VATDEXA may serve as a sufficient indicator of risk without need for additional body composition analysis from ADP. Previous literature has cited the potential of B-mode ultrasound as a convenient, cost-efficient method of determining visceral adiposity, but equivocal results suggest the need to refine this technique prior to widespread use. Practical Applications: Measures of visceral adiposity may provide valuable insight into metabolic risk independent of other body composition metrics, prompting earlier nutrition and exercise interventions for health improvement. This may be especially relevant to certain athletic populations, including linemen, track and field throwers, and other strength/power athletes, where greater body mass is considered beneficial to sport but could compromise future health status.
Contributions of Body Composition Characteristics to Aerobic and Anaerobic Cycling Performance
M. Byrd, B. Wallace, J. Clasey, J. Switalla, J. Quinn, P. Baker, P. Joshi, and H. Bergstrom
University of Kentucky
Theoretically, the critical power (CP) test provides estimates of 3 separate parameters: (a) the highest power output that can be maintained for an extended period of time without exhaustion, called the CP; (b) the total amount of work that can be performed using the stored energy sources within the activate muscles, called the anaerobic work capacity (AWC); and (c) the time to exhaustion at any power output greater than CP. No previous studies, however, have examined the contribution of body composition characteristics (body fat percent [%BF], mineral free total body lean mass [LBM], and mineral free thigh lean mass [TLM]) to CP and AWC. Purpose: The purpose of this study was to examine the ability of body composition characteristics (%BF, LBM, TLM) to predict CP and AWC. Methods: Fifteen, anaerobically trained males (mean ± SD age: 22.5 ± 2.5 years; height: 177.5 ± 7.5 cm; body mass: 83.7 ± 12.1 kg) completed this study. The total body (%BF and LBM) and regional (TLM) composition characteristics of each subject were estimated by dual energy x-ray absorptiometry (DXA). The TLM was delineated using previously published anatomical boundaries for both left and right thighs. The CP and AWC were determined from the 3-minute all-out CP test, with the resistance set at 4.5% of the total body mass. The CP was defined as the mean power output over the final 30 s of the test and the AWC was calculated using the equation, AWC = 150 s (P150–CP), where P150 equals the mean power output for the first 150 s. Statistical analyses included Pearson product-moment correlations and stepwise multiple regression analyses at an alpha level of p ≤ 0.05. Results: The correlations among the body composition characteristics (mean ± SD: %BF = 16.1 ± 4.5%; LBM = 67.0 ± 9.6 kg; TLM = 14.3 ± 2.6 kg) and the CP test parameters (CP = 210 ± 37 W; AWC = 15.1 ± 29.3 kJ) are presented in Table 1. The stepwise regression analyses indicated that only LBM contributed significantly to the prediction of CP (CP = 2.3 [LBM] + 56.7 [r2 = 0.346; SEE = 31.4 W; p = 0.021]) and only TLM to AWC (AWC = 0.8 [TLM] + 3.7 [r2 = 0.479; SEE = 2.2 kJ; p = 0.004]). Conclusions: These findings indicated that the aerobic component (CP) of the CP test was most closely related to total body LBM. The anaerobic component (AWC), however, was more closely related to the mineral free lean mass of the thigh muscles than the total body. These findings supported that during cycle ergometry, the AWC is associated with stored energy sources within the active muscle mass. Practical Applications: The LBM and TLM contributed significantly to the prediction of CP and AWC, respectively. Thus, training programs to improve CP and AWC should be designed to include resistance-training exercises to increase mineral free total body and thigh lean mass, respectively.
The Incidence of Injuries in the Texas A&M Corps of Cadets Over the 2014 Fall Semester
G. Darling,1 C. Goodenough,2 J. Carter,3 H. Hopkins,2 S. Currenti,2 N. Ono,2 L. Greenwood,2 and M. Greenwood2
1EMT Brazos County; 2Texas A&M University; and 3United States Marine Corps
The dynamic environment in which our military operates requires the ability of our military personnel to deploy immediately, which demands that our troops are physically prepared and injury free. Purpose: To determine the incidence of injuries in the Texas A&M Corps of Cadets (CoC) over the 2014 Fall semester. Methods: During the 2014 Fall semester, the research team monitored the injury profiles for all 42 units of the CoC, which consisted of approximately 2,450 cadets. Throughout the study, when a cadet could not participate fully in their unit's physical training (PT), they would fill out an injury questionnaire (QS) designed by the research team. The QS was used in prior studies by the research team. After fully returning to PT, the cadets would return and complete the QS. Results: Throughout the semester, 201 QSs were completed. Males (156 QSs) completed more QSs compared to the females (45 QSs). However, when accounting for the male to female ratio, the females had a higher incident rate for injuries (14.5 vs. 7.4%) compared to males. Freshmen had the highest injury rate (51.2%) followed by sophomores (22.9%), juniors (16.4%), and seniors (9.5%). Cadets seeking commission were injured more (54.8%) compared to the cadets not seeking a military commission (45.2%). The CoC PT accounted for 53.7% of the injuries, and 28.4% of the injuries resulted from prior injuries. During the semester, 11 cadets missed training on repeated and separate occasions due to their injuries. Furthermore, 21.5% needed to seek professional medical evaluation beyond that of the athletic trainers. Conclusions: The results of this study were similar to our prior research on the CoC for the injury rates for freshmen (51.7–52.7%), sophomores (22.9–21.6%), juniors (16.4–13.5%), and seniors (9.5–12.2%). However, it appears that the CoC PT caused greater injuries for the 2014 Fall semester compared to our previous research (53.7–27.0%). Practical Applications: In our military, a major predictor of future injuries is prior injuries. Therefore, emphasis should be placed on preventing injuries from occurring through preliminary assessments and appropriate training. Considering injuries occurred mostly in the freshmen (51.2%), entering cadets should go through a preparatory training phase early in their training to reduce injuries. Allowing the body to accommodate to the upcoming training demands can hopefully reduce the number of injured cadets (54.8%) seeking a military commission. Acknowledgments: The research team would like to acknowledge the Texas A&M Corps of Cadets, especially Major Larry Parks, MAJ. US Army (Ret).
The Type of Injuries Sustained in the Texas A&M Corps of Cadets Over a Semester
C. Goodenough,1 G. Darling,2 J. Carter,3 H. Hopkins,1 S. Currenti,1 N. Ono,1 L. Greenwood,1 and M. Greenwood1
1Texas A&M University; 2EMT Brazos County; and 3United States Marine Corps
Over the last several semesters, the Texas A&M Corps of Cadets (CoC) has placed greater emphasis on injury reduction for their cadets. For any injury prevention program, the initial stage is injury surveillance to determine the amount and type of injuries. Purpose: To determine the type of injuries sustained for the entire CoC over a semester. Methods: This study occurred over the 2014 fall semester for the CoC. When a cadet could not participate in their physical training (PT), they reported to the research team to fill out an injury profile questionnaire (QS) designed specifically for the CoC. The QS has been used in prior studies by the research team. After the cadet was able to fully participate in PT, they would return and complete the QS. Results: Throughout the study, the cadets' (n = 201) reported injuries for specific muscle groups (32.3%), joints (43.3%), bones (9.5%), skin (1.5%), and tendons/ligaments (40.3%). Only 2 cadets, experienced heat illness, and 8.5% of the cadets missed training due to an illness. Of the 65 cadets that experienced muscular injuries (32.3%), there were injuries reported for the calf (15), hamstrings (11), lower back (11), quadriceps (8), upper arm (5), gluteal region (4), upper back (3), abdominal muscles (2), neck (2), pectoralis major (1), and lower arm (1), with 2 unspecified injuries. Of the 87 cadets (43.3%) who injured their joints, injuries were reported for the ankle (41), knee (49), hip (7), lumbar spine (6), thoracic spine (2), glenohumeral (9), wrist (1), and cervical spine (2), with no injuries reported for the elbow. Conclusions: Both the joints and musculature for the knee and ankle seem to be prone to injuries for the CoC, which is in agreement with our prior research. Furthermore, in agreement with our earlier research, this is primarily the result of the abrupt increase in running volume, running in poorly lit areas on uneven ground, running while in formation, and running in boots. Practical Applications: Incoming freshmen need to condition over the summer prior to reporting to the CoC. During their first semester in the CoC, the cadets need to slowly increase running volume and intensity, while including agility, balance, and proprioceptive training. This will likely decrease injuries while running in formation due to improvement in their reactive ability. Lastly, a gradual progression of walking and running in combat boots will allow the ankle, knee, and hip anatomy to adapt to the unique stress combat boots places on the body. Acknowledgments: The research team would like to acknowledge the Texas A&M Corps of Cadets, especially Major Larry Parks, MAJ. US Army (Ret).
The Exercise Inventory Readiness Questionnaire & Its Relationship to Injuries in the Texas A&M Corps of Cadets
S. Currenti,1 G. Darling,2 C. Goodenough,1 J. Carter,3 H. Hopkins,1 N. Ono,1 L. Greenwood,1 and M. Greenwood1
1Texas A&M University; 2EMT Brazos County; and 3United States Marine Corps
Research has shown several factors associated with injuries for those who participate in Reserved Officer Training Corps programs. When compared to the upper classmen (UC), freshmen (FM) cadets are more likely to become injured. The Exercise Inventory Readiness Questionnaire (EIRQ) is a 15 question assessment to determine if an individual should increase their training volume-load. Purpose: To investigate the differences between injured FM and UC cadets of the 42 units in the Texas A&M Corps of Cadets (CoC) (approximately 2,450 cadets) using the EIRQ. Methods: When a cadet could not participate in training due to an injury during the fall 2014 semester, they would complete an injury questionnaire designed by the research team, which contained the EIRQ. The questionnaire has been used in prior studies by the research team. Results: Over the semester, 201 injuries were recorded. Using an independent-samples T-Test, there was a significant (p < 0.01) difference between the total scores for the EIRQ between UC (24.4 ± 4.3) and FM (26.1 ± 4.5). Furthermore, there was a significant difference (p ≤ 0.05) between perceived consistency of academic and employment workload (UC 1.5 ± 0.8; FM 1.9 ± 0.9), and major life changes (UC 1.7 ± 0.8; FM 2.1 ± 0.8) for the UC and FM. When using independent-samples T-Tests, there were no statistical (p > 0.05) difference between the sleep habits, perceived diet, joint pain, relaxation/energy levels, exercise load changes, the way the cadets felt their body was handling the training, presence of allergy/illness, outlook for the Corps, perceived self-image, and relationship positivity, enjoyment of responsibilities between the UC and FM using the EIRQ. Conclusions: In agreement with our previous research, there is a significant difference between the UC and FM in regards to total scores and major life changes, with no significant differences for sleep habits, joint pain, relaxation/energy levels, exercise load changes, the way the cadets felt their body adjusted to the training, presence of allergy/illness, outlook for the Corps, and relationship positivity, enjoyment of responsibilities. Practical Applications: The majority of the injuries sustained in the CoC are the FM. Based on these findings, as well as our earlier research, when using the EIRQ, it appears the FM should not increase their training volume-load as rapidly as the UC. Future research should compare injured to non-injured cadets for the CoC. Acknowledgments: The research team would like to acknowledge the Texas A&M Corps of Cadets, especially Major Larry Parks, MAJ, US Army (Ret).
The Texas A&M Corps of Cadets' Dietary Habits of Injured Cadets
H. Hopkins,1 G. Darling,2 C. Goodenough,1 J. Carter,3 S. Currenti,1 N. Ono,1 L. Greenwood,1 and M. Greenwood1
1Texas A&M University; 2EMT Brazos County; and 3United States Marine Corps
Inadequate nutrition increases the chance of injuries, decreases performance, and increases the likelihood of developing overtraining syndrome. Purpose: To investigate the dietary practices of injured cadets for the Texas A&M Corps of Cadets (CoC). Methods: When a cadet would miss physical training (PT) as a result of an injury or illness, he or she would complete a questionnaire (QS) that assessed their dietary practices. The QS was designed by the research team specifically for this population, and used in our preliminary CoC research. Results: Over the semester, 201 QSs were completed. 67.7% (n = 136) of the cadets felt their diet was suitable to meet their training requirements. However, only 6% (n = 12) of the cadets reported eating breakfast prior to morning PT. Furthermore, 22.9% (n = 46) indicated that they did not drink fluids prior to morning PT. 48.8% (n = 98) of the cadets found it difficult to eat within 1–2 hours before training. However, 78.6% (n = 158) found it easy to eat a full meal within <1 hour following training. 31.3% (n = 63) indicated that their last meal prior to becoming injured was 8–10 hours earlier. 26.4% (n = 53) were trying to gain weight, whereas 32.5% (n = 65) of the cadets were trying to lose weight. Of the injured, 18.4% (n = 37) and 36.3% (n = 73) reported taking some form of nutritional supplements or multivitamin, respectively. The most common supplements included whey protein, fish oil, multivitamins, and vitamin C. Using independent sample T-Tests, there was no significant difference (p ≤ 0.05) between upper classmen (UC) and freshmen (FM) (UC 1.4 ± 0.7; FM 1.5 ± 0.7) for their confidence in their dietary practices. Conclusions: As indicated by our previous research, the cadets should be educated on optimal nutrition for their training needs. This is especially important regarding hydration prior to morning PT in the hot and humid environment of central Texas. Practical Applications: It is recognized that proper nutrition does not guarantee success. However, improper nutrition guarantees suboptimal performance, and increases the chance of becoming injured. The freshmen cadets, who acquire the most injuries, should be educated on proper dietary habits when entering the CoC. Acknowledgments: The research team would like to acknowledge the Texas A&M Corps of Cadets, especially Major Larry Parks, MAJ. US Army (Ret).
The Non-Exercise Related Stress Factors for the Injured Cadets in the Texas A&M Corps of Cadets
N. Ono,1 G. Darling,2 C. Goodenough,1 J. Carter,3 H. Hopkins,1 S. Currenti,1 L. Greenwood,1 and M. Greenwood1
1Texas A&M University; 2EMT Brazos County; and 3United States Marine Corps
As a cadet increases their fitness through training, they also increase their fatigue level. External factors, such as additional life stresses, augment the fatigue of a cadet. The accumulation of fatigue can decrease recovery, mood, and immunity. Purpose: To investigate the non-exercise related stress factors for injured cadets for the entire Texas A&M Corps of Cadets (CoC). Methods: Over the 2014 fall semester, when a cadet was injured in the CoC, they completed an injury questionnaire (QS) that was used in our previous research. The QS investigated the non-exercise related stress factors of the injured cadets. Results: Throughout the study, 201 QSs were completed. The injured cadets' college credits taken in the fall semester averaged 14.7 ± 1.6 credits for the upper classmen (UC), and 13.5 ± 1.9 credits for the freshmen (FM). College courses per semester taken were 5.4 ± 0.8 for the UC, and 1.07 ± 1.0 for the FM. Using independent sample T-Tests, there was no significant (p ≤ 0.05) difference between sleep habits of the UC (2.8 ± 0.5 hours) and FM (2.8 ± 0.5 hours), with 89.5% of the cadets not receiving the recommended amount of sleep (i.e., 7–8 hours per night). 17.9% of the cadets indicated they received ≤6 hours of sleep the night before becoming injured. 38.8, 19.9, 13.9, 13.4 and 7.0% stayed up past midnight the week before on 1–2, 3–4, 5–6, and 7 occasions, respectively. The week before the injury, 37.8, 38.8, and 22.4% reported 0, 1–2, and 3–4 major tests/assignments, respectively. Lastly, 10.9% of injured cadets reported having a job outside of the CoC. Conclusions: As stated from our previous research, studies should determine if there is a difference in the non-exercise related stress factors between the injured and non-injured cadets to determine if a difference exists. Practical Applications: The CoC demands a large amount of the cadets' time. Life stress will always be a part of the CoC, especially if the cadet chooses to pursue a military career. Research in the athletic population has shown that educating individuals on stress management can reduce injures and overtraining syndrome. Therefore, education on sleep, stress management, and restoration tactics should be incorporated into the CoC, especially for the FM. Acknowledgments: The research team would like to acknowledge the Texas A&M Corps of Cadets, especially Major Larry Parks, MAJ. US Army (Ret).
Impact of a 4-Week Linear Periodization Program on Army Physical Fitness Test Scores in ROTC Cadets
K. Allen, C. Metoyer, M. Esco, and P. Bishop
University of Alabama
When a cadet transitions to active duty, the Army Physical Fitness Tests (APFT) becomes required. ROTC programs follow the Army Physical Readiness Training Guidelines, but programs using those skills and exercises have not been evaluated. Purpose: The purpose of this study was to determine the impact of a 4-week linear periodization program on APFT scores in ROTC cadets. Methods: Fifteen men and 5 women (age 19.95 ± 0.92 years) completed the traditional APFT, which included 2-minute max push-up test, 2-minute max sit-up test, and a 2-mile run. The APFT is a cumulative score out of 300 from the 3 events. These testing measures were evaluated before starting the periodized program, and then re-tested at the end of the fourth week of training. The 4-day per week training consisted of a mixture of anaerobic and aerobic activities. The work load of each week was titrated linearly using a progressive overload scheme. Results: Pre-testing mean scores ± SD for the APFT were 240.1 ± 41.4, and post-testing scores were significantly higher (p = < 0.001, Cohan's d = 0.57) at 260.4 ± 29.5. Max push-up test scores increased from 58.1 ± 17.7 repetitions to 61.3 ± 18.5 repetitions (p = 0.025, Cohan's d = 0.17). Sit up scores increased from 68.2 ± 12.2 repetitions to 72.4 ± 11.7 repetitions (p = 0.001, Cohan's d = 0.35). The 2 mile run times decreased from 15.7 ± 2.4 minutes to 14.8 ± 1.7 minutes (p = < 0.001, Cohan's d = 0.43). Conclusions: These results suggest that a periodized progressive overload training program, significantly improved APFT scores. Practical Applications: The Physical Readiness Training Manual includes most of the exercises that were included in the training program. A progressive overload scheme may increase APFT scores in a short amount of time. Although only 3 exercises are used to evaluate fitness levels, overall increases may impact several components of fitness including muscle strength, muscle endurance, and cardiovascular fitness.
Effects of Combining Resistance and Cardiovascular Endurance Training on Modified Raw Assessments
K. Warr, P. Meckley, J. Hornsby, J. Houck, C. Daymude, J. Boyle, J. Miller, M. Armbrust, K. Lopp, D. Stewart, and J. Schoffstall
Muscular strength, power, and cardiovascular endurance are vital for Reserve Officer Training Corps (ROTC) cadets as well as active-duty Soldiers operating in the field. These attributes are especially relevant when lifting heavy objects, traveling long distances, or moving rapidly from one area to another with maximum speed and agility. Purpose: The purpose of this study was to examine the effects (pre vs. post) of 5 weeks of resistance training combined with cardiovascular endurance training on modified Ranger Athlete Warrior Assessments (RAW-M). Methods: Eleven (males, n = 9; females, n = 2) college-aged Army ROTC cadets, who were also members of the university's Ranger Challenge Team, participated in this study. Each week of physical fitness training consisted of the following session types for a total of 5 sessions per week: 2 resistance training sessions, 2 cardiovascular endurance sessions, and one tactical session. Each session lasted approximately 90 minutes and were conducted at the same time of day. The RAW-M consisted of 7 events performed in the following order: 5-10-5 shuttle run, standing broad jump, trap bar deadlift, pull-ups, metronome push-ups, heel claps, and two 300 yd shuttle runs (separated by one minute of rest). Results: Paired samples t-tests produced the following significant differences (pre vs. post): 5-10-5 (5.32 + 0.43 vs. 5.21 + 0.38 seconds [p = 0.04]), trap bar deadlift (108.6 + 29.1 vs. 113.6 + 28.2 kg [p = 0.01]), and metronome push-ups (32.5 + 8.32 vs. 36 + 9.7 repetitions [p = 0.01]) Conclusions: This study suggests that combining resistance training with cardiovascular endurance training at a set volume with a self-selected intensity improved cadets' agility, lower-body strength, and upper-body muscular endurance. Future studies should investigate the effects of external load on these tasks as Soldiers operate under such conditions. Practical Applications: Implementing resistance and cardiovascular endurance training in other ROTC programs could improve the physical performance of cadets in the RAW-M and in other events such as The Army Physical Fitness Test. Based on these results, ROTC programs could benefit from this partnership between ROTC and health and fitness specialists. Developing these relationships would help disseminate how and why this type of training is beneficial. Lack of resources is often cited as a limitation to implementing this type of training. However, reaching out to college/university ROTC and other military groups with the necessary facilities/equipment have been shown to be successful. Lastly, workshops, seminars, or training videos are another means to help increase the flow of knowledge to those ROTC programs who may not have on-site access to health and fitness professionals to help inform cadets of the current training trends in tactical settings.
Relationship Between Functional Movement Screening Score and Identifying of Injuries in Different Adolescent Athlete
L. Lin,1 M. Lo,2 G. Li,3 and W. Tseng3
1Graduate Institute of Physical Education, Health & Leisure Studies; 2Kun Shan University; and 3National Cheng Kung University
Purpose: Musculoskeletal injuries are a primary source of disability of the adolescent athlete in Taiwan. The purpose of this study was to investigate the relating of the functional movement screening for predisposition to injury between youthful athletes. The secondary aim was to investigate whether the score of testing differed between distinct sports. Methods: Seventy high school athletes (mean age = 16.5 ± 1.0 years), participated in badminton, tennis, track & field and soccer sports for at least 5 years were recruited. The athletes were screened with 7 movement tests (deep squat [DS], trunk-stability push-up [PU], right and left hurdle step [HS], in-line lunge [ILL], shoulder mobility [SM], active straight leg raise [ASLR], and rotary stability [RS]) during the examination to determine asymmetry and total score. Injury judgment were gathered throughout medical records by orthopedic surgeons and classified into low bock, shoulder, knee, and ankle injury. Results: 33 subjects (47%) were diagnosed with injury. There were significant correlations differences between DS and ankle injury (p = 0.03), ASLR and low-back injury. In the movement score, there were significant differences between the sports in the DS, HS, ILL, ASLR and total scores (p ≤ 0.05), with the badminton and tennis athletes scoring better than track & field and soccer sports. There was no significant difference in the SM and RS score between different sports. Conclusions: The functional movement screening might provide a better ways to identify personal movement balance and symmetry for injury prevention. Acknowledgments: Sports Administration Ministry of Education National Science Council of Taiwan NO. 104-2410-H-006-121.
Relationship Between Perceived vs. Measured Physical Fitness and Occupational Readiness in Firefighters
K. Sell,1 M. Uftring,2 and M. Abel3
1Hofstra University; 2Sacramento Metropolitan Fire District; and 3University of Kentucky
Theoretical models suggest an individual's willingness or motivation to partake in healthful behavior is influenced by perceived need to maintain or improve current health status. Therefore, a greater understanding of the relationship between perceived physical fitness and measured occupational readiness, physical fitness, and physical activity behaviors, may assist fitness professionals in implementing personalized, population-specific fitness programs for firefighters (FF). Purpose: The purpose of this study was to elucidate the relationships between perceived physical fitness and occupational readiness, physical activity behaviors, and multiple components of measured physical fitness in structural FF. Methods: Twelve active-duty male structural FF (Age: 26.7 ± 10.8 years; Height: 176 ± 6.1 cm; Body mass: 89.3 ± 10.9 kg) volunteered to participate in the study. Each FF participated in a battery of fitness tests, a simulated fire ground test (SFGT), and completed questionnaires to identify self-perceived physical fitness, perceived ability to complete fire ground tasks, and frequency (degree·per week) of aerobic and strengthening activity. Fitness attributes assessed included aerobic capacity, muscular strength, flexibility, and body composition. The SFGT included a stair climb, hose drag, equipment carry, ladder raise, forcible entry, room search, and victim rescue. Bivariate correlations were conducted to identify the relationship between perceived physical fitness vs. measured occupational readiness, physical fitness, and physical activity behaviors. Results: Measured body composition was significantly correlated with self-perceived overall fitness, muscular strength, flexibility and body composition. Measured aerobic capacity was significantly correlated with self-perceived overall fitness, aerobic capacity, and flexibility. Significant correlations were also found for self-perceived overall fitness, muscular strength, and flexibility with self-perceived ability to complete the SFGT. However, only self-perceived aerobic fitness was significantly correlated with measured overall time on the SFGT (as well as the equipment carry and ladder raise tasks) (p ≤ 0.05). Frequency of strengthening activities and vigorous aerobic activity were significantly correlated to self-perceived competence on several fire ground tasks (p ≤ 0.05), but physical activity behaviors were not significantly correlated with any measured performance times on individual or overall SFGT tasks. Conclusions: Results suggest there may be a lack of agreement between self-perceived and actual physical fitness or occupational capacity on fire ground tasks in this sample of FF. The only attributes for which self-perceived and actual measures were significantly correlated were body composition and aerobic fitness. However further research with a larger sample size is still needed to confirm these findings. Practical Applications: The lack of agreement between self-perceived and actual measures of fitness, coupled with the finding that self-perceived aerobic fitness is significantly correlated with SFGT performance time supports the need for regular fitness testing to provide FF with an accurate gage of their current fitness level across multiple fitness areas. Regular feedback in this manner may help motivate FF to adhere to a regular physical conditioning program to either maintain or improve current fitness levels. Acknowledgments: Thank you to the firefighters at Ruston Fire Department and Lincoln-Parish Fire Department for participating in this study and for their ongoing service.
Comparison of On- vs. Off-Duty Sleep, Physical Activity, and Heart Rate Variability in Professional Firefighters
M. Abel,1 A. Lesniak,1 K. Sell,2 and C. Morris3
1University of Kentucky; 2Hofstra University; and 3University of Texas
The leading cause of on-duty death among structural firefighters is sudden cardiac death (4). There are numerous health behaviors associated with increased risk of cardiovascular disease (CVD), including a sedentary lifestyle and inadequate sleep via hypothalamo-pituitary-adrenal axis dysfunction (1, 3, and 5). In addition, reduced heart rate variability (HRV) is an indicator of increased sympathetic tone or decreased vagal activity and is associated with an increased risk of a first cardiovascular event in individuals without known CVD (2). Thus, monitoring HRV in a vulnerable population seems prudent. However, there is limited research objectively measuring physical activity, sleep, and HRV in firefighters while on-vs. off-duty. This information may indicate whether firefighters' health behaviors are different while at the fire station and thus provide guidance toward implementing appropriate worksite interventions to reduce CVD risk. Purpose: The purpose of this study was to determine the effect of work status on health-based outcomes of sleep, physical activity, and HRV. Methods: Twelve male structural firefighters (Age: 37.3 ± 7.6 years; Height: 183.2 ± 7.1 cm; Body mass: 90.4 ± 13.7 kg; Body mass index: 26.9 ± 2.4 kg·m−2) wore an accelerometer for 19.1 ± 5.8 days while on- and off-duty to measure physical activity and worn for 16.3 ± 3.5 days to measure sleep quantity and quality. HRV was determined with a portable ECG device upon waking for 20.8 ± 4.6 days. Specifically, SDNN, low frequency (LF) and high frequency (HF) normalized units were measured. Descriptive statistics were calculated as mean ± standard deviation and paired sample t-tests were used to compare all outcome variables between on-vs. off-duty days. The level of significance was set at p ≤ 0.05. Results: Firefighters accumulated 79.1 ± 34.5 min·d−1 of moderate-to-vigorous physical activity on combined days (i.e., on- and off-duty), exceeding the recommendation of ≥30 min·d−1. There was no difference in daily time spent in moderate, vigorous, and moderate-to-vigorous physical activity while on-vs. off-duty. Firefighters accumulated 6.3 ± 0.6 hours of sleep on combined days, which was below the recommended 7–9 hours per night. Compared to off-duty, firefighters' on-duty sleep was less efficient (86.4 ± 4.9 vs. 87.8 ± 4.7%, p = 0.009) and they spent more time awake during sleep awakenings (3.4 ± 0.9 vs. 3.0 ± 0.7 minutes, p = 0.033). Firefighters displayed similar output for total sleep time, number of awakenings, and sleep latency between on-vs. off-duty days. HRV analysis revealed a predominance of the normalized LF component indicating higher levels of sympathetic activation (SDNN: 211 ± 418 milliseconds; LF: 64.2 ± 15.2%; HF: 35.8 ± 15.7%). There were no differences in HRV outcomes between on-vs. off-duty days. Conclusions: Firefighters met the physical activity recommendations, but did not obtain adequate amounts of sleep to decrease the risk of CVD. Although physical activity recommendations were met, chronic sleep deprivation may offset the protective effects of exercise as indicated by the elevated normalized LF component. Practical Applications: Regular physical activity and adequate sleep are necessary to reduce the risk of CVD. Fire departments should encourage participation in a supervised exercise program and educate firefighters about proper sleep practices. Acknowledgments: This research was supported by the NSCA's Senior Investigator Research Grant.
Reflective Group Between Educators: a Five Step Strategy to Impact the Professional Development of Certify Olympic Weightlifting Coaches in Puerto Rico
R. Alvarez Feliciano
R. L Á. Feliciano, EdD. University of Puerto Rico, Rio Piedras-PR. To be a certified as a sport coach in Puerto Rico (SC), the state thru the Sport and Recreation Department require a 35 to 60 contact hours in Sports Science, Education and Sport Specialization. This offer is far behind from SC Programs (SCP) in other countries or even other sport related field, like the Physical Teacher. Others countries SCP require a bachelor degree and in some a thesis is needed. Purpose: In this research we evaluate the impact of the REFLECTIVE GROUP BETWEEN EDUCATORS (RG) on the professional development of Six State Certify Olympic Weightlifting Coaches (OWC), as an option to upgrade the state certification program. Methods: Six certified OWC were divides in 3 RG, depending on the type of certification (Basic, Specialize and High Performance). RG is a 5 step strategies (Organization, Planning, Data Recompilation, Analysis and Conversation) made for educators in the academic classroom (Ramos Rodriguez, 2002). Before the coaches RG take place all 6 coaches and 2 athletes of their own (n = 18), took a Pre Test (PDSE in Spanish) to know the level of dominion toward: 1. Organization of a sport session, 2. Athlete supervision, 3. Fitness, 4. Technique, 5. Tactics, 6. Theory and 7. Sports Psychology. All the 3 coaches RG focus to improve the dominion 1- (Organization of a sport session). After they implement the coaches RG with the 5 step strategies, every OWC create his own professional development plan (PDP). The PDP have different strategies to help the coaches master the best practice they need. After the PDP was completed a Post Test Questionnaire (PDSE) was give it to all 6 SC and the 12 athletes (n = 18). Also an interview was made with the 6 OWC. Results: After the 3 coaches RG 5 step strategies was implement, Athletes has the perception that the OWC professional practice improve in a 2.23% and OWC perceive a 2.70% improve. Also in the OWC interview their approach toward RG was more significant. The results of this study using athletes and coaches perception made a triangulation by source and the quantitative PDSE Test with the Qualitative OWC Interview made a triangulation by method. Conclusions: RG 5 step strategies is an option to improve the state certification sport coaching program (SCP) in Puerto Rico. Practical Applications: The RG 5 step strategies is a useful tool for: (a) SPC at universities and instituted, (b) Mentor new sports coaches and (c) Ensure the knowledge and dominion of a new sports practice as a coach. The PDP is a must know instrument for SC to keep individually, self-motivated, improving their practice. The RG with the PDP implementation could empower the coaches with an unlimited and ongoing education toward the dynamic field of sport training.
The Effect of Acute Endurance Exercise and Recovery Time on Subsequent Firefighter Performance
M. Uftring,1 M. Abel,2 D. Szymanski,3 M. Greenwood,4 S. Lacy,3 and N. Johnson3
1Sacramento Metropolitan Fire District; 2University of Kentucky; 3Louisiana Tech University; and 4Texas A&M University
Firefighting is a strenuous occupation that requires adequate aerobic fitness to perform firefighting tasks. In addition, sudden cardiac death is the leading cause of on-duty death among firefighters. The National Fire Protection Association has suggested that fire administrators allocate time for firefighters to participate in fitness programs while on-duty in order to meet occupation demands and reduce the risk of chronic disease. Aerobic endurance exercise is an effective mode of training to address these issues. However, it is possible that performing endurance exercise on-duty will produce fatigue that may negatively affect subsequent occupational physical ability. Purpose: To evaluate the effect of acute aerobic endurance exercise and recovery time on simulated fire ground performance. Methods: Twelve male firefighters (age: 30.8 ± 9.6 years; body mass index: 28.8 ± 3.2 kg·m−2; V[Combining Dot Above]O2peak: 51.2 ± 7.2 ml·kg−1·min−1) completed a timed simulated fire ground test (SFGT; i.e., work rate assessment) at baseline, and at 10 and 60 minutes post-exercise (randomized order). The SFGT was composed of the following tasks: stair climb, hose drag, equipment carry, forcible entry, ladder raise, forcible entry maneuver, search, and victim rescue. The firefighters performed the SFGT twice for familiarization purposes prior to the official trials (ICC = 0.86). Firefighters performed a 30 minutes vigorous running bout on a treadmill at 60% of heart rate reserve (HRR). The firefighters recovered passively for either 10 or 60 minutes. Blood lactate and rating of perceived exertion were measured before and after the treadmill session and SFGT. Repeated measures ANOVA were used to compare the post-exercise SFGT outcomes to baseline. Relative difference scores were calculated as follows: [(post-exercise condition − baseline condition)/baseline condition] × 100. Results: Despite substantial variability within the SFGT time samples, time to complete the SFGT 10 minutes post-exercise (relative difference = 5.2 ± 11.9%; Min–Max: −20.2 to 25.8%) and 60 minutes post-exercise (relative difference = 9.4 ± 24.2%; Min–Max: −25.5 to 50.6%) were similar to the baseline SFGT (p = 0.45). Firefighters' RPE was greater following the SFGT in the 10 minutes trial compared to baseline and 60 minutes trials (p ≤ 0.023). Pre-SFGT blood lactate was similar between all trials. There were no significant differences in post-SFGT blood lactate concentrations between all trials. Conclusions: Performing 30 minutes of aerobic exercise at 60% HRR does not decrease the work rate of subsequent fire ground tasks, however, perception of effort to complete occupational tasks increased for the 10 minutes post-exercise trial. Despite the non-significant findings, there was considerable variability in the effect that the exercise stimulus had on individual firefighters' occupational performance. There are a host of factors that influence recovery rates from exercise that may include fitness level, genetics, sleep levels, dietary/hydration status, psychological stress and lack of motivation prior to performing the exercise and SFGT protocols. Practical Applications: Most firefighters can safely perform 30 minutes of vigorous aerobic exercise while on-duty, without experiencing a negative impact on subsequent occupational performance. This suggests that aerobic exercise may be a recommended mode of exercise to perform while on-duty given that it will reduce cardiovascular disease risk and improve aerobic aspects of occupational tasks. Acknowledgments: We would like to thank the Ruston Fire Department, Lincoln Parish Fire Department, and the firefighters for their participation and support in this study.
Thursday Abstract Poster Presentations—Session B
July 07, 2016, 3:00 PM–4:30 PM—Celestin ABC
Thursday, July 07, 2016, 3:00 PM–4:30 PM
Physiological Profile of Monozygous Twins With 35 Years of Differing Exercise Habits
K. Bathgate,1 J. Bagley,2 E. Jo,3 N. Segal,4 L. Brown,5 J. Coburn,1 C. Gulick,1 C. Ruas,1 and A. Galpin5
1Human Performance Laboratory, Center for Sport Performance, California State University, Fullerton, California; 2Muscle Physiology Laboratory, Department of Kinesiology, San Francisco State University; 3Human Performance Research Laboratory, California State Polytechnic University, Pomona, California; 4Department of Psychology, California State University, Fullerton, California; and 5Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California
Variations in physical ability between individuals depend on both training background and genetics. Previous research has investigated the details of this phenomenon by studying monozygous (identical) twins with long-term, moderate differences in physical activity patterns and/or monozygous twins with short-term, but greater differences in physical activity patterns. However, no previous research has used monozygous twins with both substantial and long-term differences in physical activity patterns. Purpose: Thus, to enhance our understanding of heritability and adaptability of various performance factors we analyzed the physiological profile of a set of monozygous twins with 35 years of differing exercise habits. Methods: One pair of male monozygous twins (age = 52 years) participated in this study. DNA testing confirmed zygosity. The trained twin (TT, ht = 186 cm mass = 94 kg) is a physical education teacher and track coach who began running cross-country and track in 1981. TT has been training and competing in endurance sports (e.g., running, triathlons, etc.) consistently over the past 35 years. He has ∼39,431 running miles recorded from July 1993 to June 2015. In 2005, he qualified for All World Bronze Level in the Ironman. The untrained twin (UT, ht = 183 cm, mass = 104.5 kg) is a delivery truck driver. He was recreationally active in swimming, biking, and team sports early in life, but, has not engaged in regular or structured exercise since then (∼35 years). Since 1991 UT recreational physical activity has been limited to ∼20–30 min walks, 3–4×·wk−1. Both participants performed 4 trials of 6-second maximal isometric contractions of the right leg extensors, 5 trials of grip strength testing with both hands (hand grip dynamometer), as well as a maximal aerobic capacity (V[Combining Dot Above]O2max) test (cycle ergometer). Additionally, a dual-energy X-ray absorptiometry scan was used to determine body composition and total bone mineral content (BMC). Results: UT displayed higher absolute peak torque (254 vs. 137 N·m, 59.9% difference) and grip strength (right = 56.5 vs. 44.3 kg, 24.2% difference; left = 51.7 vs. 43.7 kg, 16.8% difference). When normalized to lean body mass (LBM), UT continued to display higher peak torque (3.40 vs. 1.83 N·m−1·kg−1, 60% difference) and grip strength (right = 76 vs. 59% of LBM, 25.2% difference; left = 69 vs. 58% of LBM, 17.3% difference). However, UT had a lower absolute (3.67 vs. 4.66 L·min−1, 23.9% difference) and relative (35.1 vs. 47.5 ml·kg−1·m−1, 30.1% difference) V[Combining Dot Above]O2max. UT also had a higher body fat percentage (BF%) (27.8 vs. 19.2%, 36.6% difference), but nearly identical LBM (74.6 vs. 74.7 kg, 11.0% difference) and BMC (3575.7 vs. 3653.0 g, 2.1% difference). Conclusions: Long-term, mixed mode endurance training positively influenced V[Combining Dot Above]O2max and BF%, did not alter LBM or BMC, and was associated with lower isometric leg extensor and handgrip strength. The percent difference between the participants also demonstrates a level of “trainability” that exceeds previous research. Practical Applications: Leg strength and V[Combining Dot Above]O2max are significant and independent predictors of mortality. Training can influence both of these variables. However, adaptations are specific to imposed demands. Therefore, an ideal lifestyle approach should incorporate resistance exercise and endurance training to maximize both leg strength and aerobic capacity.
Effect of Ibuprofen on Anti-Inflammatory Cytokine Responses to Ultra-Endurance Cycling in a High Temperature Environments
S. Rojas,1 D. Levitt,1 H. Luk,1 A. McKenzie,2 M. Ganio,3 B. McDermott,3 K. Williamson,4 C. Munoz,2 E. Lee,2 L. Armstrong,2 B. McFarlin,1 D. Hill,5 and J. Vingren1
1Applied Physiology Laboratory, University of North Texas; 2University of Connecticut; 3University of Arkansas; 4Midwestern State University; and 5University of North Texas
Introduction: Endurance exercise, especially under extreme environmental conditions such as heat and humidity, elicits an inflammatory response coordinated by cytokines. Anti-inflammatory cytokines aid in limiting the magnitude of inflammatory signaling. The inflammatory response could be affected by common behavioral practices such as ingestion of ibuprofen before the exercise bout. Independently, ibuprofen and ultra-endurance exercise affect the production of cytokines. However, the effect of ibuprofen on the anti-inflammatory cytokine response to an ultra-endurance cycling event in the heat has not been previously investigated. Purpose: To examine the effect of ibuprofen consumed before an ultra-endurance road cycling (164 km) event in the heat on anti-inflammatory cytokines. Methods: Thirty-one men experienced in cycling (age = 51 ± 9 years, height = 171 ± 20 cm, body mass = 81.2 ± 15.0 kg, body fat = 22 ± 6%) registered for the August 2015 Hotter'N Hell Hundred ride in Wichita Falls, TX. Participants ingested either ibuprofen (600 mg) or placebo (rice flour) prior to completing a 164-km bicycle ride in the heat (WBGT: 23.7–32.8° C). Blood was collected within the 2 hours prior to the ride (PRE, 0500–0700 hours) and immediately after event completion (POST). Serum was analyzed for anti-inflammatory cytokines interleukin (IL)-4, IL-5, IL-7, IL-10, and IL-13. Results: A significant (p ≤ 0.05) time × condition interaction effect was found for IL-10. From PRE to POST, there was a greater increase in IL-10 for placebo than for ibuprofen. A significant main effect for time was found from PRE to POST, which led to an increase in production of IL-4, IL-5, IL-7, and IL-13. No main effect for condition was found. Conclusions: Ingesting ibuprofen prior to an ultra-endurance cycling event in the heat attenuates the increase in production of IL-10, a key anti-inflammatory cytokine. However, ibuprofen did not affect the exercise-induced increased in the production of anti-inflammatory cytokines IL-4, IL-5, IL-7, and IL-13. Thus, ingesting ibuprofen in this context inhibits some, but not all, anti-inflammatory signaling. Practical Applications: Ibuprofen ingestion prior to ultra-endurance cycling in the heat can blunt the IL-10 response, which could alter the recovery process. Athletes should use caution when consuming ibuprofen before ultra-endurance exercise since anti-inflammatory signaling is important for exercise recovery.
Ibuprofen Does Not Affect Changes in Leukocyte Subsets in Response to Ultra-Endurance Cycling in the Heat
K. Cartas,1 D. Levitt,2 H. Luk,1 B. McFarlin,2 L. Armstrong,3 D. Hill,1 B. Kupchak,4 A. McKenzie,3 K. Williamson,5 L. Kunces,6 C. Munoz,3 E. Lee,3 and J. Vingren2
1University of North Texas; 2Applied Physiology Laboratory, University of North Texas; 3University of Connecticut; 4Uniformed Services University; 5Midwestern State University; and 6EXOS
Introduction: We have previously found that after a 164-km ultra-endurance cycling event in the heat, the concentration of leukocytes in circulation substantially increases, with an unequal contribution from each leukocyte subset. It is popular practice for participants to consume non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen prior to the start of an ultra-endurance event. However, the potential effect of ibuprofen on leukocyte subsets in the context of ultra-endurance cycling in the heat remains unknown. Purpose: To determine the effect of consuming ibuprofen prior to an ultra-endurance cycling event in the heat on the leukocyte subset response. Methods: Twenty-7 experienced cyclists (age = 52 ± 10 years, height = 170 ± 17 cm, body mass = 81.1 ± 15.7 kg, body fat = 22 ± 6%) participating in the August 2015 Hotter'N Hell Hundred bicycle ride in Wichita Falls, TX were recruited, and randomly assigned to consume ibuprofen (600 mg) or placebo (rice flour) prior to beginning the 164-km ride. The wet-bulb globe temperature (WBGT) readings during the event ranged from 23.7° C to 32.8° C. Blood was collected within the 2 hours before the beginning (PRE; 0500–0700 hours) and immediately after completion (POST) of the event. Blood samples were analyzed for the total concentration of circulating leukocytes and for the concentration of monocytes, neutrophils, lymphocytes and granulocytes. Results: No significant time × condition interaction effect was found. A significant (p ≤ 0.05) main effect for time was found for total leukocytes, monocytes, neutrophils, lymphocytes, and granulocytes which increased from PRE to POST. No significant effect for condition was found. Conclusions: Ibuprofen consumed prior to a 164 km ultra-endurance cycling event in the heat did not alter the leukocyte subset response to the exercise bout. However, completion of the ride induced a substantial increase in circulating leukocytes and the individual subsets, which is in agreement with our previous findings. Practical Applications: It is possible that ultra-endurance athletes can utilize ibuprofen as a preventative anti-inflammatory. However, athletes should use caution before deciding to use ibuprofen since the cellular responses to ibuprofen in the context of ultra-endurance exercise in the heat remains unknown.
Physical Performance and Cognitive Function to Rhythmic Exercise Training
H. Kim,1 S. Cho,2 Y. Park,3 Y. Park,1 D. Park,1 W. Jung,4 S. Kim,5 H. Park,1 D. Kim,1 and D. Kim1
1Chonnam National University; 2Mokpo National Maritime University; 3Center for Sports Science in Gwang-Ju; 4Korea Red Cross in Gwang-Ju and Channam; and 5Center for Sports Science in Gwang-Ju
Muscle mass and strength of the elderly are prone to decrease due to low level of physical activity, resulting in high rate of falling. Moreover, their brain function is concomitantly reduced with advanced age. However, rhythmic exercise training can enhance physical and brain function. Purpose: To investigate effects of rhythmic exercise for 12 weeks on physical function and cognitive function in the elderly females. Methods: Thirty-three females (over 65 year old) who had lower than 23 points of Korean version of the montreal cognitive assessmemt (MoCA-K) participated in this study and were randomly assigned to either exercise group (n = 17, EX) or control group (n = 17, CON). Subjects in the EX group performed rhythmic exercise (3 times per week and 60 minutes per session) for 12 weeks and subjects in the CON group maintained their normal physical activity level during training period. Physical performance (upper and lower body strength, flexibility, agility, balance, and endurance) and cognitive function (MoCA-K, brain derived neurotropic factor (BDNF), and Serotonin) were determined. Data were analyzed with a 2-way repeated measures ANOVA with post-hoc testing and alpha was set at 0.05. Results: Upper (arm curl [p < 0.001]) and lower body (chair stand [p < 0.001]) strength, flexibility (p < 0.001), agility (2.44 m up and go test [p < 0.001]), balance (balance with one leg (p ≤ 0.05), balance with closed eyes (p < 0.01), and functional reach test [p < 0.001]), and endurance (2 minutes step test [p < 0.01]) in the EX group were significantly increased but not in the CON group. MoCA-K (p < 0.01) and BDNF (p < 0.001) in the EX group were significantly increased but not in the CON group. Conclusions: Our findings indicate that rhythmic training for 12 weeks is able to improve physical function and improve cognitive function in the elderly females which might help to prevent neurological diseases. Thus, it may positively influence their quality of life.
Cause and Effect on High Intensity Interval Training on Aerobic Capacity and Maximal Aerobic Speed in Senior Male Gaelic Club Footballers
Institute of Technology Tallaght, Dublin, Ireland
The sport of Gaelic football is indigenous to Ireland, and characterised as an intermittent field sport with players undergoing similar demands as fellow field sports of soccer and rugby. During match play, players are required to interchange between bouts of low to high intensity activity. This outlines the importance for players to have the ability to work at maximal aerobic capacity, coupled with the ability to repeat bouts of high intensity activity as required. Purpose: To compare the effects on 2 high-intensity interval training (HIT) training protocols on changes on aerobic capacity and maximal aerobic speed in senior male Gaelic club footballers. Methods: Participants consisted of senior males club Gaelic football players (n = 21) ranging from 18 to 30 years of age, and were randomly assigned to a 2 high-intensity interval training (HIT) groups. Group 1, 120% maximal aerobic speed group (mean ± SD; Age = 21.0 ± 4.2 years, Height = 180.0 ± 4.6 cm, Weight = 84.7 ± 10.1 kg, Body fat = 19.8 ± 3.9%, BMI = 26.4 ± 2.5 kg·m−2 and Aerobic capacity = 44.2 ± 1.1 ml·kg−1·min−1). Group 2, 150% maximal aerobic speed (mean ± SD; Age = 23.1 ± 3.9 years, Height = 175.5 ± 8.0 cm, Weight = 79.9 ± 7.7 kg, Body fat = 17.5 ± 1.7%, BMI = 25.1 ± 1.6 kg·m−2 and Aerobic capacity = 46.5 ± 1.9 ml·kg−1·min−1) group. Participants trained 2 d·wk−1 for 9 training sessions (4½ weeks). Physical and physiological player data was measured at baseline and at post intervention. Aerobic capacity was accessed using a Yo-Yo IR1 field test and maximal aerobic speed using a 1 km time trial. Results: Aerobic capacity increased in both the 120% and 150% maximal aerobic speed (MAS) groups in response to the high-intensity interval training program, both groups showed improvement in aerobic capacity and maximal aerobic speed with the 120% MAS showing an increase in Yo-Yo IR1 distance of 20 m and 150% MAS group results showing an increase of Yo-Yo IR1 distance of 6 m (as in Table 1). Results for maximal aerobic speed found the 150% MAS group to have a slight improvement over the 120% MAS group of 0.5%. Conclusions: Study results suggest that the use of a 120% MAS training method as compared to a 150% MAS training method as the most effective HIT method for improving aerobic capacity, and a 150% MAS training method as the most effective HIT method to improve maximal aerobic speed in club level Gaelic football players. Practical Applications: Due to the high demands placed on both the aerobic and anaerobic systems during competitive play. Players can obtain similar aerobic and anaerobic benefits from a 120 vs. 150% supramaximal training protocol. This is encouraging news for the strength and conditioning professional, as this method offers the same physiological benefits to the players, while reducing player's weekly training load by reducing steady state aerobic training. While also aiding in reducing fatigue or overtraining from on-field training sessions over the course of a competitive season.
Sprint-Interval Cycling Training: The Effect of Tabata Protocol on Elite Level Distance Runners
B. Chapoton, M. Hetrick, D. Leonard, T. Jenkins, A. Davies, K. Zeringue, and R. Kraemer
Southeastern Louisiana University
Distance track althetes who complete excessive running mileage are at greater risk for leg injury. Until now, no research has looked at elite-level distance runners and the effects of Tabata training on cardiorespiratory fitness levels. Sprint interval cycling (SIC) has been shown to be effective in improving V[Combining Dot Above]O2max. Purpose: The purpose of this study was to determine whether Tabata training (sprint-interval cycling) 4 times a week for 2-weeks would allow collegiate distance track athletes to maintain their V[Combining Dot Above]O2max while completing a lower volume of overall exercise. Methods: Ten collegiate distance runners (mean ± SD age = 19 ± 1.2 years) participated in this experiment, and were randomly assigned to experimental (n = 5) or control (n = 5) groups. The subjects completed a graded exercise test on a treadmill in order to determine V[Combining Dot Above]O2max using a metabolic analysis system. The experimental (E) group was asked to complete 40 miles (males, M) and 15 miles (females, F) of running a week, and 8 sessions of the Tabata SIC protocol on a cycle ergometer. The control (C) group ran 60 miles (M) and 30 miles (F) at 70% V[Combining Dot Above]O2max each week with no Tabata intervention. The Tabata protocol consists of a 5-minute warm-up followed by 8 × 20-seconds at max effort & 10-seconds rest in between each sprint, followed by a 5-minute cool-down. No other running drills were performed during this time period. Results: Analysis of data using a 2 (Group) × 2 (Time) repeated measures ANOVA yielded no significant differences for V[Combining Dot Above]O2max: Group: F(1,8) = 0.25, p > 0.05, Time: F(1,8) = 2.51, p > 0.05, Group × Time interaction: F(1,8) = 2.09, p > 0.05. A Group × Meet ANOVA was used to compare running performance times from conference (before SIC training) to regional (after SIC training) cross-country meets. There was no significant Group or Meet main effect. However, a Group × Meet interaction approached significance, F(1,6) = 5.60, p = 0.056. There was a trend for running time (minute per mi) to increase slightly from conference to regional meet in C group, whereas time in the E group tended to decrease. Conclusions: The results of the study indicate that a Tabata training protocol completed 4 times a week for 2-weeks will prevent decline in V[Combining Dot Above]O2max and performance times while reducing leg stress from higher running volume. Practical Applications: The goal of a taper phase in the periodization of a training season is to minimize injury risk, maintain fitness and recovery. Those who coach distance runners should consider employing SIC training during portions of the track season in which tapering workouts is needed to prevent injury. They may also look to use this protocol when training injury prone athletes or athletes coming off of injury as a cross-training tool similar to aqua jogging. Acknowledgments: We would like to thank the Southeastern LA University Cross-Country teams for volunteering to be a part of this study.
Effects of Aquarobic Training on Blood Lipids and Body Composition in Elderly Obese Women
D. Park,1 S. Cho,2 H. Kim,1 Y. Park,3 Y. Park,1 W. Jung,4 H. Park,1 S. Kim,5 D. Kim,1 and D. Kim1
1Chonnam National University; 2Mokpo National Maritime University; 3Center for Sports Science in Gwang-Ju; 4Korea Red Cross in Gwang-Ju and Channam; and 5Center for Sports Science in Gwang-Ju
Generally, the elderly have high percentage of body fat due to physical inactivity. It leads to a higher internal fat mass, obesity and a high rate of cardiovascular diseases. Thus, it may negatively influence quality of life in the elderly. However, aerobic exercise can reduce body fat mass in the elderly. Purpose: To investigate effects of a 12-week aquarobic training on level of serum lipids and body composition in elderly obese females. Methods: Thirty one obese females (age: 70.03 ± 3.29 years and % body fat: 33.42 ± 2.74) performed aquarobic training (3 times per week, 60 minutes per session; Intensity: 12–13 on Borg Scale) for 12 weeks. Blood lipid levels (total cholesterol [TC], triglyceride [TG], low-density lipids cholesterol (LDL-C) and high-density lipids cholesterol [HDL-C]) and body composition (waist circumference and % body fat) were examined at pre and post training period. Data were analyzed with a paired t-test and alpha was set at 0.05. Results: TC (p < 0.01), triglyceride (p ≤ 0.05), and LDL-C (p ≤ 0.05) were significantly decreased. Additionally, waist circumference (p ≤ 0.05) and % body fat (p ≤ 0.05) were significantly decreased. Conclusions: Our findings suggest that Aquarobic training for 12 weeks is able to decrease serum lipid levels and improve body composition. Thus, it may hold potential for improving quality of life in the elderly population.
Determining the Relationship Between Heart Rate Deflection Point and Lactate Threshold During an Incremental Cycling Test
A. Hallmark, R. Snarr, and M. Esco
University of Alabama
Monitoring physiological markers during aerobic conditioning and performance is a key determinant of success. Several laboratory methods have previously been used to determine appropriate training levels such as lactate threshold, ventilatory threshold, and heart rate deflection point. Heart rate deflection point and lactate threshold are typically assessed as points on the curve where a slight linear decrease or exponential increase in value are observed, respectively. However, previous research has demonstrated conflicting results in regards to the ability of heart rate deflection point to determine the work output at which lactate threshold occurs in field and laboratory protocols. Purpose: The primary aim of this investigation was to determine the relationship in power outputs between heart rate deflection point and lactate threshold during a maximal incremental cycle test. Methods: Twenty men (n = 12) and women (n = 8) performed a maximal incremental cycle ergometer test until exhaustion. Blood lactate and heart rate were assessed every minute throughout the trial. Power output values from lactate threshold were determined through D-max calculations, while heart rate deflection values were determined via visual inspection. Results: The current results indicated a significant difference in power outputs (±40 W) between heart rate deflection point (136 ± 32.83 W) and lactate threshold (150 ± 34.03 W), (p = 0.015, r = 0.754). Heart rate deflection point measurements estimated power outputs significantly lower than lactate threshold in 40% of participants, while heart rate deflection point was observed in 55% of the subjects. However, heart rate deflection point overestimated lactate threshold work output in only one subject. Conclusions: Consistent with previous results, lactate threshold and heart rate deflection point do not occur at the same work outputs during incremental testing. However, the current results also conflict with previous treadmill protocols, which have shown overestimations of heart rate deflection point in relation to lactate threshold power output values. Therefore, heart rate deflection point may not be an effective marker to determine training intensities as it underestimates the point at which lactate threshold appears. Variables such as training status, testing protocol, and population studied may affect the occurrence of heart rate deflection point and lactate threshold. Practical Applications: The utilization of monitoring physiological markers during aerobic training and competition can be useful to reduce the onset of fatigue and increase aerobic capacity. Practitioners should take note that heart rate deflection work outputs are not in agreement with those of the lactate threshold during an incremental cycle test. Therefore, prescribing training intensities using lactate threshold values may be more beneficial than heart rate deflection point as it has been shown to elicit greater power outputs during incremental cycling.
Effects of Progressive Interval Training on Athletic Performance in Karate Kumite Player
J. Chen,1 Y. Ning,2 W. Tseng,3 J. Zhang,1 and K. Tseng1
Departments of 1Exercise and Health Science; 2Martial Arts, University of Taipei, Taiwan; and 3Department of Sports, Taipei City Government, Taipei, Taiwan
The duration of kumite bout is defined as 3 minutes for men and 2 minutes for women. The excellent athletic performance bases on the adequate competitive fitness which dominated by mixed aerobic and anaerobic energy metabolism system. To mimic the energy metabolism system used in kumite competition, interval training is an efficient training program. Purpose: The purpose of this study was to examine the effect of 8-week progressive interval training on athletic performance in karate kumite players. Methods: Twenty-four college karate kumite players (16 males, 8 females) participated in this study. Progressive interval training executed by cycle ergometer. The high intensity protocol was set at 50%, 60%, and 70% of average power; low intensity was 25% of average power. The duration of high intensity training was lasted for 10- and 20-second for low intensity. Each session repeated 6 times. The training session included 5-set and 3-minute recovery between each set. All the sessions were executed 3 times per week and lasting 8-week. The performance testing was including skill-related fitness, maximal oxygen consumption and knee isokinetic testing. Blood sample was collected immediately after post-exercise at week 5 and week 8 to analyze creatine kinase and lactic dehydrogenase. Results: There were significantly increased in standing long jump (pre-test: 2.30 ± 0.17 m, post-test: 2.36 ± 0.21 m, p = 0.011), 10-meter sprint (pre-test: 2.84 ± 0.21 seconds, post-test: 1.97 ± 0.25 seconds, p = 0.000), T-agility test (pre-test: 11.45 ± 0.71 seconds, post-test: 11.14 ± 0.82 seconds, p = 0.002), anaerobic power (pre-test: 10.56 ± 1.11 w·kg−1, post-test: 11.16 ± 1.08 w·kg−1, p = 0.003) and anaerobic average power (pre-test: 8.01 ± 0.93, post-test: 9.22 ± 1, p = 0.000), but not in aerobic capacity (pre-test: 51.50 ± 9.72 ml·min−1·kg−1, post-test: 52.54 ± 11.68 ml·min−1·kg−1, p = 0.376). Conclusions: The lower limb power, anaerobic power and anaerobic capability were significantly increased after 8-week progressive interval training in karate kumite players, but not in aerobic capacity. Practical Applications: Even if the results of this study indicated that the aerobic capacity did not improve, but the anaerobic power and anaerobic capacity which is the important capability for karate kumite players increased significantly. Progressive interval training is less time-consuming, and does not unduly interfere with technical training. To reduce fatigue and prevent injury, progressive interval training is one of the most effective training methods for karate kumite.
Validation of B-Mode Ultrasound Imaging as a Body Composition Measurement in Division I Football Players
K. Kiely,1 S. Rossi,1 K. Kendall,2 P. Hyde,3 N. Coker,1 and C. Fairman4
1Georgia Southern University; 2Bodybuilding.com; 3The Ohio State University; and 4Ohio State University
Background: Evaluation of body composition is of great importance to estimate an individual's physical status. The ratio of fat-mass (FM) to fat-free mass (FFM) has been shown to be associated with obesity and various diseases. Furthermore, in an athletic population, increased levels of fat mass have been shown to negatively affect performance. Purpose: The purpose of the study was to determine the accuracy of a 7 site B-mode ultrasound (US) equation in predicting percent body fat (%BF) in Division 1 college football players. Methods: 90 Division I football players, (mean ± SD; age: 20 ± 1 year, height: 184.42 ± 5.86 cm, weight: 102.98 ± 20.78 kg) underwent the following tests: Bioimpedance spectroscopy (BIS) to estimate total body water (TBW), air-displacement plethysmography (BODPOD) to determine body density (Db), and Dual energy x-ray absorptiometry (DEXA) to determine bone mineral content. Seven-site US measurements were also taken. All US measurements were taken by the same researcher using the site locations from the Jackson and Pollock 7 site skinfold equation (1978) TBW, BMC, and Db were used to determine %BF using the 4C equation developed by Lohman (1981). Pearson's product moment correlation was run to determine the strength of relationship between the sum of ultrasound measurements (
) and %BF from the 4C model. Linear regression was used to develop a prediction equation using the
. A paired samples t-test was used to compare %BF estimates from the
equation and 4C model. Results: A strong, positive correlation was observed between
and %BF from 4C (r = 0. 961, p < 0.001). Based on the significant correlation analysis, a linear regression equation was developed to predict %BF from
using half (n = 45) of the players, (%BF = 6.504+ [1.957 ×
]; standard error of the estimate [SEE] = 1.99%). Cross-validation analyses were performed using the other half (n = 45) of the players. %BF using the prediction equation and %BF from the 4C model criterion were 19.91 ± 6.84% and 19.63 ± 5.65%, respectively, with no significant difference (p < 0.001) between the 2 values. Conclusions: The findings of the current study demonstrate the validity of a B-mode ultrasound as compared to a criterion 4C model in estimating %BF. Practical Applications: Due to methodological ease and portability of the equipment, athletic coaches may seek to utilize US as a means of assessing player's body composition during season.
Comparing the Reliability of Heart Rate Variability Under Differing Postural Orthostatic Stressors
A. Kriegel, M. Elmore, M. Leatherwood, R. Herron, and P. Bishop
University of Alabama
Heart rate variability (HRV) gained notoriety as an indicator of cardiovascular autonomic control. More recently, HRV has added popularity in strength and conditioning applications with hopes of informing exercise programming and reducing injury risk. However, due to natural human day-to-day physiological variability and inconsistencies in research and field methodologies, results investigating HRV usefulness in strength and conditioning applications are equivocal. Purpose: The purpose of this study is to compare day-to-day reliability of HRV measures in differing body positions. Methods: Fourteen young (7 female, mean ± SD; 25 ± 3 years), healthy adults completed 2 testing sessions at the same morning hour, after an overnight fast. Participants were asked to avoid vigorous exercise and caffeine consumption the day prior to testing. Each session was separated by at least 48 hours. HRV measures were recorded, after a stabilization period, for 5-mins in a supine (SUP) and standing (ST) position allowing for spontaneous breathing. Results: Repeated-measures ANOVA revealed heart rate was no different and intraclass correlations reported high reliability between visits in SUP (59 ± 8 b·m−1, CV = 13.5%; 61 ± 10 b·m−1, CV = 16.4%; d = 0.22; F(1,13) = 0.867, p = 0.37; ICCR = 0.85) or ST positions (80 ± 12 b·m−1, CV = 15.0%; 82 ± 13 b·m−1, CV = 15.8%; d = 0.16; F(1,13) = 1.084, p = 0.32; ICCR = 0.86). In the time-domain, intraclass correlations revealed moderate to high reliability in the commonly used RMSSD measures in SUP (73 ± 39 milliseconds, CV = 49.4%; 77 ± 47 milliseconds, CV = 61.0%; ICCR = 0.58) and ST positions (29 ± 12 milliseconds, CV = 41.4%; 25 ± 14 b·m−1, CV = 56.0%; ICCR = 0.73). Alternatively, the frequency-domain spectral components of HFnu and LFnu provided no acceptable mount of reliability in the SUP or ST conditions (ICCR <0.2). Conclusions: These data support using the commonly reported time-domain measure of RMSSD for HRV measures when isolated observations are used to investigate changes in cardiovascular autonomic control in the absence of paced breathing. Additionally, ST measures could be superior to SUP due to higher reliability and the abolition of parasympathetic saturation experienced with orthostatic stress. Practical Applications: Coaches and strength and conditioning professionals can utilize 5-minute RMSSD measures to monitor athletes in the supine or standing position with moderate to high reliability, with preference given to the standing measure. However, future research is needed to control for potential changes contributed to differences in sleep hygiene, hydration, and the influence of known exercise stressors and truncated HR recording periods.
Anxiety and Affective Responses to Acute Moderate Intensity Walking: Effects of Varying Durations
C. Geary, J. Leeper, J. Wingo, P. Bishop, F. Conners, K. McCombs, and M. Richardson
University of Alabama
Walking is the most common form of physical activity and is often the chosen mode of exercise for the general population. Favorable anxiety and affective responses have been documented following resistance training and high intense aerobic exercise, but the effects of moderate intense walking are limited. Purpose: The purpose of this study was to investigate the dose-response relationship between an acute bout of aerobic exercise (moderate intensity walking) and anxiety and affective responses. Specifically, researchers compared anxiety and affective responses across 3 exercise durations (30, 10, and 5 minutes) over 4 time points (pre-; immediately post-; 20 minutes post- and 40 minutes post-exercise). Methods: Regularly active (mean self-reported physical activity = 173.6 ± 55 min·wk−1) college aged participants (n = 29; mean age = 21.4 ± 1.8) completed 3 acute exercise sessions involving moderate-intensity (3–5 METs) walking for 5, 10, and 30 minutes, in a counterbalanced design. Participants self-reported changes in anxiety and positive and negative affect by completing the Anxiety Likert Scale and the Positive and Negative Affect Scale prior to (pre) and at 3 time points following each walk: immediately post (Ip), 20 minutes post (20 p) and 40 minutes post (40 p). Results: There was a main effect of exercise duration for positive affect. Specifically, the 30 minutes walk induced greater positive affect than the 5 minutes walk (p = 0.044). There was a main effect of time for anxiety (p < 0.001) and both positive (p < 0.001) and negative (p = 0.009) affect. Anxiety at 20 p and 40 p was lower than both pre (p = 0.004, p < 0.001, respectively) and Ip (p = 0.012, p = 0.005, respectively). Positive affect immediately post-exercise was higher than pre (p = 0.011), 20 p (p < 0.001), and 40 p (p < 0.001); however, positive affect at 40 p was lower than both pre (p < 0.001) and 20 p (p < 0.001). Finally, negative affect was significantly less at 40 p than Ip (p = 0.026). Conclusions: The favorable effect of all 3 exercise durations on anxiety and negative affect indicates that short bouts of walking may be an effective method for alleviating anxiety and negative affective states. It should be noted that the favorable effect of exercise on positive affect experienced immediately post-exercise was not sustained for an extended time following exercise; this response contradicts previous literature. Practical Applications: Practitioners should encourage moderate intense walking for at least 30 minutes. This duration of activity may be an effective approach for decreasing anxiety. Future research should investigate the effects of multiple short bouts of exercise (e.g., three 10-minute bouts vs. one 30-minute bout) on anxiety and affective states.
The Effects of 6-Week Stair Exercise on Functional Physical Fitness in Elderly
C. Chan,1 W. Tseng,2 S. Fu,1 J. Zhang,3 and K. Tseng1
1Department of Exercise and Health Sciences, University of Taipei, Taiwan; 2Department of Sports, Taipei City Government, Taipei, Taiwan; and 3Department of Exercise and Health Science, University of Taipei, Taiwan
Aging is a rapidly developing issue in the world. Decline in physical function with age becomes inevitable and even lead to some disease which related to the aging process. Regular physical activity could improve exercise capacity and functional fitness performance in elderly. Purpose: The aim of this study was to investigate the effects of 6-week stair-descending or ascending exercise on functional physical fitness in elderly people. Methods: Sixteen healthy elderly people (aged 65 ± 5 years) participated in this study and were allocated randomly to the stair-descending or ascending group (n = 8/group). The subjects performed the stair-descending or ascending exercise twice a week for 6 consecutive weeks. The exercise began with 10 floors and gradually incremented 10 floors every week until the sixth week. Functional physical fitness (muscle strength, flexibility, cardiorespiratory endurance, balance, and agility) was examined at baseline and 4 days after interventions completion. The heart rates and rated perceived exertion (RPE) responses were measured during and immediately after each session of the stair exercise. The data were analyzed using a mixed-design 2-way ANOVA. Results: No significant difference was observed between the baseline and post-intervention in chair sit-and-reach test, 30-second chair-stand test, 8-foot up-and-go test, one-leg stance test with eyes closed, 6-m tandem walk, or 2-minute step test in either group (p > 0.05). A significant difference (p ≤ 0.05) was observed in one-leg stance test with eyes open in stair-ascending group (23.9 ± 8.8 vs. 30 ± 0 seconds, p ≤ 0.05) and descending groups (19.6 ± 11.0 vs. 30 ± 0 seconds, p ≤ 0.05), but no significant difference between the 2 groups (p > 0.05). The heart rates and RPE responses were significantly lower (p ≤ 0.05) in stair-ascending group (HR: 85.6 ± 8.3 b·m−1, RPE: 8.6 ± 2.3) than stair-descending group (HR: 72.9 ± 6.9 b·m−1, RPE: 7.0 ± 0.9). Conclusions: This study shows that both stair-ascending and descending exercise interventions improved the static balance in elderly people; however, the exercise intensity and fatigue were lower in stair-descending exercise than stair-ascending exercise. Thus, the stair-descending exercise may be provided to the elderly population as an efficient exercise for preventing falls in the future. Practical Applications: The result indicated that stair-descending and ascending exercise could improve the balance control in elderly. In this study, stair exercise would be advantageous for older adults, and it might be concern as preventing some disease related with aging in the future.
Reference Normative Values for Aspects of Skill-Related Physical Fitness in Active Children and Adolescents
A. Wolfe,1 K. Laurson,1 D. Dodd,1 D. Brown,1 and J. Eisenmann2
1Illinois State University; and 2Michigan State University
Normative reference values are commonly utilized to assess, evaluate and classify youth for aspects of physical fitness due to varying rates of growth, maturation and development. There is currently a lack of normative values for measurements of skill related physical fitness such as, muscular power, speed and agility. Purpose: The purpose of this study was to establish age and sex, normative reference values for several aspects of skill-related physical fitness in physically active children and adolescents. Methods: A sample of 209 physically active youth (136 boys and 73 girls) age 12–17 years, completed a number of different measures of skill-related physical fitness. Muscular power was assessed utilized both standing long jump (SLJ) and vertical jump (VJ). Agility was assessed utilizing the 4-square agility test (FS) and pro-agility (PA) tests and Speed was assessed by a maximal high speed treadmill test. Age- and sex-specific percentile values were calculated using IBM SPSS statistics version 20. Results: Overall, boys showed better results in all measures of physical fitness when compared to girls, across all age groups. Mean scores ranged from 182.8 to 230.9 cm and 152.3–175.4 cm for SLJ, 46.9–61.5 cm and 38.7–44.6 cm for VJ. Mean scores for speed ranged from 288.9 to 344.1 m·min−1 and 259.3–279.8 m·min−1. While agility mean scores ranged from 31.2 to 35.4 # per 10 seconds and 31.4–34.5 # per 10 seconds for FS and 5.5–5.2 and 5.7–5.6 seconds in boys vs. girls respectively. In addition, a trend was identified indicating a sequential improvement in skill-related fitness measures with increasing age groups for both boys and girls. Conclusions: This data provides age- and sex-specific normative values for a set of skill-related physical fitness tests for physically active youth. These percentile values will assist in filling the current gap in the literature for reference values in muscular strength and power. This data also provides the first reference values for FS, PA and max speed, assess utilizing a treadmill. Practical Applications: The reported normative values provide opportunities to further evaluate and classify physically active youth. These data are especially important for a sport enhancement specialist working with active youth and utilize similar fitness tests analyzed in the present study.
Relationship Between Stress-Recovery State and Running Performance in Collegiate Soccer Players
N. Coker,1 D. Griffin,2 K. Ake,2 J. McMillan,2 S. Rossi,1 and A. Wells2
1Georgia Southern University; and 2Georgia Southern University School of Health and Kinesiology
Purpose: The purpose of this study was to evaluate the relationship between changes in running performance and the stress-recovery state in Division I collegiate soccer players. Methods: Running performance was evaluated in 7 NCAA Division I male soccer players (179.39 ± 5.24 kg; 75.46 ± 5.98 kg; 20.37 ± 1.41 years) over the course of 12 games during a single competitive season. The 12 games were divided into 4 blocks (B1 [n = 3], B2 [n = 3], B3 [n = 3], and B4 [n = 3]). Running performance was assessed using a wearable Global Positioning System (GPS) module. Absolute distance, distance relative to minutes played, distance covered while engaging in walking (0.2–2.0 m·s−1; 0.72–7.20 km·h−1), jogging (2.01–3.70 m·s−1; 7.21–13.32 km·h−1), low speed running (3.71–4.99 m·s−1; 13.33–17.99 km·h−1), high speed running (5.0–6.0 m·s−1; 18.0–21.60 km·h−1) sprinting (6.01+ m·s−1; 21.61+ km·h−1), low-intensity running (LIR: 0.2–3.70 m·s−1; 0.72–13.32 km·h−1) and high-intensity running (HIR: > 3.70 m·s−1; >13.32 km·h−1) were assessed during each block. Stress-recovery state was assessed using the RESTQ 52 Sport, which was administered to each athlete at the end of each training week. The RESTQ 52 Sport provides measures of general stress (GS), general recovery (GR), sport specific stress (SSS), sport specific recovery (SSR), global stress (GLS), global recovery (GLR) and the recovery-stress balance (RSB). Results: LIR and absolute LSR were significantly greater during B4 compared to all other time points (p < 0.05). Jogging distance relative to minutes played was significantly greater during B4 compared to B1 (p < 0.001) and B3 (p < 0.001). Significant decreases in SSR were observed during B4 compared to B1 (p = 0.016), while a trend was also observed towards a decrease in SSR during B3 compared to B1 (p = 0.056). Correlations between running performance and RESTQ variables are presented in the following table. Conclusions: Results of this study indicate that running performance declined across the season, as indicated by increased measures of low intensity running. These changes coincided with a decrease in SSR towards the end of the season. Small to moderate correlations were observed between running performance and RESTQ variables, indicating that higher velocity running during a competitive game was associated with increased stress, while lower velocity running was associated with increased recovery. Practical Applications: Weekly administration of the RESTQ Sport 52 questionnaire may provide coaches with valuable information regarding the stress-recovery state of their athletes, and may allow for a speculative evaluation of match running performance.
The Effect of Temperature on Rating of Perceived Exertion: a Meta-Analysis
D. Tolusso, W. Dobbs, T. Williams, and M. Fedewa
University of Alabama
Rating of perceived exertion (RPE) is a subjective, noninvasive scale used to assess the psychophysiological state of a person at a given moment by taking into account multiple physiological and psychological markers of fatigue. While there is an abundance of research detailing the response of physiological markers to hyperthermic conditions, the effect that these conditions have on perceptual measures is not well established. Purpose: The primary aim of this study was to examine the previous literature comparing normothermic and hyperthermic conditions to determine a quantitative estimate of effect on RPE. Methods: This review was conducted in accordance with PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-analyses), and identified peer-reviewed articles comparing exercise at normothermic and hyperthermic conditions. An electronic search of 4 databases (Pub Med, SPORTDiscus, Physical Education Index, and Web of Science) yielded 2,543 records after duplicates were removed. For study inclusion, the article must meet the following criteria (a) peer-reviewed publication; (b) available in English; (c) within-subject design; (d) RPE measures at equivalent time points for each group; (e) equivalent intensities between groups. Data were extracted and independently coded by 2 authors. Hedges d effect size (ES) was calculated by subtracting the mean RPE in the normothermic condition from the mean RPE in the hyperthermic condition and dividing the difference by the pooled SD. A positive ES is interpreted as a larger change observed in the hyperthermic condition when compared to the normothermic condition. Data are presented as mean (M), standard deviation (SD), and 95% confidence interval (95% CI). Results: The cumulative results of 67 effects gathered from 16 studies published between 1994 and 2015 indicated a larger increase in RPE occurs under hyperthermic conditions (ES = 0.79, 95% CI: 0.65–0.93; p < 0.001). Sixty-four of the 67 effects (96%) were greater than zero, with no ES values below zero. The temperature difference ranged from 6 to 28.5° C (15.1 ± 6.0° C). The number of effects per study ranged from 1 to 12 (4.2 ± 3.0). The mean age of participants was 24.3 ± 3.1 (n = 223, 7.2% female). A meta-regression model including temperature difference, mode of exercise, and time point collectively explained 42% of the variance in RPE (p < 0.001). The regression established that an increase in temperature difference and time also increased the magnitude of change in RPE; also weight bearing exercise caused a greater difference in RPE than non-weight bearing exercise. Conclusions: Temperature has a large effect on rating of perceived exertion. Our analysis found that as temperature difference increases, so too does the difference in rating of perceived exertion. Practical Applications: RPE is a tool that can be used to regulate exercise intensity. However, the effect of temperature on RPE must be accounted for by strength and conditioning professionals when prescribing exercise intensity.
Validation of Multi-Sensor Biofeedback Technology for Heart Rate Tracking
K. Lewis,1 D. Directo,1 B. Dolezal,1 M. Fischer,1 D. Higuera,1 A. Osmond,1 R. Wes,1 M. Wong,1 and E. Jo2
1Human Performance Research Laboratory, Department of Kinesiology and Health Promotion, California State Polytechnic University Pomona, Pomona, California; and 2Human Performance Research Laboratory, California State Polytechnic University Pomona, Pomona, California
The rising awareness for personal health and fitness through self-monitoring is largely enabled by recent advancements in wearable sensor technology. Commercially available physical activity trackers incorporate sophisticated algorithms and multi-sensor technology capable of providing users with real-time biometrics including heart rate (HR) and energy expenditure (EE). The BP and FB are 2 such activity trackers currently available for consumer purchase. In terms of heart rate monitoring, these wrist-worn devices incorporate optical biosensors utilizing reflective photoplethymography and green light as a method of computing heart rate. With growing interest and use of these trackers for personal health and fitness, the need to validate their accuracy becomes especially important. Purpose: The primary aim of this study was to test the validity of HR tracking by BP and FB in comparison to criterion measures acquired by electrocardiography (ECG). Methods: Twenty-four healthy subjects (12 male and 12 females) (age = 20–31 years) participated in this study and underwent the same 77 minutes protocol during a single visit. Each participant completed an initial rest period (lying down) of 15 minutes followed by 5 minutes periods of each of the following activities: low cycling (60 W resistance), intense cycling (120 W), walk (3.0–3.5 mph speed), jog (4.0–5.0 mph), run (5.5–7.0 mph), arm raises with self-selected added resistance (12 reps), lunges with self-selected added resistance (12 reps), and plank (60 seconds hold). In between each exercise task was a 5 minutes rest period. Each subject wore a BP on one wrist and a FB on the opposite wrist. Wrist assignment (i.e., left and right) alternated between subjects. Care was taken to follow proper wear guidelines as suggested for each device. Criterion measurements of HR and EE were measured respectively by electrocardiography (12-lead) and indirect calorimetry using a metabolic cart (EE data omitted from present findings). Time synced data from each device were concurrently and continuously acquired second-by-second throughout the entire 77-minute protocol for each subject. Pearson correlation, mean bias, 95% limits of agreement (LoA) and standard error were computed. Results: When examining data in aggregate, there was a very strong, positive correlation between BP and ECG for HR (r = 0.92, p < 0.001) with a mean bias of −2.53 b·m−1 (95% LoA 19.31, −24.37). The FB demonstrated a moderate, positive correlation with ECG for HR (r = 0.73, p < 0.001) with an average difference of a mean bias of −8.79 b·m−1 (95% LoA 24.24, −41.84). During conditions eliciting and ECG HR >116 (mean ECG HR), the BP demonstrated r = 0.77 and mean bias = −4.86 b·m−1 (21.30, −31.02) while the FB demonstrated r = 0.58 and mean bias = −12.71 b·m−1 (28.55, −53.98). In comparison, the FB performed worse in terms of accuracy than the BP overall, above or below mean ECG HR, and during each exercise task. Conclusions: Compared to the FB, BP performed with greater agreement to both ECG HR measurements. While the FB exhibited substandard accuracy and agreement to ECG especially during exercise conditions, the BP is within reason, a valid HR tracker. Practical Applications: The BP is a valid device for heart rate tracking and may be used during resting and exercise conditions to accurately measure heart rate. The FB, however, requires further refinement to be confidently considered a valid device for heart rate tracking. Acknowledgments: Basis Peak provided funding support for this study. There were no conflicts of interest as this study was conducted in an unbiased and independent manner.
Evaluation of Seasonal Changes in Fitness, Anthropometrics, and Body Composition in Collegiate Division II Female Soccer Players
A. Hoden,1 B. Tyo,2 and C. Nicks2
1Auburn University; and 2Columbus State University
Purpose: To investigate fitness, anthropometrics, and body composition of collegiate division II female soccer players throughout a calendar year. Methods: Twelve (19.54 ± 0.88 years) NCAA division II female soccer players from the same team participated in the study. Anthropometrics and body composition variables (weight, height, abdomen circumference [AC], waist circumference [WC], hip circumference [HC], waist-to-hip ratio [WHR], body fat percentage [BF%], fat mass [FM], fat-free mass [FFM]) were assessed. In addition, participants performed a series of fitness tests: Counter Movement Jump (CMJ), Wingate Anaerobic Test (WAT), and V[Combining Dot Above]O2peak. Data were collected over 5 time points: end of competitive seasons (ECS1 and ECS2), beginning of off-season (BOS), end of off-season (EOS), and pre-season (PS). Repeated-measures analysis of variance (ANOVA) were conducted to compare test scores among all 5 data collection points. Where appropriate, Bonferroni post-hoc tests were used to determine which points were significantly different Results: HC decreased significantly (p < 0.001) from EOS (98.47 ± 6.5 cm) to PS (94.46 ± 6.8 cm). FM was significantly lower (p < 0.001) at ECS2 (12.73 ± 5.4 kg) compared to all other time points, while FFM was maintained from ECS1 to ECS2 (Table 1). CMJ, WAT, and V[Combining Dot Above]O2peak were all maintained throughout the study (Table 1). Conclusions: Anthropometrics and body composition results are similar to previous studies measuring division II to professional female soccer players both in-season and off-season. The significant drop in HC may be due to the insignificant decrease in FM and FFM from EOS to PS. CMJ results remained consistent and are comparable to results from previous studies on division I female soccer players. V[Combining Dot Above]O2peak results are generally lower than findings in previous studies evaluating division II female soccer players. Future research examining differences between playing positions, ranked vs. non-ranked, and starter vs. non-starters in division II female soccer players is recommended to establish normative data. Practical Applications: Coaches and researchers can use these data to help design and evaluate strength and conditioning training programs throughout a calendar year.
Acute Effects of Proprioceptive Neuromuscular Facilitation on Peak Torque, Muscle Imbalance, and Range of Motion
R. McManus,1 P. Costa,2 and C. Bentes3
1California State University, Fullerton, California; 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California; and 3Graduate Program in Applied Clinical Research on Women's Health, Fernandes Figueira Hospital- Oswaldo Cruz Foundation
Introduction: Strength imbalances between agonist and antagonist muscles such as the hamstring-to-quadriceps peak torque (PT) ratio have been associated with injury risk. Stretching has demonstrated to decrease PT; however, little is known regarding the effects of proprioceptive neuromuscular facilitation (PNF) stretching on PT and the hamstring-to-quadriceps (H:Q) ratios. Purpose: To examine the effects of PNF stretching on leg extension and flexion PT, H:Q ratios, and range of motion (ROM). Methods: Fifteen male (mean ± SD; age = 22.0 ± 1.2 years; body mass = 76.2 ± 11.7 kg; height = 176.5 ± 7.4 cm) and 15 female (age = 22.1 ± 1.9 years; body mass = 62.6 ± 8.4 kg; height = 160.9 ± 5.5 cm) participants performed 3 maximal voluntary unilateral concentric leg extension and flexion, as well as maximal eccentric leg flexion muscle actions at randomly ordered velocities (60, 180, and 300°·s−1 concentric; 60°and 180°·s−1 eccentric) with their dominant limb before and after a bout of PNF stretching or a control condition. Pre and post ROM assessments of the hamstrings muscles using a goniometer were also performed for both conditions. The PNF stretching protocol consisted of 4 assisted 6-second isometric hamstring muscle actions (∼60% maximal effort) followed by a static stretch of the hamstrings muscles for 30-second hold durations and 30-second rest intervals between repetitions. For the control protocol, participants sat quietly for 6 minutes. Six separate 4-way mixed-factorial ANOVAs were performed to analyze the PT, H:Q ratio, and ROM data. Results: ROM increased significantly by an average of 27.1% following the PNF protocol (p < 0.01), but not following control (p > 0.05). Post-hoc analysis revealed a 6.8% reduction in PT for quadriceps PT at 60°·s−1 in males (p < 0.001). No other significant stretching-related changes occurred for peak torque or H:Q ratios (p > 0.05). Conclusions: The results indicated that neither a control condition or the current stretching protocol affected hamstrings PT or the H:Q ratios. These findings suggest PNF stretching of the hamstrings may not adversely affect the H:Q ratios, but can lead to increases in ROM. Practical Applications: Many athletes and fitness enthusiasts seek increases in ROM, but wish to avoid related decreases in performance and associated muscle imbalances. These results suggest a short acute bout of PNF stretching can potentially increase ROM and not negatively impact strength or muscle imbalance.
Effects of Iyengar Yoga Training for 12 Weeks on Lower Body Posture in Middle-Aged Women
Y. Park,1 S. Cho,2 H. Park,1 H. Kim,1 S. Kim,3 Y. Park,3 W. Jung,4 D. Park,1 D. Kim,1 and D. Kim1
1Chonnam National University; 2Mokpo National Maritime University; 3Center for Sports Science in Gwang-Ju; and 4Korea Red Cross in Gwang-Ju and Channam
Body posture of females is prone to get faulty post pregnancy and childbirth. Yoga training, which is utilized for stretching the entire body, thus it can be used to correct faulty body postures and improve physical balance. Purpose: To examine effects of Iyengar yoga training on pelvis imbalance and lower limb length discrepancy in middle-aged females. Methods: Twenty-four females aged 35–60 years completed yoga training (3 times per week, 90 minutes per session) for 12 weeks. X-RAY with Gonstead Technique was utilized for measuring (a) height differences between right and left iliac crests, (b) width and length differences between right and left iliac fossa, (c) width differences between right and left sacrum and (d) the lower limb length discrepancy at pre and post training. Data were analyzed with a paired t-test and alpha was set at 0.05. Results: (a) The height differences between right and left iliac crests (p < 0.001), (b) width (p < 0.001) and length (p < 0.001) differences between right and left iliac fossa and (c) width differences between right and left sacrum (p < 0.001) were significantly reduced. In addition, (d) the lower limb length discrepancy was significantly reduced (p < 0.001). Conclusions: Our data suggest that yoga training for 12 weeks reduces pelvic imbalance and length differences between right and left lower limbs in middle aged females. Iyengar yoga program may be able to reduce discomfort and prevent or treat faulty posture related with pelvic imbalance and length discrepancy of the lower limbs.
The Influence of Muscle Size and Quality on Rapid Velocity Development in Older Adults
H. Giuliani,1 E. Ryan,2 G. Gerstner,2 E. Sobolewski,3 B. Thompson4
1UNC-Chapel Hill; 2University of North Carolina at Chapel Hill; 3Furman University; and 4Utah State University
Reductions in muscle size and impaired muscle quality are often suggested to be important contributors to the age-related reduction in both strength and power that lead to altered function and mobility. However, few studies exist examining the influence of both size and quality on rapid velocity characteristics. Purpose: To examine the relationships between muscle size and quality and the rate of velocity development (RVD) of the plantarflexor muscles in older adults. Methods: Twenty-two older recreationally active men (mean ± SD: age = 68.7 ± 2.9 years; stature = 176.9 ± 5.2 cm; mass = 81.6 ± 10.1 kg) visited the lab on 2 occasions. During the first visit the participants were familiarized with the strength testing, and the second visit included the ultrasound (US) assessment, followed by strength testing. The cross-sectional area (CSA) of the lateral and medial gastrocnemius was examined with a GE Logiq-e US unit. Image-J software was used to determine muscle CSA of the gastrocnemii, and the same region of interest was used to determine muscle quality from the mean gray-scale echo intensity (EI) of the image. Each participant performed 3 maximal plantarflexion isokinetic muscle actions on a calibrated isokinetic dynamometer at 120°·s−1. The foot was passively dorsiflexed until the participants experienced a slight stretch and then instructed to rapidly push against the custom designed steel foot plate as fast as possible. The peak RVD was determined as the peak derivative of the velocity-time curve. Pearson correlation coefficients (r) were used to evaluate the relationships between peak RVD and muscle CSA and EI. The alpha level was set at p = 0.05. Results: There was no significant relationship (r = −0.003, p = 0.988) between RVD and muscle CSA of the gastrocnemii; however there was a significant relationship between RVD and EI (r = −0.491, p = 0.020). Conclusions: The results of this study suggest that peak RVD during rapid isokinetic muscle actions are more related to muscle quality (i.e., increase in intramuscular fat and/or connective tissue) than muscle size. Practical Applications: It has been suggested that the age-related reduction in rapid velocity characteristics may contribute to functional limitations often seen in older adults. Training programs designed to improve muscle quality may help attenuate these changes.
Quadriceps Femoris Echo Intensity and Muscle Thickness as Independent Predictors of Athleticism in Middle-School Boys
J. Mota,1 M. Stock,1 J. Hernandez,1 and B. Thompson2
1Texas Tech University; and 2Utah State University
Previous studies have demonstrated that quadriceps femoris echo intensity and muscle thickness are moderately correlated with measures of muscle function in young and old adults. Purpose: The purpose of this study was to examine the potential for vastus lateralis (VL) and rectus femoris (RF) echo intensity and muscle thickness to be used as independent predictors of athleticism in middle-school boys. Methods: Twenty-nine middle-school aged boys (mean ± SD age = 12 ± 1 year; mass = 45.8 ± 13.2 kg; height = 156.2 ± 10.8 cm) participated in this study. All subjects were engaged in their middle school's physical education program and had participated in at least one sport program during the previous year, but none were actively engaged in a structured exercise program. Ultrasound measurements were performed on the right VL and RF. The subjects performed maximal isometric strength testing of the right leg extensors, maximal countermovement vertical jumps, as well as maximal 20 meter sprint and 5-10-5 agility assessments. Torque-time curves were used to calculate rate of torque development (RTD) values at 200 milliseconds from torque onset. Fifteen bivariate correlations were performed to examine Pearson r values between the 3 independent variables (quadriceps femoris echo intensity, VL muscle thickness, and RF muscle thickness) and each of the dependent variables (RTD200, countermovement jump height, peak jump velocity, sprint speed, and agility). Partial correlations were utilized to examine these relationships while removing the influence of body mass and age. Stepwise multiple regression analyses were performed to determine the contributions of the ultrasonography variables, age, and mass on each of the dependent variables. Results: Table 1 displays bivariate and partial correlation matrices for the relationships among the variables. Stepwise regression analyses indicated that quadriceps femoris echo intensity was the sole predictor of vertical jump height (R2 = 0.254, F = 9.91, p = 0.005), peak jump velocity (R2 = 0.149, F = 4.74, p = 0.038), and agility (R2 = 0.273, F = 10.14, p = 0.004). Interestingly, both VL (R2 = 0.307, F = 11.98, p = 0.002) and RF (R2 = 0.418, F = 19.39, p < 0.001) muscle thickness were found to be the lone predictors of agility. Furthermore, RF muscle thickness was also found to be the only predictor of peak jump velocity (R2 = 0.241, F = 8.57, p = 0.007). Conclusions: Echo intensity and muscle thickness were significantly correlated with several athletic assessments even when age and mass were accounted for. RF muscle thickness was a stronger predictor of peak velocity, sprint speed, and agility than both quadriceps femoris echo intensity and VL muscle thickness. Overall, echo intensity and muscle thickness showed the strongest relationships with agility and sprint speed. Practical Applications: With a growing interest in youth athletics, ultrasound imaging may become a non-invasive, easy-to-use tool to predict success in sports. Acknowledgments: The data presented in this abstract are part of a larger investigation which was funded by the National Strength and Conditioning Association Foundation.
Comparison of Power Output and Fatigue in Recreationally Active and Master Athlete Females
M. Stone,1 J. Glenn,2 A. Jensen,1 J. Vincenzo,3 and M. Gray1
1University of Arkansas; 2Louisiana Tech University; and 3University of Arkansas Medical Sciences, Northwest Campus
Older females are an understudied cohort with regards to exercise performance. Typically with age, individuals face diminished muscular power and increased muscular fatigue as opposed to their younger counterparts. Masters athletes (MA) are an ever growing group of exercisers, as such it is important to compare whether MA can produce power while simultaneously mitigating fatigue similar to that of younger athletes and to examine how age affects muscular power and rates of fatigue. Purpose: The purpose of this investigation was to examine the differences in peak power (PPWR), average power (APWR), total work (WRK), and fatigue index (FI) between recreationally active (RA) younger adults and MA females during anaerobic cycling exercise. Methods: Two groups, RA (n = 15; 20.6 ± 0.8 years) and MA (n = 17; 50.5 ± 8.6 years) volunteered to be participants in this study. PPWR, APWR, WRK, and FI were measured during a maximum cycling test in which the subjects completed the Wingate protocol. Subjects completed the 30 seconds protocol at a predetermined resistance of 7.5% body mass. Results: PPWR (p = 0.92; RA: 654.1 ± 114.5 W; MA: 658.6 ± 147.6 W), APWR (p = 0.09; RA: 429.8 ± 73.3 W; MA: 384 ± 73.8 W), WRK (p = 0.09; RA: 12,894.3 ± 2,198.3 J; MA: 18,044.3 ± 27,184.9 J), and FI (p = 0.30; RA: 11.8 ± 4.1 W·s−1; MA: 14 ± 5.2 W·s−1) were not significantly different when comparing the RA to the MA groups. Conclusions: By observing no significant differences between the RA and MA groups, we determined MA can produce similar power and total work when compared to RA during an anaerobic cycling protocol. MA also experienced similar rates of fatigue as RA. This conveys MA are comparable to RA in multiple parameters of high intensity exercise performance. With similar power outputs and rates of fatigue, we can theorize MA are comparable in many aspects of exercise performance as RA, and therefore, further research within the MA population is warranted. Practical Applications: As MA are an ever-growing population, it is important to understand the differences and/or similarities between them and their younger counterparts. This information will allow for advancements in all aspects of exercise training for the MA population. Results from this investigation indicate MA can maintain physical parameters similar to healthy, young females. In addition, incorporating sport-specific training later in life may help attenuate the natural physical decline associated with aging.
The Effects of Chronological Age on Landing Kinematics in Elite Male Youth Soccer Players
P. Read,1 J. Oliver,2 M. De Ste Croix,3 G. Myer,4 and R. Lloyd2
1St. Mary's University; 2Cardiff Metropolitan University; 3University of Gloucestershire; and 4Cincinnati Childrens Hospital
Purpose: Knee injuries are prevalent in male youth soccer and are the most frequent site of major injury. Available research to analyze the effects of age on knee joint kinematics using coach-friendly diagnostics in this cohort is sparse. The aim of this study was to examine possible age-related differences in dynamic knee valgus in elite male youth soccer players. Methods: Four hundred elite male youth soccer players (aged between 11 and 18 years) from the academies of 6 professional English Premier League and Championship soccer clubs participated in this study. A cross sectional design was used to examine the effects of chronological age on knee valgus during the repeated tuck jump assessment analysed using 2-dimensional video analysis. Valgus angles were subjectively classified as either minor (<10°), moderate (10–20°), or severe (>20°). Using these classifications knee valgus in the tuck jump was scored as follows: 0 = no valgus; 1 = minor; 2 = moderate; 3 = severe. Results: Intra-rater reliability for knee valgus score was strong (ICC = 0.90). The distribution of knee valgus scores for each chronological age group showed a trend of higher valgus scores in the younger age groups and the lowest frequency of 0 scores in the U18 s. The highest percentage of severe classifications (grade 3 scores) was in the U13 s on the right leg. Mode knee valgus scores are displayed in table 1. The U18 s had significantly lower valgus scores on the right leg than all other age groups (p < 0.001), except for the U16 s with effect sizes ranging from moderate to large (d = 0.62–0.88). Significantly lower scores were also recorded in the U18 s on the left leg in comparison to all other age groups (p < 0.001). Asymmetrical scores between limbs were evident in the U14 s, U15 s (2:1 right vs. left), and the U18 s (1:0 right vs. left) and within-group analysis to compare mean scores for each leg revealed that knee valgus scores were significantly higher on the right leg (p < 0.001). Conclusions: The tuck jump assessment identified reductions in knee valgus mode score with advancing age. Greater knee valgus scores on the right leg may suggest the emergence of limb dominance, and asymmetry between legs was also present in the U14-U15 age groups that may increase the risk of traumatic injury during this period due to asymmetrical loading of passive knee structures. Practical Applications: Quantifying the effects of age on knee valgus motion during repeated jumping tasks will assist coaches in identifying players who demonstrate high risk kinematics. Aberrant landing mechanics appear to be more pronounced during periods of rapid growth, specifically in the U13s-U15s. These age groups should be considered an important focus group for injury prevention strategies targeting potential neuromuscular deficits through the use of age appropriate and technique-driven strength and conditioning programs. Acknowledgments: One of the authors (Greg Myer) has declared the following potential conflict of interest or source of funding: Funding support was received from the National Institutes of Health/NIAMS (grant 1R21AR065068-01A1).
The Effects of the F-MARC 11+ Warmup on Lower Extremity Injury Prevention IN Sub-Elite Australian Soccer Players
S. Hervert and G. Deakin
James Cook University
The FIFA 11+ warm up is an injury prevention program that has been designed to decrease the risk of injuries in soccer players. No prior studies have focused on the effectiveness of using F-MARC 11+ to decrease lower extremity (LE) injuries in a sub-elite Australian team. Purpose: The purpose of this investigation was to determine the effects of F-MARC 11+ on LE injury prevention in Australian sub-elite soccer players. Methods: 31 (23.0 ± 3.7 year old) sub-elite Australian soccer players participated in the study. 2013 was used as an observational season for the team with the F-MARC 11+ intervention implemented in 2014. The 2013 season utilised a standard warm up at the beginning of each training session and game involving light jogging, dynamic stretches and leg swings. The F-MARC 11+ program used in 2014 consisted of comprehensive exercises aimed at increasing strength, body awareness and neuromuscular control. Injury data was recorded and analysed throughout the duration of the study using relative risk calculations for injury incidence per 1,000 exposure hours between seasons. Results: The intervention provided a minimal change in injuries/1,000 exposures when compared to the prior season. The team recorded 16 and 17 match injuries in 2013 and 2014 respectively. In addition, an increase from one to 3 training injuries was observed following the intervention. Thus, there was also an increase in injuries/1,000 training hours. The team reported the most common injuries to be the knee, quadriceps and ankle with knee injuries contributing over 50% of the days lost due to injury in the 2013 season. During the 2014 season this percentage was decreased to 9% and additionally, a reduced number of days were lost due to LE injury acknowledging that the knee injuries that occurred were less severe. While the team was successful in reducing the severity of LE injuries at the end of 2014, there was an increase in the total number of LE injuries between seasons (Table 1). Conclusions: The F-MARC 11+ program has previously been shown to reduce time lost and prevent LE injuries in teams. Although the Australian team did not show as conclusive results, the program was shown to be effective in decreasing the rate of more severe injuries such as ACL injuries. This difference may be due to the contrasting levels of competition, the accessibility to qualified coaches to implement strength and conditioning training and the compliance of the players to follow the protocol sufficiently. Practical Applications: Due to the high rate of LE injuries in soccer, a program such as the F-MARC 11+ may potentially decrease a player's risk of injury if implemented efficiently. While the program may not reduce the number of LE injuries, it may be useful in decreasing the severity of them and thus, reduce time lost. Further research is required to determine the effectiveness of the F-MARC 11+ in decreasing LE injuries in sub-elite teams, particularly in Australia.
Changes in Testosterone, Cortisol, and Peak-Power in Division III Football Players Following Pre-Season Training Camp
J. Kisiolek, A. Jagim, G. Wright, and M. Andre
University of Wisconsin—La Crosse
Previous research has indicated that periods of high-intensity training may yield unfavorable changes in physiological and performance measures indicative of overtraining, including symptoms of neuromuscular fatigue with concomitant increases in cortisol and reductions in testosterone. However, there are conflicting studies observing responses to a brief pre-season training camp consisting of higher-frequency higher-intensity practices in combination with a strength training program. Purpose: Therefore, the purpose of this study was to observe changes in testosterone, cortisol, and jump power following pre-season training in NCAA Division III football players. Methods: American football players (Ht: 180.160.1 cm; BM: 99.160.1 kg; FFM: 79.7 ± 8.6 kg; BF%: 19.38.6%) reported for testing immediately before and after the preseason training camp, which consisted of 18 practices and 5 strength training sessions during that time frame. Subjects were assessed for lower body power using a counter-movement vertical jump test (VJPP) and the Johnson & Bahamonde formula. Resting saliva was collected and later analyzed for testosterone (T) and cortisol (C). Paired sample t-tests were used to assess differences in lower body power and hormones (α = 0.05). Cohen's d was used to calculate effect size, and when d is greater than 0.20, 0.50, 0.80, and 1.30, the relationship is described as small, medium, large, and very-large, respectively. Pearson correlation coefficients were calculated to determine relationships between mean changes in T, C, T/C and VJPP. During practices, the athletes RPE, mechanical, and physiological load were monitored using an accelerometer attached with a chest strap. Results: No significant changes were observed for T (p = 0.253; d = 0.351), C (p = 0.281; d = 0.321), or T/C (p = 0.166; d = 0.382), but there was a trend towards a small effect for a decrease in VJPP (p = 0.059; d = 0.241) (refer to Table 1). An inverse relationship was observed between changes in VJPP and C (r = −0.519; p = 0.040). No significant relationships were observed for changes in VJPP and T/C (r = 0.192; p = 0.477), but there was a trend towards a medium inverse relationship between changes in VJPP and T (r = −0.424; p = 0.101). Conclusions: While there were trends towards a decrease in jump power which may have been somewhat related to possible changes in T, this offseason program did not show clear disruptions to the hormonal profile nor explosive power. It is possible that the monitoring methods used to give feedback to coaches (in an attempt to give extra recovery when needed), may have helped attenuate some of the potential losses of higher-frequency higher-intensity combined pre-season training. Practical Applications: When incorporating a strength training program into a pre-season training period, one should consider monitoring individual athlete recovery to help reduce potential performance decrements.
Investigation of the Injury Rate of Female Fitness Competitors
G. Waryasz,1 J. Gil,1 K. Ferrara,1 and C. Eberson2
1Brown University; and 2Rhode Island Hospital, Brown University
Purpose: Female fitness competitions are increasing in popularity. Female athletes are participating in weight cutting protocols to help reduce body fat percentage to improve muscle definition and physique. Participation is thought to result in the female athlete triad. The goal of the study was to investigate the weight cutting practices of female fitness competitors and determine if these practices were causative of increased injury rates. Methods: A survey was made with questions focusing on weight cutting practices, supplementation/steroid use, and injuries that occurred in the past 12 months of training. The survey was conducted a single Northeast regional competition in 2015. Statistical analysis was performed using a Fischer Exact test to investigate statistically significant differences between subgroups. Results: Thirty-five female fitness competitors were participated in the survey. The average pre-cutting weight was 131.1 lbs. The average competition weight was 109.4 lbs. The average lowest caloric consumption during weight cutting was 1,137.6 lbs. The calculated injury rate for female fitness competitors is 0.18 injuries per 1,000 hours of training. Age over 35 (p = 0.014) and a history of or current eating disorder (p = 0.005) were significant risk factors for sustaining an injury. No fractures were reported and no athletes reported using anabolic steroids. The injuries reported were spine strain (2), shin splints, and an injury to the rotator cuff. Menstrual cycle abnormalities were present in 11 of 35 individuals. Conclusions: Female fitness competitor injury rates are low, however injuries were more common in athletes over age 35 and those with either a history of or a current eating disorder. Further research needs to be completed to study the long-term effects of multiple competitions on long-term health and injury risk. Practical Applications: Strength and conditioning professionals, personal trainers, nutritionists and healthcare professionals should have an increased awareness in female fitness competitors with a history or current eating disorders to discuss an increased injury rate. Athletes over age 35 should also be made aware that they may have a higher injury rate.
Test-Retest Stability of Four Common Body Composition Assessments in College Students
P. Hart,1 J. Jordan,2 P. Jensen,3 M. Bingman,1 H. Russell,1 C. Allard,1 and C. Griffin1
1Montana State University—Northern; 2Tennessee State University; and 3Idaho State University
Field-based techniques are the most practical form of body composition (BC) assessment in generally healthy populations. Despite much evidence supporting the legitimacy of field-based BC assessments, a necessary prerequisite for validity is their ability to measure scores consistently across different time points. Purpose: The purpose of this study was to examine the test-retest stability of 4 common BC assessments in college students. Methods: Data for this research came from a larger BC measurement study. A total of 38 participants who signed an IRB approved consent form and had BC measurements taken from each of 4 methods at 2 different time points (within the same week) were included in this analysis. The 4 BC assessments were (a) percent body fat (PBF) by skinfold technique (SF), (b) waist circumference (WC), (c) body mass index (BMI), and (d) PBF by handheld bioelectrical impedance (HH). Three different statistical approaches were used to evaluate stability. First, descriptive procedures such as Pearson's correlation coefficient, paired t-test, and Cronbach's alpha were used to show how consistent each assessment was across trials. Second, Cohen's kappa was used after transforming each variable into quartiles to assess the amount of categorical agreement across trials. Third, Bland and Altman plots and limits of agreement (LOA) were constructed to evaluate the spread and pattern of mean differences across trials. Results: Mean differences (SD) for SF (%), WC (cm), BMI (kg·m−2), and HH (%) were −0.07 (1.52), 0.39 (3.17), −0.03 (0.53), and −0.21 (2.19), respectively. Test-retest correlations were all greater than 0.95 (p < 0.001) with non-significant t-tests (p > 0.05). Cronbach's alphas were all greater than 0.97. Weighted kappas were strong for SF, BMI, and HH (κ > 0.92) and moderately strong for WC (κ = 0.71). All LOA plots showed at least 95% of differences within range. WC LOA were clinically large (±6.2 cm). However, after the removal of 2 WC outliers, WC LOA became reasonable (±3.8 cm). Conclusions: Results of this study provide evidence for acceptable test-retest stability of common field-based BC assessments in college students. Practical Applications: Measurement theory assumes that scores from an assessment are reliable only under particular situations. That is, assessments found reliable in general populations are not necessarily reliable in college students. Many factors common on college campuses can in fact affect an assessment's stability, such as fatigue, practice, subject variability, testing circumstances, and precision of measurement. This study shows that such factors do not impede the stability of common BC assessments in college students.
New Elastic Training Devices and Weight Bars With Rotating Shafts Result in Positive Strength Adaptations in Older Adults
N. Triplett,1 A. Juesas,2 P. Gargallo,2 V. Munoz,2 J. Calatayud,2 M. Tobarra,2 M. Hernandez,2 and J. Colado2
1Appalachian State University; and 2University of Valencia
There are numerous studies corroborating the benefits of strength training in older people using different types of devices. However, what is less understood is whether the use of different devices may lead to different adaptations in physical performance because of their different characteristics. Purpose: To compare adaptations in maximum voluntary isometric strength (MVIS) of the trunk and extremities when utilizing new types of elastic devices and free weights which have weight bars with rotating shafts of 360° from a fixed point. Methods: 74 older adults without contraindications volunteered for this investigation. Subjects were divided into 2 experimental groups, elastic tubes (ETG) anchored at an exercise station (n = 39; 66.8 ± 4.4 years) and rotational weights (RWG) with a rotating bar that was fixed at one end (n = 17; 69.8 ± 5.2 years), and a control group (CG) (n = 18; 70.6 ± 6.2 years) who continued their usual activities of daily living. During 12 weeks the experimental groups performed 2 sessions per week of a strength training program with 6 exercises (Squat [normal stance]; Squat [wide stance]; Lunge; Vertical Row; Incline Row; Biceps Curl). Subjects performed 3–4 sets of 10 repetitions at an intensity of 7–9 RPE (0–10 scale) with 90 seconds recovery, and with cadence (2 seconds con-2 seconds ecc). Warm-up and cool-down were standardized. MVIS was recorded pre- and post-training for the vertical row (VR), horizontal leg press (HLP) and seated back extension (SBE). Non-parametric tests (Shapiro-Wilks) were performed and the Wilcoxon-Mann-Whitney test with the Kruskal-Wallis test was used to determine the existence of intra-group differences, and a Bonferroni correction was applied (SPSS version 22, p ≤ 0.05). Results: Both exercise groups improved MVIS in all exercises analyzed: VR +37.6% ETG and +51.9% RWG; HLP +74.4% ETG and +38.6% RWG; and SBE +49.4% ETG and +64.3% RWG. CG significantly reduced MVIS: −13.2% VR, −20.7% HLP, −15.6% SBE. Both exercise groups showed significantly improvements for all exercises analyzed when compared to the CG, and the ETG showed significantly greater improvement than RWG in HLP. Conclusions: While both types of training devices were effective in producing positive strength adaptations in older individuals, there are some variations as the anchored elastic tube device resulted in significantly greater lower body strength adaptations. Based on the results of this investigation, it appears that performing exercises with more stable equipment (i.e., exercise station) was more effective in improving lower body strength in an untrained population. It is possible that the lack of resistance training experience in the study participants made it more difficult to perform the rotational weight exercises to maximum effectiveness. Practical Applications: Variation in exercises and/or training devices in exercise programs for older persons is encouraged as multiple methods can be similarly effective in producing positive physical adaptations. Factors that should be taken into account include initial physical capacity and training experience when selecting exercises and devices to maximize training adaptations.
Upper Body Ergometry as a Predictor for Hypertension in Fit, Normotensive Male College Students With Hypertensive Parents
D. Gourley, R. Jones, B. Boudreaux, G. Stiegler, and R. Kraemer
Southeastern Louisiana University
Graded exercise tests have been shown to elicit an exaggerated blood pressure response in normotensive individuals with a family history of hypertension in comparison to their peers with no history. While this exaggerated response, which indicates increased risk of hypertension has been observed using dynamic lower body exercise, no previous study has investigated the use of dynamic upper body exercise. Purpose: The purpose of this investigation was to determine the effectiveness of an upper body ergometry graded exercise test to detect exaggerated blood pressure responses in normotensive individuals with a family history of hypertension compared with responses to a lower-body graded exercise test. Methods: Ten college-aged males (mean ± SD age = 21.7 ± 2.5) were recruited from the campus of Southeastern Louisiana University. Subjects were categorized into the experimental (EXP) or control group (CON) based on a current diagnosis of hypertension in at least one parent. Each subject participated in 2 sessions. During the first session, height, weight, resting blood pressure (BP) via auscultation, and a 3 site skinfold assessment was determined. A V[Combining Dot Above]O2max test was also conducted and used as an inclusion criterion for fitness level. For the second session, the exercise protocol began with a 10-minute resting period. BP and heart rate (HR) were measured before exercise commenced and following exercise. First, lower body exercise was performed using a Monark 828e cycle ergometer. Participants were asked to pedal at 50 RPM for 2 minutes at the following workloads in which responses were assessed: 25, 50, and 100 W. BP and HR were taken during the final 15 seconds of each stage. A 10-minute resting period preceded the upper body portion, using a Monark 881 arm ergometer. The upper body protocol matched the duration and intensity of the lower body. A repeated measures ANOVA was used to compare experimental and control group responses for dynamic upper body and lower body exercise. Results: V[Combining Dot Above]O2max (Mean ± SE EXP, 49.8 ± 4.18; CON, 47.4 ± 3.35 ml·kg−1·min−1) was not significantly different between groups. Dynamic upper body ergometry elicited significant increases in mean arterial pressure during the duration of exercise. This response was more exaggerated in subjects who had a family history of hypertension (F = 19.11, p = 0.002). During the highest workload, subjects in the EXP group had an average MAP of 118.8 ± 3.08 compared to those in the CON group with an average of 109.9 ± 3.02. This study also confirmed findings from previous studies regarding greater lower body exercise MAP responses in the EXP group (F = 6.51, p = 0.03). HR responses were similar (p > 0.05) for both groups during upper body and during lower body exercise. Conclusions: The use of dynamic upper body exercise is an appropriate mode to assess an individual's increased risk for developing hypertension. Practical Applications: Due to known differences in physiology, an assessment using dynamic upper body exercise may more finely indicate an aerobically fit individual's risk of developing hypertension.
Predicting on-Field Contribution Using the National Football League (NFL) Combine Measureables in the 2015 NFL Rookie Class
G. Ryan,1 R. Herron,2 S. Bishop,3 and C. Katica4
1Catawba College; 2University of Alabama; 3University of Montevallo; and 4Pacific Lutheran University
The National Football League (NFL) conducts an annual combine to assess anthropometric measures and athletic ability in preparation for the draft. Following the combine, many of these players, as well as others, are drafted or sign as undrafted free agents to play in the NFL. However, the best performers during the combine, do not always experience on field success. Purpose: The purpose of this study was to determine how well the performance measures of the athletes invited to the 2015 NFL Combine predicted on-field contribution, as measured by snaps taken during the 2015 NFL regular season. Methods: Data from 8 tests (2 anthropometric and 6 performance) of 309 athletes were used for analysis. The 8 tests used for analysis were: arm length; hand size; 40 yd sprint; 225 pound bench press repetitions; vertical jump; broad jump; 3-cone drill; and 20 yd shuttle. The number of offensive/defensive and special teams snaps for each rookie was averaged over the course of the season. A multiple linear regression was calculated to predict on-field contribution based on the 8 performance recorded during the NFL Combine. Results: A significant regression omnibus equation was found (F(8,143) = 3.969, p < 0.001), with an R2 of 0.182. The average number of plays an athlete was involved in was equal to 7.154 + 2.928 (arm length) + 4.765 (hand size) + 2.541 (40 yd sprint) + 0.641 (bench press repetitions) – 0.342 (vertical) + 0.094 (broad jump) + 17.687 (3-cone drill) − 64.464 (20 yd shuttle), 95% CIs (−45.945 to 60.252), (−0.264 to 6.120), [−1.794 to 11.325], [−22.819 to 27.902], [0.025 to 1.257], [−1.954 to 1.270], [−0.500 to 0.688], [−5.765 to 41.139], and [−97.136 to −31.793], respectively. Bench press repetitions and 20 yd shuttle performance were highly related to on-field contribution. Additionally, on-field contribution predictions differed among individual position groups: Running Backs (R2 = 0.252); Quarterbacks (R2 = 0.326); Tight Ends (R2 = 0.979); Offensive Linemen (R2 = 0.144); Wide Receivers (R2 = 0.212); Defensive Linemen (R2 = 0.317); Linebackers (R2 = 0.705); and Defensive Backs (R2 = 0.257). Conclusions: The findings of this study suggest that the performance testing conducted at the 2015 NFL Combine could predict on-field contribution during the 2015 NFL regular season, though the R2 prediction was varied among individual position groups. Practical Applications: These findings may help teams and scouts to assess performance and determine potential on-field contribution of draftees and undrafted free agents. However, due to the variable nature of the prediction across position groups, it is possible that the NFL and teams should reconsider what is measured at the NFL Combine to better the evaluation process of selecting and playing athletes.
Test-Retest Reliability and the Learning Effect Associated With Isokinetic Exercise in Masters Cyclists
J. Glenn,1 M. Gray,2 and N. Moyen2
1Louisiana Tech University; and 2University of Arkansas
For aging, athletic populations (i.e., masters athletes [MA]), muscular strength is a critical factor for exercise performance. Although multiple investigations have used isokinetic exercise to evaluate strength performance in MA, the test-retest reliability of these measurements in MA has not yet been established. Furthermore, it is imperative that the learning effect of isokinetic exercise be evaluated without the implementation of a familiarization trial to establish test-retest efficacy from a clinical perspective. Purpose: The purpose of this investigation was twofold, (a) to establish test-retest reliability of isokinetic exercise in MA, and (b) to determine whether a true learning effect exists with isokinetic exercise when utilized without a familiarization trial. Methods: This study included 22 masters-aged (53 ± 5 years), competitive female cyclists. Cyclists were recruited as the push/pull nature of lower-body isokinetic exercise relates to muscle pattern activation utilized during cycling exercise. Females were specifically recruited because they exhibit greater levels of internal motivation compared to males, which would minimize external factors affecting testing variability. Subjects completed 3 separate 50-repetition knee flexion/extension evaluations completed on an isokinetic dynamometer, separated by exactly 1 week. No familiarization was provided to elucidate the true learning effect of the evaluation. Variables used to determine test-retest reliability (determined a priori to testing) included the following: (a) peak torque (N·m), (b) relative peak torque (based on body weight [%]), (c) time to peak torque (milliseconds), (d) torque generated at 30° (N·m), (e) torque generated at 0.18 seconds (N·m), (f) work completed during the highest repetition (J), (g) relative work completed (based on body weight [%]), (h) total work completed (J), (i) work completed during the initial third of exercise (J), (j) work completed during the middle third of exercise (J), (k) work completed during the final third of exercise (J), (l) fatigue index (%), (m) average power (W), and (n) average peak torque (N·m). Results: Test-retest reliability (intra-class correlation [ICC]), 95% confidence intervals (CI), technical error of measurement (TEM), and MANOVA models were calculated between time points. ICCs between trials exhibited excellent comparisons during extension (0.93–0.97) and flexion (0.93–0.97) for all variables except time to peak torque (ICC = 0.35 and 0.45 for extension and flexion, respectively) and fatigue index (ICC = 0.47 for flexion). Relative TEM was minimal for extension between trial 1 vs. trial 2 (0.27%–0.97%) and trial 2 vs. trial 3 (0.27%–1.45%) for all variables. Similar results were observed for flexion between trial 1 vs. trial 2 (0.87%–2.45%) and trial 2 vs. trial 3 (0.54–1.10%). No differences (Wilks λ > 0.05) existed between trials, indicating no learning effect associated with the evaluation. Conclusions: These are the first data exhibiting strong test-retest reliability of an isokinetic dynamometer in MA or an all-female subject population. Furthermore, we demonstrate no learning effect associated with knee exercise on an isokinetic dynamometer. Practical Applications: When used in clinical or research settings, a familiarization protocol does not appear necessary before undergoing isokinetic exercise testing in a trained, female population. The removal of a familiarization trial to isokinetic exercise can save time and minimize financial requirements for athletes tracking longitudinal performance gains.
No Effect of Stick Carry on Agility in Collegiate Lacrosse Players
M. Wong,1 L. Brown,2 C. Watkins,1 S. Barillas,1 A. Bartolini,1 and C. Munger1
1Human Performance Laboratory, California State University Fullerton, Fullerton, California; and 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California
The game of lacrosse involves change of direction, running speed, and stick speed during shots. Agility, while carrying a stick, is essential to avoid contact with an opponent. Purpose: To examine the effect of carrying a stick on agility in male and female collegiate lacrosse players. Methods: 28 collegiate lacrosse players (17 female, age = 20.47 ± 1.77 years, height = 163.52 ± 6.26 cm, mass = 63.17 ± 9.30 kg) (11 male, age = 20.54 ± 2.38 years, height = 177.81 ± 7.58 cm, mass = 81.08 ± 9.73 kg) volunteered to participate. They performed a pro-agility test measured with timing gates placed 5 yd apart resulting in 4 splits. Two trials were completed with a stick and without a stick in a counterbalanced order with 3-minutes rest between trials. All participants wore cleats and males wore full pads, gloves, and helmets. Three cones were placed 5 yd apart and participants were instructed to begin by straddling the middle cone then to sprint 5 yd to the right (split 1), change direction to the left and sprint 10 yd (splits 2 and 3 were 5 yd each), then change direction and sprint 5 yd to the right (split 4) to complete the test. Timing gates were triggered by their foot crossing the sensor lines. Results: There were no interactions that included condition, split or gender nor was there for a main effect for condition. However, there was a main effect for split (p < 0.001). Split 1 (1.25 ± 0.02 s) was significantly faster than split 2 (1.73 ± 0.02 s) and split 4 (1.76 ± 0.02 s). Split 3 (1.10 ± 0.02 s) was significantly faster than all other splits. There was no significant difference between splits 2 and 4. There was also a main effect for gender where males were faster than females at all time points. Conclusions: Stick carry did not affect agility performance which suggests that coordination between upper and lower body may account for performance in collegiate lacrosse players while carrying a stick. Future investigations should examine agility during cuts and spins and in novice players while carrying a lacrosse stick. Practical Applications: Stick carry might be implemented in agility training drills to enhance coordination between upper and lower body limbs.
Gender Differences in Correlates of Speed and Acceleration in Youth Soccer Players
G. McDonald, C. Brightwell, T. Butts, M. Ivey, J. Lee, and W. Amonette
University of Houston—Clear Lake
Executing sport-specific skills, such as sprinting and accelerating, requires both horizontal and vertical ground reaction force (GRF). Previous research indicates that pure acceleration may be more accurately predicted using horizontal jump distance, but top-speed is more closely associated with vertical jump height. However, larger studies investigating these relationships have been completed using homogeneous samples of a single gender. Purpose: The objectives of this study were to quantify the relationship between athlete anthropometrics and kinetic variables associated with the vertical and broad jumps to speed and acceleration and to determine differences in relationships between male and female youth soccer players. Methods: Fifty-eight female (15.3 ± 1.1 years; 162.6 ± 7.5 cm; 59.8 ± 10.2 kg) and 58 male (16.4 ± 1.3 years; 173.1 ± 7.4 cm; 65.8 ± 8.5 kg) competitive soccer players volunteered to participate. After signing informed consent and adolescent assent forms, the following tests were completed: height using a tape measure (Ht; cm) weight with a digital scale (Wt; kg), broad jump on a rubber mat with ruler (BJ; cm), vertical jump on a force-platform (VJ; cm), speed, and acceleration with a timing light system capturing time at 10 (10 yd; seconds) and 40 yd (40 yd; seconds). Utilizing the GRF data, jump height was computed from the take-off velocity of the center of mass (COM) and peak power (PP; W) was calculated by multiplying the COM velocity by the peak GRF. PP was also normalized as a variable by dividing the absolute PP by the subject's body mass (PPnorm). Pearson correlations were determined independently in males and females between Ht, Wt, VJ, BJ, PP, PPnorm and 10 yd, 40 yd, and the interval time between 10 and 40 yd (10–40 yd; seconds). Alpha was set at p ≤ 0.05. Results: In women, BJ (r = −0.23) was significantly correlated with 10 yd time, but no other variables were statistically significant. VJ (r = −0.24), BJ (r = −0.59), and PPnorm (r = −0.25) were all associated with 40 yd speed in females; no other anthropometric or kinetic variables were significantly correlated. No anthropometric or kinetic variables tested in this project were significantly correlated with interval sprint time between 10 and 40 yd in female youth soccer players. The measured anthropometric and kinetic variables were not significantly correlated with 10 yd sprint time in males. However, VJ (−0.55), BJ (r = −0.43), PP (r = −0.63), and PPrel (r = −0.60) were significantly correlated with 40 yd sprint time. Likewise, VJ (r = −0.25), PP (r = −0.40) and PPnorm (r = −0.55) were associated with interval sprint time between 10 and 40 yd, but no other variables were significantly correlated in males. Conclusions: Athlete anthropometrics were poor predictors of speed and acceleration in youth soccer players regardless of gender. Kinetic variables associated with jumping were better predictors of 40 yd speed and interval speed between 10 and 40 yd in males than in females. BJ was the strongest predictor of speed in females, but VJ and power normalized to body weight better predicted speed in males. The poor prediction values of all variables to 10 yd sprint time may be due to the dissimilarity of accelerating from a stopped position to soccer-specific skills. Practical Applications: Strength and conditioning coaches desiring to quantify athleticism in female youth soccer players may choose BJ testing instead of VJ, but in males the kinetics of the VJ may be better indicators of speed capabilities.
Gender Based Analysis of the Eccentric Utilization Ratios of NCAA Division III Athletes
S. Williams, A. Ciepley, T. Barron, and W. Ebben
The eccentric utilization ratio (EUR) has been used to assess the activation of the stretch shortening cycle during jumping, by dividing the jump height (JH) of the countermovement jump (CMJ) by the squat jump (SJ). To date, gender differences and the underlying mechanisms of this ratio are not well understood, particularly for NCAA division III athletes. Purpose: This study assesses gender differences or similarities in the EUR and the underlying kinetic mechanisms such as ground reaction force (GRF) and power (P). Methods: Eleven women (age = 20.45 ± 1.2 years; collegiate athletic experience = 2.64 ± 1.1 years) and twelve men (age = 20.54 ± 1.5 years; collegiate athletic experience = 2.64 ± 1.2 years) served as subjects. Subjects provided informed consent prior to participating in the study, which was approved by the Institutional Review Board. Subjects participated in a habituation and test session. During the habituation session, subjects were taught the correct performance of the CMJ and SJ. During the test session, subjects performed 3 repetitions of the CMJ and SJ, in random order. During each, JH, P, and GRF were assessed with a force platform. A 2-way mixed ANOVA with repeated measures for jump type was used to evaluate the main effects for jump type, and the interaction between jump type and gender, for JH, P, and GRF. When gender differences were found, a repeated measures ANOVA was used to assess the differences in the dependent variables between the jump types, for each gender. The trial to trial reliability of dependent variables was assessed using average measures intraclass correlation coefficients. Results: Significant main effects were found for jump type (p = 0.038), and the interaction between jump type and gender (p = 0.028), for JH. Significant main effects were found for jump type (p = 0.04), and the interaction between jump type and gender (p = 0.013), for P. No significant main effect or interaction was found for GRF (p > 0.05). For men, CMJ and SJ JH were 45.02 ± 6.28 cm, and 35.25 ± 6.43 cm, respectively, representing a 22.71% difference, and an EUR of 1.28. For women, CMJ and SJ JH were 28.33 ± 6.19 cm, and 21.53 ± 4.76 cm, respectively, demonstrating a 24.01% difference, and an EUR of 1.31. Gender differences in EUR, CMJ and SJ were present (p < 0.001). For men, CMJ and SJ P was 5,693.67 ± 1,117.27 W and 4,529.71 ± 675.47 W, respectively, representing a 20.45% difference. For women, CMJ and SJ P was 3,370.66 ± 605.12 W, and 2,704.09 ± 545.42 W, respectively, demonstrating a 19.78% difference. Interclass correlation coefficients for all dependent variables ranged from 0.98 to 0.99. Conclusions: This study shows large differences between the CMJ and SJ for both men and women, demonstrating the important contribution of the stretch shortening cycle to jump height. Gender differences in P were found, potentially explaining the 37.08% greater CMJ produced by men compared to women. The gender differences in the magnitude of P produced by men may explain the gender differences in the EUR. Practical Applications: Practitioners should assess gender based differences in EUR and modify training accordingly, by either increasing strength training or higher velocity stretch shortening cycle training methods such as plyometrics, based on EUR. Acknowledgments: This study was funded by a Lakeland University Undergraduate Research Experience grant.
Validity and Reliability of the Push Wearable Device to Measure Velocity and Power During Loaded Countermovement Jumps
N. Ripley1 and J. McMahon2
1Sale Sharks RUFC; and 2University of Salford
There has been a recent development of a novel wireless device (PUSH band) that provides kinematic and kinetic feedback during strength and power training exercises, however, there is limited research that has explored this device's validity and reliability. Purpose: The purpose of this study was to determine the concurrent validity and reliability of the PUSH band for determining peak velocity and peak power during loaded countermovement jumps (CMJs). Methods: Eighteen recreationally active sports science students (15 males, 3 females, age = 23.7 ± 6.9 years, body mass 78.7 ± 10 kg, height 177.8 ± 6.7 cm) performed 3 maximal effort CMJs with a 20 kg barbell. Each repetition was performed on a Kistler force platform (“criterion method”) sampling at 1,000 Hz whilst subjects wore a PUSH band sampling at 200 Hz on their dominant forearm. PUSH band data was transmitted via Bluetooth to an Android tablet running the PUSH app (Version 1.126, Toronto, Canada). System velocity was determined by dividing vertical force (minus system weight) by system mass and then integrating the product using the trapezoid rule. System power was calculated by multiplying vertical force by velocity at each time point. Velocity values registered by the PUSH band were derived by integrating vertical acceleration data (via the in-built accelerometer) with respect to time. Power values from the PUSH band were determined using inverse dynamics with system mass manually inputted into the PUSH app. Peak velocity and peak power values were taken forward for statistical analysis. Reliability was assessed using the intraclass correlation coefficient (ICC) and coefficient of variation percentages (CV%). A dependent t-test was used to compare mean differences in peak velocity and peak power derived from the PUSH band and force platform. The PUSH band's concurrent validity was tested against the force platform using Pearson's correlation (r) coefficient and coefficient of determination (R2) to determine the relationship between the 2 methods. The alpha level was set at p ≤ 0.05. Results: High levels of within-session reliability of the peak velocity and peak power measurements were found for both the PUSH band and force platform, however, the PUSH band significantly (p < 0.001) overestimated all values compared to the force platform (Table 1). Despite this, positive relationships were found between values attained using the PUSH band and force platform (“criterion method”) with coefficient of determination (R2) values of 0.84 and 0.90 for peak velocity and peak power, respectively, therefore correction equations were subsequently produced (Table 1). Conclusions: The PUSH band is reliable but overestimates peak velocity and peak power in comparison to values obtained from a force platform. Practical Applications: Practitioners may use the PUSH band to monitor peak velocity and peak power production during loaded CMJs due to its high reliability, however, the correction equations presented in this study should be applied to resultant values if the data is used for normative purposes or if it is being compared to force platform derived measures.
Comparison of Vertical Jump Scores Measured Using Center of Mass Displacement and Jump Height With Different Standing Reach Techniques
C. Brightwell,1 B. Brightwell,2 G. McDonald,1 and W. Amonette1
1University of Houston—Clear Lake; and 2University of Texas Medical Branch
Maximal vertical displacement of the center of mass (COM) is a strong indicator of an athlete's ability to generate vertical ground reaction force (GRF) and power. It is often measured in field settings using difference in maximal jump height and standing reach height; however, athletes may be able to inflate vertical jump scores by intentionally or unintentionally minimizing standing reach height resulting in an overestimation of true force and power potential. Purpose: The purpose of this study was to compare and determine levels of agreement in vertical jump height (VJHT) measured using the take-off velocity of the COM and difference between jump height and standing reach height (RHT) using 4 different postural manipulations. Methods: Fifty-six subjects (21 f; 35 m; 25.8 ± 4.7 years; 173.8 ± 11.3 cm; 79.71 ± 7.1 kg) participated in this study after providing informed consent. They completed a self-selected 5-minute warm-up prior to measurement of height using a stadiometer. Standing RHT was then obtained using a wall-mounted ruler and 4 different postural positions: heels down with scapula depressed (HDSD), heels down with scapula elevated (HDSE), heels up with scapula depressed (HUSD), and heels up with scapula elevated (HUSE). Subjects performed 2 maximal effort countermovement vertical jumps. GRF data were collected at 400 Hz with a force platform, and reaching jump height was measured simultaneously using a free standing height scale with plastic swinging vanes in half inch increments. GRF data were used to compute VJHT using the take-off velocity of the COM and a projectile motion equation. VJHT was also calculated by subtracting the 4 RHTs from the jump height obtained from the standing height scale. For all analyses, only data from the second jump were utilized. Bland-Altman analyses were used to estimate the level of agreement (bias ± standard error of the difference) between the COM velocity technique and the 4 RHT methods. Repeated measures ANOVA with Holmes-Sidak post hoc analysis was used to determine differences between VJHT obtained from the COM velocity and the 4 RHT methods with an alpha of 0.05. Effect size calculations were completed for each comparison using Cohen's d. Results: VJHT measured using the COM velocity (36.6 ± 10.1 cm) was significantly lower (p < 0.001; d = 1.3) than HDSD (58.3 ± 14.4 cm). Comparison of the 2 methods revealed bias scores of 21.6 ± 9.7 cm. Significant differences (p < 0.001; d = 0.84) were also found between COM velocity and HDSE (48.1 ± 14.4 cm); bias between these methods was 11.5 ± 9.5 cm. HUSD (50.4 ± 14.4 cm) differed significantly (p < 0.001; d = 0.96) from the COM velocity method; bias between these 2 methods was 13.1 ± 9.0 cm. HUSE (39.4 ± 13.6 cm) also differed significantly (p = 0.002; d = 0.23) from COM velocity method; the computed bias between the 2 methods was 2.8 ± 7.7 cm. Conclusions: All 4 RHT methods significantly over estimated actual COM displacement during the vertical jump. VJHT calculated using the RHT with heels up and scapula elevated most accurately estimated actual COM displacement and only differed by approximately 3 cm. Practical Applications: Strength and conditioning practitioners who desire to more accurately measure COM displacement from the vertical jump test, eliminating differences resulting from postural manipulations, should measure standing reach height with the heels and scapulae maximally elevated.
Comparison of the Hang High-Pull and Trap-Bar Jump Squat in the Development of Vertical Jump and Isometric Force-Time Characteristics
D. Oranchuk,1 Z. Switaj,1 T. Robinson,1 and M. Jordan2
1Adams State University; and 2Canadian Sports Institute-Calgary
Weightlifting derivatives, such as the hang high-pull (HHP), are effective for improving a variety of explosive athletic performance measures. However, weightlifting movements have high skill demands and require expert coaching. Weighted jumps, such as the trap-bar jump squat (TBJS), have a comparably lower skill demand and may be equally effective for improving explosive performance. Yet, to date there is limited scientific research evaluating the effects of these movements and the transferability to high performance sport. Purpose: The purpose of the study was to compare vertical jump performance and isometric force and rate of force development (RFD) following a ten-week intervention employing the HHP or TBJS in collegiate swimmers. Methods: Eighteen NCAA Division II swimmers (Male n = 8; Female n = 10), with at least 1 year of resistance training experience, volunteered for the study. Baseline and post-training tests included the squat jump (SJ), countermovement jump (CMJ) and the isometric mid-thigh pull (IMTP) performed on force plates sampling at 500 Hz. The SJ and CMJ ground reaction forces (Fz) were analysed using a custom built software to obtain relative peak power, and the impulse-momentum method was used to calculate jump height. The peak isometric force relative to body mass, peak RFD and relative force at 5 time bands was obtained from the IMTP Fz (Table 1.). Subjects were randomly assigned to a HHP training group or TBJS training group and completed a 10-week volume and intensity equated periodized strength training program. Loads and volumes for the HHP and TBJS were determined using percentages of the subjects' one repetition maximum power clean or trap-bar deadlift and were progressed over the supervised training sessions by a certified strength and conditioning specialist. Results: Paired sampled t-tests revealed that all measured dependent variables significantly (p ≤ 0.05) increased from pre-to post-test regardless of the intervention type used. The mean increases (Table 1.) were not significant (p > 0.05) different between the HHP and TBJS, although medium effect sizes were recorded for both the SJ and CMJ relative peak power. Jump height for the SJ and CMJ showed increases of 3.4 and 2.9 cm, respectively, while relative peak force increased by 7.1 N·kg−1, after the 10-week intervention. Conclusions: Weighted jumps may be equally effective as weightlifting derivatives in the development of vertical jump height and power, and isometric force and RFD. Future studies may wish to examine different populations and other performance measures. Practical Applications: The results show that weighted jumps may be equally effective as weightlifting derivatives for improving athletic performance measures. However, weighted jumps require significantly less skill to perform, which may make weighted jumps a better option in a large team setting where coaching complex movements may be difficult or where equipment limitations may exist.
Effect of Resisted Sprint Training on Acceleration: a Systematic Review and Meta-Analysis
E. Aldrich, W. Dobbs, M. Fedewa, and P. Bishop
University of Alabama
Resisted running, such as sled or parachute towing, is commonly used to train athletes. Some research indicates resisted sprint training improves the acceleration phase of running, while other studies found traditional, un-resisted sprint training yielded greater improvements. Purpose: The purpose of this systematic review and meta-analysis was to quantitatively estimate the effectiveness of resisted sprint training on acceleration. Methods: The review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Articles published prior to October 31, 2015, were located using searches of EBSCOhost (n = 498), PubMed (n = 178), and Physical Education Index (n = 100) using combinations of the terms: towing, sled, resisted sprint, sprint acceleration, sprint performance, and sprint speed. The search returned 153 records after duplicates were removed, from which 10 publications were eligible for inclusion. Inclusion criteria were as follows: (a) peer-reviewed publication; (b) available in English; (c) participants (>18 year old) randomized to resisted or un-resisted sprint training; and (d) speed or time was recorded from 0 meters to a maximum of 30 meters. A random effects model was used to compute the mean effect size (ES). The Hedges' d ES was calculated by subtracting the mean difference of the control from the mean difference of the resisted, dividing by the pooled standard deviation, and adjusting for small sample bias. A positive ES indicated resisted sprint training led to a greater improvement in acceleration compared to the un-resisted sprint training. Results are presented as mean (M), standard deviation (SD), and 95% confidence interval (CI). Results: The cumulative results of 19 effects collected from 10 studies indicated that resisted sprint training did not improve acceleration (ES = 0.047 + 0.50, 95% CI: −0.177 to 0.270, p = 0.68). Effect size distribution is shown in Figure 1. Participants ranged from highly fit physical education students to professional athletes (n = 191). Gender was not specified for 2 of the studies; the other 8 studies had a male to female ratio of 80:73. The number of effects ranged from 1 to 3 per publication (1.90 + 0.57), with 12–24 participants per effect (19.10 + 3.41). Conclusions: Results from research published between 2005 and 2015 indicate that resisted sprint training resulted in a trivial, non-significant improvement in acceleration. Given the small number of effects and lack of heterogeneity, thorough moderator analysis could not be performed. Practical Applications: When designing a training program, coaches should understand current data suggest resisted sprint training does not improve acceleration any more than traditional sprint training. Future research should address possible moderators such as sprint training background, resistance load, sex, and training prescription.
No Potentiating Effect of Weighted Depth Jumps on Vertical Jump Impulse in Recreational Female Volleyball Players
E. Thomson,1 C. Munger,1 L. Brown,2 J. Coburn,3 and A. Galpin2
1Human Performance Laboratory, California State University, Fullerton, California; 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California; and 3Human Performance Laboratory, Center for Sport Performance, California State University, Fullerton, California
Vertical jumping is a critical component in volleyball competition. The use of post-activation potentiation (PAP) is a popular means of enhancing vertical jump performance. Common protocols to elicit PAP include use of a heavy resistance exercise, which is not practical in a competition setting. A different approach, without the use of heavy equipment, is through weighted depth jumps. Purpose: To determine the effect of varying intensities of weighted depth jumps on bodyweight (BW) countermovement vertical jump (CMVJ) impulse. Methods: Ten recreational female volleyball players (age = 23.90 ± 3.14 years; ht = 168.90 ± 5.34 cm; mass = 64.89 ± 12.02 kg) attended 5 sessions separated by 24 hours. They performed the same dynamic warm-up (20 m of walking knee hugs, walking lunges and Frankenstein's) before every session. On session one, they performed 3 control BW CMVJ with arm swing on an AMTI force plate. They then performed 5 BW (0%) depth jumps, rested for 2 m then performed 3 post BW CMVJ. On sessions 2–5, they performed 5 depth jumps with a weighted vest under one of 4 experimental conditions in random order; 5, 10, 15 or 20% BW with 15 s rest between jumps, then 2 m rest and finally 3 post BW CMVJ. Depth jump box height was 30 cm for all conditions. Results: A 1 × 6 repeated measures ANOVA demonstrated no differences in post BW CMVJ impulse between conditions (control: −263.23 ± 47.80 Ns, 0% −262.57 ± 47.33, 5% −257.36 ± 53.18 Ns, 10% −251.40 ± 49.24 Ns, 15% −253.37 ± 56.50 Ns, 20% −255.79 ± 49.72 Ns). Conclusions: Varying intensities of weighted depth jumps did not improve post BW CMVJ impulse. Practical Applications: These results suggest that recreational female volleyball players should not use this protocol to elicit acute increased CMVJ performance. PAP has been shown to have a greater response in trained individuals. Therefore, trained female volleyball players should be investigated using varying intensities of weighted depth jumps on CMVJ.
Kinetic Analysis of the Role of Upper Extremity Segmental Inertia on Vertical Jump Performance
T. Barron, A. Ciepley, S. Williams, and W. Ebben
Ballistic movement of the upper extremity is believed to increase countermovement jump (CMJ) performance. The forceful extension of the upper extremities at the shoulder joint during the eccentric phase of the CMJ is thought to potentiate the stretch shortening cycle. The forceful flexion of the upper extremity during the concentric phase of the CMJ, likely increases system inertia and jump height. Purpose: This study assessed the contribution of forceful arm swing during the eccentric and concentric phases of the CMJ, in order to determine the effect on CMJ performance. Methods: Fourteen women (age = 20.5 ± 1.2 years; height = 166.96 ± 5.73 cm; weight = 71.19 ± 12.27 kg; collegiate athletic experience = 2.67 ± 1.1 years) served as subjects for this study. Subjects signed an informed consent form prior to participating in the study, which was approved by the Institutional Review Board. Subjects participated in a habituation and testing session. During the habituation session, subjects were instructed on and practiced the correct performance of the test jumps. Test jumps included the CMJ with no shoulder extension during the eccentric phase, CMJ with no shoulder flexion during the concentric phase, and the performance of the normal CMJ characterized by maximal shoulder flexion and extension. During the test session, subjects performed 3 repetitions each of these test exercises, in random order. During each, subject jump height (JH), power (P), and GRF data were collected with force platform (Accupower, Advanced Mechanical Technology, Inc. Watertown, MA, USA). A repeated measures ANOVA was used to assess the differences between the test exercises for JH, P, and GRF. When significant differences were found, a Bonferroni post hoc analysis was performed in order to identify specific differences between test exercises. Results: Analysis demonstrated significant differences between test conditions for JH (p < 0.001) and P (p < 0.001), but not for GRF (p > 0.05). Results of the post hoc comparison are shown in Table 1. Interclass correlation coefficients for the test exercises and all dependent variables ranged from 0.95 to 0.99. Conclusions: This study demonstrated significant differences between jumping conditions that sought to maximize arm swing, and thus segmental inertia. Eliminating the downward arm swing results in jump heights that are 3.51% less than the normal countermovement jump. Eliminating the upward arm swing results in jumps heights that are 12.1% less than the normal countermovement jumps. Thus, arm swing is important to both the eccentric and concentric phase of jumping. Practical Applications: During training, and the performance of jumping in sport, practitioners should teach athletes to maximally accelerate their arms into shoulder extension during the countermovement phase of jumps, and into full range of motion shoulder extension during the concentric phase, in order to maximize power and jump height. Acknowledgments: This study was funded by a Lakeland University Undergraduate Research Experience grant.
Comparison of Two Devices for Measuring Bat Velocity of High School Baseball Players: A Pilot Study
E. Nevala and D. Szymanski
Louisiana Tech University
Research on baseball hitting has reported that bat velocity (BV) is an important component for successful hitting. The ability to measure BV has not been easily accessible. However, with more advances in technology, new products are now available that claim to measure BV accurately. One of the new and novel devices sold to measure BV is a 3-axis gyroscope and dual accelerometer (3-AGA) synchronized with a cell phone. No previous studies have compared the new device to devices used in previous research to measure BV. Purpose: To compare a new 3-AGA for measuring BV of high school (HS) baseball players to a 2-beam infrared sensor chronograph (2-BISC). Methods: Nine HS baseball players (age = 16.7 ± 1.6 years; Ht = 177.5 ± 5.3 cm; BM = 72.0 ± 10.7 kg; %BF = 14.7 ± 4.7) participated in a familiarization day consisting of hitting baseballs off a 75 cm standardized batting tee for 3 sets of 10 swings with the 3-AGA device attached to the knob of the 83.8 cm, 850.5 g (33-in., 30 oz) standard testing baseball bat and using the app on their coach's cell phone. The next week, players completed 2 testing sessions with at least 48 hours rest in between sessions. After a 10 minutes dynamic warm-up, players took 2 × 10 practice swings with the testing bat hitting baseballs off a batting tee, rested for 5 minutes, and then completed the 1 × 10 experimental swings with the same bat and batting tee. The 3-AGA and 2-BISC were used to measure BV from 10 maximal effort game swings with 20-seconds of rest between swings while hitting a baseball off the standardized batting tee. The mean of the last 6 swings was calculated to represent each player's BV for each testing day similar to previous research. The relation of BV between the 2 devices was determined using a Pearson's product moment correlation. Independent sample t-tests and paired sample t-tests were also calculated for BV to determine if there were differences between days with each device and differences between devices on the same day. Statistical significance was accepted at an alpha level of p ≤ 0.05. Results: Test-retest reliability (day 1 vs. day 2) for assessing BV using the 3-AGA device was 0.792 with a technical error of measurement of 0.98% while test-retest reliability using the 2-BISC was 0.786 with a technical error of 0.95%. A significantly high positive correlation existed between BV for 3-AGA and 2-BISC test day 1 (r = 0.845), as well as a significantly high positive correlation between BV for 3-AGA and 2-BISC test day 2 (r = 0.807). There were no significant differences in mean BV between devices (3-AGA vs. 2-BISC) on the same day or within devices (3-AGA day 1 vs. day 2 and 2-BISC day 1 and day 2) on different days. Conclusions: Assessment of BV using the 3-AGA device is similar to the 2-BISC. Therefore, the 3-AGA can be used to accurately measure BV. Practical Applications: The 3-AGA is relatively inexpensive and requires minimal technical expertise to use. Because all swings taken with the 3-AGA are recorded by the app and are saved to a cell phone, coaches or players can see their previous BV and compare them to the most current recorded BV. Therefore, they should feel confident using the new, commercially available 3-AGA device as an accurate assessment and monitoring tool.
Relationship Between Margaria-Kalaman Stair Climb and Vertical Jump Power in Males and Females
J. Thornberry,1 D. Dunnick,1 S. Barillas,1 K. Malyszek,1 and L. Brown2
1Human Performance Laboratory, California State University, Fullerton, California; and 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California
Anaerobic power is vital to sport performance, yet a multitude of available tests yield different results. The Margaria-Kalaman stair climb test (MK) is a basic anaerobic power test which takes the vertical height of the stairs into consideration. Purpose: To use the original MK vertical equation to determine the correlation with a countermovement vertical jump test (CMVJ). Methods: Fourteen recreationally trained males (23 ± 1.5 years; 175.0 ± 12.5 cm; 78.7 ± 15.5 kg) and 15 females (23 ± 2.7 years; 165.2 ± 5.7 cm; 62.6 ± 7.1 kg) completed the MK and CMVJ tests. The MK test was conducted using a 6 meter approach then climbing 9 stairs, 3 at a time. Time was recorded using timing gates on the third and ninth steps. Subjects were given 3 practice runs followed by 3 test trials. The CMVJ required subjects make a preliminary downward movement followed by a forceful jump in order to reach the highest vanes on an EPIC device. Power was determined as the product of force and velocity on a force plate. Results: Males demonstrated a moderate correlation (r = 0.527) (CMVJ, 4,768.7 ± 1,365.3 W; MK, 1,470.6 ± 479.9 W), but none (r = 0.031) for females (CMVJ, 3,201.4 ± 635.8 W; MK, 927.8 ± 98.0 W). Conclusions: The low correlation in females may be due to short stature and leg length, which made it difficult for them to climb stairs 3 at a time. Further research should investigate the relationship between height and the MK test. Practical Applications: Practitioners could use the MK test to determine vertical power in males but a CMVJ test would be more applicable for females.
The Relationship Between the Auditory Stimuli of Footstrike and Ground Reaction Force During Jump Landings
A. Ciepley, T. Barron, S. Williams, and W. Ebben
Force platforms have been used to provide an accurate measurement of ground reaction forces (GRF) during plyometrics. Anecdotal evidence suggests that the sound of the foot strikes during jump landings may be representative of higher ground reaction forces. The auditory stimulus of foot strike may be a parsimonious measure of plyometric intensity. Purpose: The purpose of this study was to determine if the sound of foot contact, as assessed by a decibel meter, is correlated with GRF during plyometric jump landings. Methods: Fifteen women (age 19.6 ± 1.4 years, height 166.29 ± 6.14 cm, weight 63.21 ± 4.43 kg, collegiate athletic experience of 2 ± 1.2 years) volunteered to serve as subjects. Subjects signed an informed consent form prior to participating in the study, which was approved by the Institutional Review Board. Subjects participated in a habituation and test session. During the habituation session, subjects were taught the correct performance of the squat jump, countermovement jump, tuck jump, and line hop. During the test session, subjects performed 3 repetitions of each of the 4 test exercises, in random order. During each, subject GRF and foot strike sounds were simultaneously assessed with a force platform (Accupower, Advanced Mechanical Technology, Ins. [AMTI], Watertown, MA, USA) and a digital sound level meter (72–942; Tenma, MCM Electronics, Springboro, OH, USA), respectively. Pearson's bivariate correlations coefficient were calculated to determine the existence of a relationship between GRF and sound, quantified as decibels (dB), for each plyometric exercise. The significance of the relationship between GRF and dB was assessed using a repeated measures ANCOVA. The trial to trial reliability of each dependent variable was determined using average measures intraclass correlation coefficients. Results: Results revealed a significant correlation between GRF and dB for the line hop (r(13) = 0.52, p = 0.04), but not for the other test exercises (p > 0.05). Repeated measures ANCOVA showed significant interaction between GRF and dB for the line hop, but not for any of the other test exercises (p > 0.05) (Table 1). Interclass correlation coefficients for the test exercises for the GRFs and dB ranged from 0.76 to 0.93 and 0.67 to 0.77, respectively. Conclusions: This study shows that the sound of subject foot strike is significantly correlated with GRF for only one of the plyometric exercises studied. Practical Applications: Practitioners should progress plyometric exercise intensity in their exercise prescription. To comprehensively do this, they should use force platforms, or take recourse to the published literature that has quantified plyometric exercise intensity via force platforms. Acknowledgments: The study was funded by a Lakeland University Undergraduate Research Experience grant.
Comparison of the Effectiveness of Treadmill vs. Overground Sprint Training on Overground and Treadmill Maximum Running Speed
J. Perales, S. Dorgo, and S. Bajpeyi
University of Texas at El Paso
The effects of traditional overground sprint training on sprint performance have been well investigated. However, no previous studies have investigated the effectiveness of weight-bearing sprint training on high-speed treadmills. Purpose: To examine the effects of a 6-week high-speed treadmill sprint training intervention on sprint performance in comparison to traditional overground sprint training. Methods: Forty-one recreationally active college-age subjects (Age ± SD: 23.1 ± 2.6 years; BMI ± SD: 24.3 ± 3.8 kg·m−2) underwent an initial 50-yd maximal sprint speed familiarization test, followed by a 1-week sprint drill familiarization period. The 50-yd track sprint test was then repeated and a maximum speed treadmill test was also conducted (baseline). Maximal track sprint speed was assessed from the 30–50-yd split time for all subjects (SP2). Subjects performed 3 maximal sprints with 3–4 minutes rest between attempts for track testing. The treadmill sprint test was applied increasing speed till the subjects' loss of control. Safety was ensured with a suspension safety harness, adjusted to not interfere with the subjects' full bodyweight bearing. Following the pre-test, subjects were randomly assigned to a track (TR) training group (n = 21; 11 males, 10 females), and a treadmill (TM) training group (n = 20; 10 males, 10 females). Subjects in the TR and TM groups performed 2 training sessions weekly, performing 4 maximal sprints with 3–4 minutes rest between attempts. TR group trained exclusively on the track, while the TM group trained exclusively on the treadmill. Sprint attempts were closely replicated between the 2 conditions with a progressive acceleration to maximal speed and 5–6 seconds maximal sprint speed maintained before deceleration. Track and treadmill assessment data were analyzed by 2-way ANOVA with alpha level set at p < 0.05. Results: There was no significant difference between TR and TM groups at pre-test in the 50-yd sprint time (p = 0.46), SP2 time (p = 0.46), and the maximal treadmill speed (p = 0.37). TR subjects showed a significant improvement in the 50-yd sprint time (Mean ± SD: 6.89 ± 0.70 to 6.82 ± 0.69 seconds; p = 0.02), SP2 time (2.46 ± 0.30 to 2.41 ± 0.29 seconds; p = 0.007), and the maximal treadmill speed (16.68 ± 2.18 to 18.11 ± 2.15 mph; p<0.001). TM subjects showed a significant improvement in SP2 time (2.39 ± 0.29 to 2.35 ± 0.27 seconds; p = 0.02), and the maximal treadmill speed (17.29 ± 2.11 to 19.16 ± 2.01 mph; p<0.001), but not in the 50-yd sprint time (6.73 ± 0.68 to 6.68 ± 0.65 seconds; p = 0.16). Conclusions: Sprint training on either overground or high-speed treadmill can improve maximal overground sprint speed in recreationally active subjects. Furthermore, both modalities can also improve attainable maximal sprint speed on the treadmill. However, treadmill training appears to result in higher attainable maximal speed on the treadmill. This is likely the result of training-testing specificity. Practical Applications: To enable sprint training in a year-round program with no access to an indoor track or sprint training facility, a treadmill sprint training regimen may be implemented. While treadmill sprint training can be used as a supplemental method of traditional overground sprint training, if used alone improvement may be limited to maximal sprint speed only with little to no effect to acceleration ability.
Stick Carry Decreases Sprint Speed in Collegiate Lacrosse Players
C. Watkins,1 L. Brown,2 M. Wong,1 S. Barillas,1 A. Bartolini,1 and C. Munger1
1Human Performance Laboratory, California State University, Fullerton, California; and 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California
Lacrosse requires the non-stop carry and use of a stick which could inhibit certain performance factors. Purpose: To examine the effect of carrying a stick on sprint performance in men and women collegiate Lacrosse players. Methods: Subjects performed a 20-meter sprint test measured with timing gates placed at the start line and every 5 meters, resulting in 4 splits and an overall time. Twenty-eight collegiate lacrosse players (17 females, age = 20.47 ± 1.77 years, height = 163.52 ± 6.26 cm, mass = 63.17 ± 9.30 kg), (11 males, age = 20.54 ± 2.38 years, height = 177.81 ± 7.58 cm, mass = 81.08 ± 9.73 kg) completed a standardized warm-up before performing 2 trials per condition: running while holding a lacrosse stick, and running without a stick in a counterbalanced order. Males were required to wear full pads, gloves, and their helmet for all trials; all participants were instructed to wear cleats. For each trial, participants started the test on their own accord, timing initiated as their foot crossed the sensor line created by the start line timing gates. They were given 3-minutes rest between trials. Results: There was no interaction of sex × condition × split. However, there were main effects for all 3 (p < 0.01). Split 1 (1.20 ± 0.10 s) was longer than split 2 (0.84 ± 0.07 s), split 3 (0.78 ± 0.06 s) and split 4 (0.75 ± 0.06 s). Split 2 was longer than split 3 (0.78 ± 0.06 s, p = 0.002), and split 4 (0.74 ± 0.01 s). Split 3 was longer than split 4. For condition, running without a stick (3.55 ± 0.03 s) was faster than running with a lacrosse stick (3.60 ± 0.04 s). For sex, men (3.37 ± 0.05 s) were faster than women (3.78 ± 0.04 s). Conclusions: Both men and women ran faster without a stick compared to when they held a lacrosse stick. This could be explained by an increased arm-swing when running without a stick, resulting in increased linear speed. These findings suggest that linear sprint speed is somewhat dependent on reciprocal-actions of the upper and lower limbs. Practical Applications: Coaches may want to implement sprinting drills while carrying a stick to attempt to close the sprint speed gap.
Relationships Among Vertical Leap, 40 m Time and Nonlocomotor Foot Quickness
V. Buccigrossi and T. Keating
Various athletic drills and assessments have been developed targeting lower limb “quickness,” often characterized by non-locomotor patterns. The relevance of these in the light of more established measures of anaerobic performance remains unclear. Purpose: The purpose of this investigation was to determine the relationship among vertical leap, 40 m sprint times and scores on a simple, non-locomotor assessment of foot quickness. Methods: Thirty Division I athletes (22 M, 8 F; 178.4 ± 11.1 cm; 77.4 ± 13.1 kg; 20.3 ± 2.1 years) volunteered for participation. After several familiarization trials, the best of 3 attempts was recorded for vertical leap VL, 40 m sprint 40 and counts on a simple, non-locomotor foot quickness assessment Q. Forty was recorded using an infrared timing system, VL with a pressure switch timing system. Foot quickness was assessed using a digitally interfaced agility training device that counted foot contacts for 10 seconds. Subjects were asked to stand on the board and tap their feet in opposition while striking 2 large sensors beneath. The simple pattern required no directional changes and little displacement of the center of mass. Tasks were presented in counterbalanced sequence on the same day with at least 5 minutes of passive recovery between. Pearson correlations were calculated among all dependent measures. Results: Significant (p ≤ 0.05) correlations were revealed among each of the 3 dependent measures (VL vs. 40: r = −0.84; VL vs. Q: r = 0.45, 40 vs. Q: r = −0.43). Conclusions: While it is possible that shared underlying abilities contribute, to varying degrees, to 40, VL and Q, the strength of the relationships presented here call the practical significance of the latter somewhat into question. Practical Applications: While drills and assessments addressing non-locomotor foot quickness may have some applicability in strength and conditioning, owing to their ease of application, use of space and limited demands on athletes, their predictive ability appears lacking when compared with more established measures.
Did Higher Drafted Rookies Perform Better in the Scouting Combine and On-Field During the 2015 NFL Season?
E. Langford,1 M. Leatherwood,1 S. Brackmann,1 J. Casey,1 G. Ryan,2 and R. Herron1
1University of Alabama; and 2Catawba College
Accurately predicting on-field performance based on off-field testing is a valuable measurement and evaluation issue. The National Football League (NFL) conducts an annual combine to assess anthropometric measures and athletic ability in a variety of tests in preparation for the draft. Teams and front offices use these data to determine which players to draft, and the order in which they will be drafted. Purpose: The purpose of this study was to determine if playing time and combine performance was significantly influenced by the round the players were drafted in the 2015 NFL Draft. Methods: Data from 309 athletes' tests (2 anthropometric and 6 performance) were used for analysis. The 8 tests used for analysis were: arm length; hand size; 40 yd sprint; 225 pound bench press repetitions; vertical jump; broad jump; 3-cone drill; and 20 yd shuttle. Data from completed tests were normalized (Z-scores) and averaged to calculate an average Z-score value for each athlete. The number of offensive/defensive and special teams snaps for each rookie was averaged over the course of the 2015 season. A multivariate ANOVA was run to determine if the athletes' performance during the combine, and number of snaps played during the season was influenced by the round the athlete was drafted in the 2015 NFL Draft. Results: A significant omnibus result was observed between the number of plays an athlete participated in, and the round the athlete was drafted, F(7,301) = 2.324, p = 0.025, and combine performance, F(3,301) = 28.943, p < 0.001. Post-hoc analysis noted that players drafted after the fourth Round, or went undrafted, played significantly less plays during the 2015 NFL season compared to athletes drafted in the first 3 rounds (all p ≤ 0.05). Conclusions: The findings of this study suggest that individuals drafted in the first 5 rounds of the NFL draft had better combine performance and that players drafted in the first 3 rounds participated in a significantly greater number of plays compared to the rest of the athletes invited to the 2015 NFL Combine. Practical Applications: These findings support the use of normalized Z-scores to supplement team and scout assessments to determine an athlete's draft status. These findings also suggest that players drafted in the first 3 rounds are the most likely to contribute during their rookie year.
The Effects of Lower Body Fatigue on Vertical Jump Performance
N. Sauls, J. Davis, C. Cooper, H. Velasquez, C. Perez, and N. Dabbs
California State University, San Bernardino
Introduction: Vertical jump performance is an important measure of explosive lower body power and strength in all sports. Lower body fatigue can lead to a decline in vertical jump performance due to decreased motor control and muscle coordination. Purpose: The purpose of the study is to determine the effects of lower body fatigue on vertical jump performance. Methodology: Nineteen recreationally trained (age 22.84 ± 1.77 years; height 168.82 ± 10.22 m; weight 68.70 ± 14.87 kg) individuals participated in a single one-hour familiarization and testing session. During familiarization phase, participants completed an informed consent, health history questionnaire, and Physical Activity Readiness Questionnaire. Age, height, and weight were also recorded followed by a dynamic warm-up that included: 2 sets of a 15 m jogs, high knees, and butt kickers, and 2 sets of 10 repetitions each of air squats, forward arm circles, and backward arm circles. Participants were then familiarized with 2 types of vertical jumps using the Vertec. The 2 types of vertical jumps were static jump (SJ) and countermovement jump (CMJ). Next participants were familiarized with the Bosco fatigue protocol defined as 60 seconds of continuous 90° jump squats with hands placed on hips. Once familiarized, participants began the pre-testing phase and completed 3 successful trials each of a SJ and CMJ in a randomized order. For the CMJ, participants were instructed to perform a maximal countermovement jump with an arm swing. For SJ, participants were instructed to perform a maximal jump from a squat position. They were instructed to squat down to a 90-degree knee angle with both arms held out directly in front of them, and maintain that position for 3 seconds, before performing the vertical jump. Equipment was then set up for the Bosco protocol fatigue phase. An elastic band was placed at the 90-degree squat position for each participant. Participants then performed 60 seconds of continuous squat jumps with their hands placed on their hips. Participants had to squat down to a 90-degree position indicated by the band and explode back up as high as possible. After completing the Bosco protocol, participants immediately completed 3 SJ's and 3 CMJ's, in a randomized order. Jump height was recorded for SJ and CMJ and peak power (PP) was calculated from the CMJ using Sayers equation. Dependent t-tests were conducted to analyze the difference between pre and post jump height in both jump conditions as well as CMJ PP. Results: There was a significant (p < 0.001) difference between the pre and post measures for both SJ height, CMJ height, and CMJ PP. Conclusions: The Bosco protocol acutely decreases peak power during the CMJ and vertical jump height in both SJ and CMJ. This could be due to decreased muscle control and coordination as a result of the fatigue protocol. Practical Applications: Generating large amounts of lower body power is key to performance in many sports. Being aware of the effects of lower body fatigue on peak lower body power production is crucial for strength and conditioning coaches, both during training and during competition. A well-designed resistance-training program is a key component to increasing lower body power and involves fatiguing the lower body on certain days. This study indicates that 60 seconds of fatiguing work is enough to elicit changes in performance. Therefore, when designing a program, proper rest time should be considered so optimal performance gains can be achieved. There are also implications for performance since decreasing lower body power often results in altered performance measures, like vertical jump. Keeping a fatigued player in the game may also increase their overall risk for injury due to decreased coordination and proper movement. The goal in any level of sport is to maintain maximum performance throughout play, so continuing to broaden our understanding through research of what increases and decreases performance should be a primary focus.
Acute Effects of Exercise Between Sets on Upper-Body Power
A. Fava,1 P. Bishop,1 M. Esco,1 S. Tomek,1 and S. Truhett2
1Univsersity of Alabama; and 2St. Vincent's Hopsital
Purpose: Performing exercise between sets allows for increased workload in a given training session. Prior use of exercises can contribute to muscle activation or mobility which can aid in the performance of the following set. The purpose of this study was to determine the acute effects on upper-body (UB) power when performing different exercise types between sets. Methods: Resistance-trained (men: N = 7, age = 24 ± 2.4 years, Ht = 176 ± 6.1 cm, Wt = 92.5 ± 18.4 Kg, Body Comp = 18 ± 6.3% fat; women N = 3, age = 21 ± 1.2 years, Ht = 170 ± 5.1 cm, Wt = 66.5 ± 7.16 Kg, Body Comp = 29 ± 6.0% fat) volunteers participated in this study. All subjects underwent 7 experimental trials and one familiarization trial. Each trial incorporated an exercise that was repeated between 4 sets of an UB-power test. The effects of 6 different exercises were tested. A pre-power measurement (PreP) was the first set prior to the start of the exercise and used as a comparison measurement. Exercise performed between sets included: resistance exercise to agonist muscle groups using suspension training (RA), mild stretching exercises to agonist muscle groups (SA), resistance exercise to antagonist muscle groups using suspension training (RAnt), mild stretching exercises to antagonist muscle groups (SAnt), plyometric to agonist muscle groups (PlyoA) and rest as control (C). Treatments were counterbalanced and randomly assigned to participants. Results: There was no significant effect on UB power among treatments performed (p = 0.080), independent of sets. There was no significant effect on UB power across sets (p = 0.449), independent of treatment. There was a significant interaction between treatment and sets (p = 0.038). Conclusions: UB power responded significantly different among treatments and across sets. Mean UB power (MUBP) increased from the first set to the second set for all treatments except control. MUBP for RA and SAnt then decreased on the third set before increasing on the fourth, showing fluctuation in UB power across sets. Over time PlyoA and SA increased until the third set before decreasing on the fourth set demonstrating a ceiling effect, yet effective for early sets. MUBP for RAnt continued to increase across all sets. MUBP remained above C for all treatments for sets 2, 3 and 4 except RA and the fourth set of SA. Practical Applications: Use of these treatment types between sets may be useful for promoting increased workloads or soft tissue maintenance without a negative effect on acute UB performance. Strength coaches can incorporate similar exercise types between sets in programs focused on power development.
Effect of Drop Jump Exercise Added During a Dynamic Full-Body Warm Up on Agility and Lower Extremity Power in Strength-Trained Intercollegiate Athletes
G. Ehlers, B. Boettcher, R. Crane, C. Grenz, K. Hansen, J. Lehr, B. Lustro, A. Patel, and K. Putskey
Concordia University Wisconsin
Athletes commonly utilize a variety of warm-up strategies with the goal of enhancing athletic performance. It is known that a dynamic full-body warm up enhances performance. However, there is debate as to the best type of warm up technique to use in order to enhance short duration power and agility performance. Purpose: The purpose of this study was to determine if high intensity ballistic exercise, shown to elicit a post-activation potentiation response, added during a generalized full-body warm-up, can acutely enhance lower extremity power output and agility in strength trained intercollegiate athletes. Methods: Eighteen healthy NCAA Division III college athletes (females, n = 7; males, n = 11; age = 20.2 ± 1 year) participated in a randomized, counterbalanced, crossover, experimental trial to assess lower extremity power and agility changes in response to ballistic exercise added to a warm up routine. Participants were randomized to one of 4 different warm-up protocols: (a) Control/no warm up (C), (b) dynamic full-body warm up (DWU), (c) dynamic full-body with a 0.6 meter drop jump (DDJ) and (d) 0.6 meter drop jump (DJ) only. Agility was assessed using the pro-agility test and a laser timing system. Lower extremity power was assessed using the Margaria-Kalamen test and a pressure mat timing system. A 2 × 4 repeated measures ANOVA was used to analyze for significant interactions between the different warm-up protocols. Cohen's D effect sizes were calculated to determine the effect that each warm-up protocol had on performance. Results: A statistically significant interaction was noted between warm up protocols (p = 0.002) for agility. For lower extremity power, there were no statistically significant interactions (p = 0.24) between warm up sessions. Although all of the warm up activities resulted in small effect sizes, the warm ups with the largest effect sizes included those that utilized the ballistic activity. See the Table 1 below for means ± standard deviations and Cohen's D effect sizes for each warm up activity. Conclusions: Although the agility and lower extremity power effect sizes for each warm up were small, results from this study suggest that the inclusion of ballistic activity can have a beneficial effect on agility and, possibly, on lower extremity muscular power. Practical Applications: Athletes that perform ballistic lower extremity activity should include ballistic activity in their pre-activity warm up routine.
Thursday Thematic Poster Presentations
July 07, 2016—12:00 PM to 1:00 PM—Celestin ABC—Thematic Area
Thursday, July 07, 2016, 12:00 PM–1:00 PM
Position-Specific Changes in Body Composition and Resting Energy Expenditure Following Pre-Season Training Camp in NCAA Division III American Football Players
A. Jagim,1 G. Wright,1 J. Kisiolek,1 M. Meinking,1 J. Ochsenwald,1 M. Jones,2 and J. Oliver3
1University of Wisconsin—La Crosse; 2George Mason University; and 3Texas Christian University
In American football, pre-season training camp often involves the performance of multiple intense training bouts over a short period of time. Multiple intense training bouts increase daily caloric expenditure, which may influence body composition and metabolism, specifically resting energy expenditure (REE). However, to what extent pre-season training camp may impact body composition and REE in collegiate football players is unknown. Purpose: The purpose of this study was to assess changes in body composition and REE following pre-season training in Division III American football players. In addition, we sought to compare differences between linemen and non-linemen. Methods: Seventeen Division III football players (Ht: 1.80 ± 0.6 m; BM: 99.1 ± 60.1 kg; FFM: 79.7 ± 8.6 kg; BF%: 19.3 ± 8.6%) had their body composition and REE assessed in a rested and fasted state (>12 hours) before and upon completion of pre-season training camp. Body composition was determined using air displacement plethysmogrophy (BODPOD; Cosmed, USA) and REE was assessed via indirect calorimetry (ParvoMedics, UT, USA). Pre-season training consisted of 14 days of intense training bouts (17 practices in total; 3 days of 2× practices per day). A 2-way (position × time) repeated measures analysis of variance was used to compare changes in body composition and REE with baseline values used as covariates. Results: As expected, linemen had a higher body mass, fat-free mass, and fat mass likely contributing to the higher REE (p < 0.01). There was a main effect for time observed in regard to changes in fat-free mass (p < 0.001) and body fat % (p = 0.024). A significant group × time interaction was observed for fat-free mass with linemen experiencing a greater reduction in fat-free mass (−1.73 ± 0.37 vs. −0.43 ± 0.74 kg; p < 0.001). Linemen (L) also experienced a greater reduction in REE compared to non-linemen (NL) (L: −223.0 ± 308.4 vs. NL: 3.27 ± 200.1 kcals; p = 0.085) albeit not statistically significant. Conclusions: The greater size in linemen prior to pre-season likely contributed to their higher REE. However, counter to expectation, the multiple intense training bouts reduced REE in linemen, which may have been driven by the observed losses in FFM. Further, intense pre-season training camp increased body fat % in both linemen and non-linemen. Practical Applications: The addition of a maintenance-focused strength training program could help mitigate the losses in fat-free mass observed in the current study, particularly with linemen. Further, a nutritional intervention or education program prior to the start of the season may also help. Particular attention should be directed at increasing total energy and/or protein intakes of linemen as they appear to be more susceptible to these negative outcomes, which may be attributed to their increased body size and subsequent higher energy requirements.
Off-Season and In-Season Plasma Cortisol Responses in National Collegiate Athletic Association Division-I Football Players
J. Stone,1 A. Kreutzer,1 J. Mata,1 A. Jagim,2 M. Jones,3 and J. Oliver1
1Texas Christian University; 2University of Wisconsin—La Crosse; and 3George Mason University
Cortisol, a glucocorticoid released from the adrenal gland, is a purported biomarker for whole body stress. Contact sports, such as football, consist of periods of intense training and repetitive high impact collisions; both of which may result in possible skeletal muscle damage and increased cortisol levels. This heightened response has been illustrated following a single football competition, with significantly higher concentrations in starters compared to non-starters. However, the paucity of research examining the effects of a complete football season and off-season training protocol on cortisol levels warrants further investigation. Purpose: Therefore, this investigation sought to examine the effect of off-season training and in-season participation on plasma cortisol in National Collegiate Athletic Association (NCAA) Division-I (DI) football athletes. Given that some football athletes are known to perform a greater number of plays (repetitions) per game, plasma cortisol was compared between starters and non-starters. Methods: Nineteen (n = 19) NCAA DI football athletes (mean ± SD; age, 20 ± 1 years) volunteered for this study. Blood was sampled at specific times over the course of 189 days coincident with changes in intensity, volume, and competitive play. Baseline values for cortisol were obtained prior to the start of summer conditioning during a non-contact period spanning at least 9 weeks. Additional samples were obtained before and after pre-season camp. Subsequent samples were collected over the course of the season in 14–28 days intervals for a total of 8 samples. Athletes were categorized as starters (n = 11) and non-starters (n = 8), with starters defined as those known to go out with the first or second team, first or second on the depth chart, and take a majority of repetitions (∼20–40+ per game). A 2 (STARTER STATUS) by 8 (TIME) repeated measures ANOVA was used to analyze differences. Alpha was set at p ≤ 0.05. Results: No significant effect of STARTER STATUS (p = 0.613) or interaction (p = 0.840) was observed. A significant time effect was noted (p = 0.041). Plasma cortisol was significantly elevated after the first time point measured during the competitive season in both starters (650.5 ± 123.4 nmol·L−1) and non-starters (635.9 ± 68.9 nmol·L−1) which was greater than all other time points (p ≤ 0.05), except the second measurement during the competitive season. Conclusions: Despite changes in training intensity and volume, plasma cortisol concentrations remained relatively constant over the course of summer conditioning and pre-season camp. However, elevations during the first 2 time points of the competitive season, which coincide with start of semester, suggest a heightened arousal state associated with the start of a new competitive season. The decline in cortisol is likely due to proper training and management of psychological and physiological stress. Practical Applications: These findings suggest an extensive strength and conditioning program not only pre-season, but also in-season can be an effective strategy for regulating cortisol levels. A close monitoring of athlete's hormonal profiles during the course of a season is suggested to accredit any extracurricular training as effective while not adding unwanted stress. Further, individualized profiles would enable personalized exercise protocols to accentuate in-season performance, manage stress, and mitigate injury risk.
The Effect of Training Status on Heart Rate Variability in Division-1 Collegiate Swimmers
A. Flatt, B. Hornikel, and M. Esco
University of Alabama
Resting heart rate variability (HRV) fluctuates on a daily basis in response to physical and psychological stressors and may provide useful information pertaining to fatigue and adaptation. However, there is limited research comparing HRV profiles between athletes of the same sport who differ by training status. Purpose: The purpose of this study was to compare resting heart rate (RHR) parameters between national and conference level Division-1 Collegiate swimmers and to determine if any differences were related to psychometric indices. Methods: Twenty-four subjects were categorized as national (NAT, n = 12, 4 female) or conference level competitors (CONF, n = 12, 5 female). Over 4 weeks, daily HRV was measured in the seated position by the subjects after waking and elimination with a validated smartphone application and pulse-wave finger sensor (app) utilizing a 55-second recording period. Subjects then completed a questionnaire on the app where they rated perceived levels of sleep quality, muscle soreness, mood, stress and fatigue on a 9-point scale. The HR parameters evaluated by the app include RHR and the log-transformed root-mean square of successive RR interval differences multiplied by 20 (lnRMSSD). The 4-week mean for RHR (RHRm) and lnRMSSD (lnRMSSDm) in addition to the coefficient of variation (CV) for RHR (RHRcv) and lnRMSSD (lnRMSSDcv) were determined for comparison. In addition, psychometric parameters were also averaged between groups and compared. Independent t-tests and effect sizes ±90% confidence limits (ES ± 90% CL) were used to compare the HR and psychometric parameters. Results: NAT was moderately taller (184.9 ± 10.0 vs. 175.5 ± 12.5 cm; p = 0.06, ES ± 90% CL = 0.83 ± 0.70) and moderately heavier (80.4 ± 9.7 vs. 75.2 ± 11.9 kg; p = 0.26, ES ± 90% CL = 0.48 ± 0.67) than CONF, though not statistically significant. The results comparing HR and psychometrics are displayed in Table 1. lnRMSSDm and lnRMSSDcv was moderately higher and lower, respectively, in NAT compared to CONF (p ≤ 0.05). Conclusions: Higher training status is associated with moderately higher lnRMSSDm and lower lnRMSSDcv compared to those of lower training status. This was observed despite no significant difference in perceived stressors that may affect HR parameters. Practical Applications: Training status appears to be a determinant of daily HRV and its fluctuation. This may be because higher level athletes are more fit and recover faster from training, resulting in a more stable HRV pattern. This information can be useful to practitioners when interpreting HRV trends in athletes. For example, an increase in HRV with reduced daily fluctuation may indicate improvements in an athletes training status. Alternatively, an athlete with high training status demonstrating reduced HRV and greater daily fluctuation may be showing signs of fatigue or loss of fitness depending on the context of the current training phase and program.
Investigation of the NSCA Minimal Readiness Standards for Upper Body Strength, Speed, and Performance of High-Intensity Plyometrics in College Athletes
M. Finn,1 J. Kovaleski,2 S. Mitchell,2 P. Norrell,2 and J. Schwind2
1Providence Hospital; and 2University of South Alabama
The NSCA guidelines specify that before beginning high-intensity upper-body plyometric training the athlete minimally bench press their bodyweight (BW) if weighing greater than 90 kg and 1.5 × BW if weighing less than 90 kg, and perform a 5-repetition bench press in 5 seconds or less at 60% BW. The pre-training evaluation data supporting these standards are based on information presented in the literature and a 1993 NSCA position statement. These standards appear based on the premise that men and women possess equal strength and speed prerequisites prior to plyometric training. Purpose: To determine the percentage of college athletes who met the minimal plyometric readiness standards and to examine differences between those who passed and failed the readiness standards using plyometric performance indicators. Methods: Seventy-four male (316.4 ± 57.5 kg 1-RM max bench press) and 27 female (121.9 ± 23.6 kg 1-RM max bench press) NCAA Division I athletes, aged 19 to 25 participated. Each performed the BW or 1.5 × BW bench press and the 5-repetition bench press at 60% BW. Plyometric performance indicators included the seated medicine ball chest throw, peak power and power at peak velocity obtained from the 5-repetition bench press, and peak vertical ground reaction force (GRFv) obtained from a 1-RM plyometric push-up performed on a force plate. Performance differences between athletes who passed and failed the readiness standards were made using Independent samples t-tests. Results: Seventy percent of the males and none of the females passed the 1-RM Strength Standard. One female and 89% of the males passed the 5-RM Speed Standard (4.07 ± 0.4 seconds). No additional analyses for the females were performed. Males who passed the 1-RM Strength Standard threw the medicine ball significantly farther than those who failed (5.84 ± 0.89 vs. 5.31 ± 0.84 m; p = 0.03, d = 0.60). No significant difference in throw distance was found between males who passed or failed the 5-Repetition Speed Standard. The males who passed the 1-RM Strength Standard produced significantly higher peak power (W) (766.93 ± 141.5 vs. 468.74 ± 94.22; p =.001, d = 0.84) and higher power at peak velocity (Watts per second) than those who failed (678.78 ± 137.9 vs. 566.68 ± 97.5; p =.002, d = 0.81) the 5-repetition bench press speed test. Males who passed the 5-Repetition Speed Standard also produced significantly higher peak power (W) than those who failed (745.51 ± 140.7 vs. 633.0 ± 48.9; p = 0.020, d = 0.80) and higher power at peak velocity (Watts per second) than those who failed (658.5 ± 137.3 vs. 540.67 ± 45.9; p =.013, d = 0.86) on the 5-repetition bench press speed test. The males who passed the 1-RM Strength Standard produced significantly higher peak GRFv (N·kg−1) than those who failed (1,894.27 ± 617.6 vs. 1,527.26 ± 416.9; p =.019, d = 0.59) on the 1-RM plyometric push-up test. No significant difference was found for peak GRFv (1,792.62 ± 591.9 vs. 1,652.68 ± 622.1; p =.509, d = 0.24) between those males who passed or failed the 5-Repetition Speed Standard. Conclusions: Plyometric performance findings support the NSCA Bench Press Strength and Speed Standards for determining readiness prior to upper body plyometric training for males, but not females. Practical Applications: Revised bench-press strength and speed readiness standards with greater discriminating power should be developed to assess plyometric readiness in female athletes. These findings have implications for injury prevention when evaluating readiness prior to implementing upper extremity plyometrics.
Tracking Changes in Performance and Body Composition Over an Academic Year of Conditioning and Competition in NCAA Division I Women Volleyball Players
W. Kraemer, W. DuPont, L. Caldwell, E. Barnhart, E. Bordon, T. Szivak, and S. Flanagan
The Ohio State University
Purpose: The purpose of this study was to determine the effects of a year of conditioning on strength, power, and body composition in NCAA Division I women volleyball players. Methods: Fifteen members of a NCAA Division I women's volleyball team gave informed consent to participate in a training program over the academic year. Training consisted of a non-linear periodized training program (rotating light, moderate, heavy, and power workouts) over the year with testing in August (T-1), October (T-2), February (T-3) and May (T-4) of the academic year. Test retest reliability of the measures was determined to have ICC Rs of R > 0.95 for control purposes of measurement stability. Testing consisted of force plate countermovement vertical jump and approach vertical jump, 1 RM bench press and leg press, body composition via skinfolds, and 2 mile run. Results: Significant (p ≤ 0.05) improvements in vertical jumps and strength were seen from T-1 to T-2 with no changes from T-2 at T-3. Vertical jump and strength tests improved from the T-3 at T-4 testing time frame (e.g., cmvj T-1 3,800 to T-2 4,388 to T-3 4,322 to T-4 5,100 W). Percent body fat decreased from T-1 to T-4 along with an increase in fat free mass. Two mile run times significantly improved from T-1 to T-4. Conclusions: A plateau exists from October to February in physical performance variables related to strength and power with body composition measures and aerobic capabilities maintained until the end of the academic year. Performance changes appear to be related the higher intensity pre-season and off-season conditioning without competition for strength and power. Holiday vacation appears to provide a recovery phase with no performance detraining changes observed. Practical Applications: A year around strength and conditioning program is effective in stimulating strength and power changes during time frames where higher frequency and volume can be implemented in a non-linear program. However, natural holiday breaks may allow for needed recovery and rest in a collegiate training program for women volleyball players.
Friday Abstract Podium Presentations
July 08, 2016—8:30 AM–11:30 AM—Strand 11
Friday, July 08, 2016, 8:30 AM–8:45 AM
Maximal Strength Is Related to Explosive Power in Advanced Powerlifters
L. Gillen, M. Mosiman, A. Askow, J. Allen, E. Morrisette, A. Jagim, C. Gillette, and M. Andre
University of Wisconsin-La Crosse
Purpose: The purpose of this study was to measure relationships between maximal strength, explosive power, and salivary testosterone in advanced collegiate powerlifters. Methods: Five advanced male collegiate powerlifters (1.79 ± 0.06 m, 111.3 ± 32.8 kg; competition best: squat = 240.0 ± 64.5 kg, bench press = 167.5 ± 40.4 kg, deadlift = 272.0 ± 38.6 kg; Wilks = 408.9 ± 57.7), all competing in the USAPL Junior Raw category and all using the same program, gave a resting saliva sample and were tested for body-weight (BW), vertical jump (VJ), and VJ peak power (VJPP) before their final training session during a taper leading into the USAPL state powerlifting meet. Power was calculated using the Johnson & Bahamonde equation. Saliva was later analyzed for testosterone (T). Pearson correlation coefficients were calculated to determine relationships between VJ, VJPP, T, and competition performance: 1RM barbell back squat (SQ), 1RM barbell bench press (BP), 1RM barbell deadlift (DL), the total of the 3 lifts (Total), and the Wilks coefficient points (WILKS), which is strength relative to body-weight. This report focuses on effect sizes (r), which is a growing trend in sport science studies with necessarily-small n sizes. Consistent with previous literature, when r is greater than 0.10, 0.30, 0.50, and 0.70, the relationship is described as small, medium, large, and very large, respectively. Results: Group means were as follows (X ± SD): VJ = 67.1 ± 10.0 cm; VJPP = 7,974.6 ± 1,691.5 W; T = 1.112 ± 0.097 nmol·L−1. For reference, VJ and VJPP for collegiate male athletes has been reported as 64.7 cm and 5,782 W, respectively, while the reference range for T in healthy young men has been reported as 0.190–0.680 nmol·L−1. Very strong relationships (r ≥ 0.70) were observed between VJPP and WILKS, SQ, BP, DL, Total and BW. Strong positive relationships (r ≥ 0.50) were observed between T and SQ, BP, and Total. There was also a very strong inverse relationship between T and VJ; however, since BW was very strongly related to T but inversely related to VJ, it is apparent that the athletes with the highest T were also the heaviest and were unable to jump as high as the lighter athletes, suggesting that BW was a mediating factor between T and VJ. This was also evidenced by the medium positive correlation between T and VJPP. Refer to Table 1 for all Pearson correlation coefficients, highlighting very-large relationships. Conclusions: Maximal strength and explosive power are very strongly related in advanced collegiate powerlifters. Additionally, advanced collegiate powerlifters are more powerful than other collegiate athletes and have dramatically higher concentrations of T compared to other healthy young men, with each athlete being above the reference range. Practical Applications: When the goal is to improve explosive power or rate of force development, one should consider first training to improve maximal strength and maximal force production to set the foundation for future improvements in power. Acknowledgments: Supported by UWL Graduate Student Research, Service, and Educational Leadership Grant.
Friday, July 08, 2016, 8:45 AM–9:00 AM
Does Focus of Attention Influence Snatch Lift Kinematics?
K. Schutts,1 W. Wu,2 J. Becker,1 A. Vidal,1 and J. Hiegel3
1California State University—Long Beach; 2Center for Sport Training and Research; and 3Long Beach State Athletics
Purpose: Recent motor control literature has demonstrated that using verbal cues to direct a performer's attention externally (i.e., toward the movement outcome) enhances motor skill performance (Wulf, 2013). This differs from the large amount of internal cues typically seen in coaching literature. The purpose of this study was to investigate how an athlete's focus of attention impacts kinematic performance of the snatch. It was hypothesized that an EXT FOA would lead to improved kinematic performance, relative to an INT FOA. Methods: A within-participant experimental design was used to observe performance differences in the snatch when using internal and external focus of attention strategies. Participants performed snatch lifts in 2 conditions: a block of 3 repetitions with instructions designed to elicit an external FOA (EXT), and a block of 3 repetitions with instructions designed to elicit an internal FOA (INT). All participants performed a warm up block followed by either the INT and EXT instructional blocks in a randomized order. Prior to lift-off, the participant was instructed to “concentrate on moving your elbows high and to the side rapidly” for the INT block of repetitions and “concentrate on moving the barbell back and up rapidly” for the EXT block of repetitions. Whole kinematics of both the lifter and bar were recorded using a 12-camera motion capture system sampling at 250 Hz. The barbell-cervical-hip (BCH) angle was used as the primary performance measure. The BCH angle is an investigative measure that views the barbell and lifter as a single system represented by the angle between a vector from the barbell to seventh cervical vertebrae and the greater trochanter to seventh cervical vertebrae (Chen and Chiu, 2011; Chiu and Liang, 2010). The BCH angle is evaluated at 6 separate events: lifting the barbell off the floor (LO), barbell clearing the knee (CK), extension of the hip to push barbell away from body (PB), barbell reaching maximum forward position (MF), barbell reaching maximum height (MH), and barbell being caught overhead (CB). The following dependent variables were calculated: BCH angle at 6 events, peak instantaneous vertical barbell velocity (Peak BarVV), peak instantaneous horizontal barbell velocity (Peak BarHV), and peak instantaneous vertical elbow velocity (Peak ElbowVV). Paired samples t-tests were used to establish whether attentional focus cues influences BCH angles at LO, CK, PB, MF, MH, and CB. Differences in Peak BarVV, Peak BarHV, and Peak ElbowVV were also examined with paired samples t-tests. An alpha level of p ≤ 0.05 was used for all tests. Results: Results showed that, when cued internally, athletes significantly increased elbow velocity (1.90 ± 0.29 m·s−1) relative to being cued externally (1.78 ± 0.29 m·s−1), while the external cue significantly increased horizontal barbell velocity (1.05 ± 0.31 m·s−1), relative to an internal cue (0.91 ± 0.29 m·s−1). Additionally an internal focus cue resulted in significantly larger BCH angles at maximum height of the barbell (MH) (156.34 ± 15.71°) compared to an external cue (153.75 ± 16.83°). Conclusions: Based on the results, the hypothesis was supported. Performance improved in the EXT block, as supported by previous kinematic analyses revealing that athletes lifting larger loads relative to their body mass demonstrated smaller BCH angles at MH (Chiu, 2011). It was suggested that a greater BCH angle at MH indicates that the lifter begins turning underneath the barbell to initiate the squat early, increasing the difficulty to absorb the vertical and anterior-posterior momentum of the barbell at the catch. Practical Applications: The present study adds to the body of literature suggesting verbal instructions should be developed with attentional focus in mind. Strength and conditioning coaches can teach athletes how to optimally focus their attention to improve performance by making simple changes to cues they are already using. This can be done by using cues that direct an athlete's focus externally, toward the outcome of the movement.
Friday, July 08, 2016, 9:00 AM–9:15 AM
Ten Weeks Full Squat Training in Persons With Anterior Cruciate Ligament Injury: Preliminary Results
L. Jean,1 I. Hallworth,2 D. Gross,3 and L. Chiu1
1University of Alberta; 2Glen Sather Sports Medicine Clinic; and 3Department of Physical Therapy
Individuals with anterior cruciate ligament (ACL) injuries avoid using the quadriceps during multi-joint tasks, resulting in quadriceps weakness and movement dysfunction. Training with partial squats is ineffective to reduce quadriceps avoidance strategies used by ACL injured persons. Full squats, defined as maximum knee flexion where the posterior thigh contacts the calf muscles, increase quadriceps size, strength and function in healthy individuals. Full squats have not been studied in ACL injured persons. Purpose: The purpose of this study was to investigate if full squat training reduces use of a quadriceps avoidance strategy during sit-to-stand in ACL injured persons. Methods: ACL deficient men (n = 6) and women (n = 3) participated in a 10-week training intervention focusing on restoring quadriceps strength through full squats. Motion analysis was performed using 7 optoelectronic cameras and 2 force platforms to assess sit-to-stand mechanics before and after the intervention. Inverse dynamics were used to calculate ankle plantarflexor, knee extensor and hip extensor work. For this preliminary analysis, repeated measures effect sizes (ES) were used to compare within and between the involved and non-involved limbs pre- and post-intervention. Results: The involved limb performed less knee extensor work than the non-involved limb pre-intervention (ES = 0.52); this difference was reduced post-intervention (ES = 0.20; Figure 1). Knee extensor work increased in both the involved (ES = 1.05) and non-involved (ES = 0.69) limbs. The involved limb performed more ankle plantarflexor work than the non-involved limb pre-intervention (ES = 0.84); this difference was similar post-intervention (ES = 0.69). There was minimal change in ankle plantarflexor work in both the involved (ES = 0.23) and non-involved (ES = 0.36) limbs. The involved limb performed more hip extensor work than the non-involved limb pre-intervention (ES = 0.53); this difference was smaller post-intervention (ES = 0.42). Hip extensor work decreased in both the involved (ES = 0.50) and non-involved (ES = 0.44) limbs. Conclusions: Preliminary results indicate that training with full squats increases knee extensor work performed in both limbs during sit-to-stand. Moreover, knee extensor work performed increased more in the involved limb than the non-involved limb. Consequently, there is a decrease in knee extensor work asymmetry between the involved and non-involved limb. This suggests that training with full squats can decrease the use of a quadriceps avoidance strategy in ACL injured persons. Practical Applications: ACL injured persons are capable of performing full squats. An exercise intervention emphasizing full squats appears to be effective to increase quadriceps function during multi-joint tasks, reducing the use of a quadriceps avoidance strategy. Acknowledgments: This research was conducted at the University of Alberta Glen Sather Sports Medicine Clinic and funded by a NSCA Graduate Research Grant.
Friday, July 08, 2016, 9:15 AM–9:30 AM
Increasing Calcaneal Plantar Flexion as a Method to Improve Weight-Bearing Leg Dorsiflexion: Preliminary Results
G. vonGaza, J. Carey, and L. Chiu
University of Alberta
Previous research on foot and ankle mechanics has shown that weight-bearing leg dorsiflexion range of motion is positively correlated to calcaneal plantar flexion. Gastrocnemius promotes while the plantar fascia and plantar intrinsic muscles restrict calcaneal plantar flexion. Thus reducing plantar fascia and plantar intrinsic muscle tension while increasing gastrocnemius strength may improve weight-bearing leg dorsiflexion range of motion. Purpose: To examine the effects of reducing plantar aponeurosis and plantar intrinsic muscle tension and increasing gastrocnemius strength on calcaneal plantar flexion and leg dorsiflexion range of motion during a weight-bearing squat. Methods: Potential participants were screened based on leg dorsiflexion during a lunge. Twelve participants with poor (<25°) leg dorsiflexion were enrolled and randomly assigned to one of two 6-week intervention groups. Group 1 performed self-massage and stretching of the plantar fascia and plantar intrinsic muscles 3 days per week. Group 2 performed the same self-massage and stretching plus gastrocnemius strengthening exercise 3 days per week. Gastrocnemius exercise was a modified glute-ham-gastroc raise, emphasizing the gastrocnemius' thigh flexion function. Three-dimensional motion analysis was used to measure calcaneal plantar flexion, leg flexion and thigh flexion during partial squats before and after the 6-week interventions. For this preliminary analysis, mean ± SD are reported and repeated measures effect sizes (ES) were used to compare pre- and post-intervention values for each group. Results: In group 1, calcaneal plantar flexion, leg dorsiflexion and thigh flexion were −5 ± 4°, −27 ± 4° and 22 ± 7° before; and −7 ± 2°, −28 ± 3° and 22 ± 6° after the intervention. ES suggest group 1 may have had small increases in calcaneal plantar flexion (ES = 0.43 SD) and leg dorsiflexion (ES = 0.37 SD), but trivial change in thigh flexion (ES = 0.08 SD). In group 2 calcaneal plantar flexion, leg dorsiflexion and thigh flexion were −3 ± 2°, −23 ± 4° and 23 ± 8° before; and −4 ± 3°, 26 ± 3° and 26 ± 8° after the intervention. ES suggest group 2 may have had small increases in calcaneal plantar flexion (ES = 0.43 SD) and thigh flexion (ES = 0.50 SD), and moderate increases in leg dorsiflexion (ES = 0.81 SD). Conclusions: The combination of gastrocnemius exercise with plantar fascia and plantar intrinsic muscle self-massage and stretching may elicit improvements in calcaneal plantar flexion, leg dorsiflexion and thigh flexion. Self-massage and stretching alone elicits similar increases in calcaneal plantar flexion but smaller increases in leg dorsiflexion. Improvements in leg dorsiflexion (3°) in group 2 are greater than has been reported for calf stretching (1°), the traditional approach to increasing leg dorsiflexion. These preliminary results suggest that plantar fascia and plantar intrinsic muscle self-massage and stretching in combination with modified glute-ham-gastroc raise exercise could be an alternative to calf stretching to improve weight-bearing leg dorsiflexion range of motion. These findings are preliminary results of an ongoing investigation; a larger sample size is required to confirm these findings. Practical Applications: Individuals with poor weight-bearing leg dorsiflexion could implement plantar fascia and plantar intrinsic muscle self-massage and stretching, combined with modified glute-ham-gastroc raise to improve lower extremity range of motion.
Friday, July 08, 2016, 9:30 AM–9:45 AM
A Simplified Prediction Model for Thigh and Shank Bone Stress Injuries in Male Collegiate Endurance Athletes
A. Carbuhn,1 Z. Sanchez,2 A. Fry,1 M. Reynolds,1 and L. Magee2
1University of Kansas; and 2Kansas Athletics, Inc.
Purpose: To develop a novel simplified prediction model for all thigh and shank bone stress injuries (TSBI) (i.e., tibia, fibula, and femur) using dual energy x-ray absorptiometry (DEXA) derived body composition and leg bone mineral density (BMD) values in division 1 male endurance athletes aimed to identify “at risk” athletes and potentially prevent TSBI injuries. Methods: DEXA and anthropometric measurements were completed each competitive year (pre and post fall season, mid spring season) in addition to gathering every reported TSBI incidences from August 2013 to August 2015 in 27 Caucasian male endurance athletes. The mean and SD for all continuous variables were computed in the 2 groups of subjects with and without a TSBI. To compare between these groups, we used unpaired T-test. The bivariate correlation between the existence of a TSBI (which is a dichotomous variable) and the continuous variables was computed by Pearson product-moment correlation, with the corresponding p value, which is computed after Fisher's z transformation (Table 1). Backward stepwise elimination method was used to achieve a model that adequately describes the data and does not include noncontributory factors at p > 0.10. For multivariate analysis, we used binary logistic regression. The dependent variable in our analysis is the presence of a TSBI, which is a dichotomous variable. The predictor variables (independent) were a set of the measured variables from DEXA derived bone density and body composition values in addition to anthropometric measurements (Table 1). Results: All measurements were used to construct a new prediction model. The model successfully predicts 96.3% of the male endurance athletes with and without a TSBI as follows: PTSBI = 23.465 − 0.896 BMI + 1.043 TUB − 34.536 leg BMD, where PTSBI is the TSBI prediction according to the log odds (TSBI); odds (TSBI) is the ratio between probability of TSBI existence and nonexistence; BMI is the body mass index (kg·m−2), leg BMD (g·cm−2), and total upper body mass (TUB) (kg) is the total fat, muscle, and bone weight in the trunk and arms. We analyzed, using the receiver operating characteristic curve (ROC) method, the true positive rate (sensitivity) against the false positive rate (1 − specificity) of TSBI's for the different potential cut points of the prediction model. Thus, the sensitivity and the specificity from the ROC method described how well the model discriminated between athletes with and without a TSBI. The area under the curve was found to be 0.873, which is considered a good prediction model. Conclusions: A division 1 Caucasian male endurance athlete is at risk for a TSBI during the competitive year with a higher relative TUB and lower BMI in combination with a low leg BMD. However, further evaluation is required in larger sample sizes in addition to similar sample populations to evaluate these results. Practical Applications: Currently, to the author's knowledge, there is no practical method to assess collegiate male endurance athletes for a potential TSBI that might occur during a competitive fall and spring season. The ability to risk profile male endurance athletes could help avoid a would-be TSBI. An additional benefit is the opportunity for a DEXA derived screening process at the beginning of each competitive year to help alert the respective sport coach, strength and conditioning coach, and sports medicine staff of athletes with a high probability of developing a TSBI if included in team's normal training regime. Acknowledgments: The author would like to acknowledge and thank Kansas Athletics, Inc. for access to their facilities and DEXA technology as well as the track and field coaching staff and student-athletes for the their willingness to be involved in this study. The authors have no conflict of interest to disclose.
Friday, July 08, 2016, 9:45 AM–10:00 AM
A Low-Carbohydrate Ketogenic Diet Combined With 6 Weeks of High-Intensity Power Training Improves Body Composition and Performance
R. Gregory,1 H. Hamdan,2 D. Torisky,3 and J. Akers3
Departments of 1Sports Medicine; 2Mathematics and Statistics; and 3Health Sciences, James Madison University
A low-carbohydrate ketogenic diet (LCKD) is a popular approach to weight and fat loss. High-Intensity Power Training (HIPT) is a type of exercise that aims at sustaining high power outputs through periods of combining aerobic and resistance exercises with the main focus on multiple joint movements. No previous research has been found which examines body composition changes or performance in individuals consuming a LCKD and participating in popular HIPT. Purpose: The purpose of this research was to examine the effects of a 6-week LCKD and HIPT program on body composition and performance. Methods: Twenty-seven non-elite subjects (mean ± SD age = 34.58 ± 9.26 years) were randomly assigned to a LCKD (males, n = 3; females, n = 9) or control (CON) (males, n = 2; females, n = 13) group. LCKD was instructed to consume an ad libitum diet and restrict carbohydrate intake to less than 50 g·d−1. Results: Compared to the CON group, the LCKD group significantly decreased weight (0.18 ± 1.30, −3.45 ± 2.18 kg), BMI (0.07 ± 0.43, −1.13 ± 0.70 kg·m−2), percent body fat (%BF) (0.01 ± 1.21, −2.60 ± 2.14%), and fat mass (FM) (0.06 ± 1.12, −2.83 ± 1.77 kg), respectively. There was no significant difference in lean body mass (LBM) change between or within groups. We found no significant difference in total performance time change between the CON group and the LCKD group; however, both groups significantly decreased total performance time (CON: −41.20 ± 43.17 seconds; LCKD: −55.08 ± 44.29 seconds). Additionally, there were no significant differences in vertical jump and standing long jump change between or within groups. For both groups, the overall change in vertical jump was significant (2.31 ± 4.55 cm) but the change in standing long jump was not. Carbohydrate intake was significantly lower (11.4 ± 5.6%, 40.06 ± 6.81%) and fat intake was significantly higher (62.88 ± 4.19%, 38.38 ± 4.18%) in LCKD at weeks 2, 4, and 6 compared to CON, respectively. There was no statistical difference in total kilocalories or protein intake between or within groups throughout the study. Conclusions: A LCKD combined with 6 weeks of HIPT can lead to significant decreases in %BF, FM, weight, and BMI while maintaining LBM. Additionally, significant improvements in total performance time and power can be achieved. Practical Applications: With the overwhelming increase in obesity and metabolic disease throughout the United States many Americans are searching for the most effective diet and exercise program which promotes fat loss and increases overall quality of life. This study provides valuable insight into the use of a LCKD combined with HIPT for 6 weeks to improve body composition and performance outcomes.
Friday, July 08, 2016, 10:00 AM–10:15 AM
Effect of Three Different Cluster Set Structures on Force, Velocity, and Power During a High-Volume Back Squat Session
J. Tufano,1 J. Conlon,2 S. Nimphius,2 J. Frick,2 B. Williamson,2 A. Petkovic,2 and G. Haff2
1Charles University, Prague; and 2Edith Cowan University
Cluster sets (CS) have been shown to maintain force, velocity, and power output better than traditional sets (TS) during resistance-training. However, most studies compare an individual CS protocol to a single TS protocol. Therefore, information comparing various CS structures to one another using the same subjects within the same study design with equal total rest is lacking. Purpose: The purpose of this study was to determine the effects of 3 different CS protocols on peak force (PF), mean force (MF), peak velocity (PV), mean velocity (MV), peak power (PP), and mean power (MP) during a high-volume back squat session. Methods: Eight resistance trained men (25.2 ± 4.1 years; 76.7 ± 5.1 kg; 1.75 ± 0.07 m; 1RM 135.0 ± 168 kg; 1RM: body mass ratio of 1.76 ± 0.22 kg/kg) performed 36 back squat repetitions using 75% 1RM during 3 different set configurations: cluster sets of four (CS4) inclusive of 30 seconds rest after the fourth, eighth, 16th, 20th, 28th, and 32nd repetition in addition to 120 seconds of rest after the 12th and 24th repetition; 8 sets of 4 (FOURS) with 52.5 seconds of rest after every 4 repetitions; or individual repetitions (SINGLES) with 12 seconds of rest between repetitions. In this manner, all protocols contained 420 seconds of total rest, but the frequency and duration of the rest periods were different. Subjects were instructed to perform full squats (mean peak knee flexion 129.5 ± 11.5°) and were verbally encouraged to perform the eccentric phase under control and concentric phase as explosively as possible. Between 48 and 96 hours were required between protocols, which were performed in random order. All force-time data were collected at 1,000 Hz. Results: Repeated measures ANOVAs were followed by paired comparisons which were then corrected for Type I error using the Holm's Sequential Bonforroni. An alpha of <0.05 was used for the ANOVA tests. There were no significant differences between protocols for any variable when all 36 repetitions of each protocol were averaged together (Table 1). Conclusions: By equating the total rest time between protocols, there were no differences between protocols for PF and MF, PV and MV, or PP and MP when all 36 repetitions were averaged together. Therefore, various CS structures inclusive of the same total rest time resulted in similar force, velocity, and power outputs. These data indicate that a variety of CS structures may be used if back squat velocity or power output is to be maintained during a bout of high-volume resistance training. Practical Applications: The use of CS structures may alleviate fatigue and allow for the maintenance of force, velocity, and power during high-volume resistance training when compared to TS. Additionally, changes to the frequency and duration of rest periods may not impact force, velocity, or power output. However, future research should investigate the effects of CS on other performance variables and the effects of CS on other exercises.
Friday, July 08, 2016, 10:15 AM–10:30 AM
Heart Rate Variability and Perceived Recovery Responses to Overload and Taper Preceding Conference Championships in D-1 Sprint-Swimmers
A. Flatt, B. Hornikel, and M. Esco
The University of Alabama
Daily heart rate variability (HRV) and wellness questionnaires are useful metrics for monitoring fatigue in athletes throughout competition preparation for endurance events. However, longitudinal HRV and wellness responses to competition preparation in athletes involved in anaerobic events such as sprint-swimming have yet to be studied. Purpose: The purpose of this investigation was to observe HRV and psychometric responses to competition preparation in NCAA D-1 sprint-swimmers. Methods: Ten sprint-swimmers (60% male; height = 183.7 ± 9.7 cm, weight = 80.9 ± 10.2 kg) performed seated HRV recordings (i.e., log transformed root mean square of successive RR intervals multiplied by 20, lnRMSSD) daily after waking with a validated smartphone application and pulse-wave finger sensor. Wellness questionnaires were also completed daily via the application where the subjects rated perceived levels of sleep quality, muscle soreness, mood, stress and fatigue on a 9-point scale. Mean values for psychometrics, lnRMSSD (lnRMSSDM) and the coefficient of variation (lnRMSSDCV) were calculated from 1 week of normal training to serve as a baseline (BL) followed by 2 weeks of overload (OL) and 2 weeks of tapering (T) leading up to conference championships. Comparisons between phases were made with repeated measures ANOVA and effect sizes (ES). Results: Comparison statistics are displayed in Table 1. Significant decreases in lnRMSSDM, fatigue and soreness were observed during the OL and returned to BL levels or peaked during T. lnRMSSDCV demonstrated a significant increase during OL and returned to BL levels during T. Conclusions: Overload training is associated with a reduction and greater daily fluctuation in lnRMSSD, concurrent with decrements in perceived fatigue and muscle soreness. These effects are reversed during a taper, where these values return to baseline or peak leading into competition. Practical Applications: Competition preparation in sprint-swimmers is characterized with an inverse bell-shaped pattern for lnRMSSDM, fatigue and soreness, demonstrating the sensitivity of these metrics to intensified training. Reduced lnRMSSDM with greater day-to-day fluctuation (i.e., increased lnRMSSDCV) may serve as a warning sign of inadequate recovery. Tracking of these variables may therefore be useful for monitoring the effects of overload periods and guiding training load manipulation leading into competition.
Friday, July 08, 2016, 10:30 AM–10:45 AM
Effects of Inspiratory Muscle Training on Slow Component O2 Uptake and Performance During 3 Minutes All-Out Exercise
Y. Kuo,1 W. Hsu,2 C. Pan,3 Y. Lai,1 P. Lin,3 and C. Cheng3
1Department of Physical Education, National Taiwan Normal University; 2Graduate Institute of Sports Training, University of Taipei; and 3Department of Athletic Performance, National Taiwan Normal University
Inspiratory muscle training (IMT) improves pulmonary function and aerobic capacity and attenuates the slow component of increasing O2 uptake (V[Combining Dot Above]O2sc) amplitude during high-intensity exercise. Fatigue of the inspiratory muscles during intense exercise might compromise O2 delivery in the exercising muscles, thereby limiting exercise performance. A single-bout sprint with maximal effort, which is called 3-minute all-out cycling test (3MT), has been developed to estimate the critical power (CP) and anaerobic work ability, which are named the end power (EP) and work rate above EP (WEP), respectively. No previous studies have investigated the effectiveness of IMT to attenuate fatigue when performed in 3 MT. Purpose: The aim of this study was to assess the effect of 4-week IMT on the change in the V[Combining Dot Above]O2sc value and high-intensity exercise performance in athletes. Methods: Twenty-five male collegiate athletes (age = 18 ± 2 years; height = 1.78 ± 0.08 m; weight = 68 ± 9 kg) were randomly assigned to receive 4-week of either the IMT group (30 breaths twice daily at ∼80% maximal inspiratory mouth pressure [MIP]) or the control group (CON). The subjects completed pulmonary function tests, including the forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), maximum voluntary ventilation (MVV), and MIP. During the following visits, the subjects performed the incremental exercise test and 3MT to determine the V[Combining Dot Above]O2max, VT, V[Combining Dot Above]O2sc amplitude, and performance (i.e., EP, WEP, peak power, mean power, total work, and power output averaged every 30 seconds). All exercise tests were performed on 3 different days separated by at least 24 hours before (pre) and after (post) 4-week of intervention. Results: MVV was significantly increased (pre vs. post, 179.4 ± 34.1 vs. 196.0 ± 32.6 L·min−1, p ≤ 0.05) after IMT, and the changes in MIP in IMT was significantly greater than that in CON (IMT vs. CON, 26.7 ± 14.2 vs. 8.4 ± 22.7 cmH2O, p ≤ 0.05). However, there were no significant changes in FVC and FEV1 values. No significant differences in EP, WEP, peak power, and V[Combining Dot Above]O2sc amplitude values were found between IMT and CON. The mean power (pre vs. post, 275.0 ± 44.7 vs. 283.4 ± 46.9 W, p ≤ 0.05) and total work (pre vs. post, 49.5 ± 8.1 vs. 51.0 ± 8.4 kJ, p ≤ 0.05) during 3MT were significantly increased in IMT; however, no changes were found in CON. The average of power output 0–120 seconds (pre vs. post, 310.4 ± 46.3 vs. 320.7 ± 52.8 seconds, p ≤ 0.05) and 0–150 seconds (pre vs. post, 289.4 ± 45.1 vs. 299.2 ± 49.3 seconds, p ≤ 0.05) during 3MT were significantly increased in IMT, but there was no significant difference in CON. Conclusions: The 4-week IMT program improved pulmonary function and power output performance during high-intensity exercise. Although IMT may not enhance the amplitude of V[Combining Dot Above]O2sc and CP in athletes, it appears that the improvement in the efficiency of inspiratory muscles may be due to the attenuation of decrements in power output with no change in V[Combining Dot Above]O2sc amplitude at the latter stage. Practical Applications: These findings indicate that the IMT program can enhance the energetic contribution from respiratory function, and closer correspondence of the request of high ventilatory demands during sports performance may support the fact that the requirement for high-order motor units need to be recruited to sustain power output. Therefore, it is recommended that the 4-week IMT program at an intensity of 80% MIP can be added to athletes who train and compete during intense exercises.
Friday, July 08, 2016, 10:45 AM–11:00 AM
Associations Among Functional Motor Competence, Health-Related Fitness, and Injury Prevalence in Youth Sport: A Pilot Study
C. Pfeifer, D. Stodden, and E. Moore
University of South Carolina
Millions of youth suffer injuries related to youth sport participation each year. However, research on mechanisms and correlates of musculoskeletal injury across youth sport is scant. The development of Functional Movement Skill (FMS), or lack thereof, has been linked to injury prevalence and aspects of physical fitness (i.e., strength, endurance, and cardiovascular endurance) in college and professional sport, however, the impact of FMS on injury prevalence and fitness levels in youth sport has not been examined. Thus, examining these constructs may provide insight to sport injury in youth, and provide foundational knowledge for injury prevention as well as long-term athletic development programs. Purpose: To examine associations between FMS, physical fitness, and injury prevalence in youth sport participants over one competitive season. Methods: Sixty participants from a youth sports organization (24 female, 36 male; mean age 15.06 ± 1.8 years; 11 football, 11 volleyball, 38 soccer) were recruited. Before preseason of their respective sports, participant's FMS was measured via: Functional Movement Screen, and qualitative coordination patterns (developmental sequences) and performance of single leg hopping (speed and distance/ht) and standing long jump (SLJ; distance/ht). Two component sequences of hopping (Halverson and Williams, 1985) were coded individually (i.e., arm action—4 levels, leg action—5 levels). The SLJ was assessed relative to take-off and landing phases (Clark and Phillips, 1985). Take-off components analyzed were arm (4 levels) and leg action (4 levels), while landing components were arm (4 levels), shank (2 levels), and foot action (3 levels). Physical fitness of cardiovascular endurance (interval shuttle), muscular endurance (curl up), strength (grip strength) and weight status (BMI) were assessed. Injury data (i.e., any practice or game time lost due to injury related to sport participation) were compiled through respective sport seasons. Spearman correlations were calculated to examine relationships between individual's FMS score, physical fitness, and injury. Results: Injury was inversely correlated with 3 tasks of the Functional Movement Screen (right lunge raw, r = −0.292, p ≤ 0.05; straight leg raise r = −0.289, p ≤ 0.05; rotary task r = −0.383, p < 0.01), directly correlated with BMI (r = 0.328, p ≤ 0.05) and positively correlated with number of injuries sustained (r = 0.968, p < 0.01). Additionally, Cardiovascular endurance was positively associated with hopping speed (r = 0.405, p < 0.01), hopping developmental sequence (r = 0.455, p < 0.01), and SLJ developmental sequence (r = 0.595, p < 0.01). Conclusions: This study demonstrated low to moderate associations between some FMS measures and injury and cardiovascular fitness in this sample of youth sport participants. These data indicate an individual's core and lower extremity coordination and control may be an important factor to address to reduce injury potential. Further testing is needed with a larger sample and sport distribution to enhance generalizability and understanding of the potential impact of developing FMS on injury prevalence and fitness in youth sport. Practical Applications: Examination of these constructs across youth sport enhances the available information for strength and conditioning specialists to advance injury prevention and physical development programs; specifically addressing the need to enhance functional core and lower extremity coordination and control.
Friday, July 08, 2016, 11:00 AM–11:15 AM
A 4-Month Circuit Functional High-Intensity Training Program Improves Body Composition and Performance of Overweight Women
A. Batrakoulis,1 K. Georgakouli,1 N. Zourbanos,1 K. Papanikolaou,1 D. Draganidis,1 A. Chatzinikolaou,2 C. Deli,1 M. Michalopoulou,2 A. Jamurtas,1 and I. Fatouros1
1University of Thessaly; and 2Democritus University of Thrace
High-intensity interval training (HIIT), functional fitness and circuit training are included in the top trends of the health and fitness industry while adult obesity and physical inactivity rates have grown immensely worldwide. Purpose: This study examined the effectiveness of a time-effective, functional integral HIIT program to improve body composition and performance of inactive overweight women. Methods: Sedentary overweight women (n = 33; 36.4 ± 4.5 years; 166.0 ± 0.1 cm; 78.9 ± 9.3 kg; 28.8 ± 2.9 kg·m−2) volunteered to participate in a progressive, circuit-based HIIT program, which was conducted 3 times per week with 48 hours recovery between sessions for 16 weeks and consisted of whole-body functional exercises. A control group (n = 20) of women of similar characteristics participated only in measurements. Participants were tested (body mass index [BMI], body composition by dual-energy X-ray absorptiometry [DXA], resting metabolic rate [RMR], waist-to-hip ratio [WHR], maximal strength [1RM] in chest and leg press, maximal oxygen uptake [V[Combining Dot Above]O2peak], and subjective vitality). Results: Training reduced body mass index, body fat and WHR declined (p < 0.001) by 3.8, 6.4 and 5.8%, and increased (p < 0.001) fat-free mass, RMR, 1RM, V[Combining Dot Above]O2peak, and vitality by 2.8, 7.2, ∼20, 25, and 51%, respectively. Conclusions: There is very limited data regarding the effects of circuit functional HIIT programs on the anthropometric profile and performance of sedentary overweight women. Results of the present investigation suggest that a circuit-based functional HIIT using body weight exercises and functional fitness equipment may induce a considerable improvement of body composition and performance of premenopausal, previously inactive, overweight women. These results may be attributed to an induced rise in RMR and fat-free mass. Practical Applications: Since the physical inactivity and obesity have reached epidemic proportions globally, exercise professionals are encouraged to apply a whole-body workout routine that combines HIIT, functional fitness, and circuit training seeking a time-efficient and evidence-based practice that enhances weight management, physical performance, and wellness within the health and fitness industry.
Friday, July 08, 2016, 11:15 AM–11:30 AM
Mechanical Similarity, Set Volume and Recovery Duration All Require Manipulation in Order to Elicit Postactivation Potentiation in 30 m Sprint Performance
A. Dinsdale,1 C. Cooke,2 and A. Bissas1
1Leeds Beckett University; and 2Leeds Trinity University
A popular coaching recommendation is the acute coupling of a mechanically similar resistance exercise with an explosive movement, which in combination elicits an acute enhancement termed Post-Activation Potentiation (PAP). Purpose: The aim of this study was to systematically evaluate the PAP model with regards to sprint performance. Methods: Fifteen well trained university male students (age 21.8 ± 3.0 years, height 1.78 ± 0.07 m and mass 85.4 ± 13.8 kg) completed 11 randomised protocols (10 experimental and 1 control [no exercise]). Each protocol consisted of a structured warm-up, a 30 m sprint pre-test, a randomly assigned resistance exercise and a 30 m sprint post-test performed at 4 recovery durations (1, 5, 9 and 13 minutes). Five resistance exercises were selected (Resisted Sprinting [high], Hang Cleans [medium] at 85% of 1RM, Jump Squats [medium] at 60% of 1RM, Depth Jumps [medium] and Back Squats [low] at 85% of 1RM) based on a previous analysis of mechanical similarity undertaken by the authors. Two set volumes (1 set and 3 sets) were implemented for each resistance exercise. The 30 m sprint time was measured by a pair of Brower timing gates. Results: The 6 × 2 × 4 Repeated Measures ANOVA (Similarity, Volume and Recovery) identified significant differences within these factors: Volume (p < 0.01), Similarity × Recovery (p ≤ 0.05), Volume × Recovery (p < 0.01). Simple contrasts identified a significant (p < 0.01) PAP enhancement with regards to the single set of R-sprint post 1 minute recovery (−0.07 ± 0.05 s). Simple contrasts also identified significant reductions in sprint performance after implementing both 3 sets of HC at 1 minute recovery (0.08 ± 0.11 seconds, p ≤ 0.05) and 3 sets of BSQ at 1 minute recovery (0.08 ± 0.1 seconds, P ≤ 0.05). None of the other protocols were significantly different from the control protocol. Conclusions: Only one of the multiple conditions evaluated elicited a significant PAP response, which suggests that an optimal interaction exists between each of the manipulated factors. The resisted sprint was selected due to it exhibiting a high mechanical similarity with sprinting. Hence, the findings would suggest that a high mechanical similarity was an important factor in eliciting the PAP mechanism, although in combination with a low set volume and low recovery duration. Conversely, performance impairing fatigue can be induced after implementing Back Squats or Hang Cleans with a high set volume and low recovery duration. Practical Applications: The use of a single set of resisted sprinting 1 minute before performing a 30 m sprint is an effective strategy that enhances acute performance. However, other combinations of this activity, as well as other combinations of exercises appear to offer no benefit to sprint performance. Furthermore, some couples actually reduce performance and as such should be avoided when trying to acutely enhance sprint performance. Acknowledgments: Carnegie Research Special Conference Fund—Leeds Beckett University.
Friday Abstract Poster Presentations—Session A
July 08, 2016—11:30 AM–1:00 PM—Celestin ABC
Friday, July 08, 2016, 11:30 AM–1:00 PM
Velocity Specific Differences in Plantar Flexion Performance Resulting From 50 Hz Whole Body Vibration
M. Gonzalez, B. De Leon, S. Harper, E. Nunn, and W. Amonette
University of Houston—Clear Lake
Purpose: To quantify differences in plantar flexion isokinetic performance at high and low velocities resulting from 50 Hz whole body vibration. We hypothesized that 50 Hz vibration would increase plantar flexion peak torque, total work, and time-to-peak torque at 30 and 120°·s−1 compared to an isometric control condition. Methods: Ten subjects (5m, 5f; 24 ± 3 years; 170.7 ± 6.8 cm; 70.8 ± 8.5 kg; 23.6 ± 8.8%fat) participated in this study. They performed 4 randomized sessions consisting of either 50 Hz whole body vibration (VIB) or no vibration (CON). A familiarization session was completed one week prior to the first test session to eliminate any learning effects and to document the isokinetic machine settings. Prior to and following 2 testing sessions, prone isokinetic testing of the dominant ankle was completed at 30°·s−1; isokinetic testing prior to and after the additional 2 testing sessions was completed at 120°·s−1. In all sessions, a 5-minute warm-up was performed prior to a baseline test, and 3 tests following the VIB or CON intervention at minute-2, minute-7 and minute-12. During each test, 5 maximal plantar flexion and dorsiflexion movements were completed. The VIB and CON conditions consisted of 5, 1-minute sets of unilateral isometric semi-squats with 30 seconds rest between sets. During the VIB condition, the plate was set to vibrate at 50 Hz, with 4 mm of peak-to-peak displacement. During the CON sessions, the same unilateral semi-squat protocol was completed standing on the vibration plate in the off position. Two-way repeated measures ANOVAs with condition (VIB vs. CON) and time (4 testing times) with Tukey's HSD were utilized to determine differences with an alpha of p ≤ 0.05. Results: There were no interactions (p = 0.84) or main effects for either condition (p = 0.87) or time (p = 0.62) for plantar flexion peak torque at 30°·s−1. However, an interaction (p = 0.03) was present for plantar flexion peak torque at 120°·s−1. At minute-12, VIB was significantly greater than CON (11.6 ± 3.6%). No interactions (p = 0.62) or main effects were evident for condition (p = 0.54) or time (p = 0.53) for plantar flexion total work at 30°·s−1. An interaction (p = 0.004) was present at 120°·s−1 for plantar flexion total work. Compared to CON, greater total work was performed in the VIB at both minute-7 (11.2 ± 4.0%) and minute-12 (16 ± 6.0%). No interactions (p = 0.27) or main effects for condition (p = 0.98) or time (p = 0.18) were present for plantar flexion time-to-peak torque at 30°·s−1. There was a main effect for time (p = 0.03), but not condition (p = 0.35) in plantar flexion time-to-peak torque at 120°·s−1. Overall, pooled time-to-peak torque data were significantly faster (6.1 ± 2.0%) at minute-2 compared to baseline. Conclusions: These data indicate that whole body vibration at 50 Hz does not affect plantar flexion isokinetic peak torque at slower isokinetic velocities, but higher speed isokinetic torques and work are enhanced 7–12 minutes after vibration. Practical Applications: High velocity muscle performance may be enhanced following 50 Hz vibration, but it may require longer rest periods after the exercise bout. This may be practical in events where a single strength effort is required for peak performance, but may be impractical during training sessions that are limited by time.
Effects of Two Volume-Equated Resistance Training Protocols on Muscle Thickness and Muscular Strength
C. Worthey,1 V. Bendotti,1 D. Dodd,1 T. Langosch,1 E. Smith,1 B. Schoenfeld,2 N. Selkow,1 and K. Laurson1
1Illinois State University; and 2Lehman College
The manipulation of exercise volume, intensity, and order is associated with producing different musculoskeletal changes. Purpose: The purpose of this study was to examine the effects of 9 weeks of 2 different volume-equated total body exercise protocols using compound exercises on muscle thickness and muscular strength. Methods: Fifteen well-trained men, with at least one current year of resistance training experience, were randomly assigned to a hypertrophy-style protocol (HG) performing 3 sets of 10 repetitions with 90 seconds rest between sets (n = 8) or a strength-style protocol (SG) performing 7 sets of 3 repetitions with 3 minutes rest between sets (n = 7). Both groups performed the same exercise routine consisting of one upper-body push exercise, one lower-body exercise, and one upper-body pull exercise each day for 3 days a week for a total of 9 different exercises. All exercise sets were carried out to concentric muscular failure. All subjects underwent pre-, mid-, and post-testing in body composition analysis via air displacement plethysmography, circumference measurements at 5 sites, and muscle thickness imaging of 4 different sites: elbow flexors (EF), elbow extensors (EE), rectus femoris (RF), and vastus lateralis (VL). Imaging was done at 2 separate lengths of each muscle site: proximal and distal. One repetition maximum (1RM) testing for the barbell back squat and barbell bench press was also conducted. Results: Preliminary data show that SG experienced more favorable changes in 7 of the 8 muscle thickness measurement sites compared to HG (proximal EF = 2.87 vs. −6.35%, distal EF = −0.55 vs. −3.72%, proximal EE = 7.99 vs. −2.49%, distal EE = 19.42 vs. −2.05%, proximal RF = 3.89 vs. −0.04%, distal RF = 4.64 vs. −4.85%, proximal VL = −2.81 vs. 8.84%, distal VL = 10.30 vs. 5.34%). SG experienced greater effect size responses than the HG for the back squat (ES = 0.55 vs. 0.32) and bench press (ES = 0.69 vs. 0.45). Conclusions: When equated for training volume, a total-body exercise protocol produces more favorable changes using high-intensity loads when compared to a moderate-intensity training protocol. High-intensity compound movement training protocols create greater gains in muscular strength than moderate-intensity training protocols. Nonuniform regional hypertrophy can occur in high- and moderate-intensity training using compound movements. Practical Applications: These data suggest that high-intensity training may have a greater effect on muscle hypertrophy than moderate-intensity training when using a total body exercise routine 3 d·wk−1 in well-trained men. In addition, the absence of metabolic stress associated with hypertrophy-style training using a split-body routine may have negative effects on muscle hypertrophy in well-trained men when using a total-body routine. Acknowledgments: This study was supported by a grant from Dymatize Nutrition (Dallas, TX, USA).
Is More Really Better? A Comparison of Three vs. Six Training Days With Equated Volume on Maximal Strength and Body Composition in Resistance-Trained Males
R. Colquhoun,1 C. Gai,2 B. Campbell,2 D. Bove,2 A. Vargas,2 J. Dolan,2 D. Aguilar,2 K. Couvillion,2 S. Beaugrand,2 S. Donelson,2 P. Lamadrid,2 P. Hinebaugh,2 B. Stokich,2 R. Jimenez,2 and S. Best2
1Oklahoma State University; and 2University of South Florida
Introduction: The most common methods of resistance training programming involve the manipulation of training volume and intensity. However, training frequency is often an overlooked variable. Previous research has examined the effects of different weekly and daily training frequencies, but there is little to no research on the effects of high (>5) weekly training sessions. Purpose: The purpose of this study was to compare the effects of a high (6x/week) vs. a moderate (3x/week) training frequency on maximal strength and body composition in resistance-trained males. Methods: Twenty-eight resistance-trained males were randomly assigned to one of 2 groups: 3x/week (3x; n = 16; Age: 22 ± 3 years; Height: 177 ± 11 cm; Body Mass: 79 ± 19 kg) or 6x/week (6x; n = 12; Age: 22 ± 3 years; Height: 177 ± 6 cm; Body Mass: 84 ± 9 kg). All participants possessed a minimum of 6-months of previous resistance-training experience and were required to have a minimum squat, bench press, and deadlift 1RM of 125, 100, and 150% of their body mass, respectively. Dependent variables (DVs) were assessed at baseline and after the training intervention. DVs included: squat 1RM, bench press 1RM, deadlift 1RM, powerlifting total, Wilk's coefficient, body mass, lean body mass, and fat mass. The supervised, volume-equated resistance-training intervention was 6 weeks in duration. Both groups completed the squat and bench press exercise in every training session and the deadlift in 1/3 of their respective training sessions. Data for each DV was analyzed via a 2 × 2 between-within factorial repeated measures ANOVA. Results: There were no differences in training volume or intensity between groups (p > 0.05). Data is presented as the change/increase over the 6-week training period. There was a main effect for time (p < 0.001) for squat 1RM (3x: +16.8 kg; 6x: +16.7 kg), bench press 1RM (3x: +7.8 kg; 6x: +9.6 kg), deadlift 1RM (3x: +19 kg; 6x: +21 kg), powerlifting total (3x: +43.5 kg; 6x: +47.3 kg), Wilk's coefficient (3x: +27; 6x: +27.1), body mass (3x: +1.4 kg; 6x: +2.4 kg), and lean body mass (3x: +1.7 kg; 6x: +2.6 kg). Additionally, there were no significant differences in Fat Mass and Body Fat % from pre-to post-testing. There was no interaction effect between the 3x and 6x groups on any of the dependent variables assessed. Conclusions: The primary finding was that 6-weeks of resistance training lead to significant increases in maximal strength and lean body mass in previously resistance-trained males. Additionally, it appears that increased training frequency does not lead to additional gains in hypertrophy and strength, when volume and intensity are equated. Practical Applications: High frequency (6x/week) resistance training does not appear to offer additional strength and hypertrophy benefits over lower frequency (3x/week), when volume and intensity are equated. Coaches and practitioners can therefore expect similar increases in strength and lean body mass with both 3- and 6-weekly sessions in previously resistance-trained males. Acknowledgments: The authors would like to thank Dymatize Nutrition for their donation to this study.
The Relationship Between Heart Rate Variability and Training Volume During a Peaking Block in a Competitive Female Powerlifter
T. Williams, A. Flatt, and M. Esco
The University of Alabama
Heart rate variability (HRV) is a non-invasive measure that can be used to objectively monitor physiological responses to stress in athletes. Previous research has shown HRV to be beneficial in regulating training loads in endurance athletes, however the application for strength athletes has been understudied. Purpose: The purpose of this case study was to observe the relationship between HRV and weekly fluctuations in training volume in a female powerlifter peaking for competition. Methods: An elite female powerlifter (age = 23; height = 166.25 cm; weight = 74.4 kg; body fat = 31.0%) trained 4 days a week utilizing a daily undulating periodized (DUP) training program. Back squat and bench press variations were performed 4 days a week, while deadlift variations were performed twice a week. The DUP training program lasted 5 weeks, with the third week being an overload week (high volume, high intensity) followed by a 2-week taper. Daily HRV was self-measured by the subject in a seated position after waking and elimination using a validated smart phone application and Bluetooth-enabled chest-strap transmitter. The HRV metric used in the study was the log-transformed root mean square differences of successive R-R intervals multiplied by twenty. Training loads were adjusted based on daily perceptual recovery status and exercise-specific set rating of perceived exertion. Effect sizes (ES) were calculated to determine weekly mean differences in HRV and total training volume (TL) when compared to the 5-week average. Pearson correlation coefficients were used to quantify the relationship between HRV and TL. Results: HRV and TL values are displayed in Figure 1. Changes in HRV ranged from trivial to moderate (ES = 0.11 to −0.60) while changes in TL ranged from small to large (ES = −0.22 to 1.06). HRV was strongly related with TL (r = −0.97), squat volume (r = −0.99), bench press volume (r = −0.92), and deadlift volume (r = −0.81). The athlete set personal records in each of the powerlifts (+4% in total) and set a new USPA American Junior deadlift record (167.5 kg). Conclusions: Weekly HRV demonstrated a strong inverse relationship with TL, as well as training volume for each of the specific powerlifts. Of note, the overload week resulted in the largest reduction in HRV which subsequently rebounded and peaked throughout the taper leading into a successful competition. The results of this case study show promise for HRV as a potentially useful monitoring tool among strength athletes and thus may encourage future research with larger samples. Practical Applications: Monitoring TL and recovery status in athletes is important to optimize performance and minimize the risk of overtraining. HRV is a convenient, non-invasive tool that can provide an objective physiological measure that may be useful in creating an individualized training approach, particularly in monitoring the effects of overload and taper during powerlifting competition preparation.
Within-Subject Correlation of Session-Rating of Perceived Exertion and Player Load in American Football
P. Ward,1 B. Drust,2 A. Batterham,3 A. Coutts,4 A. Hulton,2 S. Ramsden,1 R. Dean,1 and T. Garcia1
1Seattle Seahawks; 2Liverpool John Moores University; 3Teesside University; and 4University of Technology Sydney
Background: Measurement of training load using Rating of Perceived Exertion (sRPE) and GPS has been well documented in collision sports. However, little is known about such relationships in American Football. Objective: The aim of this study was to understand the within-subject correlation between sRPE and Player Load in American Football. Methods: Eighty players from one NFL team were monitored throughout the pre- and in-season periods. Training monitoring consisted of a modified sRPE and Player Load, an accelerometer metric reported as an arbitrary unit. Player Load was determined using an accelerometer located within a GPS tracking unit worn between the shoulder blades in a custom made shirt for the duration of practice. Approximately 10–15 minutes following practice sRPE was collected by asking players to rate the intensity of the session using a 1–10 point Likert Scale (1 = easy/10 = maximal). This figure was multiplied by the session duration (minutes) to produce an arbitrary training load. Athletes were classified into positional groups: DB (n = 18), DL (n = 14), LB (n = 9), TE (n = 8, WR [n = 13], RB [n = 6], OL [n = 12]). Collectively, the athletes provided 1,702 observations. Within-subject correlation between sRPE and Player Load was calculated for the entire team and for players in their positional groups. This approach prevents violating the assumption of independence due to repeated measures therefore allowing for a more precise measure of correlation between sRPE and Player Load. Results: A large within-subject correlation was found between sRPE and Player Load across the entire team (0.60; 95% CI: 0.57–0.63). A trivial correlation for the RB group (r = 0.006; 95% CI: −0.17 to 0.18) and moderate to large correlation for the WRs (r = 0.50, 95% CI: 0.39–0.60) was discovered. All other positional groups saw large within-subject correlations ranging from r = 0.61–0.69. Conclusions: A large within-subject correlation between sRPE and Player Load was found for the team and several position groups (OL, DB, DL, LB, and TE). The trivial and moderate correlations for the RB and WR groups suggest that it is possible different metrics may better relate to the subjective evaluation of training demands for these positions. Practical Applications: These findings indicate that sRPE may be a useful metric for the evaluation of training load for several position groups in American Football.
A Correlational Analysis of Readiness Measures and Peak Barbell Velocity Performance
A. Bryce, A. Fry, A. Sterczala, and J. Nicoll
University of Kansas
Athlete readiness, or the physical and mental state of being fully prepared to engage in physical activity, is intrinsically related to fatigue and performance. As such, accurate determination of readiness is of paramount importance to strength and conditioning professionals. Currently, research correlating readiness measures with acute resistance exercise performance is limited. Purpose: The purpose of this study was to determine relationships between Likert-scale measures of physical (PR) and mental readiness (MR), and peak velocity performance on the barbell squat jump (SJ) and barbell bench press (BP). Methods: As part of a larger study, eighteen male subjects of recreational training status (age = 21.89 ± 2.82 years, height = 1.78 ± 0.06 m, weight = 84.16 ± 15.08 kg) participated in 20 total training sessions over the course of 8 weeks. Prior to training, subjects completed 2 Likert questionnaires, rating MR and PR on a scale of 1–10 (10 = high readiness). Subjects then performed 2 sets of 3 repetitions of maximum effort jump squats, and 2 sets of 3 maximal effort “speed” bench press repetitions at 20% 1RM, with peak concentric velocity (meter per second) recorded for all repetitions. Velocity was determined using the EliteForm system (Lincoln, NE, USA), a rack-mounted, video motion capture system used to detect and track barbell velocity and power. Pearson product moment correlations compared jump squat peak velocity, speed bench press peak velocity, mental readiness, and physical readiness. Significance was set at p ≤ 0.05. Results: Significant relationships were observed between the Likert-scale variables, MR and PR, and between the 2 performance variables, BPP and SJ. Additionally, significant relationships were observed between MR and BP, and PR and BP. No relationship was found between SJ and MR or PR. Results of the investigation are presented in Table 1. Conclusions: The results of this investigation suggest subjective readiness measures, such as mental and physical readiness, may associate with some aspects of physical performance. Physical and mental readiness measures may have predictive power for acute resistance training performance, however the correlation between self-reported measures of mental and physical readiness may suggest that individuals struggle to distinguish between the 2. The significant relationship between upper and lower body performance as measured via BP and SJ may suggest that readiness is largely affected by central mechanisms. Practical Applications: Measuring readiness, or tracking changes in readiness over time, may be an effective way for strength and conditioning professionals to approximate the myriad variables that create an athlete's physiological state, and could serve as a useful tool to monitor fatigue or prevent injury. More research is needed to determine the most appropriate measures and methods to determine readiness.
The Effect of Different Training Frequencies on Maximal Leg Strength: A Pilot Study
J. Trammell, D. Szymanski, and B. Romer
Louisiana Tech University
Progressive overload is often achieved through alterations in volume and intensity throughout a resistance training program; however, alterations in training frequency are rarely considered as a potential source for volume and intensity manipulation. Purpose: To examine the differences in one-repetition maximum (1RM) back squat (BS) between a group who squatted 3 days per week (3D) and a group who squatted 5 days per week (5D). Methods: Fifteen recreationally trained male and female college students (age = 21.1 ± 2.4 years, height = 175.4 ± 12.1 cm, weight = 79.2 ± 10.6 kg) in a university weight training class were pair matched for 1RM BS and then randomly assigned to a 3D group (n = 8) or a 5D group (n = 8). Both groups used a daily undulating periodization model with both volume and intensity equated over the course of the study. The 3D group performed a hypertrophy (H) day on Monday, a power (P) day on Wednesday, and a strength (S) day on Friday. The 5D group performed 2 days each of H (Monday and Thursday) and P (Tuesday and Friday), with the volume half that of the 3D group on each day. An S day was performed on Wednesday. Subject's 1RM BS was tested before and after 6 weeks of training. After pre-training 1RM BS testing occurred, an independent sample t-test was run to determine if there were differences between the groups. After 6-week post-training 1RM BS testing occurred, data were analyzed using a 2 (group) × 2 (trials) repeated measures ANOVA and paired sample t-tests with a Bonferroni adjustment to assess statistical differences in 1RM BS strength. Results: There were no significant differences for 1RM BS between groups before (3D = 100.1 ± 45.6 kg vs. 5D = 97.2 ± 23.4 kg) or after (3D = 121.9 ± 49.9 kg vs. 5D = 120.9 ± 25.2 kg) 6 weeks of training (p > 0.05); however, the 3D and 5D groups both statistically (p ≤ 0.05) improved 1RM BS (21.8% and 23.3%, respectively) after 6 weeks of training. Conclusions: Although both resistance training protocols had statistically similar improvements, data indicated that there is no additional benefit of training 5D compared to 3D when attempting to improve 1RM BS strength for recreationally trained college students. Practical Applications: If a college student's week is busy and they do not have time to go to the gym to resistance train daily, they can be confident that 3D is just as beneficial as 5D to improve leg strength if volume and intensity of training are equal.
Whole Body Vibration Frequency Affects Neuromuscular Potentiation Responses in the Plantar Flexors
S. Harper, B. De Leon, M. Gonzalez, E. Nunn, and W. Amonette
University of Houston—Clear Lake
Purpose: To quantify neuromuscular potentiation responses in the plantar flexor muscles resulting from vibration at 30 and 50 Hz. We hypothesized that both high (50 Hz) and low (30 Hz) frequency vibration would increase plantar flexion peak torque, total work, and time-to-peak torque compared to an isometric control condition. Methods: Twenty subjects (10m, 10f; 25 ± 3 years; 70.4 ± 9 kg; 168.8 ± 7.9 cm; 24.8 ± 7.8%fat) participated in the study. After informed consent was obtained, all subjects completed 3 testing sessions. Session one was used to collect basic data and to complete a reference plantar flexion isokinetic test in prone for familiarization and group assignment. Based on peak torque data obtained from the reference test, subjects were match-paired for strength, gender, and then randomly assigned to either a 50 or 30 Hz group. Subjects then completed 2 testing sessions. During both testing sessions concentric isokinetic plantar flexion data were collected at 120°·s−1 prior to exercise, and 2-, 7-, and 12-minutes after exercise; one set of 5 repetitions was completed at each testing point. In one exercise session (WBV), the subjects performed 5, one minute sets of unilateral isometric semi-squats on the dominant leg with either 30 or 50 Hz vibration (4 mm peak-to-peak displacement) depending on their random group assignment. In the other exercise session (CON), they performed the same isometric squat protocol, with no vibration. The order of exercise sessions, WBV and CON, were assigned at random and 30 seconds recovery was provided between sets in both sessions. Two-factor ANOVAs accounting for condition (WBV × CON) and time (4 measurement points) with Tukey's HSD were used to determine significant differences. Alpha was set at p ≤ 0.05. Results: Peak torque data indicated no significant effects for condition (p = 0.92), time (p = 0.74) and there were no interactions (p = 0.14) subsequent to 30 Hz vibration. A condition by time interaction (p = 0.03) was observed following vibration at 50 Hz. Peak torque was significantly greater at minute-12 in WBV (44.0 ± 4.1 N·m) compared to CON (30.5 ± 4.04 N·m), but was similar at all other time points. Total work data resulting from WBV at 30 Hz showed no statistical difference by condition (p = 0.89) or time (p = 0.66) and no interaction (p = 0.21) was present. However, a condition by time interaction (p = 0.004) was present in total work following vibration at 50 Hz. At minute-7, total work was significantly greater in WBV (35.4 ± 3.9 J) compared to CON (30.5 ± 3.4 J). Likewise, at minute-12, participants completed more total work in WBV (34.4 ± 3.8 J) than CON (29.1 ± 3.7 J). There was no effect for condition (p = 0.35) or interaction (p = 0.58) for time-to-peak torque, but there was a main effect for time (p = 0.03). Pooled data at baseline (0.26 ± 0.02 s) was significantly slower than at minute-2 (0.25 ± 0.01 s). Conclusions: These data indicate that whole body vibration at 30 Hz does not affect higher velocity isokinetic torque production or total work. However, 50 Hz may stimulate a neuromuscular potentiation response 7–12 minutes following an acute bout of vibration exercise. Practical Applications: The use of higher frequency vibration may be beneficial for improving plantar flexor muscle performance, but 7 minutes of rest may be required before the positive effects are present. This could be used in strength and power phases of training where longer rest periods are prescribed.
Monitoring Recovery in Collegiate Wrestlers
C. Bastian, G. Wright, D. Malecek, and M. Andre
University of Wisconsin-La Crosse
Purpose: The purpose of this study was to monitor changes in performance, perceived recovery, and hormonal status in collegiate wrestlers across a season. Methods: Nine collegiate wrestlers, all from the same team, attended regularly-scheduled practice and gave a resting saliva sample at 4 different time points across a season. After saliva collection, they performed their team warm-up and were assessed for Reactive Strength Index (RSI), Perceived Recovery Status (PRS), and a sandbag throw conditioning test. Saliva was later analyzed for testosterone (T), cortisol (C), and T/C ratio. Repeated measures ANOVA with effect sizes were calculated to determine changes in these variables across time. Results: Overall ANOVA models were significant for T (F(3) = 4.018, p = 0.019,
= 0.334), C (F(3) = 5.267, p = 0.006,
= 0.397), PRS (F(3) = 3.048, p = 0.048,
= 0.276), RSI (F(3) = 50.616, p < 0.001,
= 0.864), sandbag test (F(3) = 3.125, p = 0.045,
= 0.281), and body weight (F(3) = 5.426, p = 0.005,
= 0.404), but not for T/C (F(3) = 1.586, P = 0.219,
= 0.165). Refer to Table 1 for time-point comparisons. Significant correlations occurred between T and RSI (R = 0.457, P = 0.005). Conclusions: Across the season, there was a large reduction in T, which corresponded with a large reduction in RSI, sandbag test performance, and body weight, suggesting reduced ability to recover later in the season. This reduction was despite an increase in PRS at the final time-point. Additionally, RSI and T are positively related; therefore, changes in RSI may reflect changes in T. Practical Applications: Wrestling coaches should consider monitoring T, RSI, and the sandbag test (in addition to other variables), and adjust training based on recovery needs. Additionally, monitoring changes in RSI may reflect changes in T, giving further evidence that RSI may help monitor neuromuscular recovery. Acknowledgments: Supported by UWL Undergraduate Research & Creativity Grant.
Daily Monitoring of Collegiate Powerlifters Across the Final Week of a Competition Taper
A. Askow, M. Mosiman, J. Allen, E. Morrisette, L. Gillen, C. Gillette, A. Jagim, and M. Andre
University of Wisconsin-La Crosse
Purpose: The purpose of this study was to monitor daily changes in power, perceived recovery, perceived stress, and hormonal status in collegiate powerlifters across the final week of a competition taper. Methods: Five advanced male collegiate powerlifters (1.79 ± 0.06 m, 111.3 ± 32.8 kg; best competition: squat = 240.0 ± 64.5 kg, bench press = 167.5 ± 40.4 kg, deadlift = 272.0 ± 38.6 kg; Wilks = 408.9 ± 57.7), all competing in the USAPL Junior Raw category and all using the same program, gave a saliva sample and body weight (BW) before training on 5 consecutive days (Monday–Friday) during the final week of a 4-week taper leading into the USAPL state powerlifting meet on Saturday. The final week of the taper involved attempting planned opening weights (91% 1RM) on Monday, followed by no training for the remainder of the week. During saliva collection, they reported Perceived Recovery Status (PRS) and answered the Perceived Stress Scale (PSS). Then, they performed a brief dynamic warm-up followed by vertical jump (VJ) testing. Peak power for VJ (VJPP) was calculated using the Johnson & Bahamonde equation. Saliva was later analyzed for testosterone (T) and cortisol (C). Repeated measures ANOVA with LSD pairwise comparisons were calculated to determine changes in these variables across time. While P is reported to allow the reader to determine probability of a type I error, this report focuses on effect sizes (partial eta squared [
] for ANOVA and Cohen's d [d] for LSD), which is a growing trend in sport science studies with necessarily-small n sizes. Consistent with previous literature, when
is greater than 0.02, 0.13, 0.26, and 0.39, the relationship is described as small, medium, large, and very-large, respectively; when d is greater than 0.20, 0.50, 0.80, and 1.30, the relationship is described as small, medium, large, and very-large, respectively. Results: Overall ANOVA models had very-large effects (time) for VJPP (F(4) = 2.796, P = 0.062,
= 0.411); large effects for T (F(4) = 1.792, P = 0.180,
= 0.309), PRS (F(4) = 1.672, P = 0.206,
= 0.295), PSS (F(4) = 2.312, P = 0.102,
= 0.366), VJ (F(4) = 2.191, P = 0.116,
= 0.354), and body weight (F(4) = 2.021, P = 0.140,
= 0.336); medium effects for C (F(4) = 1.339, P = 0.298,
= 0.251); small/trivial effects for T/C (F(4) = 0.466, P = 0.760,
= 0.104). Refer to Table 1 for daily data, highlighting large to very-large d, based off of LSD. Conclusions: By the end of the week, the athletes trended towards a decrease in T and C while maintaining T/C, in addition to higher perceived recovery while maintaining explosive power and weight. There was an increase in VJPP from Tuesday to Friday (P = 0.04, d = 0.23, 90% CI: 106–690), with a small (but potentially worthwhile) effect for this group. All athletes had personal-best totals at the meet, including 7 state records. Practical Applications: Four consecutive days with no training leading into an important meet can be used to enhance recovery and lead to a personal-best performance in advanced collegiate powerlifters. Acknowledgments: Supported by UWL Graduate Student Research, Service, and Educational Leadership Grant.
An Examination of Systolic Blood Pressure Post Upper Body Resistance Exercise in Pre-Hypertensive Males
C. Munger,1 P. Drouet,1 D. Archer,1 M. Wong,1 P. Costa,2 J. Coburn,3 and L. Brown2
1Human Performance Laboratory, California State University, Fullerton, California; 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California; and 3Human Performance Laboratory, Center for Sport Performance, California State University, Fullerton, California
Resistance exercise is used to improve health, fitness, and sport performance. This may be more important for individuals who have a resting systolic blood pressure (SBP) categorized by the American Heart Association as pre-hypertensive. An acute increase in SBP followed by a reduction is expected post-exercise. However, the effects of upper body resistance exercise (UBRE) on SBP are unknown. Purpose: To investigate SBP during a 60 minutes rest period following UBRE. Methods: Eight recreationally trained pre-hypertensive males (age = 25.4 ± 4.1 years; ht = 174.9 ± 6.7 cm; mass = 84.8 ± 18.0 kg; resting SBP = 126.1 + 4.1 mm Hg) completed 20 minutes of quiet, seated rest followed by an upper body warm-up with a elastic band. Then, they performed UBRE followed by 60 minutes of quiet seated rest. UBRE consisted of bench press, lat pull-down, and seated strict press (4 sets of 6 repetitions with 2 minutes rest between sets, and one minute rest between exercises). SBP was measured immediately prior to and immediately post UBRE and every 10 minutes for 60 minutes. Results: There was a significant (P ≤ 0.05) main effect for time where SBP at 60 minutes post-exercise (120.00 + 7.60 mm Hg) was less than immediately prior (128.00 + 4.88 mm Hg), immediately post (137.63 + 14.47 mm Hg), 30 minutes post (127.50 + 5.66 mm Hg), and 50 minutes post (126.00 + 9.83 mm Hg). Ten minutes post (123.63 + 8.28 mm Hg) and 40 minutes post (123.75 + 5.68 mm Hg) were less than immediately post (137.63 + 14.47 mm Hg). Thirty minutes post (127.50 + 5.66 mm Hg) was less than 10 minutes post (123.63 + 8.28 mm Hg). Conclusions: SBP gradually reduced to below resting values following 60 minutes of rest. This hypotensive response to UBRE can be attributed to decreased sympathetic nervous system activation, or increased parasympathetic activation post exercise. Practical Applications: Coaches can utilize UBRE to achieve an acute reduction in SBP. Future research should investigate the effects of habitual UBRE on SBP response.
Comparison of Hex Bar Deadlift vs. Back Squat Postactivation Potentiation on Vertical Jump Force, Power, and Velocity Interpeak Times
W. Leyva,1 D. Archer,1 C. Munger,1 A. Galpin,2 J. Coburn,3 and L. Brown2
1Human Performance Laboratory, California State University, Fullerton, California; 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California; and 3Human Performance Laboratory, Center for Sport Performance, California State University, Fullerton, California
Strength coaches are searching for the best way to train their athletes to be bigger, faster, and stronger in order to increase performance. One unique form of training is postactivation potentiation (PAP), which has been largely researched using back squats (BS). PAP is based on the premise that performing a heavy resistance exercise followed by an explosive exercise, will result in increased power. It is largely unknown how the hex bar deadlift (HBDL) affects PAP and if jumping mechanics are altered after performing a heavy resistance exercise. Purpose: To compare the effects of BS vs. HBDL PAP on vertical jump force, power, and velocity interpeak times. Methods: Ten resistance-trained men (age = 24.20 ± 3.49 years, ht = 176.15 ± 4.57 cm, mass = 80.78 ± 4.05 kg) volunteered to participate and performed 3 pre countermovement jumps (CMJ) then 3 repetitions of BS or HBDL at 85% 1RM. To perform the CMJ, subjects jumped with arm swing on a force plate. The BS (1RM: 284.00 ± 48.64 lbs) was performed with a standard barbell in a power rack with a safety squat device to insure a quad parallel position. The HBDL (1RM: 356.00 ± 46.89 lbs) was performed using the low handles without straps. Following the BS or HBDL, subjects rested 8 minutes then performed 3 post CMJ. A control condition consisted of 3 pre CMJ, 8 minutes of standing rest, then 3 post CMJ. Interpeak values were the times from peak ground reaction force (PGRF) to peak power (PP), PGRF to peak velocity (PV), and PP to PV. Results: Three separate ANOVAs analyzed each interpeak time. There were no interactions of condition × time for any interpeak time, but there was a main effect for time where PP to PV post (0.041 ± 0.003 seconds) was longer than pre (0.039 ± 0.003 seconds). There were no significant main effects for PGRF to PP (pre 0.052 ± 0.047 seconds, post 0.057 ± 0.038 seconds) or PGRF to PV (pre 0.092 ± 0.047 seconds, post 0.098 ± 0.038 seconds). Conclusions: The increased CMJ interpeak time from PP to PV may be due to altered jump mechanics caused by differential body positions. Practical Applications: Strength and conditioning coaches should be aware that vertical jump mechanics might be altered following exercise.
No Effects of Different Footwear on Isometric Force Production
S. Barillas,1 A. Manolovitz,1 D. Archer,1 and L. Brown2
1Human Performance Laboratory, California State University, Fullerton, California; and 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California
Footwear is marketed towards specificity of exercise. However, there is a lack of evidence to validate the advantages of different types when exerting maximal force. Purpose: To investigate differences in force production between different footwear types. Methods: Sixteen resistance trained males (age = 25.75 ± 2.05 years; ht = 178.19 ± 5.37 cm; mass = 88.73 ± 13.41 kg) performed an isometric mid-thigh pull on an AMTI force plate. Three trials each were done in cross-training shoes, weightlifting shoes, and while barefoot. They were instructed to pull as hard and fast as possible for 3 seconds at a knee joint angle of 135°. Delta peak force (DPF, peak force − bodyweight) and rate of force development (RFD) every 50–250 milliseconds were recorded. Results: A 3 × 5 (footwear × time) repeated measures ANOVA for RFD demonstrated no interaction or main effect for footwear, but there was a main effect for time (p = 0.016) where RFD decreased as time increased (50 ms = 9,412.50 ± 106.22 N·s−1, 100 ms = 8,798.37 ± 915.00 N·s−1, 150 ms = 8,950.24 ± 536.45 N·s−1, 200 ms = 8,403.12 ± 451.63 N·s−1, 250 ms = 7,314.74 ± 337.12 N·s−1). In addition, DPF was not different between weightlifting shoes (2,306.94 ± 359.36 N), cross-training shoes (2,432.97 ± 804.74 N), or barefoot (2,220.95 ± 335.36 N). Conclusions: There was no specific advantage for the use of any footwear when performing an isometric mid-thigh pull. Practical Applications: Strength coaches may allow athletes to perform isometric resistance training in shoes they use in their sport. While no advantages were shown in isometric force production in this study between different footwear, future research should investigate dynamic strength.
The Effectiveness of Prilepin's Chart for Powerlifting Strength Improvements in Resistance Trained Males
H. Pritchard,1 M. Barnes,2 J. Keogh,3 and M. McGuigan1
1Auckland University of Technology; 2Massey University; and 3Bond University
Prilepin's chart (or Prilepin's table) was developed, based upon observations of elite weightlifters training methods, to act as a guide in the selection of optimal set, rep and intensity schemes when training to improve performance in weightlifting. It has also been used, anecdotally, to successfully guide resistance training in powerlifting and other sports. However, there is currently no research investigating the effectiveness of its guidelines for strength improvements specific to the 3 powerlifts. Purpose: To determine the effectiveness of using Prilepin's chart to guide strength training for improving powerlifting performance over a 4 week period in resistance trained males. Methods: Nine resistance trained males (mean ± SD; age = 24.7 ± 4.9 years, bodyweight 82.7 ± 8.8 kg) participated in this investigation. The participants were tested for one repetition maximum (1RM) in the powerlifts, as well as for their 2–10RM to estimate 1RM's on accessory movements (or variations on the powerlifts), before and after the 4 weeks of training. Pre-testing took place a minimum of 3 and no more than 7 days prior to the commencement of the training period, and post testing occurred a minimum of 4 and no more than 7 days following the final training session. The training program was based on Prilepin's chart (Table 1). Statistical analysis involved using 2 tailed, paired, T-tests with a significance level set at p ≤ 0.05. Effect size (ES) was calculated by dividing the change in 1RM by the initial SD. Results: Significant absolute strength improvements occurred for all powerlifts; squat from 122.2 ± 26.6 to 134.2 ± 25.5 kg (p < 0.001, ES 0.45), bench press from 94.7 ± 22.3 to 100.6 ± 22.7 kg (p = 0.006, ES 0.26), and deadlift from 158.9 ± 34.1 to 172.2 ± 36.4 kg (p < 0.001, ES 0.39). Significant strength improvements also occurred for all powerlifts relative to bodyweight; squat from 1.47 ± 0.22 × BW to 1.60 ± 0.21 × BW (p < 0.001, ES 0.61); bench press from 1.14 ± 0.19 × BW to 1.20 ± 0.19 × BW (p = 0.028, ES 0.33), and deadlift from 1.91 ± 0.28 × BW to 2.05 ± 0.30 × BW (p = 0.002, ES 0.50). Conclusions: With only 4 weeks of powerlifting specific strength training, based on the guidelines provided by Prilepin's chart, strength gains can be made in the 3 powerlifts in resistance trained males. Improvements tended to be greater for the lower body dominant powerlifts of the squat and deadlift. Practical Applications: Prilepin's chart can be used as a strength training tool in sports where increasing strength in the muscle groups and movements associated with the powerlifts is important. This research confirms the anecdotally reported success of this training methodology in improving strength in the 3 powerlifts.
Volume Load and Blood Lactate Concentrations as a Result of Five Different Resistance Training Techniques in Resistance Trained Individuals
W. Wallace,1 C. Ugrinowitsch,2 M. Stefan,1 A. Barninger,3 C. Irvin,3 R. Lowery,3 R. Barroso,4 M. Sharp,3 K. Shields,1 J. Andersen,1 and E. De Souza1
1The University of Tampa; 2Department of Sport, The University of São Paulo; 3Applied Science and Performance Institute; and 4State University of Campinas
Introduction: Volume load has been considered an important training-variable to optimize training-induced adaptations. It has been suggested that different strength-training techniques could potentiate volume load responses. Purpose: The purpose of this study was to determine which training techniques optimizes volume load responses in resistance trained individuals. Methods: Eleven resistance-trained individuals (age: 24 ± 4 years, ht: 71 ± 4 cm, body mass: 92 ± 4 kg, resistance training experience: 6 ± 5 years, 10RM: 87 ± 61 kg) underwent 5 different training techniques (Traditional-TR, Pre-exhaust A-PA, Pre-exhaust B-PB, Forced Repetition-FR, Superset-SS) in a randomized cross-over design. Subjects performed 2 familiarization sessions prior to beginning the study. Baseline 10RM values were recorded during the familiarization sessions with the TR protocol. This 10RM load was used for the first set of all conditions as followed: TR had subjects perform 5 × 10RM on the bench-press, followed by 5 × 10RM for incline bench-press. PA began with 5 × 10RM of a triceps pushdown exercise and PB began with the incline bench-press. FR performed both incline and bench-press exercises following an 8RM to failure plus 2 forced repetitions with assistance for a total of 10 repetitions per set. SS consisted of 5 × 10RM on bench-press immediately followed by 5 × 10RM on incline bench press. A 120 seconds rest interval and 180 seconds rest between sets and exercises was granted, respectively. All protocols were performed twice per week on their respective weeks, separated by 48 hours. Blood lactate concentration [La−] was taken at baseline, between exercises rest interval, immediately post, and 5 minutes post, except in the case of SS where [La−] was taken after set 3. A mixed model was used to scrutinize the effects of different training techniques on dependent variables (e.g., volume load and blood lactate), assuming condition (TR, PA, PB, FR, SS) and day (1, 2) as fixed factors, and participants as a random factor. In addition for [La−]: condition, day, and time (baseline, mid, post, 5 min post) were assumed as fixed factors (SAS 9.2, SAS Institute Inc., Cary, NC, USA). Results: There was a significant main group effect for conditions where SS produced lower overall volume load than TR, PB, and FR (TR = 6,471 ± 932 kg, PA = 6,030 ± 633 kg, PB = 6,629 ± 759 kg, FR = 6,612 ± 851.7 kg, SS = 5,564 ± 602 kg) (p < 0.0002). In addition, there was a trend for day 2 to produce higher volume loads than day 1 (day 1 = 6,182 ± 868 kg, day 2 = 6,342 ± 849 kg) (p < 0.08). There was a main group effect for [La−], which demonstrated that the TR protocol produced lower [La−] than PA, PB, FR, and SS (TR = 7.3 ± 3.8 mmol·L−1, PA = 8.8 ± 4.5 mmol·L−1, PB = 8.4 ± 4.3 mmol·L−1, FR = 8.4 ± 4.7 mmol·L−1, SS = 8.2 ± 4.5 mmol·L−1) (p ≤ 0.05). Furthermore, there was a main time effect in which all conditions increased [La−] similarly (time 1 = 1.9 ± 1.0 mmol·L−1, time 2 = 10 ± 2.5 mmol·L−1, time 3 = 11.2 ± 2.6 mmol·L−1, time 4 = 9.8 ± 2.7 mmol·L−1) (p < 0.0001). Conclusions: Despite recommendations to use different training techniques to produce greater volume load, our findings showed that volume load amongst different techniques was similar to TR scheme, except for SS, which produced lower volume load when compared to TR, PB and FR conditions. Interestingly, despite similar volume load across conditions, the [La−], was significantly lower in the TR protocol than any other technique. Practical Applications: In order to maximize volume load using the investigated training techniques, super-setting heavy compound exercises is not ideal. Furthermore, resistance-trained individuals may be able to perform 2 high intensity, high volume training sessions separated by 48 hours without declines in total volume load.
Acute Effects of Lower Body Resistance Exercise on Systolic Blood Pressure in Pre-Hypertensive Males
P. Drouet,1 C. Munger,1 D. Archer,1 M. Wong,1 P. Costa,2 J. Coburn,3 and L. Brown2
1Human Performance Laboratory, California State University, Fullerton, California; 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California; and 3Human Performance Laboratory, Center for Sport Performance, California State University, Fullerton, California
Exercise has been used as a method to achieve, maintain, and improve health, fitness, and sport performance. Furthermore, it is often prescribed to treat, manage, or prevent the onset of hypertension. This may be more important for individuals that have a resting systolic blood pressure (SBP) categorized by the American Heart Association as pre-hypertensive (PHT). Aerobic exercise leads to a reduction in SBP post-exercise, however, it is unknown whether lower body resistance exercise (LBRE) results in similar reductions. Purpose: To investigate SBP during 60 minutes rest following LBRE. Methods: Eight recreationally trained PHT males (age = 25.4 ± 4.1 years; ht = 174.9 ± 6.7 cm; mass = 84.8 ± 18.0 kg) completed 20 minutes of quiet seated rest then were measured for resting SBP followed by a lower body warm-up with a resistance band. They then performed LBRE followed by 60 minutes of quiet seated rest. LBRE consisted of back squat, leg curl, and leg extension (4 sets of 6 repetitions at 75% 1RM with 2 minutes rest between sets, and 1 minute rest between exercises). SBP was measured immediately post LBRE and every 10 minutes for 60 minutes thereafter. Results: A significant (p < 0.001) main effect for time was observed, with SBP at 50 minutes post (121.63 + 1.99 mm Hg) being less than resting (126.13 + 1.46 mm Hg) but not different than any other time point. Also, immediately post (147.50 + 9.44 mm Hg) was greater than resting, 10 minutes (127.75 + 8.35 mm Hg), 20 minutes (122.13 + 9.72 mm Hg), 30 minutes (123.63 + 7.69 mm Hg), 40 minutes (124.38 + 10.04 mm Hg), 50 minutes, and 60 minutes (123.75 + 10.71 mm Hg). Conclusions: SBP decreased below resting values 50 minutes post LBRE. This hypotensive response may be due to decreased peripheral resistance, which may be attributed to either decreased sympathetic nervous system activation, or increased parasympathetic activation post exercise. Practical Applications: LBRE can lead to an acute post-exercise hypotensive response similar to aerobic exercise. The chronic use of LBRE may contribute to lowering resting SBP.
Effect of Hex Bar Deadlift vs. Back Squat Postactivation Potentiation on Vertical Jump Time to Peak Force
T. Eckel,1 W. Leyva,1 D. Archer,1 C. Munger,1 A. Galpin,2 J. Coburn,3 and L. Brown2
1Human Performance Laboratory, California State University, Fullerton, California; 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California; and 3Human Performance Laboratory, Center for Sport Performance, California State University, Fullerton, California
A unique form of power training is to engage post-activation potentiation (PAP), which has been researched in regards to a high-intensity resistance stimulus. PAP involves the process of going from a high-load exercise to a high-velocity explosive movement with the goal of increasing power output. Previous research has demonstrated an acute decrease in peak force following a back squat PAP protocol. However, it is unknown if time to peak force is altered or if a hex bar yields similar results. Since rate of force development is the quotient of delta force and delta time, it is important to understand total muscular performance changes. Purpose: To examine acute vertical jump time to peak force following a back squat vs. hex bar deadlift. Methods: Ten resistance-trained men (age = 23.36 ± 3.80 years, ht = 175.50 ± 4.22 cm, mass = 79.53 ± 5.28 kg) volunteered to participate and performed 3 pre countermovement jumps (CMJ) then 3 repetitions of the back squat (BS) or hex bar deadlift (HBDL) at 85% 1RM. To perform the CMJ, subjects jumped with arm swing on a force plate. The back squat was performed with a standard barbell in a power rack. Participants wore a safety squat device, which insured they achieved a quadricep parallel position. For HBDL, participants used the low handles. Following the BS or HBDL and 8 minutes rest, subjects performed 3 post CMJ. A control condition consisted of 3 pre CMJ, 8 minutes standing rest, then 3 post CMJ. Results: Repeated measures ANOVA revealed a significant main effect (p = 0.03) for time with post values (0.363 ± 0.034 seconds) being shorter than pre (0.384 ± 0.034 seconds). Conclusions: No differences were found between HBDL and BS, but there was a decrease in CMJ time to peak force following both exercises. This might increase rate of force development when performing a subsequent explosive movement. Coaches should be aware of the time it takes to reach peak force when training. They could utilize either the HBDL or BS to elicit an acute decrease in CMJ time to peak force. Practical Applications: Time to peak force can allow strength coaches to monitor their athlete's performance across a training program.
Examining the Effect of Bench Press Variations on Electromyographical Activity: A Systematic Review and Meta Analysis
R. Snarr, M. Fedewa, and M. Esco
The University of Alabama
Electromyography (EMG) is a laboratory technique designed to measure the electrical activity and motor unit recruitment pattern of skeletal muscle. Despite consistent evidence indicating that EMG activity is related to strength of contraction during exercise, conflicting evidence exists regarding EMG activity in a specific muscle during exercise modifications. To date, comprehensive EMG research has mainly focused on the acute and chronic effects of resistance training in regards to alterations in volume, intensity, or periodization models. Purpose: The primary aims of this study was to examine the differences in EMG between bench press variations in an attempt to determine the most effective method of motor unit recruitment of the primary movers. Methods: A systematic review of peer-reviewed articles published before September 16, 2015 was conducted in accordance with the PRISMA guidelines. All studies included in the current analysis were: (a) Published in English, (b) Peer-reviewed, and (c) compared the EMG activity of the pectoralis major from a bench press to a similar exercise modification. Each exercise variation was examined and categorized into one of 2 groups: (a) mimics traditional movement of bench press; or (b) altered joint pattern and range of motion. Exercise variations that did not restrict movements in a particular plane or changed body position were considered to reproduce the same movements as one would encounter during the bench press. Exercises that were completed standing (i.e., cable press), with the assistance of a uni-planar machine (i.e., Smith machine), or changed movement pattern in the body (i.e., Swissball Bench) were classified as group 2. Data are presented as mean (M), standard deviation (SD), and 95% confidence interval (CI). Results: Data from 119 participants was analyzed (23.42 ± 2.15 years). The cumulative results of 15 effects gathered from 8 studies (1.88 ± 2.47 effects per study) published between 2006 and 2013 indicate that no significant change in EMG activity within the pectoralis major occurs with modification of a flat bench press (mean ES = −0.19; 95% CI: −0.70 to 0.33; p = 0.47). Meta regression analysis determined that exercise movement variation independently explained 44.3% of the variation in EMG activity (β = 0.67, p < 0.001), and remained significant after accounting for the variation explained by the number of repetitions performed and exercise intensity (β = −0.16, p = 0.40; β = 0.13, p = 0.48; respectively). Exercises that altered joint pattern and range of motion produced significantly lower EMG activity (ES = −0.94; 95% CI: −1.59 to −0.28) when compared to exercises that mimicked the traditional movement of the bench press (ES = 0.91, 95% CI: 0.11–1.70) (p < 0.001). Conclusions: The data indicates that altered joint pattern and range of motion during exercise significantly reduced EMG activity, and explained nearly half of the variation in EMG activity of the pectoralis major during exercise. Practical Implications: Exercise variations should closely mimic the motions and joint patterns of the bench press in an attempt to maximize muscular activation. Additionally, modifications of the bench press that result in reduced degrees of freedom, changes in joint mechanics, or alterations in body position may reduce the ability of the individual to produce similar activation of the muscle compared to a standard bench press.
Effects of Short Term Jump Squat Training With and Without Chains on Back Squat 1RM
D. Archer,1 C. Munger,1 W. Leyva,1 P. Drouet,1 M. Wong,1 A. Galpin,2 J. Coburn,3 and L. Brown2
1Human Performance Laboratory, California State University, Fullerton, California; 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California; and 3Human Performance Laboratory, Center for Sport Performance, California State University, Fullerton, California
The use of chains in resistance training is a way to accommodate the muscular strength curve. Short-term training and loaded jump squats have been shown to increase back squat strength, but not in conjunction with each other or with chains. Purpose: To investigate the effects of short-term jump squat training with and without chains on back squat strength. Methods: Eighteen resistance-trained men volunteered to participate (age = 24 ± 2.44 years, ht = 174.81 ± 6.49 cm, mass = 83.99 ± 12.02 kg) and were randomly assigned to one of 2 groups (no chains [NC] = 10, chains [CH] = 8). Participants had their 1RM back squat tested before and after one week of training. Both groups performed 3 training sessions separated by 48 hours and each session consisted of jump squats for 5 sets of 3 reps at 30% 1RM with 30 seconds rest between sets. The CH group had 20% of their load added by chains when standing erect. Results: Repeated measures ANOVA revealed no significant interaction or main effect for group. However, there was a main effect for time where squat 1RM increased from pre (315.56 ± 41.16 lbs) to post (321.39 ± 40.4 lbs). Conclusions: Although there were no differences between conditions, the CH group was still able to increase their 1RM strength while lifting less overall weight. Practical Applications: Coaches may use short term training with chains to yield a similar increase in back squat strength as traditional loaded jump squats.
Perceived Exertion, Neuromuscular Fatigue and Endocrine Responses in Power, Strength and Hypertrophy Resistance Exercise
D. Hiscock, B. Dawson, and P. Peeling
The University of Western Australia
This study examined the influence of power, strength and hypertrophy resistance exercise workouts on session rating of perceived exertion (sRPE: Borg CR-10 scale), neuromuscular fatigue and endocrine responses. Twelve participants performed a workout comprising 4 exercises (bench press, back squat, deadlift and horizontal bench pull) as either: Power: 3 sets × 6 repetitions at 45% of 1 repetition maximum (1RM) going every 3 minutes; Strength: 3 sets × 3 repetitions at 90% 1RM going every 3 minutes; or Hypertrophy: 3 sets × 10 repetitions at 70% 1RM × 1 minute recovery. Power sRPE (3 ± 1, p = 0.01) was lower than Strength (4.5 ± 1, p = 0.01), despite matched work rate, and both were lower than Hypertrophy (8.5 ± 1, p = 0.01). Duration of countermovement jump decrement was greater (p ≤ 0.05) for Hypertrophy (72 hours) compared to Power (12 hours) and Strength (24 hours). Testosterone concentration was significantly greater (p ≤ 0.05) immediately post-training in Hypertrophy compared to Power and Strength. In conclusion, resistance training workouts with greater work rate and intensity (%1RM) may increase sRPE, duration of neuromuscular performance decrement and salivary testosterone responses.
Effects of Explosive Back Squats on Maximal and Rapid Torque of the Leg Extensors
J. Schnaiter, R. Thiele, and D. Smith
Oklahoma State University
Previous research has examined the effects of fatigue protocols on maximal and rapid strength recovery patterns. However, functional bouts of dynamic exercise using the free-weight back squat may serve as a relevant approach to understanding the acute recovery response of maximal and rapid strength. Purpose: Examine the effects of an explosive back squat protocol on maximal and rapid torque of the leg extensors before, immediately following, and during a 30-minute recovery period. Methods: Fourteen females (age = 21.43 ± 1.01 years, 1RM 91.88 ± 22.03 kg) participated in a familiarization trial followed by an experimental testing session separated by 7 ± 4 days. All participants were considered anaerobically trained (≥3 d·wk−1 of resistance training for the previous 6 months, including the back squat once a week). The first visit included an assessment of each participant's one repetition maximum (1RM); followed by a familiarization trial with the dynamometer assessments. During the second visit, participants performed an explosive bout of back squats (5 × 16 at 40% 1RM) performed at a standard cadence (60 b·min−1), regulated by a metronome, of a 2 second eccentric and one second explosive concentric phase. Maximal and rapid torque variables were assessed on an isokinetic dynamometer with the knee angle set at 120° of the right leg. Two isometric maximal voluntary contractions (MVCs) were performed before (Pre) and immediately post (Post0), 7 (Post7), 15 (Post15) and 30 (Post30) minutes following the completion of the explosive protocol. Peak Torque (PT) was determined as the highest 0.5 seconds epoch during a 3–4 seconds MVC. Peak RTD (RTDpeak) was determined as the peak of the signal during the initial ascent of the torque-time curve. Rate of Torque Development (RTD) was determined from the linear slope of the torque-time curve at early (30 milliseconds), and late (100 and 200 milliseconds) time intervals. Five separate one-way repeated measures ANOVAs were used to analyze PT, RTDpeak, RTD30, RTD100 and RTD200 at all time points. Results: PT was greater at Pre compared to Post0, Post7, and Post15 (p = 0.000–0.014). No differences were observed for RTDpeak, RTD30, and RTD100 at all recovery time points (Post 0, 7, 15, 30) compared to Pre (p = 0.287–1.000). However, RTD200 was decreased (p = 0.010) immediately following the explosive back squat protocol. Conclusions: The findings from the present investigation reveal differential recovery patterns between maximal and rapid torque characteristics in highly trained females following an explosive back squat protocol. A functional free-weight explosive back squat protocol may induce greater amounts of fatigue for maximal strength compared to rapid torque characteristics. Practical Applications: These outcomes highlight the delayed recovery observed in maximal strength following an explosive free-weight back squat exercise, with negligible effects on early and late rapid torque characteristics. These acute time-course responses may provide valuable insight regarding the swift recovery of rapid torque characteristics and the delayed recovery of maximal strength following the performance of low-intensity functional movements. Therefore, clinicians, coaches, and practitioners should use caution when designing workouts in which explosive movements may precede strength-based exercise. This may be exceedingly important for determining appropriate rest intervals to optimize maximal strength output.
The Use of Countermovement Jumps to Monitor Fatigue in Collegiate Female Soccer Athletes
N. Haffner,1 E. Langford,1 J. Casey,1 N. Chamberlain,2 G. Ryan,3 and R. Herron1
1The University of Alabama; 2Auburn University at Montgomery; and 3Catawba College
Research related to field-monitoring of fatigue and recovery in female athletes is under-investigated. However, countermovement jumps (CMJ) have shown promise as a quick and effective measure of global and neuromuscular fatigue. Purpose: This study aimed to investigate the use of CMJ to detect acute neuromuscular fatigue in female collegiate soccer athletes. Methods: Female collegiate soccer athletes (n = 13, age = 20 ± 2 years) completed CMJ pre- (PRE) and post-practice (POST). The CMJ protocol included 2 traditional vertical jumps (VJ) and 2 drop jumps (DJ) from an electronic mat. The DJ started from a 51 cm box and the highest VJ and DJ attempts were recorded for analysis. Additionally, one week later 10 athletes repeated the procedure to investigate reliability. Results: Intraclass correlations revealed PRE and POST practice jumps were reliable; (n = 10) ICCR = 0.97 and 0.98 respectively. Furthermore, paired-samples t-Tests detected differences between pooled PRE and POST VJ (n = 23 [46 ± 6 cm; 45 ± 5 cm, d = 0.22, p = 0.04]) as well as PRE and POST DJ (n = 23 [28 ± 4 cm; 26 ± 6 cm, d = 0.47, p = 0.01]). However, there was no difference in time spent on the mat during the eccentric portion of DJ PRE vs. POST (n = 23 [0.45 ± 0.11 seconds, 0.46 ± 0.14 seconds; d = 0.14, p = 0.27]). Conclusions: To our knowledge this is the first investigation to utilize CMJ to monitor fatigue in female soccer athletes. These data support the use of CMJs to detect acute neuromuscular or global fatigue in female collegiate soccer athletes. Due to the larger effect size observed in DJ, these data support DJ to be more sensitive to acute fatigue. Practical Applications: Coaches and strength and conditioning professionals can utilize CMJ jumps to monitor acute fatigue. However, future research is needed to investigate the efficacy of using CMJ to track fatigue over a season or training period of interest in female soccer athletes.
Allometric Modeling for the Bench Press and Squat for Division I Collegiate Athletes
J. Keller, R. Lyn, and A. Crecelius
University of Dayton
Purpose: This study aimed to determine the most appropriate (population specific) allometric exponent for NCAA division I athletic teams in order to help Strength and Conditioning coaches better scale athletes' performance and to eliminate body mass bias. Methods: Data was collected between 2011 and 2015 by the University of Dayton's Head and Assistant Strength and Conditioning coaches. A total of 65 male and 368 female observations were made between 2 male teams (Soccer and Tennis) and 7 female teams (Soccer, Tennis, Basketball, Volleyball, Track and Field, Softball and Rowing). Bench press and squat 1 repetition maximums (1RM) were measured to determine strength. Body composition was calculated via the 7 point skin caliper protocol. An allometric equation, y = bx, was log transformed to log y = b log x. Log-linear regression analysis provided sport specific b values for both squat and bench press for males and females. Unadjusted values suggested there to be body mass bias when ranking individuals' 1RMs. Results: The population specific adjusted bench press values yielded b = 0.91 (males) and 0.91 (females). The same was calculated for 1RM squat, b = 1.09 (males) and 1.04 (females). For each population, sport specific coefficients were also calculated. Conclusions: The slopes of the adjusted regression models are approaching zero, which suggests the calculated allometric exponents effectively eliminate body mass bias. Practical Applications: As a result, the adjusted index scores would ultimately provide strength and conditioning coaches with a new system which would allow athletes with significantly varying body mass to be appropriately ranked among each other. This may also provide additional insight to strength and conditioning professions to accurately evaluate the effectiveness of the assigned training protocol.
Implications of a High-Fat Breakfast Meal Replacement on Body Composition, Metabolic Markers, and Satiety
K. Hirsch, E. Trexler, M. Mock, M. Blue, and A. Smith-Ryan
University of North Carolina at Chapel Hill
High-fat, low-carb diets have become increasingly popular as a means for weight loss. While many are concerned with unhealthy increases in blood lipids, high-fat, low-carb diets have been shown to have positive benefits on blood lipids, weight loss, and decreasing hunger. A minimal nutrition intervention of a high-fat breakfast may have benefits for weight loss, metabolic function, and satiety. Purpose: To determine the effects of replacing breakfast with a high-fat meal replacement on body composition (fat mass [FM], lean mass [LM], percent body fat [BF%], visceral fat [VAT]), resting metabolic rate (RMR), resting fuel utilization (RER), clinical blood values (total cholesterol [TC], low-density lipoproteins [LDL], high-density lipoproteins [HDL], triglycerides [TRG], glucose [GLUC]) and satiety in overweight and obese adults. Methods: In a randomized, delayed-controlled intervention, 41 overweight and obese adults (Males = 19; Females = 22; Mean ± SD; Age = 35.0 ± 9.5 years; BMI = 33.5 ± 5.4 kg·m−2) were randomized to control (CON; n = 22) or meal replacement (MRP; n = 19) treatment groups. Basic dietary recommendations were given prior to testing, followed by a 2-week run-in period to allow dietary intake to normalize. Baseline testing was completed in a fasted state (8 hours) and consisted of a body composition assessment (DEXA), a 30-minute resting test (indirect calorimetry to determine RMR and RER) and a fasted blood draw; the Satiety Labeled Intensity Magnitude Scale (SLIM) was used to evaluate satiety. The MRP group consumed one scoop of MRP powder mixed with water (15% carb, 70% fat, 16% protein) every morning for 8 weeks; CON group maintained normal dietary habits. Four-day diet logs were completed every 2 weeks throughout the intervention period. Testing was repeated after 8 weeks. Results: There were no significant changes in FM (p = 0.509; MRP = −0.41 kg; CON = +0.03 kg), LM (p = 0.757; MRP = −0.03 kg; CON = −0.16 kg), or VAT (p = 0.895; MRP = +0.11 lbs; CON = +0.13 lbs) for MRP or CON. Both groups had a significant decrease in BF% (p = 0.009), with no difference between groups (p = 0.659; MRP = −0.56%; CON = −0.36%). There was a significant increase in RMR (p < 0.001; MRP = +21.05 kcal·d−1; CON = +116.59 kcal·d−1) and decrease in RER (p < 0.001; MRP = −0.05; CON = −0.04) for both groups, with no significant differences between groups (RMR p = 0.606; RER p = 0.870). There were no significant changes in blood factors for either group (TC [p = 0.179], LDL [p = 0.092], HDL [p = 0.367], TRG [p = 0.794], GLUC [p = 0.309]). MRP and CON groups had similar satiety responses throughout the morning pre and post, but MRP had increased satiety in the afternoon compared to CON. Conclusions: Eight weeks of replacing breakfast with a high-fat meal replacement had no significant impact on body composition in overweight and obese individuals. Despite high-fat, there were no negative impacts on blood lipids and increased satiety may be beneficial for controlling mid-afternoon cravings. Practical Applications: Skipping breakfast is common among adults. Meal replacements may be an effective approach to help individuals consistently consume a healthier breakfast and mitigate afternoon cravings. Meal replacements may also be a healthy option for athletes looking for low-carb breakfast alternatives or for convenience during times of travel to help maintain satiety. Acknowledgments: This study was supported by Scivation Inc.
The Effects of Various Protein Types on Indicators of Ketosis
C. Irvin,1 R. Lowery,1 M. Sharp,1 J. Partl,2 W. Wallace,3 A. Barninger,1 M. Stefan,3 J. Rauch,3 C. Ugrinowitsch,4 E. de Souza,3 M. Roberts,5 and J. Wilson1
1The Applied Science and Performance Institute; 2The University of Florida; 3The University of Tampa; 4University of Sao Paulo; and 5Auburn University
A ketogenic diet is a high fat, very low carbohydrate diet that seems to have many therapeutic and performance benefits. It is often recommended for protein to make up 20–25% of total caloric intake when consuming a ketogenic diet. Consuming a large bolus of protein can cause an influx in circulating amino acids leading to a rise in blood glucose through gluconeogenesis and drop in blood ketones which could be harmful for a ketogenic athlete. Purpose: Considering that supplemental proteins contain varying digestion rates, the purpose of this study was to test effects of 3 different types of protein (Whey, Casein, and Egg) on blood markers of ketosis. Methods: Twenty-two resistance trained men and women 18–30 years old (mean ± SD, Age: 22 ± 3, Weight: 78.25 ± 11.95 kg, Height: 175.78 ± 10.40 cm) were placed on a calorie controlled ketogenic diet for 2 weeks to allow for adaptation to occur. In a randomized, crossover design, subjects were given 25 g of supplemental protein in the form of either whey, casein, or egg protein. Subjects arrived to the laboratory following a 10-hour water only fast, consumed supplemental protein, and were instructed to remain seated to prevent activity induced changes in blood glucose. Blood glucose and ketone levels were monitored via Precision Xtra Monitoring Device at baseline, 30, 60, 90, 120, and 180 minutes. Subjects completed a 48-hour washout period between conditions. Two-way ANOVA for repeated measures assessed plasma glucose and ketone concentrations assuming condition (Whey, Casein and Egg) and time as fixed factors. Area under the curve (AUC), Cmax, and Tmax were analyzed by one-way ANOVA for repeated measures. Whenever a significant F-value was obtained, a Tukey post-hoc test was performed. Significance level was set at p ≤ 0.05. Results: At baseline there were no between-condition differences or differences for total AUC for blood glucose or blood ketones, Cmax, or Tmax. Within-condition comparisons for blood ketone levels indicated no changes occurred relative to baseline in any condition. The Whey condition demonstrated within-condition differences for blood glucose wherein the mean value at 30 minutes was significantly higher than baseline (p ≤ 0.05), 120 (p ≤ 0.05) and 180 minutes (p < 0.0001). Additionally, the Casein condition was significantly higher at 30 minutes than 60 (p < 0.01), 120 (p < 0.01) and 180 minutes (p < 0.0001) with a strong trend compared to baseline (p = 0.052). Conclusions: Our data suggests that protein source does not impact blood ketone levels relative to baseline. However, dairy proteins do elevate blood glucose. Practical Applications: Athletes attempting to maintain ketosis can use a variety of dairy and egg protein sources. However, if attempting to keep blood glucose from rising egg based sources may be a better selection.
The Effects of Jiaogulan Tea on Resting Metabolism in a Sample of College Aged Males
G. Gallien, G. Davis, and D. Bellar
University of Louisiana at Lafayette
With such a wide variety of weight management products available, there are an increasing number of people seeking out herbal and botanical solutions. Herbal teas are one solution that have been purported to assist with weight management. Purpose: To examine the effects of a tea made from Jiaogulan (gynostemma pentaphyllum) leaves on the resting metabolic rate (RMR) of a sample of college aged males. Methods: Eight college-aged men (mean ± SD age = 22.4 ± 0.7 years; body mass = 85.9 ± 19.0 kg; height = 69 ± 3.4 in; body fat = 20.8 ± 6.7%) volunteered to participate in this study. Subjects completed 3 separate visits in which they drank tea followed by 15 minutes of data collection in a supine position with legs elevated to quantify resting metabolic rate (RMR). The tea was administered using a randomized, cross-over design and included (a) low dose (LD) dried Jiaogulan tea (1.5 g), (b) high dose (HD) dried Jiaogulan tea (3 g), and (c) a zero-calorie, uncaffeinated black tea. Each of the 3 trials were ≥72 hours apart. The tea leaves were weighed using a calibrated digital scale and were steeped in 8 ounces of 77 degree Celsius water for 5 minutes. Participants consumed their respective tea then sat in a non-stimulating, neutral temperature environment one hour leading up to RMR data collection. Results: There was no significant difference by treatment for RMR (F = 0.0278, p = 0.9726). The average RMR/24 for the HD tea, LD tea, and black tea were 91.1 ± 12.5, 92.7 ± 15.1, and 91.1 ± 18.8 kcal, respectively. There was significant difference by treatment for RQ (F = 4.3101, p = 0.0270) and npRQ (F = 4.3101, p = 0.0270). The average RQ was 0.82 ± 0.05 for the HD tea, 0.81 ± 0.05 for the LD tea, and 0.75 ± 0.04 for the black tea. There was also significant difference by treatment for percent fat (F = 3.7262, p = 0.0412) and percent carbohydrate (F = 3.7267, p = 0.0412). The average energy used consisted of 61.4 ± 17.9% FAT and 39.1 ± 17.9% CHO for the HD tea, 64.3 ± 17.2% FAT and 36.2 ± 17.3% CHO for the LD tea, and 82.0 ± 13.4% FAT and 18.46 ± 13.5% CHO for the black tea. Conclusions: Consumption of the Jiaogulan tea provided no increase in resting metabolic rate in a sample of college-aged men. There was, however, a noticeable increase in lipolysis when drinking the black tea compared to the Jiaogulan tea. Practical Applications: When consumed in tea form, Jiaogulan does not appear to have any direct ability to increase resting metabolic rate compared to black tea.
Effects of Rumenic Acid Rich Conjugated Linoleic Acid Supplementation on Handgrip Performance and Cognitive Function in Older Men
N. Jenkins, T. Housh, A. Miramonti, C. Smith, E. Hill, K. Cochrane, and J. Cramer
University of Nebraska-Lincoln
Purpose: To investigate the effects of rumenic acid rich (RAR) conjugated linoleic acid (CLA) supplementation on handgrip performance and cognitive function in older men. Methods: Twenty-two older men (mean ± SD age = 73.0 ± 6.5 years) were randomly assigned to the RAR CLA (n = 10) or placebo (PLA; high oleic sunflower oil; n = 12) group and consumed 6 g·d−1 of their allocated supplement for 8 weeks. Before (visit 1) and after supplementation (visit 2), subjects completed Rey's Auditory Verbal Learning Test (RAVLT) to measure cognitive function. The RAVLT included 5, 15-item auditory word recalls (R1–5), an interference word recall (RB), a sixth word recall (R6), and a 15-item visual word recognition trial (RR). For handgrip performance, subjects completed maximal voluntary isometric handgrip strength (MVIC) testing before (MVICPRE) and after (MVICPOST) a handgrip fatigue test at 50% MVICPRE. Hand joint discomfort was measured during the handgrip fatigue test. Results: R1, R2, R3, R4, R6, and RR improved in both the RAR CLA and PLA groups from visit 1 to 2. R5 improved from visit 1 to 2 (8.9 ± 2.4 to 11.1 ± 2.5 words) in the RAR group only. RB did not change over time and was not different between groups. The decrease in handgrip strength was not different between RAR CLA and PLA groups (MVICPRE = 40.5 ± 6.9 and 36.7 ± 10.8 kg; MVICPOST = 28.3 ± 4.8 and 26.2 ± 7.1 kg, respectively). For hand joint discomfort, there was a group × visit × time interaction (p < 0.01; Figure 1). Joint discomfort increased throughout the fatigue test; however, post-hoc analyses indicated no significant differences between groups. Conclusions: RAR supplementation had a small effect on cognitive function as indicated by the R5 score. However, all other RAVLT scores improved similarly (R1, R2, R3, R4, R6, and RR) for both the RAR and PLA groups. There were no treatment differences for handgrip strength. Despite a statistical interaction for hand joint discomfort as shown near the end of the handgrip fatigue test (80, 90, and 100% completion, Figure 1), post-hoc analyses indicated no significant differences between the RAR and PLA groups. Practical Applications: RAR CLA supplementation may improve cognitive function, but has no effect on handgrip strength or endurance. The effects of RAR CLA on hand joint discomfort were relatively small and inconclusive. Due to the relatively long time course for effects of dietary fatty acids, future studies may wish to examine RAR CLA supplementation for longer than 8 weeks. Acknowledgments: These data were from a clinical trial funded by Stepan Speciality Products, LLC.
A Ketogenic Diet's Effects on Athletic Performance in Two Professional Mixed-Martial-Arts Athletes: Case Reports
J. Joy,1 R. Vogel,1 A. Tribby,2 J. Preisendorf,3 P. Falcone,2 M. Mosman,4 M. Kim,2 and J. Moon5
1Texas Woman's University; 2MusclePharm Corp.; 3The Superhero Maker; 4Maximum Mobile Fitness LLC; and 5American Public University System
Very low-carbohydrate, high-fat ketogenic diets (KD) are receiving increased attention for their effects on health parameters, with one of the consistently prevailing effects being body fat reduction. As such, KDs have become an attractive option for athletes competing in weight-class restricted sports, yet KDs have not been evaluated in nearly all athletic populations. Purpose: The purpose was to examine the effects of an 8-week KD on strength, power, and anaerobic fatigue. Methods: Two professional, weight-stable, mixed-martial-arts athletes (athlete 1: 21 years, 77.35 kg, 179.6 cm; athlete 2: 36 years, 94.45 kg, 187.8 cm) with more than 3 professional bouts who have not recently (>2 weeks) practiced a calorie- or carbohydrate-restricted diet participated in this study. Two testing sessions took place before and after a eucaloric 8-week KD intervention (5% carbohydrate, 75% fat, and 20% protein) while they continued their standard training. On each testing day, the athletes reported to the laboratory in a 10-hour fasted state. Upon arrival, each athlete submitted a blood sample, consumed a snack (210 Cals, 7 g fat, 12 g net carbohydrate, 20 g protein), rested for 30 minutes, and then performed the performance tests. The order of performance testing is as follows: bench press 1RM, vertical jump height and power, a 30 seconds Wingate, and then 5 sets of 6 seconds Wingates. Peak power fatigue was calculated as the peak power difference between the final and first Wingate test. Watt:mass was calculated as average power divided by bodyweight, and Watt:mass fatigue was calculated as the difference between the final and second Wingate set to account for the difference in test duration. Fasting blood ketones were assessed biweekly to ensure ketosis. Results: Baseline blood ketones were <0.2 mmol·L−1, and blood ketones from weeks 2–8 were >0.3 mmol·L−1. Individual data and change values are presented in Table 1. Briefly, bodyweight decreased by 2.5–4.0%. Upper body strength either increased or did not change. Vertical jump height (+5.36–15.38%) and fatigue resistance relative to bodyweight (+98.04–151.52%) improved in both athletes, while other power measures were divergent between each athlete. Conclusions: Professional-level mixed-martial-arts athletes may experience improved fatigue resistance without decrements in strength at a lower bodyweight following 8-weeks adaptation to a KD. Practical Applications: In the present study, 2 professional mixed-martial arts athletes experienced mixed results, no change, or improvements in performance and a reduction in bodyweight following 8-weeks of a KD. Therefore, mixed-martial-arts athletes may use a KD for a possible benefit to athletic performance, while simultaneously easing the process of meeting weight requirements of their sport. Acknowledgments: MusclePharm Corp. paid the direct costs of this study.
The Impact of Steady State and Interval Exercise on Keto-Adaptation
A. Barninger,1 R. Lowery,1 C. Irvin,1 M. Stefan,2 M. Sharp,1 J. Rauch,2 E. de Souza,2 J. Partl,3 W. Wallace,2 C. Ugrinowitsch,4 M. Roberts,5 and J. Wilson1
1Applied Science and Performance Institute; 2The University of Tampa; 3The University of Florida; 4The University of São Paulo, Department of Sport; and 5Auburn University
Introduction: Ketogenic dieting (KD) is categorized as very high fat, very low carbohydrate eating patterns that requires approximately a 2- to 4-week adaptation period. We investigated the effects of high intensity interval cycling (HIIT) vs. steady state cycling (SS) in regards to ketogenic adaptation (defined as blood ketone concentration as >0.5 mmol·L−1). To date, no studies have examined how these different approaches affect the adaptation process. Purpose: The purpose of this research was to investigate if high intensity interval cycling induced a state of ketosis to a larger extent than steady state cycling. Methods: Twenty-two college aged, resistance training individuals participated in this study (mean ± SD, age: 22 ± 3, Weight: 78.25 ± 11.95 kg, Height: 175.78 ± 10.40 cm). All participants in the study followed a ketogenic diet of 75% Fat, 20% Protein, and 5% Carbohydrate for the duration of the intervention. Baseline calories were set at the basal metabolic rate as determined by the Moxus Metabolic Cart. The HIIT group (n = 12) followed a 2-d·wk−1 wingate interval session, while the SS group (n = 10) completed a work matched steady state cycling session. Furthermore, each group followed a standard periodized resistance training protocol 3 days per week on non-cycling days. On day 0, subjects completed 4 standardized performance tests including wingate peak power, 1RM bench press, 1RM shoulder press, and 1RM leg press. The performance tests were repeated at the end of the intervention (day 14). Ketones were evaluated at baseline, day 7, and day 14, in the morning, 10 hours fasted. Repeated measures ANOVA was used to assess group, time and group by time interactions. Whenever a significant F-value was obtained, a Tukey's Post-Hoc analysis was used for multiple comparison purposes. Results are expressed as mean ± SD. Additionally, the upper and lower limits values of confidence intervals of the absolute differences (CIdiff) are presents as this approach allows us to know how much the experimental groups affected the dependent variables investigated, rather than only the level of statistical significance. Results: No significant differences between-groups for blood ketone levels were detected at the baseline (HIIT: 0.2 ± 0.1; SS: 0.1 ± 0.1; p > 0.05). No between-group differences were noted for blood ketone levels (p > 0.05). However, within-group differences were demonstrated for both HIIT and SS groups. The HIIT group demonstrated significantly higher blood ketone levels at week 1 (1.5 ± 1.1, CIdiff: 0.7–2.0, p < 0.0001) and week 2 (0.8 ± 0.6, CIdiff: 0.04–1.3, p = 0.04) relative to baseline values whereas the SS group's blood ketone level was significantly higher only at week 1 (1.7 ± 1.2, CIdiff: 0.9–2.2, p < 0.0001) relative to baseline. Additionally, both groups resembled lower blood ketone levels at week 2 compared to week 1 (HIIT: 1.5 ± 1.1 to 0.8 ± 0.6, CIdiff: −1.3 to −0.1, p = 0.2; SS: 1.7 ± 1.2 to 0.4 ± 0.3, CIdiff: −1.9 to −0.6, p = 0.0001). Practical Applications: HIIT may be a viable tool to induce and sustain keto-adaptation during the initial phases of the introduction of a ketogenic diet when combined with resistance exercise.
The Acute Effects of a Caffeine and Polyphenolic Compound on Anaerobic Performance and Energy Expenditure Following High Intensity Interval Exercise
D. Higuera,1 K. Lewis,1 D. Directo,1 A. Osmond,1 M. Wong,1 and E. Jo2
1Human Performance Research Laboratory, Department of Kinesiology and Health Promotion, California State Polytechnic University, Pomona, Pomona, California; and 2Human Performance Research Laboratory, California State Polytechnic University, Pomona, California
Thermogenic supplements, which typically include key ingredients such as caffeine and green tea extract are rising in popularity because they have consistently shown to produce a significant rise in energy expenditure and fat oxidation in human subjects. The purpose of this study was to investigate the acute effects of green tea extract polyphenol and caffeine supplementation on subsequent muscular performance during a bout of sprint interval exercise (SIE) as determined by power output while also examining responses in metabolic rate at rest and after exercise. In a double-blind, randomized, placebo-controlled, crossover study and following an initial familiarization visit, 12 subjects (male: n = 11; female: n = 1) (bodyweight = 76.1 ± 2.2 kg; height = 169.8 ± 1.6 cm; BMI = 22.7 ± 3.0 kg·m−2; body fat % = 21.6 ± 2.0%) underwent 2 testing sessions during which time they consumed either a caffeine-polyphenol supplement or placebo. After supplementation, resting energy expenditure, heart rate (HR), and blood pressure (BP) were assessed. Subsequently, subjects performed 30 minutes of SIE while researchers collected performance data. Subjects were then tested for post-SIE energy expenditure, HR, and BP. The caffeine-polyphenol treatment resulted in significantly (p ≤ 0.05) greater energy expenditure (+7.99% rest; +10.16% post-SIE), V[Combining Dot Above]O2 (+9.64% rest; +12.10% post-SIE), and fat oxidation rate (+10.60% rest; +9.76% post-SIE) vs. placebo at rest and post-SIE. No significant differences were detected for peak and average power at all sprint intervals between treatments. Post-SIE HR was significantly (p ≤ 0.05) greater with caffeine-polyphenol supplementation vs. placebo (90.8 ± 3.5 vs. 85.1 ± 3.6 b·min−1). There were no significant between-treatment differences for BP. It may be concluded that the observed thermogenic response post-SIE was directly attributable to caffeine-polyphenol supplementation as opposed to an indirect manifestation of enhanced performance and work output. Collectively, these results corroborate the use of dietary caffeine and polyphenols to support efforts to reduce adiposity and improve overall body composition especially in conjunction with sprint interval exercise.
Comparing Acute Hemodynamic Responses to Energy Drink Consumption vs. a Controlled Beverage of Equal Volume
S. Brackmann, E. Langford, M. Leatherwood, R. Herron, and P. Bishop
The University of Alabama
Energy drink consumption is common among young adults. However, research investigating the influence of energy drink ingestion on resting hemodynamics is equivocal. Purpose: The purpose of this study was to compare acute blood pressure responses after consuming commercially available energy drink (ED) to an isovolumic control (CON) beverage. Methods: Fourteen young (7 female, mean ± SD; 25 ± 3 years), healthy adults completed 2 testing sessions at the same morning hour, after an overnight fast. Participants were asked to avoid vigorous exercise and caffeine consumption the day prior to testing. Each session was separated by at least 48 hours. A baseline supine blood pressure was measured continuously, via automated non-invasive beat-to-beat oscillometry for 5 minutes (PRE). After which participants consumed a 473 ml control or energy drink in a single-blind, repeated-measures, counter-balanced crossover design. After a 30 minutes digestion period, post blood pressure monitoring resumed as described above (POST). Results: PRE measures of mean arterial blood pressure (MAP) and HR were reliable (ICCR = 0.64 and ICCR = 0.85, respectively). Repeated-measures 2-way ANOVA (drink × time) revealed no interaction (p > 0.10) or main effects (drink, p > 0.85: time, p > 0.22) for MAP ([mean ± SD] PRE-ED = 87 ± 9 mm Hg, POST-ED = 92 ± 9 mm Hg, PRE-CON = 90 ± 8 mm Hg, POST-CON = 90 ± 11 mm Hg). Alternatively, no interaction (p > 0.27) or main effect of drink (p > 0.52) was observed in heart rate, although a main effect of time was detected ([mean ± SE] PRE = 61 ± 2 b·min−1, POST = 58 ± 2 b·min−1, d = 0.17; F(1,13) = 0.43, p = 0.002). Conclusions: According to these data, energy drink consumption does not acutely alter resting hemodynamics when compared to a control beverage of equal volume. Interestingly, HR decreased in the supine position after ingesting either beverage suggesting that stroke volume increase due to plasma expansion. Practical Applications: During resting conditions, young adults do not experience changes in MAP after consuming a beverage of any type. Therefore, consumption of energy drinks can be safely consumed in the absence of any underlying cardiovascular pathologies in habitual caffeine drinkers. However, further research into exercise and post-exercise hemodynamic responses is warranted.
The Effect of a Meal Replacement Shake on Body Composition in Overweight and Obese Firefighters
G. Gerstner,1 E. Ryan,1 A. Tweedell,2 C. Kleinberg,3 and T. Barnette1
1University of North Carolina Chapel Hill; 2Department of Defense; and 3Under Armour
Although firefighting is considered a physically demanding occupation, firefighters have a higher prevalence of overweight and obesity than the general population. Consequently, nutritional interventions such as meal replacement (MR) programs have been studied as a means to produce favorable weight changes and have been shown to reduce percent body fat (%BF) in overweight and obese populations. Purpose: The purpose of this study was to examine the effect of a 14-week ad libitum commercially available meal replacement shake on body composition in overweight and obese firefighters. Methods: Forty-five overweight and obese firefighters (age: 37.5 ± 7.3 years [25–50]; stature: 179.5 ± 7.2 cm [161.4–194.0]; mass: 106.7 ± 20.2 kg [72.3–152.4] BMI: 33.0 ± 4.8 [25.6–43.6]) volunteered for this 14-week intervention and were cluster-randomized by fire station to the treatment or wait-list control group. The treatment group (n = 22) was provided with a commercially available meal replacement shake (Protein: 25 g; Carbohydrate: 6 g; Fat: 6 g), and the control group (n = 23) received the meal replacement shakes following post-testing. All participants were asked to continue and maintain current physical activity and exercise routines for the duration of the study. The treatment group participants consumed one meal replacement (MR) shake per day for the first week, then consumed 2 MR shakes per day for the remaining 13 weeks ad libitum. No other dietary restrictions were given to the treatment group. The control (CON) group participants were instructed to continue with their normal diet for the 14 weeks. Participants visited the lab on 3 separate occasions. The first visit of the study was for familiarization. The second visit (2–10 days after) consisted of pre-test baseline assessments (PRE) including stature and body mass (BM), and a whole body dual-energy X-ray absorptiometry scan to obtain %BF, fat mass (kilogram) (FM), and lean body mass (kilogram) (LM) values. The same procedure was performed again during the third visit (POST), following completion of the 14-week intervention at the same time of day (±2 hours). All participants were instructed to come in 8 hours fasted (except water) prior to testing. An analysis of covariance (ANCOVA) was used to examine whether the PRE-POST difference means, adjusted for PRE scores, differed between the 2 groups. Four separate ANCOVAs were performed for BM, FM, LM and %BF. An alpha level was set a priori at p ≤ 0.05 for all analyses. Results: There were significant main effects between groups for BM (MR: −1.17%Δ; CON: −0.06%Δ; p = 0.022), FM (MR: −1.89%Δ; CON: 2.43%Δ; p = 0.010), and %BF (MR: −1.01%Δ; CON: 2.41%Δ; p = 0.037) when compared to the CON group. However, there were no differences between groups for LM (MR: −0.62%Δ; CON: −1.183%Δ; p = 0.655). Conclusions: These findings indicate that the MR shake program resulted in significant but modest reductions in BM, FM, and %BF in overweight and obese firefighters. Practical Applications: Practical and feasible nutritional interventions are needed within the fire service. Simply consuming a ready-to-drink MR shake twice daily may be an attractive long-term strategy to combat the overweight and obesity epidemic in the fire service. Future studies are needed to determine the synergistic effect of ad libitum MR shake programs combined with evidence-based exercise on body composition.
The Acute Effects of a Caffeine-Containing Supplement on Anaerobic Power and Subjective Measurements of Fatigue in Recreationally-Active Males
C. Hahn, A. Jagim, C. Camic, and M. Andre
University of Wisconsin-La Crosse
The consumption of caffeinated beverages to enhance performance is common in young adults. The potential acute effects of these supplements has mixed results in the scientific literature, with limited data for acute anaerobic performance during resisted sprinting. Purpose: The purpose of this study was to examine the acute effects of a caffeine containing supplement on anaerobic power (AP) and subjective measurements (SM) of fatigue during resisted sprinting. Methods: Fourteen recreationally-active college-aged males (mean ± SD: age = 21.0 ± 0.7 years, height = 178.5 ± 5.1 cm, weight = 77.3 ± 9.6 kg, percent body-fat = 12.6 ± 4.8) participated in a double-blind, placebo-controlled, crossover design study and ingested an energy drink or a non-caffeinated placebo prior to a bout of exercise. Participants first reported to the laboratory for baseline assessment of body composition and familiarization with the testing protocols. Subjects then completed 2 experimental sessions separated by 48–72 hours in a rested (>24 hours without exercise) state. Subjects ingested 1 serving of a caffeine-containing or placebo beverage, which was then followed by a 20-minute rest period and a dynamic warmup prior to testing. Anaerobic power was assessed using a counter-movement vertical jump (CMVJ) test and a non-motorized treadmill sprint test. During the sprint test, subjects sprinted against 18% of their individual body mass for 25-seconds. Perceived fatigue was scored using a 5-point Likert scale. Paired sample t-tests were used to determine differences in performance between conditions. Two-way RM ANOVAs with Tukey post-hoc analyses were used to analyze the pre- and post- Likert scale scores (α = 0.05). Results: No statistically-significant differences were observed between conditions for mean and peak power (p = 0.58) as determined by the CMVJ and AP variables from the non-motorized treadmill sprint test (p = 0.22 and 0.43 for mean and peak power, respectively). A significant time-by-group interaction occurred between conditions for energy (pre-caffeine: 3.36 ± 0.63, post-caffeine: 3.00 ± 0.96, pre-placebo: 3.50 ± 0.52, post-placebo: 2.57 ± 0.76) (p = 0.04) and fatigue (pre-caffeine: 2.64 ± 0.50, post-caffeine: 3.57 ± 1.02, pre-placebo: 2.43 ± 0.65, post-placebo: 4.14 ± 0.54) (p = 0.03), suggesting that energy was greater and perceived fatigue was lower following ingestion of the caffeinated beverage. Conclusions: Consumption of a caffeine-containing supplement did not affect AP, despite increased perceived energy and decreased perceived fatigue. It is possible that the decreased fatigue could lead to enhanced performance in subsequent trials of intermittent exercise. Practical Applications: The consumption of a caffeinated beverage may be beneficial for reducing perceived fatigue during acute anaerobic exercise, but may not enhance power during one maximal effort. Acknowledgments: Lead researcher was an independent distributor for the company that produces the supplement researched at the time of the study.
The Effect of BCAA Supplementation on the Suppression of DOMS: A Meta-Analysis
S. Spencer, T. Williams, M. Fedewa, and M. Esco
The University of Alabama
Delayed onset muscle soreness (DOMS) is a symptom of exercise-induced muscle damage that occurs following exercise. Feelings of pain, stiffness, and discomfort begin hours after exercise and may last for days, gradually decreasing as the muscle recovers. Previous research has indicated that branched-chain amino acid (BCAA) supplementation may attenuate exercise-induced muscle damage that causes delayed onset muscle soreness, however the results are inconsistent. Purpose: The primary aim of this study was to examine the previous literature assessing the effect of BCAA supplementation on DOMS after exercise, and to provide a quantitative estimate of effect on recovery status. Methods: This review was conducted in accordance with PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-analyses), and identified peer-reviewed articles comparing a BCAA supplement to a placebo non-BCAA supplement following an acute bout of exercise. An electronic search of 3 databases (EbscoHost, Web of Science, and SPORTDiscus) yielded 39 articles after duplicates were removed. All studies included in the current analysis were: (a) peer-reviewed publications; (b) available in English; (c) utilized a random control design that compared a BCAA group to a placebo control group following exercise; (d) and assessed soreness of muscle tissue during recovery. Data were extracted and coded by 3 authors. Data are presented as mean (M), standard deviation (SD), and 95% confidence interval (CI). A negative effect is interpreted as a decrease in DOMS. Results: Data from 93 participants (22.3 ± 2.7 years, 87% male, 18.6 ± 2.3 per study) were included in the analysis. The cumulative results of 26 effects gathered from 5 studies published between 2007 and 2013 indicated that DOMS decreased following BCAA supplementation (ES = −0.90, 95% CI: −1.10 to −0.68; p < 0.001). The number of effects per study ranged from 2 to 8 (5.2 ± 1.1). Conclusions: A large decrease in DOMS occurs following BCAA supplementation after exercise compared to a placebo supplement. Practical Applications: BCAA supplementation can reduce muscle soreness following exercise, which allows for faster recovery. Faster recovery time will inherently lead to greater frequency of exercise.
Relationships Between Weekly Group Changes in Dietary Intake and Other Monitoring Variables in Collegiate Powerlifters
J. Allen, M. Mosiman, A. Askow, E. Morrisette, L. Gillen, C. Gillette, A. Jagim, and M. Andre
University of Wisconsin-La Crosse
Purpose: The purpose of this study was to measure relationships between weekly changes in dietary intake, power, perceived recovery, and hormonal status in powerlifters. Methods: Five advanced male collegiate powerlifters (1.79 ± 0.06 m, 111.3 ± 32.8 kg; competition best: squat = 240.0 ± 64.5 kg, bench press = 167.5 ± 40.4 kg, deadlift = 272.0 ± 38.6 kg; Wilks = 408.9 ± 57.7), all competing in the USAPL Junior Raw category and all using the same program, gave a resting saliva sample before training on 4 consecutive Mondays across a 4-week taper leading into the USAPL state powerlifting meet, which occurred on the Saturday immediately following the fourth Monday testing session. The taper, which was preceded by a relatively high-volume block, focused on barbell back squat, barbell bench press, and barbell deadlift with minimal assistance work, and featured a linear weekly increase in load with a linear weekly decrease in both volume and volume-load across the block. During saliva collection, they reported Perceived Recovery Status (PRS) and answered the Perceived Stress Scale (PSS) and then were measured for body-weight (BW). Then, they performed a brief dynamic warm-up followed by vertical jump (VJ) testing. Peak power for VJ (VJPP) was calculated using the Johnson & Bahamonde equation. Saliva was later analyzed for testosterone (T) and cortisol (C). Athletes also reported the previous day's dietary intake, specifically total calories (CAL), grams of protein (PRO), grams of carbohydrate (CHO), and grams of fat (FAT). Pearson correlation coefficients were calculated to determine relationships between weekly changes in the group averages of these variables across time. This report focuses on effect sizes (r), which is a growing trend in sport science studies with necessarily-small n sizes. Consistent with previous literature, when r is greater than 0.10, 0.30, 0.50, and 0.70, the relationship is described as small, medium, large, and very large, respectively. Results: The strongest relationships (r ≥ 0.90) were observed between T and VJPP, C and CAL, C and FAT, VJ and FAT, PRS and PSS, PRS and CAL, PRS and CHO, PRS and BW, PSS and CAL, PSS and CHO, PSS and FAT, PSS and BW, CAL and BW, CHO and BW, and FAT and BW. Refer to Table 1 for all Pearson correlation coefficients, highlighting very-large relationships. Conclusions: In advanced collegiate powerlifters, increases in T are related to increases in jump power, increases in C are related to increases in perceived stress and decreases in perceived recovery, perceived recovery is inversely related to perceived stress, increased dietary intake is related to increased perceived recovery and decreased perceived stress, and increased BW is related to increased perceived recovery, decreased perceived stress, and increased dietary intake. Practical Applications: Advanced strength/power athletes should consider increasing dietary intake, especially CHO and FAT, to enhance recovery. Additionally, jump power can be monitored to potentially estimate changes in T. Acknowledgments: Supported by UWL Graduate Student Research, Service, and Educational Leadership Grant.
Relationships Between Daily Group Changes in Dietary Intake and Other Monitoring Variables in Collegiate Powerlifters
E. Morrisette, M. Mosiman, A. Askow, J. Allen, L. Gillen, A. Jagim, C. Gillette, and M. Andre
University of Wisconsin-La Crosse
Purpose: The purpose of this study was to measure relationships between daily changes in dietary intake, explosive power, perceived recovery, and hormonal status in powerlifters. Methods: Five advanced male collegiate powerlifters (1.79 ± 0.06 m, 111.3 ± 32.8 kg; competition best: squat = 240.0 ± 64.5 kg, bench press = 167.5 ± 40.4 kg, deadlift = 272.0 ± 38.6 kg; Wilks = 408.9 ± 57.7), all competing in the USAPL Junior Raw category and all using the same program, gave a resting saliva sample before training on 5 consecutive days, Monday through Friday, during the final week of a taper leading into the USAPL state powerlifting meet, which occurred on the Saturday immediately following the final testing session (Friday). The only training was done on Monday late afternoon (after testing), and involved attempting planned opening weights (91% 1RM) for the meet. During saliva collection, they reported Perceived Recovery Status (PRS) and answered the Perceived Stress Scale (PSS) and then were measured for body-weight (BW). Then, they performed a brief dynamic warm-up followed by vertical jump (VJ) testing. Peak power for VJ (VJPP) was calculated using the Johnson & Bahamonde equation. Saliva was later analyzed for testosterone (T) and cortisol (C). Athletes also reported the previous day's dietary intake, specifically total calories (CAL), grams of protein (PRO), grams of carbohydrate (CHO), and grams of fat (FAT). Pearson correlation coefficients were calculated to determine relationships between daily changes in the group averages of these variables across time. This report focuses on effect sizes (r), which is a growing trend in sport science studies with necessarily-small n sizes. Consistent with previous literature, when r is greater than 0.10, 0.30, 0.50, and 0.70, the relationship is described as small, medium, large, and very large, respectively. Results: The strongest relationships (r ≥ 0.80) were observed between T/C and CHO, PSS and PRO, and CALS and FAT. The strongest performance relationship was between VJ and PRS. Refer to Table 1 for all Pearson correlation coefficients, highlighting very-large relationships. Conclusions: In advanced collegiate powerlifters, increases in T/C are related to increases in CHO, while increases in VJ and VJPP are related to increases in PRS. Practical Applications: Increasing CHO consumption may help improve T/C in strength/power athletes during a taper, potentially increasing competition performance potential. Additionally, since changes in explosive power were strongly related to changes in perceived recovery, it is suggested that coaches communicate with athletes about their subjective perceptions of recovery and take the athletes' perceptions into consideration when planning training. Finally, since PRS and VJ were strongly correlated, one could consider monitoring changes in PRS alone to assess recovery without physical exertion during a taper. Acknowledgments: Supported by UWL Graduate Student Research, Service, and Educational Leadership Grant.
The Effects of Pre-Exercise Glycerol Hyperhydration on Subsequent Performance: A Meta-Analysis
T. Stone, J. Wingo, D. Tolusso, and M. Fedewa
The University of Alabama
Adequate thermoregulation is crucial during exercise under conditions of heat stress. Excessive sweating results in dehydration and compromised thermoregulatory homeostasis unless fluids are replenished appropriately. Hence, optimizing pre-exercise hydration has become a topic of much research. More specifically, glycerol has been tested as a hyperhydrating agent when used with large volumes of water for pre-hydration purposes. Although glycerol plus water hyperhydration has been shown to increase total body water when compared to just water, results have been conflicting when assessing the effect of pre-exercise glycerol hyderphydration on subsequent performance. Purpose: The goal of this analysis was to determine if glycerol is indeed a viable ergogenic aid in enhancing performance. Methods: This review was conducted in accordance with PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-analyses), and identified peer-reviewed articles including a glycerol and control/placebo group and some measurement of performance including time to exhaustion, time to complete a certain distance or race, total work, or distance covered. Other inclusion criteria were: peer-reviewed publication; available in English; and involving human subjects. An electronic search of 4 databases (PubMed, SPORTDiscus, Physical Education Index, and Web of Science) yielded 223 records after duplicates were removed. Data were extracted and independently coded by 2 authors (TS and DT). Results: The cumulative results of 16 effects gathered from 14 studies published between 1996 and 2015 demonstrated glycerol supplementation in a pre-exercise beverage has a greater effect on performance than just water with a mean ES equal to 0.35 (95% CI: 0.11–0.58, p = 0.0038). Sample size ranged from 6 to 20 subjects per treatment group (mean ± SD, 10 ± 4), the mean age of participants was 23 ± 4 years (n = 175, 93% male), and the average dose of glycerol for treatment groups was 1.05 ± 0.13 g·kg−1. The improvement in performance after glycerol supplementation exhibited minimal heterogeneity (Q15 = 10.63, p = 0.78, I2 = 0%), with sampling error accounting for 100% of the variance. Conclusions: Glycerol hyperhydration has a moderate effect on performance based on Cohen's guidelines for magnitude of d. However, due to minimal heterogeneity and the small number of effects, a thorough moderator analysis could not be performed. Practical Applications: Maintaining hydration during exercise or work in the heat is essential to attenuate decreases in performance. These results may be useful for athletes and individuals working in environments of extreme heat stress, such as firefighters or soldiers.
Caffeine's Affects on Delayed Onset Muscle Soreness Following a Bout of Resistance Training Exercise
S. Bradley, M. Cunningham, and R. Jeffreys
FGCU Exercise Science
Purpose: The aim of this study was to determine if a commercially available (2, 200 mg pills) of a caffeine-supplement would elicit a reduction in delayed onset muscle soreness (DOMS) following a bout of resistance training exercise. Methods: Male college age adults participated in a blind, placebo-controlled trial consisting of 1 testing day and 2 exercise days each separated by 48 hours. Initial testing determined individual 1 Repetition Maximum (1RM). On day 3 of the study participants performed barbell bench press (3 sets of 10 reps at 70% of 1RM) and on day 6 of the study participants performed the barbell squat (3 sets of 10 reps at 70% of 1RM). Prior to exercise on day 3 and 6 participants ingested either 2 caffeine pills (200 mg each) or 2 multivitamin placebo pills. Ratings of perceived exertion (RPE) and muscle soreness were recorded after each set of bench press and squat. Heart rate and blood pressure were recorded 5 minutes before and after each exercise session. Each participant recorded his perceived muscle soreness for 48 hours following each exercise session as well as kept a nutrition log for the length of the study. Subjects were asked to refrain from exercise and caffeine consumption over the course of the study and Institutional Review Board Approval was obtained. Results: Ten male college students participated in the study; mean ± SD of age and BMI were 22.10 ± 1 years and 24.97 ± 3.42 kg·m−2 respectively. The mean reported pain measures were higher on the 2 days after the squat exercises (4.67 ± 2.18 and 3.56 ± 2.79) vs. chest exercises (1.2 ± 1.48 ± 1.1 ± 1.97). When both groups were combined the differences between reported pain after squat and chest exercises were statistically significant (p = 0.007). There were no statistically significant differences between the caffeine and placebo group on reported pain on any day. The highest mean pain was reported on day 7 (1 day post) squat exercises (5.00 ± 1.58 Caffeine vs. 4.25 ± 2.99-placebo). Conclusions: This study suggests a small decrease in pain perception after caffeine consumption (NS), however, some individuals reported an increase in pain and a decrease in strength following caffeine consumption. Additional studies with a larger sample size are necessary. Practical Applications: The majority of the research on caffeine consumption and DOMS has used caffeine consumption at 5–7 mg·kg−1 of body weight, an amount not easily available to a recreational exerciser. This study was designed to be translational in nature: to determine the effect of a commercially available caffeine pill on DOMS after a “typical” workout. Additional research is needed in this area due to 3 participants in this study reporting a decrease in strength (70% of 1RM almost impossible) after consumption of the caffeine supplement; those subjects also reported no daily caffeine consumption prior to the start of the study.
Does Access to a Sports Dietitian Affect Dietary Habits and Nutrient Timing Practices of NCAA Division I Baseball Athletes
M. Jones,1 A. Jagim,2 K. Gravani,3 M. Greenwood,4 J. Oliver,5 and D. Busteed1
1George Mason University; 2University of Wisconsin-La Crosse; 3Stanford University; 4Texas A & M University; and 5Texas Christian University
Collegiate athletes are challenged by practice schedules, courses, strength training sessions, and, therefore, may not follow an optimal dietary plan for sports performance. The field of sports nutrition has grown rapidly, yet there is little research to indicate the impact a full time sports dietitian (SD) may have upon an athlete's dietary practices. Purpose: A survey questionnaire, which examined dietary habits and nutrient timing practices, was designed and administered to baseball athletes at 3 universities, 2 that employed a full-time SD and one that did not; therefore, the purpose was to examine the SD's effect on athletes' dietary practices. Methods: Prior to training, 99 men (mean ± SD: age = 20.7 ± 1.4 years), consisting of 19% freshmen, 19% sophomores, 34% juniors, 26% seniors, and 2% graduate students, from 3 athletic conferences (Atlantic 10 [n = 31], Atlantic Coast [n = 32], Conference USA [n = 36]) completed the 15-minute survey, which consisted of items related to dietary habits (DH, 31 items) and nutrient timing (NT, 20 items). Descriptive statistics and 2-way Pearson X2 analyses were used. Results: The majority were on athletic scholarship (72/99, 72.7%), and 67.7% (67/99) lived off-campus. Sport position was: 9.2% catcher, 44.9% pitcher, 10.2% corner infielder (IF), 19.4% middle IF, 16.3% outfield. Sport dietary planning assistance was sought by 57% (36/63) of those with SD access. Responses on 10 DH and 5 NT items were different (p ≤ 0.10) between athletes who worked with a SD (ASD, n = 36) and those who did not (ANSD, n = 63). In regard to DH items, ASD found it easier to eat before activity (92 vs. 71%, X2 = 7.32, p = 0.03), did not consume fast food (31 vs. 14%, X2 = 18.57, p = 0.02), caffeinated beverages (57 vs. 46%, X2 = 18.27, p = 0.02), or soda (56 vs. 37%, X2 = 10.56, p = 0.10), and prepared their own meals more often (86 vs. 73%, X2 = 19.96, p = 0.07). The ASD group drank less soda on weekends (50 vs. 62%, X2 = 11.2, p = 0.08) and was more likely to take a daily multi-vitamin (56 vs. 32%, X2 = 17.78 p = 0.02) than the ANSD group. The ANSD group ate more frequently at burger locations (21 vs. 6%, X2 = 12.28, p = 0.02) during a 7-day week. In regard to NT items, ASD ate breakfast before training/lifting sessions (67 vs. 37%, X2 = 8.03, p = 0.02), and was more likely to have post-workout nutrition options provided (61 vs. 27%, X2 = 9.91, p = 0.01). Protein shakes and bars were popular options for post-workout nutrition in both the ASD (56%) and ANSD (46%) groups; however, ANSD was more likely to consume additional food such as eggs (56 vs. 22%, X2 = 8.15, p = 0.02) and fruit juice (35 vs. 11%, X2 = 7.02, p = 0.03). The ANSD reported pre-competition meals of fast food on team trips (58 vs. 45%, X2 = 9.98, p = 0.01), and their sport coaches to be less conscious of healthier options for the team when travelling (39 vs. 65%, X2 = 9.67, p = 0.05). Conclusions: ASD had healthier dietary habits and nutrient timing practices. They consumed less high calorie/low nutrient dense items like fast food and soda. Further, the timing of their nutrient intake was more optimal for performance as they were likely to eat before exercise and consume healthier options following exercise. The presence of SD influenced sport coaches and was linked to provision of healthier food options during team trips. Practical Applications: The SD can serve as an asset to an athletics program. The evidence-based eating strategies and sport dietary plan provided by a SD may lead to improved performance and recovery.
Lower Body Muscle Endurance and Power Following Acute Supplementation With a Select Amino Acid Combination
B. Wax,1 A. Kavazis,2 E. Hall-Palmer,1 A. Walton,1 and B. Thebaud1
1Mississippi State University; and 2Auburn University
Glycine-arginine-α-ketoisocaproic acid (GAKIC) has been reported to enhance muscular strength and endurance performance; however, there is a paucity of research regarding its effect on muscular power output. Purpose: To investigate the potential ergogenic effects of acute GAKIC ingestion during repeated bouts of lower body resistance exercise during a power protocol. Methods: Ten resistance trained males (age = 22.1 ± 1.4 years, mass = 82.2 ± 10.6 kg, height = 1.80 ± 0.05 m, body fat = 10.9 ± 3.7%) participated in a randomized, crossover, double blind study. Participants were randomly assigned to GAKIC (11.2 g) or placebo and performed 5 rounds of 2 sets of leg press at 75% of one-repetition maximum, followed by 3 vertical jumps in place while measured by a Tendo Unit. One week later, participants ingested the other supplement and the same exercise protocol was performed. Results: GAKIC supplementation failed to significantly increase leg press repetitions (GAKIC = 89.0 ± 32.9; placebo = 79.8 ± 29.6, p > 0.05), leg press peak velocity (GAKIC = 0.56 ± 0.14 m·s−1; placebo = 0.53 ± 0.09 m·s−1, p > 0.05), leg press peak power (GAKIC = 1,203.5 ± 357.4 W; placebo = 1,065.4 ± 228.8 W, p > 0.05), vertical jump peak velocity (GAKIC = 2.53 ± 0.29 m·s−1; placebo = 2.52 ± 0.31 m·s−1, p > 0.05), and vertical jump peak power (GAKIC = 1,944.6 ± 680.1 W; placebo = 2,040.6 ± 418.6 W, p > 0.05). Conclusions: These findings suggest that GAKIC does not increase power output during repeated bouts of lower body resistance exercise. Practical Implications: Our data suggest that acute GAKIC ingestion prior to a lower body resistance protocol does not increase the repetitions or power output of trained males. Acknowledgments: This study was supported by a gift from Iovate Health Sciences International Inc.
A Comparison of Fitness Scores Between Injured vs. Uninjured Police Academy Cadets
J. Dawes,1 R. Orr,2 R. Pope,2 and C. Elder1
1University of Colorado Colorado Springs; and 2Tactical Research Unit, Bond University
The purpose of this investigation was to determine whether there were significant mean score differences on selected fitness tests between cadets who sustained an injury while attending a 27-week state patrol training academy and their uninjured counterparts. Methods: Archival data for 81 cadets from two 27-week state patrol training cohorts were utilized for this analysis. This data was collected as part of the agency's normal training academy fitness assessment prior to commencement of training. The data included self-reported age (years); height (inches) and weight (lbs); and push-up, sit-up, vertical jump and 20 m multi-stage fitness test (20 m-MSFT) scores. Injury was defined as any musculoskeletal damage that resulted in the cadet being assigned to altered training duty or that led to exit from the training academy. Injuries were routinely documented by the state patrol training staff and provided to the primary investigator for analysis. Fifteen cadets reported an injury during their time at the training academy. Independent t-tests were performed to examine mean score differences between injured and uninjured cadets. The level of statistical significance was set a priori at 0.05. Results: Descriptive data for both injured and uninjured groups is presented in Table 1, with any significant differences between injured and uninjured personnel in mean scores on the measured variables indicated by an asterisk. Injured personnel were significantly older and exhibited poorer push-up, sit-up, vertical jump and 20 m-MSFT performance at baseline than their uninjured counterparts. Conclusions: There were significant mean score differences in age and fitness levels between injured and non-injured state patrol cadets attending academy training, with injured cadets being significantly older and less conditioned. Practical Applications: Initial fitness levels may impact a cadets chance of successfully completing their academy training. Subsequently, acceptable, and legally defensible, entry level standards may reduce injuries (and associated costs) and improve cadet retention.
Reproductive Health and Female Firefighters: A Needs Analysis
A. Kehler,1 S. Jahnke,2 B. Hollerback,1 and K. Heinrich1
1Kansas State University; and 2Center for Fire, Rescue & EMS Health Research, National Development & Research Institutes
Although female firefighters account for a small percentage of the fire service (3–5%), this still represents more than 10,000 women in the United States. Despite a growing body of research on the health impact of firefighting occupations, women are not usually included in published study data due to small sample size. There has been very little research to date on the reproductive health of female firefighters. Purpose: To determine the health and safety concerns, attitudes and policies in place regarding the reproductive health of women in the fire service. Methods: A nationally representative sample of 73 current female firefighters (n = 46) and fire service leaders (n = 27) were solicited for participation in key informant interviews and focus groups. The discussion began with the question “What concerns exist related to reproductive health among women in the fire service?” All focus groups and interviews were transcribed verbatim, and a 2-phase coding process was used by 2 researchers to capture meanings and analyze themes behind the transcribed text using NVivo qualitative analysis software. Results: The following major themes were identified: (a) lack of knowledge on pregnancy policy within the fire department, (b) uncertainty in who should make decisions on job tasks when a female firefighter announces a pregnancy, and (c) little education or training was given to firefighters on reproductive health (male or female). Conclusions: Addressing the issues identified in this study though firefighter reproductive health education and establishing policy will benefit all members in the fire service. Adoption of a clear departmental pregnancy policy such as the National Fire Protection Association Standard 1582, section 9.18 will help minimize confusion, clarify timelines and job roles for females, and may consequently help with both female recruitment and retention strategies. Practical Applications: Firefighting is a physically demanding occupation with many potentially hazardous conditions. Establishment and clarification of departmental pregnancy policy in addition to increased education about potential impacts of certain occupation-specific tasks is necessary for optimal reproductive health of female firefighters. Acknowledgments: Supported by National Heart Lung and Blood Institute, NIH Grant R21HL119024.
Female Firefighters' Attitudes, Perceptions, and Experiences With Injury
B. Hollerbach1 and S. Jahnke2
1Kansas State University; and 2Center for Fire, Rescue & EMS Health Research, National Development & Research Institutes
Firefighting is an inherently dangerous occupation. National firefighter injury rates have been well documented for males, however there are little data regarding females, who represent 3–5% of the fire service. In the U.S., around 6,200 women currently work as full-time, career firefighters and officers and it is estimated that 35–40,000 women are in the volunteer fire service. Despite increased attention to performance, health and wellness, there remains little focus on how occupational demands uniquely affect the growing population of female firefighters. Purpose: This systematic investigation sought to explore perceptions, attitudes, and experiences with injury for females on the fire ground. Methods: A nationally representative sample of 73 current career female firefighters and fire service leaders, aged 25–66 years, were purposely solicited for participation in 60–120 minutes focus groups and 60 minutes key informant interviews. Participants were asked about perceived threats to safety and standard operating procedures that might lead to injury with regards to gender differences in the fire service. A 2-phase process was used to capture the meaning of the transcribed text and a thematic qualitative analysis was conducted by 2 researchers. The data was coded into themes and sub-themes. Results: The following themes were identified: (a) males and females experienced the same rates/types of injury, (b) females were operating in a male-dominated field, (c) females lacked functional movement techniques/muscular endurance, (d) fire service training was inadequate for females, (e) females experienced ill-fitting gear, and (f) females experienced harassment on the job. Responses were similar across the leader and firefighter groups. Perceived common injuries for females include mostly upper body injuries: back, neck, shoulder, but also include knee and ankle injuries. Some of the most difficult tasks for women included activities requiring upper body strength. A gap was identified in traditional training methods, both for men and women. Women had different musculature and often used different body mechanics when lifting/moving equipment/doing work on scene. As firefighters aged, they needed different training and techniques taught to accommodate their changing bodies. Education was identified as a limiting factor regarding training as well as training on different methods of accomplishing the same task to allow those with different body types to use a method that complimented their strengths as opposed to enhancing their weaknesses. Conclusions: Addressing the issues identified in this study will require policy change for injury prevention. In order to perform fire suppression and rescue duties safely and effectively it is necessary that firefighters possess strength, stamina, and agility. The data suggest the fire service must include female-specific drills and fitness training, including strength training, with a consideration for female anatomy and musculature. Standard operating procedures must be reviewed for relevance to today's female fire service personnel. Practical Applications: Females are an integral part of the workforce. Better understanding how they differ from their male counterparts in size, stature, and training requirements will allow for advances in training methods, decreased time away from the job due to injury, and decreased injury costs for fire departments. Acknowledgments: Supported by National Heart Lung and Blood Institute, NIH, Grant R21HL119024.
On-Ice Performance Characteristics According to Position in Elite, College-Level, Male Hockey Players
Z. Rourk,1 B. Peterson,2 J. Fitzgerald,3 C. Dietz,1 D. Warnke,1 and E. Snyder1
1University of Minnesota; 2Catapult Sports; and 3University of North Dakota
Introduction: Previous research has identified differences between ice hockey defenseman and forwards using a combination of on-ice skating ability measures and off-ice general fitness measures. The current study is the first to assess on-ice skating ability using accelerometers for the calculation of player load; a metric used to describe instantaneous, multi-directional accelerations. Purpose: To identify differences in Playerload (PL), Total Strides (TS) and Average Force per Stride (FPS) between defenseman and forwards during an on-ice game like repeated sprint test. Methods: Twenty-Two NCAA division I hockey players (8 defensemen, 14 forwards) were outfitted with accelerometers. They performed an on-ice skating test consisting of 8 maximal effort bouts, performed in full gear, lasting approximately 22.7 seconds with 90 seconds of passive recovery in between. PL was calculated as the quotient of the square root of the sum of the squared instantaneous rates of change in all acceleration planes over 100. Playerload Decrement (PLD) was calculated as 100 times the quotient of the lowest PL value over the greatest PL value minus 100. TS and FPS were calculated using a “Hockey Strides” algorithm and individual bodyweight. These metrics incorporate data from a tri-axial gyroscope and tri-axial accelerometer. Results: PL was found to be significantly greater in forwards, compared to defenseman, during all 8 sprint repetitions. Forwards were also found to take significantly more TS towards the end of the repeat sprint test (the seventh [p = 0.05] and eighth [p = 0.004] repetitions). Defensemen were found to have a trend towards a decrease in FPS (p = 0.067) from the first to the last sprint repetition, whereas forwards did not. There were no significant differences in PLD. Conclusions: There are significant differences between forwards and defensemen in terms of PL and TS during a maximal effort repeated sprint test, supporting the theory that, at the elite level, there are inherent differences between defensemen and forwards. Practical Applications: The reason behind the differences found in PL and TS should be identified through further research and taken into account when designing training programs, assessing talent and creating gameplay strategy.
The Relationship Between HRV and Army Physical Fitness Test Scores in ROTC Cadets
K. Allen, C. Metoyer, A. Flatt, P. Bishop, and M. Esco
The University of Alabama
Performance on the Army Physical Fitness Test (APFT) may be closely associated with baseline activity of the autonomic nervous system, as indicated by vagal-indices of heart rate variability (HRV). Purpose: The purpose of this study was to determine the relationship between the mean HRV measured over a 3-day period and performance on the APFT. Methods: Thirteen ROTC Cadets (males = 69%, age = 20.5 ± 0.8 years), across a 3-day period measured their HRV using a validated smartphone application immediately upon awakening. The mean lnRMSSD over the 3-day period was recorded. Participants also completed a traditional APFT which included a 2-minute max push-up test (PU), 2-minute max sit-up test (SU), and a 2-mile run (2 MR). Results: Mean performance indicators were as follows: APFT = 245.2 ± 38.2 points (out of 300), 2 MR = 16.0 ± 2.9 minutes, PU = 55.7 ± 20.6 repetitions, SU = 70.8 ± 9.4 repetitions. Mean lnRMSSD was 86.5 ± 9.4. The performance metrics provided the following correlation coefficients (all p ≤ 0.05 except as shown) to lnRMSSD r = 0.66 for APFT; r = −0.64 for 2 MR; r = 0.49 (p = 0.09) for PU; r = 0.67 for SU. Conclusions: Significant correlations were found between the 3-day mean lnRMSSD and all performance measures, except PU. This suggests that a higher mean lnRMSSD was associated with better performance in the APFT. Practical Applications: Smartphone applications, which allow for convenient HRV measures in field settings, may be predictive of APFT and other physical performances. This non-invasive marker of cardiovascular-autonomic control method may objectively predict military personnel's ability to perform physically.
Relationship Between Laboratory and On-Ice Measures of Fitness and Power of a Division 1 Collegiate Ice Hockey Team
E. Groezinger,1 J. Roethlingshoefer,2 and R. Cox3
1Shift Human Performance; 2Miami University Hockey Team; and 3Miami University Kinesiology Department
Introduction: Ice hockey has always been considered an anaerobic sport but in recent years, research on the aerobic demands have shown that this might not be the case. Both on and off ice testing has shown that aerobic measures of fitness correlate to various game performance measures. In fact, the NHL combine includes several off ice measures as a part of their testing protocol. The purpose of the study is to examine the relationship between aerobic fitness and anaerobic power to on ice performance during a division 1 hockey game. Methods: The 24 Miami University Hockey players participated in some manner in this study with all data analysis done on the 21 forwards and defensemen. All athletes were put through a series of on and off ice measures over the course of a month prior to the start of the season. Off ice measures included the following: V[Combining Dot Above]O2 ramp test, Wingate test, vertical jump height test, body fat analysis (7 site skinfold and Inbody BIA). The on ice measures included the following: 89 ft sprint test, random direction sprint test and the 6 sprint test. Correlations were run between on and off ice measures of performance in order to see if a relationship existed between the tests. Results: Significant correlations existed between Average Power (Wingate) and ml·kg−1·min−1 (V[Combining Dot Above]O2): (−0.44); peak power and ml·kg−1·min−1: (−0.41); peak w·kg−1 and vertical jump height: (0.57); BW in lbs and peak power: (0.37); % body fat and 89 foot sprint time: (0.52); % body fat and 6 sprint total time: (0.35); accelerations during a game and w·kg−1: (0.41); and finally, accelerations during a game and % body fat: (−0.35). Conclusions: Contrary to traditional belief, hockey is a very aerobic sport. In addition to the anaerobic demands of a shift, aerobic fitness allows a player to recover quicker on the bench, which is more beneficial during a 60 minutes regulation game. Looking ahead, strength and conditioning coaches should be sure to incorporate a proper mixture of aerobic and anaerobic training in order to maximize performance potential for their athletes.
C-Reactive Protein and Risk of Cardiovascular Disease in Firefighters
L. Adlof and L. Cosio-Lima
University of West Florida
Heart attacks are the leading cause of on-duty deaths in firefighters. As tactical athletes, firefighters have a high occupational demand and require cardiorespiratory fitness and strength to perform their duties. However, firefighters also have a high prevalence of obesity and CVD, which puts them at high risk of sudden cardiac death. Therefore, the need for frequent and reliable CVD risk factor screening for firefighters is essential. Purpose: The purpose of this study was to identify a relationship between hs-CRP, blood lipid levels, and CVD risk factors in firefighters. A secondary aim was to determine the need for long-term prevention and CVD screening in this population. Methods: Twenty-one career firefighters (Age = 34 ± 7 years) participated in this study. Blood lipid analysis and hs-CRP levels were determined by blood draws, which were repeated after 2 weeks and mean values were reported. Anthropometrics were also taken and cardiovascular risk factors were analyzed using χ2 statistics. Results: Mean hs-CRP level was 3.1 ± 3.8 mg·L−1, which is considered high risk for CVD. Other results included SBP = 134.9 ± 14.2 mm Hg, DBP = 85.4 ± 12.3 mm Hg, TG = 120.9 ± 63.1 mg·dl−1, CHOL = 168.7 ± 46.4 mg·dl−1, HDL = 57.9 ± 23.4 mg·dl−1, LDL = 101.9 ± 35.4 mg·dl−1, GLU = 76.8 ± 21.7 mg·dl−1. Conclusions: This study demonstrated that local firefighters have a high risk of developing CVD, based on elevated hs-CRP levels. Due to their increased risk of on-duty heart attacks, the need for frequent and reliable CVD screening for firefighters is essential. Practical Applications: Due to the occupational and physiological demands of their job, tactical athletes like firefighters are at high risk of on-duty sudden cardiac death. Therefore it is of utmost importance for tactical strength and conditioning professionals to develop screening methods that will aid in early detection and prevention strategies to help decrease the incidence of on-duty sudden cardiac death in firefighters. Acknowledgments: This project was supported by a grant from the University of West Florida through the Office of Research and Sponsored Programs.
Comparative Study of Army ROTC Training Physical Readiness Protocol vs. High Intensity Interval Circuit Training
R. LaFountain,1 P. Hyde,1 C. Fairman,1 C. Mattern,2 and T. Henry2
1The Ohio State University; and 2College at Brockport, State University of New York
Military physical training (PT) is an essential component throughout all ranks and operational task assignments. Despite development of contemporary, evidence-based PT, non-combat injury rates remain unacceptably high amongst military personnel. Purpose: The purpose of the current study was to compare the effectiveness of 2 training programs' on both fitness and injury predictors. Methods: Ten participants, from various ROTC ranks, MSI-II (n = 5; mean ± SD age = 19.6 ± 0.5 years) and MSIII (n = 5; 21.4 ± 1.5 years) were enrolled. Participants completed a baseline battery of tests, evaluating muscular strength (isokinetic dynamometer), endurance (Push-Up to Failure), aerobic capacity (Forestry Step Test), and flexibility (Sit-and-Reach). Participants then underwent a 4-week exercise training intervention. The MSI-II cohort trained according to TC 3-22.20 protocol, while the MSIII cohort completed high intensity interval circuit training. Each cohort trained 3 days per week at normally scheduled PT time, as sanctioned by ROTC Leadership. Pre and post-test measures were recorded. Results: Pooled outcomes (n = 10) demonstrated a non-significant increase in peak torque in both dominant (D) and non-dominant (ND) legs by 7.6% (p = 0.82) and 6.4% (p = 0.79); respectively. Concentric Hamstring to Quadriceps ratio (Hcon:Qcon) were statistically unchanged following training. Hcon:Qcon in each group, both dominant and non-dominant legs, were <0.6 (Figure 1) both pre- and post-training. Non-significant changes were recorded for upper body strength, muscle endurance, aerobic capacity, and flexibility. Conclusions: Despite non-significant increases in torque following a 4-week training period, results indicate the deficiency in Hcon:Qcon was not ameliorated. Thus, military personnel involved in established training regimes may be at a heightened risk for lower body injuries due to muscular imbalance. Practical Applications: Research has shown military training accounts for a majority, 45–50%, of injury incidence in military personnel while combat injury represents 5–6%. This, coupled with the results of our study suggests an increased emphasis on targeting muscular imbalances, particularly in the lower body, is of critical need in military training programs. Acknowledgments: Thank you to Dr. Henry, Dr. Mattern, and Rob Larson those who helped support and guide me through study design, data collection associated with this project. Special thanks to volunteer participants and my esteemed colleagues who contributed to statistical analysis and editing process.
Push-Up Test Predicts 2-Mile Run Performance in ROTC Cadets
C. Metoyer, K. Allen, P. Bishop, and M. Esco
The University of Alabama
The Army Physical Fitness Test (APFT) is composed of the 2-mile run (2 MR), 2-minute max push-up test (PU), and the 2-minute max sit-up test (SU). The training process is quite grueling and cadets are often injured. Purpose: Therefore, the purpose of this study was to develop and validate a reliable regression equation that could predict 2 MR based upon PU and SU. Methods: Forty-two Army ROTC cadets (male = 83%, age 19.75 ± 0.95 years) completed the traditional APFT, which included 2-minute max push-up test (PU), 2-minute max sit-up test (SU), and a 2-mile run (2 MR). Following a 4-week training program, 34 of the participants returned to the facility for a follow up APFT. The results of baseline testing (n = 42) were used to develop a model that would predict 2-mile run performance with SU and PU scores using a stepwise linear regression. The developed model was cross-validated using the data from the follow-up APFT results (n = 34). Validity was confirmed with paired t-tests, correlation (r), and standard error of estimate (SEE). Results: The step-wise regression analysis showed that only PU served as a significant predictor of 2-mile run performance (r = 0.86, R2 = 0.74, p < 0.001). SU did not add statistical significance and was excluded from the model. The resulting prediction model was as follows: Predicted 2-mile run performance = 22.5 + (PU × −0.118). The cross-validation group showed an actual 2-mile run of 14.8 ± 1.7 minutes. Predicted 2-mile run was 15.3 ± 2.2 minutes, which as significantly different compared to actual scores (p = 0.008, Cohen's d = 0.25 [trivial effect size]). The correlation procedure between the predicted and actual 2-mile run scores showed a strong, significant correlation (r = 0.90, p < 0.001). The prediction model's SEE was 0.73 minutes. Conclusions: Based upon these results a regression equation has been developed and cross-validated, reliably predicting 2 MR based upon PU scores. Practical Applications: The practitioner can use this regression equation to reliably predict 2 MR from PU scores, in the event that 2 MR cannot be performed.
Glucocorticoid Receptor Content After Heavy Squat Exercise Is Not Affected by Acute Ethanol Consumption
H. Luk,1 A. Duplanty,2 R. Budnar,3 D. Levitt,1 A. Fernandez,3 D. Fancher,3 B. McFarlin,1 D. Hill,3 and J. Vingren1
1Applied Physiology Laboratory, University of North Texas; 2Louisiana State University Health Science Center; and 3University of North Texas
Binge drinking is common after athletic events or regular exercise and reports show that athletes and active individuals have consumed ethanol (alcohol) with a greater frequency than their non-athlete peers. Ethanol consumption could interfere with muscle adaptation and recovery after heavy resistance exercise and subsequently affect athletic performance. It has been found that ethanol consumption and exercise individually increase cortisol concentration (a ligand for the glucocorticoid receptor; GR). However, the combined effects of ethanol consumption and resistance exercise on GR content has not been studied. Purpose: The purpose of this study was to examine the effect of acute ethanol consumption on the GR response to a bout of heavy squat exercise. Methods: Seventeen men and women (24 ± 3 years; 169.0 ± 5.3 cm; 72.3 ± 11.0 kg; 21 ± 5.8% body fat), who were resistance trained, completed 2 identical heavy squat resistance exercise tests (HSRET: 6 sets of 10 repetitions at 80% of 1-repetition maximum) on a Smith machine, separated by approximately 28 days. Ten minutes after the HSRET, participants consumed an artificially sweetened and calorie free beverage with either grain ethanol (EtOH condition, 1.09 g·kg−1 lean mass) or no ethanol (placebo condition) within 10 minutes. Muscle biopsies were collected before (PRE), 3 (3 hours) and 5 hours (5 hours) after the HSRET and analyzed for GR protein content using Western blotting. Results: GR was not affected by ethanol ingestion, but a significant (p ≤ 0.05) time × gender interaction effect was observed for the GR response to heavy squat exercise. In women, there was a significant increase in GR in response to resistance exercise at 3 hours and 5 hours. In men, there was a trend (p = 0.093) for an effect of time on GR (increase at 3 hours and reduction at 5 hours). Conclusions: According to our result, moderate- to high-dose ethanol consumption after heavy squat exercise did not affect GR content in either gender. However, the squat exercise bout did appear to have a different effect on GR content between the genders 5 hours into recovery. Practical Applications: In resistance-trained men and women, ethanol consumption after heavy resistance exercise does not appear to affect the acute response of the receptor for cortisol. Thus, ingestion of alcohol after resistance exercise might not augment catabolic signaling through the GR. Acknowledgments: This project was funded in part by a grant from the NSCA.
Myosin Heavy Chain Composition Relationships to Fatigability During a DCER Exercise
M. Lane,1 A. Fry,2 T. Herda,2 J. Weir,2 and A. Herda2
1Eastern Kentucky University; and 2University of Kansas
Introduction: Muscle fiber type influences athletic performance when fast twitch (II) fibers are compared to slow twitch (I) fibers. However, research has rarely examined the effects of the different isoforms of the fast twitch muscle fibers (IIa and IIx) for their individual contributions to athletic performance. Purpose: This study examined the relationships between muscle fiber composition and performance during a fatiguing dynamic constant external resistance (DCER) exercise protocol. Methods: Forty-two college aged males (Mean ± SD; age = 22.4 ± 3.5 years, BW = 78.7 ± 13.3 kg, hgt = 1.78 ± 0.07 m) from a variety of training statuses (sedentary, recreational, resistance, aerobic) participated in a fatiguing DCER unilateral leg extension (LE) protocol on a Biodex dynamometer. All tests were performed on the right side of the body. Subjects came in for an initial visit where consent was obtained and they were familiarized with both one repetition maximum (1RM) testing and a brief fatiguing protocol. One week later subjects came in for a second visit where they were tested for their one repetition maximum. One week after that visit the subjects came in for their final visit where they performed 15 repetitions at 70% of their 1RM. Subjects were instructed to perform each repetition with maximal velocity. Subjects then had a muscle biopsy taken from their vastus lateralis. These samples were analyzed for their myosin heavy chain composition (MHC) using SDS-PAGE methodology. Zero-order correlations determined relationships between % MHC content and fatigue indexes for torque, velocity, and power. The fatigue index formula was: = ([highest rep − lowest rep]/highest rep) × 100. Results: Relative MHC content was IIx = 13.8 ± 12.9%, IIa = 49.5 ± 10.3%, and I = 36.8 ± 11.3%. Fatigue indexes are shown in the Table 1 below. Mean velocity fatigue index was positively related to type IIa MHC composition (r = 0.319, p = 0.039). Peak torque fatigue index was positively related to type IIa MHC composition (r = 0.464, p = 0.002) and negatively related to type I composition (r = −0.473, p = 0.002). There were no other significant relationships. Conclusions: MHC composition is related to measures of fatigability during a DCER leg extension exercise. In particular, increased % IIa MHC was related to greater velocity and torque fatigue. As might be expected, greater % type I MHC was associated with less torque fatigue. Up to 22% (r2) of the fatigability indices were explained with an easy to administer leg extension test. Further research is needed to establish any link between IIx fiber type and DCER exercise performance. Practical Applications: This research shows that muscle fiber MHC content is related to fatiguing DCER exercise protocols. These data may be used to help develop simple to administer performance tests for non-invasive assessment of muscle fiber characteristics.
The Efficacy of Platelet Rich Plasma as an Intervention for Patellar Tendinopathy: A Case Series of Athletic Individuals
M. Kolber,1 M. Tabor,2 B. Emerson,1 W. Hanney,3 L. Huff,1 and C. Liggins1
1Nova Southeastern University; 2Private Practice; and 3University of Central Florida
Purpose: To determine the efficacy of platelet rich plasma (PRP) injections on pain, function, global rating of improvement, and tendon morphology among athletic subjects with chronic patellar tendinopathy. Patellar tendinopathy is a common pathology among athletic individuals with a point prevalence ranging from 3 to 45%. The condition itself has a predilection for chronicity, with persistent symptoms being reported up to 15-years following diagnosis. Interventions range from conservative to surgical with evidence suggesting that approximately one-third of individuals diagnosed are unable to return to their sport for 6-months following diagnosis and more than 50% have symptoms well-beyond conclusion of formal care that interferes with training. PRP is a viable alternative to more aggressive surgical interventions and has the potential to reverse the pathological cascade without the cost, risks, and down-time associated with surgery. Methods: This study was a one-group pretest to posttest design using 5 athletic individuals (age 20–26) diagnosed with chronic patellar tendinopathy (symptom range 3–months to 4 years) based on musculoskeletal ultrasound (MSK/US) and clinical diagnosis. Subjects received a total of 3 PRP injections over the course of 6-weeks. During the 6-week intervention period subjects were allowed to continue training and sport participation as tolerated, with the only exception being the day of the intervention where rest was required. Dependent variables (verbal pain rating [VRS], palpable tenderness, patient specific functional scale [PSFS]) were assessed at baseline, 2-week, 1- and 3-month. Global rating of change (GROC) and tendon morphology using MSK/US was assessed at 2 weeks, 1- and 3 months following the initial intervention. All outcome measures have previously established reliability and where appropriate clinimetric properties were used to consider true change. Results: All 5 subjects demonstrated objective improvement on MSK US (determined by a physician with particular expertise in this imaging modality) with deceased thickening, increased linear patterning of tendon fibers, and decreased hypoechogenicity at the 3-month follow-up. With regard to dependent variables, improvement occurred at all time points with change exceeding the minimum clinically important difference (MCID) and minimum detectable change (MDC) for all instruments used (VRS, PSFS, GROC). At the 3-month follow up, average pain on the VRS changed from a mean of 4/10 to 1/10 with 4 of the subjects having complete resolution of tenderness. Functional-sport impairments based on the PSFS identified an improvement from a mean 60% perceived activity-sport limitation to 10%. The GROC identified self-perceived improvement among all participants. Conclusions: A 3-injection PRP intervention improved pain, tenderness, function, and global rating of change to a level that satisfied the reported MCID and MDC for these outcome measures. Follow up MSK/US images showed return to normal tendon morphology and regeneration of tendon collagen supporting overall tendon healing. Practical Applications: PRP may be a viable treatment option for athletic individuals who are recalcitrant to conservative efforts and desire to avoid the down-time or training interruption associated with more aggressive surgical interventions. Acknowledgments: The authors would like to acknowledge the Nova Southeastern University President's Faculty Research and Development Grant as well as the Health Professions Division, Faculty Research Grant for providing funding.
The Effect of Menstrual Cycle on Agility
K. Kheniser, E. Kullman, K. Sparks, and K. Little
Cleveland State University
It has long been speculated that the menstrual cycle affects athletic performance. Whether athletic performance is impacted by menstrual cycle phase is dependent upon an array of factors. Namely, these include: the type of activity (i.e., aerobic or anaerobic); oral contraceptive (OC) use; and, possibly, if mental processing required during the execution of the task. As it pertains to the latter, prior research has indicated that alteration in estradiol (E2) affects cognitive performance. Little is known about whether E2 modulates the speed of cognitive processing in a sports setting, which may cause alterations in sport performance throughout the menstrual cycle. Additionally, variations in E2 levels throughout the menstrual cycle are associated with changes in joint laxity, which may translate into changes in quick and powerful movements, such as multidirectional running patterns that are required in many sports. Purpose: The present study aimed to deduce if fluctuations in E2 influence agility performance in the reactive agility test (RAT), which requires mental processing during its execution, as well as the agility T-Test, which does not require mental processing, but does entail a high degree of agility. Methods: Following consent, healthy female subjects (n = 8, 61.2 ± 6.2 kg, 23.3 ± 4.1 years old) were tested on the RAT and agility T-Test, during mid-cycle ([MC], high E2) and the early follicular phase ([EF], low E2) of the menstrual cycle. Subjects monitored urine levels of luteinizing hormone (LH), which coincide with elevated levels of E2, to determine the MC test timing. Data were analyzed using a paired samples t-test. Results: With respect to the agility T-Test, the results indicated that the subjects were significantly faster during EF (MC = 12.6 ± 0.96 seconds, EF = 12.3 ± 0.95 seconds; p = 0.007), relative to MC. However, there were no significant differences in RAT times between EF and MC (MC = 1.91 ± 0.10 seconds, EF = 1.91 ± 0.15 seconds, p > 0.05). Conclusions: In conclusion, cognitive function (i.e., mental processing) during the execution of sports-related movements is not affected, but the neuromuscular system may be negatively influenced by increases in E2, given that the subjects were slower in the agility T-Test during MC. Practical Applications: Strength and conditioning professionals and athletes may need to perform agility trials during EF, rather than MC, given that the ability to execute agility drills appears to be hindered at MC. Furthermore, fluctuations in hormones during the menstrual cycle may impact sports performance, particularly when a high degree of agility is required.
Friday Abstract Poster Presentations—Session B
July 08, 2016—3:00 PM–4:30 PM—Celestin ABC
Friday, July 08, 2016, 3:00 PM–4:30 PM
Electromyography and Force Comparison of the Quadriceps After Application of Specialty Tapes for Muscle Activation Over Time
M. Miller,1 W. Dahl,1 R. Ledwon,1 T. Sullivan,1 T. Michael,1 N. Hanson,1 and B. Hatzel2
1Western Michigan University; and 2Grand Valley State University
Specialty tape, commonly referred to as kinesiology tape, has gained popularity in its proposed ability to relieve pain, increase muscle activity, and possibly improve athletic performance. Purpose: The purpose of this study was to determine electromyography (EMG) and force production of the quadriceps after application of specialty tape. Methods: The study took place in a Human Performance Research Laboratory. Fourteen subjects (age: 23.21 ± 1.89 years; height: 177 ± 11.97 cm; weight: 81.32 ± 19.10 kg) volunteered for the study. Three within treatment conditions were used (KT Tape Pro, RockTape, and no tape) and 4 measurement times (immediate, 1 hour post-application, 24 hours post-application, 48 hours post-application). During an orientation session, subjects performed 5 maximal voluntary contractions (MVIC), which served as baseline force production and maximal muscle EMG activity values. After warm-up on the first treatment condition session, subjects completed 5 MVIC, followed by EMG and force measures immediately, 1, 24, and 48 hours post tape application. Two Kendall surface EMG electrodes were placed approximately 1.5–2 cm apart on the abraded area of the rectus femoris muscle belly. Surface electromyography signals were interpreted with ADInstruments Chart 5 Software. Force production measurements were measured at 60° of knee flexion on a KinCom dynamometer. Force production in Newtons and sEMG RMS values were measured for all 3 conditions. All tape was applied in accordance to brand specifications and a Latin Square technique was used to assign conditions. Results: A repeated measures ANOVA was used to investigate the differences between the 3 taping conditions (KT Tape Pro, RockTape, and no tape) and measurement times (immediate, 1 hour post-application, 24 hours post-application, 48 hours post-application). There was no significant condition by time interaction for muscle activation (p > 0.05) or main effect of time and condition (p > 0.05). There was no significant condition by time interaction for force production (p > 0.05) or main effect of time and condition (p > 0.05). Conclusions: This study shows that the application of specialty tape does not increase muscle activity or force production. Practical Applications: While many athletes utilize specialty tape, muscle force and activation does not appear to augment resistance training or sport performance conclusively. Therefore, the use of specialty tape by coaches or strength and conditioning professionals should be used cautiously. While specialty tape may not enhance force or muscle activation, it may provide some psychological effects and strength training professionals should not discourage the use.
Electromyographical Comparison of Muscle Activation Patterns Across Three Commonly Performed Kettlebell Exercises
B. Wax,1 B. Lyons,2 J. Mayo,3 S. Tucker,3 and R. Hendrix4
1Mississippi State University; 2University of Wisconsin-Parkside; 3University of Central AR; and 4College of the Ozarks
Kettlebell (KB) training has become one of the most popular fitness trends to hit the U.S. in recent years; however, there is a paucity of research regarding the muscle activation patterns of KB exercises. Purpose: To compare the muscle activation patterns of 3 different KB exercises using electromyography (EMG). Methods: Fourteen resistance trained males (mean ± SD age = 21.5 ± 2.03 years, height = 180.87 ± 3.76 cm, mass = 105, 85.53 ± 8.11 kg, and body fat = 12.86 ± 3.32%) participated in this investigation. Subjects completed one-arm swing (Swing), one-arm swing style snatch (Snatch), and a one-arm clean (Clean) using a self-selected 8–10RM load for each exercise. Trial sessions consisted of subjects performing 5 repetitions of each kettlebell exercise. Integrated EMG (iEMG) was used to assess the muscle activation of the biceps brachii (BB), anterior deltoid (AD), posterior deltoid (PD), erector spinae (ES), vastus lateralis (VL), biceps femoris (BF), contralateral external oblique (EO), and gluteus maximus (GM) during each lift using surface electrodes. The iEMG was normalized using maximal voluntary contractions obtained from manual muscle testing. Results: The results of the statistical analysis revealed significant differences for 3 of the 8 muscles. Pairwise comparisons revealed that for the ES (F(2,26) = 12.015; p < 0.001), the Swing (60.89 ± 24.34%) elicited greater muscle activation compared to the Snatch (38.38 ± 17.67%); for the EO, there was greater muscle activation (F(2,26) = 11.196; p < 0.001) during the Clean (23.36 ± 10.06%) and Snatch (20.71 ± 7.72%) compared to the Swing (15.59 ± 5.91%); and the VL was significantly more active (F(2,16) = 5.786; p = 0.008) during the Swing (56.81 ± 27.37%) compared to the Clean (40.9 ± 36.14%). Effect sizes computed as partial eta squared were 0.701 (ES), 0.630 (EO), and 0.630 (VL). Statistical power ranged between 0.952 and 0.990 for all statistically significant findings. There were no significant differences in the muscle activation of the AD (F(2,26) = 0.2224; p = 0.801), PD (F(2,26) = 1.764; p = 0.191), BB (F(2,26) = 2.79; p = 0.08), BF (F(2,26) = 1.588; p = 0.224) and GM (F(2,26) = 0.160; p = 0.853). Conclusions: Our findings indicate that while the KB Swing, Snatch, and Clean are total body exercises, they place different demands on the ES, contralateral EO, and the VL. Therefore, KBs represent an authentic alternative for lifters, and the Swing, Snatch, and Clean are not redundant exercises. Practical Implications: Our data establishes that the KB Swing, Snatch, and Clean are whole body exercises. This study also demonstrated that while the lifts are similar, they are not exactly the same. Therefore, we conclude that the Swing, Snatch, and Clean, place different demands on the ES, contralateral EO, and the VL. KBs represent an authentic alternative for lifters, and the Swing, Snatch, and Clean are indeed whole body exercises and they are similar, but not redundant.
Mechanical Work Performed on the Barbell During Three Variations of the Clean
T. Dæhlin,1 T. Krosshaug,1 and L. Chiu2
1Norwegian School of Sport Sciences; and 2University of Alberta
The clean may be executed with different objectives. For example, maximal effort can be exerted during the pulling phase to elevate the barbell as high as possible, receiving the bar in a full (i.e., maximal effort clean) or partial (i.e., power clean) squat. In contrast, the barbell can also be raised to the minimal height required to receive the bar in a deep squat position (minimal height clean). Due to the work-energy relationship, mechanical work performed on the barbell during a clean is proportional to the barbell's mass and its change in height and velocity. Therefore, the mechanical work performed during the clean may vary depending on how it is executed. Purpose: The purpose of this investigation was to compare barbell kinematics and work performed on the barbell during maximal effort, minimal height and power cleans. Methods: Six males and 2 females (age: 26 ± 6 years; height: 1.76 ± 0.09 m; mass: 93.6 ± 19.5 kg) with 3 years minimum experience performing cleans participated in 2 sessions. In session one, participants' one repetition maximum (1RM) clean was determined. Concomitantly, technique was assessed using digital video; all participants demonstrated the towards-away-towards barbell trajectory. In session 2, participants performed 4 repetitions each of maximal effort, minimal height and power cleans at 80% 1RM in a randomized order. The trajectory of 2 reflective markers on the left and right ends of the barbell were recorded using 3D motion analysis at 120 Hz. Marker data were used to calculate changes in gravitational potential and kinetic energies from lift-off to peak vertical barbell velocity, and summed to yield total work performed on the barbell. Barbell kinematics and total work were compared between the 3 conditions using one-way repeated measures ANOVA and post hoc t-tests with Bonferroni correction (α = 0.05). Results: Peak barbell height was greater in both the maximal effort (1.21 ± 0.07 m) and power (1.21 ± 0.07 m) cleans compared to the minimal height clean (1.15 ± 0.07 m; p ≤ 0.05). Total work performed on the barbell was not different between the maximal effort (9.1 ± 1.4 J·kg−1) and power (9.3 ± 1.3 J·kg−1; p > 0.05) cleans; however, both were greater than in the minimal height clean (8.7 ± 1.3 J·kg−1; p ≤ 0.05). Peak vertical barbell velocity was not different between cleans (p > 0.05). Conclusions: Maximal effort and power cleans require more work to be performed on the barbell to lift the barbell to a greater height, but not to increase the barbell's vertical velocity. Practical Applications: Exerting maximal effort to elevate the barbell during the pulling phase of a clean can be considered inefficient, as it requires more mechanical work to be performed than is necessary. Further, exerting maximal effort to elevate the barbell may unintentionally increase training intensity beyond the desired, as near maximal or maximal work is performed. If a greater training intensity is desirable, more work can be performed by raising a barbell of heavier mass to the minimum height rather than raising the barbell to a maximal height. Further research is required to examine if these different methods of executing the clean influence inter-muscular coordination.
Muscle Activation During Treadmill vs. On-Ground Running
R. Fisher, A. Waldhelm, and V. Freedman
University of the Incarnate Word
Heel-strike running requires the hamstrings to activate in pulling the center of gravity of a person forward. Treadmills employ a movable belt that creates and backward force not normally present during running. Discrepancies exist in the literature regarding differences in joint kinematics, muscle activation, and energy costs associated with on-ground running (O) and treadmill running (T). Purpose: The authors sought to identify lower extremity muscle activation differences while running on a treadmill (T) compared to on-ground in heel-strike runners. The backward motion of the treadmill was hypothesized to decrease hamstring activation which would in turn require a new forward propulsion mechanism to exist. Methods: Ten recreational runners (6 male, 4 female, age: 24.0 ± 2.71, weight: 72.3 ± 13.4 kg, height: 1.72 ± 0.12 m) volunteered for the study. Active surface electrodes (rectangular shape 37 × 26 mm) were placed on the following muscles of the right lower extremity: Rectus femoris, Semitendinosus, Biceps femoris, Tibialis anterior, Soleus, Gastrocnemius, Gluteus maximus and Gluteus medius. Participants then underwent a 5-minute jogging warm-up on a treadmill (Biodex Medical Systems, Shirley, NY, USA) at their own preferred pace. Maximum voluntary isometric contractions (MVICs) were performed for each of the 8 muscles. Following the MVIC, muscle activation data were collected and analyzed for O and T with participants running at their preferred pace. The running condition order was randomized and there was a 5 minute break between bouts. Paired t-tests were performed to determine differences in muscle activation between O and T running for each of the 8 muscles. The level of significance was set at 5%. Results: No significant differences were observed between T and O running for each of the 8 muscles tested (Table 1). Individual muscle activity was similar between T and O with the soleus exhibiting the highest activity and the rectus femoris demonstrating the lowest for both scenarios. Conclusions: Muscle activation patterns between the 2 running conditions were similar and no significant differences were observed for each of the 8 lower extremity muscles. Practical Applications: Based on the results of this study, muscle activitation patterns are not significantly different between T and O. Therefore, based solely on muscle activation, the treadmill is an acceptable alternative to on-ground running.
The Validity and Reliability of Inexpensive Portable Force Plate Jump Height
J. Lake,1 J. Murrell,1 P. Mundy,2 P. Comfort,3 and T. Suchomel4
1University of Chichester; 2Coventry University; 3University of Salford; and 4East Stroudsburg University
Study of vertical jump height is often of interest to strength and conditioning practitioners. The force plate method is considered the “gold standard” but is often financially and logistically unfeasible. Contact mats are often used and jump height is derived from flight time. However, researchers have shown that this method can overestimate jump height by up 12%. Purpose: The purpose of this study was to determine the concurrent validity and reliability of countermovement jump height obtained from an inexpensive portable force plate system. Methods: Twenty-eight men (age: 20.0 ± 0.8 years, body mass: 83.2 ± 7.9 kg, height: 1.80 ± 0.56 m) performed 4 bilateral countermovement jumps (CMJ) without arm swing on 2 portable force plates that were each placed on top of an in-ground force plate. Vertical ground reaction force was recorded at 1,000 Hz from both force plate systems, and jump height was calculated from take-off velocity derived from their respective force-time data. All data were used for the validity analysis, while data from 10 subjects who returned to the laboratory for a second testing session 7 days later were included in the reliability analysis. Before assessing reliability and validity, normality, uniform distribution and linearity were checked. Ordinary least-products regression was used to assess fixed and proportional bias between data from the 2 testing sessions and the portable and laboratory force plates. If the 95% confidence interval for the intercept did not include 0, then fixed bias was present. If the 95% confidence interval for the slope did not include 1.0, then proportional bias was present. Furthermore, the mean and standard deviation of the differences between the data from the 2 testing session and the portable and laboratory force plates and the 95% Limits of Agreement (LOA: mean of the differences ±1.96 seconds) were calculated. Practically unacceptable LOA were determined a priori as greater than 0.05 m. Results: Mean jump height obtained from the laboratory force plates was 0.33 ± 0.06 m and 0.33 ± 0.06 m for days one and 2, respectively. Similarly, mean jump height obtained from the portable force plates was 0.33 ± 0.07 m and 0.33 ± 0.06 m for days one and 2, respectively. These were not significantly different, with no fixed or proportional bias present, and limits of agreement results were in line with previous research and were practically acceptable. The results of the validity analysis revealed the presence of proportional and fixed bias. However, validity limits of agreement were practically acceptable. Conclusions: The portable force plates provide a reliable and valid method of obtaining jump height when compared to the laboratory force plates. Practical Applications: The portable force plate system provides a reliable and economical method to obtain accurate measures of jump height. It is therefore suggested that practitioners interested in measuring and monitoring jump height calculated from center of mass take-off velocity, but do not have access to laboratory standard force plates, can use the relatively inexpensive portable force plate system interchangeably.
Energy as a Basis of Analyzing Series Elastic Band Qualities During Acceleration Training
J. Anning,1 C. Hays,2 D. Tommarello,1 A. Cook,1 S. Sprigle,3 and C. Hughes1
1Slippery Rock University; 2The George WA University; and 3Georgia Institute of Technology
Purpose: The purpose of this study was to examine the effects of series elastic bands on energy during resisted running. Methods: Twenty participants (mean ± SD; age: 20 ± 1 years; body mass: 74.6 ± 10 kg; height: 177.2 ± 11.8 cm) volunteered for this study. Four different colors of bands (Flexbands, Speed and Explosion, Stow, OH) were tested: (a) micro (RED), (b) monster mini (BLACK), (c) light (PURPLE), and (d) average (GREEN). Tying 4 bands of the same color in a series created the elastic band chains (EBC). One end of the EBC was then secured to a custom designed slide tension assembly (Sweeney Automation, Baltimore, MD) while the other end went around the waist of each participant prior to walking forward to the 14-foot starting position so the slack was removed from the EBC. Elastic potential energy (PE), kinetic energy (KE), and total energy (TE) for each EBC were then determined at one-foot intervals within a resisted 10-foot acceleration training range distance. The slide tension assembly was used to record band force as a function of EBC elongation length, and an electronic technology timing system (bower Training Systems, Speedtrap 2, Draper, UT) was used to record the time taken to complete the resisted range distance. Force and time at the one-foot intervals were used to calculate energy. PE was calculated for each EBC using an elastic constant (k) determined by the slope of a zero intercept regression line using force and displacement. KE was calculated using subject mass and calculated velocity. Results: The constants used to calculate PE for each EBC included the following equations: RED: 25.223x (r2 = 0.9609), BLACK: 38.347x (r2 = 0.957), PURPLE: 58.842x (r2 = 0.9573), and GREEN: 88.11x (r2 = 0.9692). Based on these constants and the energy calculations, higher stiffness associated with each EBC resulted in greater parabolic increases in TE and PE compared to KE (Figure 1). Conclusions: For each EBC within the 10-foot distance, the stiffer bands resulted in the generation of increasingly greater PE with a less pronounced increase in KE. This resulted in greater TE being generated using the stiffer EBC, indicating a greater amount of mechanical work being performed. Practical Applications: Even though many coaches and trainers use EBC as a form of resistance during acceleration training, this study provides a basis for the need to conduct further research regarding the resistance offered from these bands. The identification of higher elastic PE than KE at greater resistances indicates band selection may influence the benefit potential of resisted band running on acceleration training. Acknowledgments: The Slippery Rock University Faculty/Student Research Grant Program and Student Scholarly, Creative, Entrepreneurial, Civic or Research Projects Grant supported this study.
Stability Reliability and Precision of Laterality-Based Foot Moment Arms Under Three Different Loading Conditions
L. Weiss,1 J. Caia,1 B. Schilling,1 L. Chiu,2 and M. Paquette1
1The University of Memphis; and 2University of Alberta
The ankle and foot contain first- and second-class levers operating through the sagittal plane during jumping. The respective moment arm lengths for both levers affect the moments of force that must be resisted by the ankle plantar flexor muscles during such activities. Grouping measures for laterality (dominance) under different loading conditions may be revealing with respect to jumping performance. However, the reliability and precision of said measures is currently unclear. Purpose: To determine the stability reliability and precision of laterality-grouped moment arm lengths of the foot based upon surface landmarks while under different static loading conditions. Methods: Longitudinal foot dimensions were obtained in 27 men and 27 women including the anterior-posterior distance between the posterior calcaneus and: (a) talocrural (TALO) and (b) metatarsophalangeal (META) joints. Dominance was based on the preferred kicking foot. Bilateral measurements were obtained using a digital sliding caliper. Measures were obtained twice, separated by either 24 or 48 hours. Loading conditions included: (a) seated, (b) bilateral standing, and (c) unilateral standing. Stability reliability was determined using intraclass correlation coefficient (ICC) and precision using both standard error of measurement (SEM) and coefficient of variation percent (CV%). Results: The scatter of points around the trend lines for all 54 participants appear to be uniform and the separate CV%s for men and women were similar for the respective variables. Assuming homoscedasticity, data are reported for the combined groups. Descriptive, reliability, and precision findings are included in Table 1. Conclusions: Surface landmarks and digital calipers can be used to reliably and precisely measure the 2 laterality-grouped foot dimensions in question under 3 different static loading conditions. Although acceptable, the reliability for TALO was noticeably less than for META. Practical Applications: The designated laterality-based foot moment arms may be obtained from surface measures under static seated, bilateral- and unilateral-standing conditions in young adults.
A Case Study: An Analysis of the Punch Force, Biomechanics, and Fitness Levels of a Novice and Advanced Boxer
E. Leal,1 and F. Spaniol2
1Houston ISD; and 2Texas A&M University-Corpus Christi
Purpose: The purpose of this study was to analyze the punch force, biomechanics, and fitness levels of a novice and advanced boxer. Subjects included 2 male boxers (mean + SD, age = 20.5 + 2.5 years, height = 171.45 + 6.35 cm, weight = 64.5 + 0.5 kg) recruited from the local Police Officers Association Boxing Team. Methods: Data was collected for each subject using a motion capture system for biomechanical analysis and a strike system for punch force. Subjects wore 17 sensors when performing straight and hook punches onto a strike sensor. A maximum of 3 trials per punch were administered with the max punch recorded in compound units (cu). Additional anthropometric, physiological, and fitness data was collected for: height, weight, percent body fat, lean body mass, grip strength, leg power, muscular endurance, rotary power, and eye-hand coordination. Results: Fitness data revealed that the amateur boxer was athletically superior to the advanced boxer in all areas except for rotary power, muscular endurance, and eye-hand coordination. However, punch force results, as measured in compound units (cu), proprietary to the strike system, indicated that the maximum punch performed by the advanced boxer was significantly greater than that of the novice boxer. For the straight punch, the advanced boxer generated 19,002 cu compared to 9,448 cu for the novice boxer. For the hook punch, the advanced boxer generated 26,368 cu compared to 8,187 cu for the novice boxer. In addition, biomechanical analyses indicated that the advanced boxer utilized his core and rotary power much more than the novice boxer. For both boxers, as ground reaction forces increased, punch force also increased. Conclusions: The findings of this study suggest that, although 2 boxers may have similar physiques and physiological skills, individual biomechanical efficiencies can play a significant role in the development of punch force. Results also suggest a positive relationship between ground reaction forces and punch force. Practical Applications: Results of this study indicate that boxing coaches and fighters should consider including training that enhances rotary power through strength and power exercises. It is also suggested that emphasis be placed on developing biomechanical efficiency that utilizes sequential kinetic linking and summation of forces to deliver maximum power from the ground, through the core, and to the upper extremities. Acknowledgments: Thank you to Texas A&M University-Corpus Christi and the Kinesiology Department.
The Kinematic Similarity of Commonly Selected Resistance Exercises With Sprinting
A. Dinsdale,1 C. Cooke,2 and A. Bissas1
1Leeds Beckett University; and 2Leeds Trinity University
Coaches and researchers suggest that certain resistance exercises possess mechanical similarity with sprinting tasks. However, limited comparative mechanical evidence exists between sprinting and resistance exercises commonly selected by strength and conditioning coaches. Purpose: The aim of this study was to evaluate the kinematic similarity between commonly selected resistance exercises with the horizontal sprinting. Methods: Four well trained male university students (age 20.8 ± 1.1 years, height 1.79 ± 0.06 m and mass 81.5 ± 6.5 kg) performed 5 trials of 7 exercises (Back Squat [BSQ], Hang Clean [HC], Jump Squat [JSQ], Depth Jump [DJ], Resisted Counter Movement Jump [R-CMJ], Step Bounding [Step-B] and Resisted Sprinting [R-Sprint]), as well as 5 trials of a 10M sprint. The free weighted exercises were evaluated at 2 different intensities (JSQ 30% and 60%, BSQ and HC 85% and 95% of 1RM). The movements were captured in the sagittal plane by a Red Lake Motion Pro high-speed camera set at 125 Hz. Following digitizing and filtering, joint angular displacement and velocity variables were obtained for the ankle, knee and hip. A point by point statistical analysis of difference was implemented to generate a kinematic similarity ranking list. Results: The resistance exercises were ranked in the following order from highest to lowest similarity with sprinting, with a score of 0 considered as absolute similarity: (a) R-sprint (0.18), (b) HC95% (0.37), (c) step B (0.38), (d) HC85% (0.39), (e) DJ (0.55), (f) JSQ60% (0.63), (g) JSQ30% (0.68), (h) BSQ95% (0.77), (i) R-CMJ (0.82) and (j) BSQ85% (0.82). Conclusions: The R-sprint closely matched the timing and magnitudes of the angular variables observed in sprinting. The BSQ85% and R-CMJ exhibited a low kinematic similarity, which identifies that their angular movement patterns are clearly different to sprinting. Further research is needed to evaluate the similarity within joints and muscle groups, in order to ascertain whether muscle moments and muscle activity patterns display the same similarity with kinematics. Practical Applications: The R-sprint exhibited a high level of mechanical similarity, which suggests this exercise, based on the principle of specificity, provides the ideal mechanical stimulus for speed development training programmes. The findings of this study would also suggest that BSQ85% and R-CMJ could be selected for general hip, knee and ankle strength development, but coaches should be aware that they do not offer mechanical similarity with sprinting. Acknowledgments: Carnegie Research Special Conference Fund—Leeds Beckett University.
Sagittal Plane Biomechanics of the Hip and Knee Joint in Two Squat Variations
K. Choe,1 A. Quon,1 M. Vakula,1 R. Dudley,1 D. Pamukoff,1 and S. Lynn2
1California State University, Fullerton, California; 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California
The squat is a commonly used movement and is effective in training programs with multiple goals including performance enhancement, rehabilitation, and general fitness. Although this exercise is effective, multiple variations of the squat exist, which may influence joint loading. As such, it is essential to examine loading characteristics of squat variations for effective and safe exercise programming Purpose: The purpose of this study is to investigate the peak net internal joint moments of the knee and hip in the sagittal plane during the back squat (BS) and front squat (FS) exercise. Methods: Seventeen subjects volunteered to participate in the study (males = 9, females = 8, age 22.8 ± 1.8 years, body mass 76.4 ± 16.7 kg, height 1.70 ± 0.08 m). Participants were experienced squatters who had squatted once a week for the last 3 months, were familiar with FS and BS techniques, had no lower body injury in the last year, and were free from current pain. The study involved 2 visits separated by at least 2 days. During the first visit, subjects' 1 repetition maximum (RM) was evaluated for the FS. During the second visit, 3-dimensional lower extremity kinematics and kinetics were evaluated during 3 repetitions of the FS at 50% 1RM, and 3 repetitions of the BS at 50% 1RM of the FS. The same load was used for both squats to ensure that changes in moments were not due to the external load. A metronome set at 55 b·min−1 was utilized to ensure all squats were of the same cadence. Outcomes included peak internal hip and peak internal knee extension moments on the dominant leg in the sagittal plane. All moments were normalized to the subjects' body mass. A paired sampled t-test was used to compare outcomes between squat techniques. Results: No differences were found between the FS and BS in peak net internal extension moments at the hip (FS = 2.01 ± 2.02 N·m, BS = 3.10 ± 4.64 N·m, p = 0.334) or knee (FS = 2.44 ± 1.27 N·m, BS = 2.90 ± 2.08 N·m, p = 0.115). A strong positive correlation was observed between the internal knee extension moments in the FS and BS (r = 0.878, p < 0.001). Conclusions: Although no differences were found between knee and hip moments during the BS and FS, a strong positive correlation was found between knee moments. Therefore, the FS and BS could be used synonymously with regard to sagittal plane knee and hip joint loading. However, we treat these results with caution, as there could be kinematic and kinetic differences in different planes or at other joints. Practical Applications: Since activities of daily living and in sport require extension of the hip and knee, the squat should be incorporated when designing an exercise program. This study failed to find group differences in sagittal plane knee and hip loading during the FS and BS as there was great variability in the movement patterns selected by each subject in each condition. Therefore, the needs and movement patterns of the individual should be evaluated before prescribing either exercise.
Maximal Jaw Opening Elicits Concurrent Activation Potentiation in Males and Not Females
C. Allen, S. Terrell, S. Carrillo-Chavez, and H. Norrström
Florida Southern College
Introduction: Concurrent activation potentiation (CAP) is defined as the ergogenic advantage of increased force production attained through remote voluntary contractions (RVC) simultaneously with prime mover activation. Maximum jaw clenching is one example of RVC and has been demonstrated to elicit CAP during physical activity involving forceful exertion. Maximum jaw opening has yet to be investigated as a possible method of eliciting CAP. Purpose: The purpose of this investigation was to examine the impact of maximal jaw opening on vertical jump performance and bilateral grip strength assessment. Methods: Twelve male (age 21.4 + 1.7 years; height 176.9 + 7.7 cm; mass 84.9 + 10.6 kg) and 11 females (age 21.1 + 1.6 years; height 165.0 + 6.2 cm; mass 68.4 + 9.9 kg) completed a dynamic warm up followed by vertical jump and grip strength assessments on both dominant and non-dominant hands under 2 experimental conditions: jaw maximally opened and jaw relaxed. The experimental conditions were counterbalanced to eliminate possible order effect with 10 minutes of quiet rest separating testing conditions to ensure recovery. Paired-sample t-tests were used to determine differences between the jaw relaxed and jaw maximally opened conditions. Results: Male participants had significant differences in vertical jump height (p = 0.037), dominant hand grip strength (p = 0.025), and non-dominant hand grip strength (p = 0.018) for the jaw maximally open condition. There were no differences between testing conditions for jump height or grip strength assessments in females (p > 0.05). Conclusions: Maximal jaw opening improved vertical jump performance and bilateral grip strength assessment in men but not women. Practical Applications: Maximally opening the jaw is an effective form of RVC for men but not women in eliciting CAP during activities requiring forceful exertion. Strength and conditioning professionals may encourage maximal jaw opening during plyometric and resistance training in an effort to enhance athlete force production which also may be of particular benefit to athletes who have sensitive teeth and would want to avoid maximal jaw clenching. Although performance was not improved for women during the maximal jaw opening condition, it was also not attenuated. Future research should continue to explore additional activities comparing maximal jaw opening and jaw clenching to elicit CAP in both male and female athletes. Keywords: concurrent activation potentiation, maximal jaw opening, vertical jump, grip strength.
Propulsion and Impact Force Characteristics Between Three Lower Extremity Plyometric Lunge Exercises
D. Hooper, B. Riemann, and G. Davies
Armstrong State University
Plyometric exercises utilize the stretch-shortening cycle to produce larger concentric forces than can be produced without a preceding rapid eccentric contraction. Many studies have reviewed the ground reaction forces that are produced in a wide variety of lower body plyometric exercises, such as horizontal jumps, vertical jumps and drop jumps. However, few data are available for one of the most common lower body exercises, the lunge, and how its variations can impact ground reaction forces. Purpose: To compare the propulsion and impact peak forces between the lunge jump (LJ), scissors (SC), and half scissors (HS) plyometric lunges on the dominant extremity. Methods: Twenty-three physically active adult males (29.5 ± 3.4 years, 87.3 ± 13.1 kg, 178.8 ± 7.9 cm) performed 5 repetitions of each lunge variation (LJ, SC and HS) in a counterbalanced order following a standardized warm-up. Only trunk staying vertical and hands on hips were standardized. The average of 3 repetitions was calculated for each dependent variable, which included impact peak force (IPF), propulsion peak force (PPF), time to peak impact force (TPIF), and time to peak propulsion force (TPPF). All dependent measures were calculated for the dominant limb on AMTI forceplates (Watertown, MA). Statistical analysis were separate one factor repeated analysis of variance. Results: PPF was significantly different between exercises (p = 0.007), with the HS being significantly higher than the LJ (HS: 1.09 ± 0.10 BW vs. LJ: 1.19 ± 0.10 BW). There were no significant differences in PPF (LJ: 1.34 ± 0.24 BW vs. SC: 1.31 ± 0.23 BW vs. HS: 1.42 ± 0.25 BW), TPIF (LJ: 0.25 ± 0.18 seconds vs. SC: 0.31 ± 0.19 seconds vs. HS: 0.22 ± 0.17 seconds) or TPPF (LJ: 0.11 ± 0.03 seconds vs. SJ: 0.13 ± 0.05 seconds vs. HS 0.12 ± 0.04 seconds) between the variations of the plyometric lunge. Conclusions: Ground reaction force differences between variations were much smaller than expected. Some of this may be accounted for by differences in anterior-poster shear forces, therefore future research should consider anterior-posterior shear force differences between variations. Practical Applications: When prescribing lower body plyometric exercises, practitioners should be aware that seemingly subtle variations in common exercises can result in significant differences in impact forces. More specifically, the half scissor variation of the lunge can increase peak propulsion forces. As a result, this variation of the lunge could be used as a progression during rehabilitation from an injury, or as a means to stimulate greater adaptation in uninjured populations.
Smaller Size of Drag Devices and Less Body Immersion Results in Higher Angular Velocities During Aquatic Strength Exercises
N. Triplett,1 S. Borreani,2 J. Furio,2 J. Calatayud,2 S. Pinto,3 V. Tella,2 and J. Colado2
1Appalachian State University; 2University of Valencia; and 3Federal University of Pelotas
It has been established that if movements are performed at the highest volitional speed, muscle activity levels will typically reach equal values during strength training in the aquatic medium with drag devices (DD) of different sizes, refuting the idea that larger DD are necessary for increased aquatic exercise intensity. However, stability of the body in the aquatic environment must be taken into account and is dependent on immersion depth as well. Thus, the optimal size of DD is a combination of being able to maximize speed during movement execution while remaining stable. Purpose: The aim of this study was to determine if there are differences in the angular velocities and angular speeds during shoulder extension at maximal speed performed with 2 different sizes of DD and with 2 different levels of body immersion. Methods: Eight recreationally-trained male university students volunteered for this investigation. After being familiarized with the exercise in the aquatic conditions, the subjects performed 3 repetitions of shoulder extensions at maximum voluntary velocity using 2 different DD (small/large surface area) and at 2 different immersion depths (to the xiphoid process or clavicle). To compare DD size, immersion depth was standardized at the xiphoid process. To compare immersion depth, DD was standardized at the large DD size. The order of conditions was randomized with a recovery time of 90 seconds between conditions. Exercise cadence was controlled by a metronome and each repetition was filmed for each of the 3 conditions. From the sagittal plane, angle of movement of each repetition (shoulder extension from 90° of flexion at 0°) and the time spent in execution was calculated using motion analysis software. A marker on the pisiform bone was applied to determine the position of the arm and another at the pivot point of shoulder joint. Average angular velocity of the 3 repetitions on each of the 3 conditions was measured and angular speed (angular velocity/2π) was calculated. Normality of the data distribution was confirmed using the Shapiro-Wilks test. Comparisons of the conditions were performed using analysis of variance with repeated measures (DD size) and Student's paired t-tests (immersion depth). Significance was set at p ≤ 0.05. Results: Angular velocity (radian per second ± SEM) was significantly lower with the large DD (78.40 ± 3.69) than with the smaller DD (123.73 ± 4.49). In addition, angular speed (radian per second ± SEM) during immersion to the level of the clavicle was significantly lower (60.28 ± 2.49; radian per second ± SEM) than during immersion to the xiphoid process (78.40 ± 3.69). Conclusions: There is an inverse relationship in the size of the DD compared to the maximum volitional speed attained but muscle activation is not as affected unless body stability is compromised in the aquatic environment. Moreover, a lower immersion level guarantees a higher stability of the body, which can result in a higher speed of the exercises performed. Practical Applications: Trainers, who aim to optimize neuromuscular responses to aquatic strength training, should ensure conditions of maximum body stability and sizes of DD that provide high-speed execution.
Comparison and Association of Static and Dynamic Strength Capacities vs. Rapid Limb Velocity Across Three Athletically Distinct Populations
B. Thompson,1 E. Ryan,2 and E. Sobolewski3
1Utah State University; 2University of North Carolina at Chapel Hill; and 3Furman University
Previous studies have shown interrelationships among maximal and rapid strength variables, such as peak torque (PT) and rate of torque development (RTD). However, less attention has been given to the relationship between torque production and velocity-specific measures. Moreover, the influence of elite sport participation type, and gender, may influence the attributes and relationships of these variables due to the unique demands and body mass differences of the sport. Purpose: To compare the absolute and body mass normalized differences among 3 athletically distinct college-aged populations and determine the relationships between maximal and rapid torque vs. rapid velocity capacities. Methods: Thirty-one division I collegiate American football players (mean ± SD; age = 20.6 ± 1.5 years), 17 division I collegiate female soccer players (20.2 ± 1.3), and 22 recreationally active male controls (21.8 ± 1.9) performed strength testing of the right leg extensors on a dynamometer. Participants performed 3 maximum voluntary contractions each for isometric and isokinetic modes of contraction. Isokinetic contractions were performed at 240°·s−1. Isometric measurements included PT and RTD at 50 milliseconds from torque onset. Isokinetic measurements included PT, rate of velocity development (RVD), peak power (PP), and rate of power development at 50 milliseconds (RPD) from onset. RTD, RPD, and RVD were defined as the linear slope of the ascending portion of the torque, power, or velocity curves, respectively, to either 50 milliseconds (RTD and RPD) or terminal velocity (RVD; 240°·s−1). Results: Table 1 presents the absolute and normalized variables for all group comparisons. For the football and control groups, RVD was significantly related to isokinetic PT (r = 0.65 and 0.63; p < 0.01, football and control, respectively), isometric PT (r = 0.66, 0.52; p < 0.01 and 0.02), and RTD (r = 0.81 and 0.60; p < 0.01). For the soccer players, RVD was related to isokinetic PT (r = 0.70; p < 0.01), and RTD (r = 0.48, p = 0.05), but not isometric PT (r = 0.31; p = 0.23). Conclusions: Maximal and rapid torque variables are generally related to the capacity to develop rapid limb velocity for various college-aged populations. The strongest association was for RTD in football players (r2 = 0.66), indicating the high explosive strength demands of football may highly influence strength-velocity relationships. Normalized strength and power variables were lower in soccer players, although normalized RVD was not different, suggesting a relative inferiority in dynamic strength and power production in this group. RPD was the largest discriminator across all groups and may be a useful assessment variable. Practical Applications: Increases in rapid limb acceleration may be achieved by enhancing explosive strength, in various college-aged populations. Enhancing RPD in particular may be an important factor for sport performance, and female soccer athletes may need further focus on strength/power attributes.
Utilizing an Inertial Measurement Unit for Measuring Bat Swing Mechanics: Within and Between Session Reliability
C. Bailey, T. McInnis, and J. Batcher
Introduction: Athlete monitoring appears to be increasingly prevalent in sports. Some published methods of athlete monitoring specifically in baseball include pitch counts and velocities, body composition, and vertical jump testing. Changes in sport performance testing, such as vertical jumping, have been shown to be indicative of fatigue. Similarly, changes in bat swing mechanics may also be indicative of fatigue, but a way to non-invasively and reliably measure bat swing mechanics needs to be developed. Purpose: The purpose of this study was to evaluate the within and between session reliability of an inertial measurement unit (IMU) for analyzing bat swing mechanics. Methods: Sixteen male collegiate baseball players (89.5 ± 12.5 kg, 180.6 ± 6.5 cm, 20.1 ± 0.8 years) participated in this investigation. Each athlete performed 5 swings, hitting a ball off a tee with a bat instrumented with the IMU, on 3 separate days. Variables included: peak velocity at contact, peak hand velocity, time to contact, attack angle, and vertical angle at contact. Relative reliability was calculated by Intraclass Correlation Coefficients (ICC), while absolute reliability was evaluated with coefficients of variation (CV) and limits of agreement. Variables were also evaluated for heteroscedasticity by determining the correlation coefficient between the trial to trial and session to session individual differences and variable means. Results: All data were transformed with the natural log as heteroscedasticity was indicated for most variables. Excellent relative and acceptable absolute reliability was observed of all acceleration/time variables within and between sessions (ICCs 0.88–0.99, CVs 1.85–9.20%). The reliability measures for the gyroscope derived variables were not as consistent (ICCs 0.49–0.88, CVs 11.80%–108.56%). Conclusions: The main finding of this study was that the IMU is a reliable method of monitoring bat swing mechanics from acceleration/time data, but not for the gyroscope derived bat position variables. The lack of reliability in bat position measurement is unfortunate as body position has been shown to be altered by fatigue in vertical jump performance and bat position may also be influenced. Based on the presence of heteroscedasticity, variables for measuring bat swing mechanics also appear have differing levels of variability between those producing higher values than those producing lower values. It should be noted that only one IMU was utilized in this study. Future investigators may wish to compare IMU products from differing manufacturers. Practical Applications: The authors recommend monitoring bat swing velocity measures and time to contact with an IMU as it may signal accumulation of fatigue. However, practitioners should use caution when interpreting baseball monitoring data from players with higher bat swing velocities as they may have potential to produce higher variability. Acknowledgments: The authors would like to thank the LaGrange College baseball team for their involvement in this study. This study did not receive any form of funding from public, private, commercial or other sources.
Effect of Arm and Leg Constraints on Gait Kinetics During Bipedal Acceleration
J. Patel,1 C. Greenleaf,1 and W. Weimar2
1Palmetto Health Orthopedics; and 2Auburn University
Acceleration is an integral role to developing the best overall velocity during competition that involves sprinting. Literature indicates propulsive ground reaction forces assist in greater acceleration and braking ground reaction forces yield lower increases in acceleration, however, little research has focused on the effects of arm and leg constraints on these reactive forces and impulses. Purpose: The purpose of this project was to investigate the differences in ground reaction forces in response to different constraint conditions on the body. Methods: Fifteen club-level male rugby players (22 ± 2.85 years, 182 ± 6.4 cm and 77.95 ± 10 kg) volunteered following consent to participate. Participants completed 12 total bouts of a 10 m sprint for 4 different constraint conditions and control. The following conditions were randomized before completion: Normal (N), constrained upper arm (CUA), constrained full arm (CFA) and constrained hip (CH). Each participant completed 3, 10 m sprints for each of the 4 conditions. Peak vertical ground reaction force and impulse (VGRFPEAK and VGRI) data were collected at the fourth step, which was also on the right foot for the participants. In addition, Peak braking and propulsive ground reaction forces (BGRFPEAK and PGRFPEAK) and impulses (BGRI and PGRI) were investigated. Results: Data from the current study is shown in Table 1. CH yielded a significant decrease of BGRFPEAK when compared to condition N (F(1,14) = 18.225, p = 0.001, η2 = 0.566, Power = 0.977) when compared to condition N (312.9 ± 0.163.4 N and 488.8 ± 232.2 N, respectively). In addition, CH yielded a significant decrease of BGRI (F(1,14) = 5.852, p = 0.030, η2 = 0.295, Power = 0.615) when compared to the control (7.1 ± 6.1 N·s and 14.6 ± 14.6 N·s, respectively). Conclusions: The results indicate there were no significant changes between conditionings on braking and propulsive forces and impulses. It can be noted that the center of gravity from the athlete plays a more significant role than the position of the limbs in decreasing braking forces and increasing propulsive forces. Practical Applications: To increase horizontal velocity, an athlete must have the ability to increase the amount of force being applied to the ground, in turn, increasing the amount of force coming back to the athlete. Though no significance was noted for VGRFPEAK, the values were greatest during N condition supporting literature that athletes running at higher velocities exhibit greater VGRFPEAK. The main purpose in investigating the effects of constraints is to further investigate the effects of arm swing and the thoracolumbar fascia line on the posterior chain with their roles in bipedal acceleration.
Effects of a 4-Week Whole Body Vibration on Postural Stability
J. Hong,1 Y. Choi,2 Y. Kang,1 and E. Choi1
1Kookmin University, Seoul, South Korea; and 2Korea Institute of Sport Science
Whole body vibration (WBV) training has been shown to improve neuromuscular control. Among the related variables, postural stability is one of them. Despite many studies have shown the similar results, the exact mechanisms of how WBV training induces such an improvement are not clearly understood. Rambling (RM) and trembling (TR) have been introduced as the static postural stability related variables that can be used to decompose the COP trajectory during the postural sway into 2 components. RM and TR are known to be the supraspinal and spinal processes for analyzing static postural stability. Dynamic postural stability can be measured by time to stabilization (TTS) that examines the length of time it takes to return to a baseline during jump and landing tasks. No previous studies have examined the effectiveness of WBV training on the both of static and dynamic postural stabilities. Purpose: The primary purpose of this investigation was to analyze the effects of a 4-week of WBV training on static and dynamic postural stability with the parameters of RM and TR and the TTS, respectively. A secondary aim was to investigate how the neuromuscular effectiveness of WBV mechanism contributes to the static and dynamic postural stabilities. Methods: Twenty healthy volunteers were randomly assigned into WBV group (WG, n = 10, 25.4 ± 2.0 years, 177.7 ± 5.6 cm, 76.3 ± 9.1 kg) and control group (CG, n = 10, 25.0 ± 2.7 years, 172.8 ± 4.7 cm, 71.4 ± 5.0 kg). Static postural stability of each subject was tested under 4 conditions: quiet standing with eyes open (EO), quiet standing with eyes closed (EC), single leg standing with dominant leg (DL), and single leg standing with non-dominant leg (NL). Path length (LEN), root mean square (RMS), range (RA), mean velocity (MV), area, and total mean velocity (TMV) of COP, RM, and TR trajectory were measured. All subjects performed TTS protocol for dynamic postural stability. TTS protocol consisted of a single leg landing from a jump height equivalent to 50% of maximum jump with a starting position the leg length of participant from center of force plate. The subjects in the WG visited to laboratory 3 times per week and received total 12 sessions of WBV training for 4 weeks. WBV training consisted of 3 bouts of 1 minute (30 Hz, 2 mm) with 1-minute break between the bouts. Results: For the static postural stability, there were no significant differences observed under the EO, EC, and DL conditions. The measured parameters of COP, RM, and TR trajectory showed a statistically significant main effect in the both of anterior-posterior (AP) and medial-lateral (ML) direction under the NL condition. The LEN of COP (15.37%; F(1,18) = 5.106, p = 0.036) and TR (15.75%; F(1,18) = 5.130, p = 0.036), the MV of COP (15.12%; F(1,18) = 4.892, p = 0.04), RM (16.25%; F(1,18) = 4.669, p = 0.044), and TR (15.74%; F(1,18) = 5.086, p = 0.037), and the TMV (17.28%; F(1,18) = 4.735, p = 0.043) in ML direction and the LEN of RM (12.89%; F(1,18) = 7.417, p = 0.014) and the MV of RM (12.68%; F(1,18) = 7.247, p = 0.015) in the AP direction were significantly shorter and slower in the WG. For the dynamic postural stability, there were no statistically significant findings were associated with the all directions of TTS (p > 0.05). Conclusions: A 4-week WBV training decreased the length and velocity of sway indicating that a better static postural stability in non-dominant single leg standing. However, the single leg landing for TTS was not shown any improvement for dynamic postural stability. Our findings suggest that constant long-term WBV training have a significant effect on static postural stability. Practical Applications: Since stability is considered one of important factors for athletic performance and many activities of daily living, special populations such as injured individuals, elders, etc. are required stability training for performance enhancement, rehabilitation, or injury prevention. WBV is simple and easy to use in any environment for these special populations. Strength and conditioning professionals are encouraged to emphasize the WBV training when attempting to design training programs. Acknowledgments: This research project was supported by the Sports Promotion Fund of Seoul Olympic Sports Promotion Foundation from Ministry of Culture, Sports and Tourism.
Evaluation of the Functional Movement Screen as an Injury Prediction Tool for Collegiate Basketball Players
C. Bond,1 J. Dorman,1 T. Odney,2 S. Roggenbuck,2 S. Young,2 and T. Munce1
1Sanford Orthopedics and Sports Medicine/Sanford Research; and 2Sanford Orthopedics and Sports Medicine
Identifying injury risk and implementing preventative measures can reduce injury occurrence and improve performance. Improper movement patterns and biomechanical deficiencies often contribute to the most common musculoskeletal (MSK) injuries in athletes. The Functional Movement Screen (FMS) was created to identify limitations and asymmetries in movement that purportedly affect optimal function. The FMS has subsequently been studied and recommended as an injury risk assessment; however, its validity as an injury prediction tool remains unclear, particularly among specific athletic populations. Purpose: This prospective cohort study examined the association of FMS scores and injury occurrence in collegiate basketball players over a competitive season. It was hypothesized that players with an FMS score ≤14, a frequently used cut-off value, would have a higher risk for injury. Methods: Fifty-six female (20.2 ± 1.4 years, 1.77 ± 0.05 m, 71.2 ± 7.8 kg) and 63 male (21.0 ± 1.4 years, 1.91 ± 0.08 m, 88.1 ± 11.0 kg) NCAA division II collegiate basketball players from 4 upper Midwest schools participated in this study. Pre-season FMS assessments were performed by the same rater in accordance with published instructions. Health history and in-season injury records were collected from the athletic trainers at each respective school. In-season injuries were classified by type (MSK, concussion, etc.) and severity, according to days of lost participation (0 days, 1–9 days, and ≥10 days). Data for women and men were pooled for analyses. Using a FMS cut-off score of ≤14 for a positive test indication, sensitivity, specificity, and odds ratio (OR) values were calculated using standard diagnostic testing methods. T-tests were used to compare the uninjured to injured players' scores. Results: The mean FMS score for all players was 15.7 ± 1.4 (range 11–20). Fifty-six players were injured during the season, resulting in 96 total injuries. The mean FMS score for uninjured and injured players was 15.8 ± 1.4 and 15.7 ± 1.4, respectively (p = 0.69). Fourteen players sustained a musculoskeletal injury causing ≥10 days of lost participation. When all accrued injuries were included in the analysis, the FMS had a sensitivity of 0.14 (95% CI: 0.06–0.26), a specificity of 0.86 (95% CI: 0.75–0.93), and an OR of 1.00 (95% CI: 0.35–2.79). When considering only the MSK injuries that resulted in ≥10 days of lost time, the FMS also had a sensitivity of 0.14 (95% CI: 0.02–0.43), a specificity of 0.86 (95% CI: 0.78–0.92), and an OR of 1.00 (95% CI: 0.20–4.92). Discussion: While specificity was relatively high, low sensitivity indicates that the FMS is limited in its ability to accurately identify collegiate basketball players who are at an increased risk for injury (non-specific or MSK). Differences between this investigation and others may be related to the populations studied. The mean FMS scores in the current study were in the upper range of what has previously been reported. Thus, using a cut-off score specific to this population may have resulted in higher sensitivity and specificity measures. Practical Applications: Although the FMS may be suitable for identifying MSK limitations and asymmetries, it does not accurately determine injury risk in collegiate basketball players. Injury risk assessments may be improved by targeting movement deficiencies related to injury mechanisms and being more specific to the demands of an athlete's sport.
The Relationship Between Strength and Lower Extremity Landing Patterns in Young Adult Males
K. McCurdy, and J. Walker
Texas State University
The purpose of this study was to compare the relationship between several measures of isometric and squat strength and unilateral and bilateral landing mechanics at the hip and knee. Twelve healthy male subjects with previous athletic experience (height 179 ± 5.6 cm, mass 86.5 ± 10 kg, age 21.4 ± 1.7 years) participated in this study. Three-dimensional hip and knee flexion and knee valgus were measured using electromagnetic sensors during bilateral (60 cm) and unilateral drop jumps (30 cm). On a separate day, isometric hip extension, external rotation, and abduction along with knee extension and flexion strength (lbs) were measured using a handheld dynamometer. Pearson Product-Moment correlations revealed that hip extension strength was significantly correlated with peak bilateral hip flexion (r = 0.64, p = 0.048) while hip abduction strength was significantly correlated with bilateral knee valgus (r = −0.60, p = 0.040). Knee extension/hip extension strength ratio was significantly correlated with unilateral hip flexion (r = −0.72, p = 0.018). Squat strength was also measured using free weight. The strongest correlations were found between squat strength and knee valgus (−0.77 ≤ r ≤ −0.83) and hip adduction (−0.5 ≤ r ≤ −0.65). After controlling for squat strength, hip external rotation strength and unilateral knee valgus (−0.41), hip abduction strength and bilateral knee valgus (−0.43), and knee flexion strength and bilateral hip adduction (−0.57) remained significant. Eccentric knee flexion strength and unilateral knee internal rotation was the only significant correlation for eccentric strength (−0.40). Squat strength appears to be the best predictor of knee valgus and was consistently related to hip adduction. Isometric and eccentric measures demonstrated few significant correlations with hip and knee excursion while demonstrating a low to moderate relationship. Hip and knee flexion and rotation do not appear to be related to strength. Squat strength should receive consideration during risk assessment for non-contact knee injury.
The Effect of Initial Knee Angle on Concentric Only Jump Squat Performance
D. Chapman,1 L. Mitchell,2 C. Argus,3 and J. Sheppard4
1Australian Institute of Sport; 2Queensland Academy of Sport; 3Brumbies Rugby Union Club; and 4Canadian Sport Institute
Purpose: Currently, there is uncertainty at which depth of a squat jump (SJ) that produces maximal jump performance. Importantly, understanding this information will aid in determining appropriate ratios for the assessment and monitoring of the explosive characteristics of athletes. Therefore, this study compared SJ performance across a range of different knee angles and a self-selected depth for jump height and other kinetic characteristics. For comparison between SJ (an unconstrained dynamic movement), participants also performed a counter-movement jump (CMJ) from a self-selected depth. Methods: Sixteen participants (age 24.9 ± 3.4 years; height 1.8 ± 0.07 m and weight 78.4 ± 10.3 kg) were recruited and tested for their SJ performance. Prior to each testing session participants completed a standardised warm up consisting of 5 minutes cycling at a self-selected intensity, dynamic lower limb stretches, three 10 m running efforts (70, 80, 90% maximal effort), and 3 sets of 4 SJ (80, 90, 100% maximal effort). Participants were then fitted with an electronic goniometer (Measurand Inc., Fredericton, NB, Canada) attached to the lateral side of their left leg using a series of anatomical landmarks. The position of the goniometer was checked prior to and following each jump. The knee angle was displayed on a monitor directly in front of the participant throughout the session, except for the self-selected squat depth in which the participant was blinded to the knee angle. One final warm up set of self-selected depth SJ was then completed. Each participant performed 3 CMJ at a self-selected knee angle. Next, participants performed 3 SJ at knee angles of 90, 100, 110, 120, 130°, and a self-selected knee angle using a Latin Square (randomisation) design. Each of the 3 jumps at each knee angle was separated by 15 seconds with, 3 minutes rest separating each set at each knee angle. A portable force plate (9290AD Quattro Jump, Kistler, Switzerland) and a linear position transducer (Ballistic Measurement System, Fitness Technology, Adelaide, Australia) were interfaced using a PowerLab (ADInstruments, Sydney, Australia) data acquisition system sampling at 200 Hz to record ground reaction forces and vertical displacement. The linear transducer was attached to a lightweight (0.4 kg) aluminium bar that was positioned across participant's shoulders to remove the effect of arm swing. The force plate and linear transducer were calibrated with known weights and distances prior to each testing session. Results: In the SJ maximal jump height (35.4 ± 4.6 cm) was produced using a self-selected knee angle, however differences between 90 and 100°, and self-selected knee angles were trivial (0.8–2.1 cm) and not significantly different. Differences between all other knee angles ranged from small (3.8 ± 2.0 cm; 90% CL) to large effect sizes (16.6 ± 2.2 cm). Conclusions: This investigation reports that the use of a self-selected depth in the SJ results in optimal performance and has only a trivial difference to a constrained squat depth of either 90 or 100° of knee flexion. A self-selected squat depth produced the greatest jump height (but was only trivially different from a 90 or 100° knee angle), suggesting that there may be an innate ability to determine the optimal depth for SJ performance. As such, it is appropriate for practitioners to utilize a self-selected depth to monitor athletic qualities using the SJ. Practical Applications: The use of a self-selected depth of squat jump as part of a regular monitoring routine will speed up the process while retaining the necessary high level of data integrity required for making informed actionable decisions for use in athlete programming.
Elevated Heel Heights Effects During Near Maximum Lifting
B. Romer, H. Lu, Z. Harris, and J. Trammell
Louisiana Tech University
During the past few decades, elevated heel heights have become a common fixture in many types of recreational and sport related footwear. As footwear design for these activities varies widely, especially with regards to heel height differentials, generating a greater understanding of heel heights on lower extremity coordination is necessary. Previous research has indicated an increased heel height led to altered trunk kinematics during the execution of a barbell squat. Elevated heel heights have also been shown to alter peak lower extremity kinematics and maximum acceptable weight of lifts (MAWOL), likely due to differences in muscle activation and interjoint coordination patterns. Purpose: The purpose of the present study was to examine the influence of elevated heel heights on lower extremity coordination during the execution of a near maximal effort barbell back squat. Methods: Twelve (age = 23.3 ± 3.3 years) resistance trained participants (males, n = 6; females, n = 6) took part in a randomized protocol of 3 repetitions at 75% of their maximal effort barbell squat at a 0, 5, 10, or 15° incline. Participants performed 3 consecutive repetitions during each condition, followed by 5 minutes of rest. Heel height was adjusted to the designated heel height through custom-made wooden-lifting platforms set to specific incline levels (0, 5, 10, and 15%). Sagittal plane kinematics were collected through a single Basler Scout camera recording at 100 Hz and processed through MaxTRAQ2D (Innovision Systems, Inc., Columbiaville, MI, USA). A custom Matlab program (The Mathworks, Inc., Natick, MA, USA) was utilized to determine the continuous relative phase (CRP) ratios of the thigh-shank during each condition, with sagittal plane joint angles and velocities calculated for 3 squat cycles to determine the CRP mean and the deviation phase (DP) of the thigh-shank. Separate repeated measures ANOVA's were completed, with dependence on the CRP mean and DP. Results: Results indicated no significant differences in the CRP mean or DP of the thigh-shank during lifting gradients. Descriptive statics indicate that individuals tend to display a more out-of-phase coordination pattern (Average Eccentric CRP mean: −495.8; Average Concentric CRP mean: −563.1°) and greater coordination variability (Average Eccentric DP: 47.8°; Average Concentric DP: 64.7°) during concentric motions as opposed to eccentric motions. Conclusions: The results of the present study suggest that elevated heel heights have no significant effects on coordination patterns or coordination variability; however, descriptive statistics indicate a multivariate effect may be present may exist when examining the muscular contraction patterns. Practical Applications: A vital component of performance training is the cyclical nature of eccentric and concentric muscle actions. Greater eccentric motion involved in squat like motions are often associated with a greater influence of exercise induced muscle damage (e.g., delayed onset muscle soreness). The present study indicates that heel heights commonly found in many commercially available footwear designs do not significantly alter lower extremity coordination patterns; however, future research is needed to examine the potential role of muscular contractions on coordination variability.
Asymmetries in Knee Extension Strength Do Not Correlate With Sagittal Plane Knee Landing Mechanics in Resistance Trained Men
J. Rosengarten,1 J. Arevalo,2 S. Lynn,1 J. Spencer,2 L. Brown,1 P. Costa,1 and A. Galpin2
1California State University, Fullerton, California; and 2Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California
Poor landing mechanics are often a result of weak lower body musculature. Yet, no study has compared knee-landing mechanics from a drop vertical jump to knee extension strength. In addition, no study has examined these variables in relation to leg dominance. Purpose: To examine the relationship between landing mechanics, knee extension strength, and leg dominance in resistance-trained men.