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
1 Applied Physiology Laboratory, University of North Texas; 2 Louisiana State University Health Science Center; 3 Institute for Exercise and Environmental Medicine; and 4 University 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
1 Department of Exercise and Health Sciences, University of Taipei; 2 Department of Exercise and Health Sciences, University of Taipei, Taiwan; and 3 Department 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
1 The Citadel–The Military College of South Carolina; 2 East Tennessee State University; and 3 East 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
1 University of Kansas; and 2 Kansas 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 (R 2 = 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 (R 2 = 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
1 Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California; 2 Biochemistry and Molecular Exercise Physiology Laboratory, Department of Kinesiology, California State University, Fullerton, California; and 3 Muscle 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
1 Texas Christian University; 2 University of Wisconsin—La Crosse; and 3 George 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
1 Department of Exercise and Health Science, University of Taipei; 2 Department of Chinese Martial Arts, Chinese Culture University; 3 Physical Education Office, National Taipei University of Technology; and 4 Department 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
1 Upper Iowa University; and 2 University 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
1 University of North Texas; 2 Applied Physiology Laboratory, University of North Texas; 3 Uniformed Services University; 4 University of Arkansas; 5 EXOS; and 6 University 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
1 Applied Physiology Laboratory, University of North Texas; 2 Louisiana State University Health Science Center; and 3 University 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
1 The University of Oklahoma; and 2 University 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
1 Philadelphia University; and 2 Seton 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
1 University of Oklahoma; and 2 The 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; r 2 = 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; r 2 = 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
1 University of North Carolina Chapel Hill; 2 University of North Carolina at Chapel Hill; 3 Department of Defense; and 4 Under 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
1 University of Alabama; 2 Catawba College; and 3 Life 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
1 The University of Memphis; and 2 University 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
1 University of Alabama; and 2 Life 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
1 Norwegian School of Sport Sciences; and 2 University 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
1 Department of Exercise and Health Sciences, University of Taipei, Taiwan; 2 Department of Sports, Taipei City Government, Taipei, Taiwan; and 3 Department 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
1 University of Kansas; 2 Eastern Kentucky University; and 3 Dynamic 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
1 University of Mississippi; and 2 California 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
1 Palmetto Health Orthopedics; and 2 Auburn 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
1 Western Michigan University; and 2 University 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
1 University of North Carolina at Chapel Hill; 2 University of Missouri; and 3 Truman 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
1 University of North Carolina—Wilmington; and 2 University 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 [r 2 = 0.346; SEE = 31.4 W; p = 0.021]) and only TLM to AWC (AWC = 0.8 [TLM] + 3.7 [r 2 = 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
1 EMT Brazos County; 2 Texas A&M University; and 3 United 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
1 Texas A&M University; 2 EMT Brazos County; and 3 United 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
1 Texas A&M University; 2 EMT Brazos County; and 3 United 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
1 Texas A&M University; 2 EMT Brazos County; and 3 United 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
1 Texas A&M University; 2 EMT Brazos County; and 3 United 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
1 Graduate Institute of Physical Education, Health & Leisure Studies; 2 Kun Shan University; and 3 National 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
1 Hofstra University; 2 Sacramento Metropolitan Fire District; and 3 University 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
1 University of Kentucky; 2 Hofstra University; and 3 University 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
1 Sacramento Metropolitan Fire District; 2 University of Kentucky; 3 Louisiana Tech University; and 4 Texas 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
1 Human Performance Laboratory, Center for Sport Performance, California State University, Fullerton, California; 2 Muscle Physiology Laboratory, Department of Kinesiology, San Francisco State University; 3 Human Performance Research Laboratory, California State Polytechnic University, Pomona, California; 4 Department of Psychology, California State University, Fullerton, California; and 5 Department 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
1 Applied Physiology Laboratory, University of North Texas; 2 University of Connecticut; 3 University of Arkansas; 4 Midwestern State University; and 5 University 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
1 University of North Texas; 2 Applied Physiology Laboratory, University of North Texas; 3 University of Connecticut; 4 Uniformed Services University; 5 Midwestern State University; and 6 EXOS
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
1 Chonnam National University; 2 Mokpo National Maritime University; 3 Center for Sports Science in Gwang-Ju; 4 Korea Red Cross in Gwang-Ju and Channam; and 5 Center 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
1 Chonnam National University; 2 Mokpo National Maritime University; 3 Center for Sports Science in Gwang-Ju; 4 Korea Red Cross in Gwang-Ju and Channam; and 5 Center 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 1 Exercise and Health Science; 2 Martial Arts, University of Taipei, Taiwan; and 3 Department 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
1 Georgia Southern University; 2 Bodybuilding.com; 3 The Ohio State University; and 4 Ohio 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
1 Department of Exercise and Health Sciences, University of Taipei, Taiwan; 2 Department of Sports, Taipei City Government, Taipei, Taiwan; and 3 Department 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
1 Illinois State University; and 2 Michigan 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
1 Georgia Southern University; and 2 Georgia 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
1 Human Performance Research Laboratory, Department of Kinesiology and Health Promotion, California State Polytechnic University Pomona, Pomona, California; and 2 Human 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
1 Auburn University; and 2 Columbus 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
1 California State University, Fullerton, California; 2 Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California; and 3 Graduate 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
1 Chonnam National University; 2 Mokpo National Maritime University; 3 Center for Sports Science in Gwang-Ju; and 4 Korea 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
1 UNC-Chapel Hill; 2 University of North Carolina at Chapel Hill; 3 Furman University; and 4 Utah 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
1 Texas Tech University; and 2 Utah 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 (R 2 = 0.254, F = 9.91, p = 0.005), peak jump velocity (R 2 = 0.149, F = 4.74, p = 0.038), and agility (R 2 = 0.273, F = 10.14, p = 0.004). Interestingly, both VL (R 2 = 0.307, F = 11.98, p = 0.002) and RF (R 2 = 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 (R 2 = 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
1 University of Arkansas; 2 Louisiana Tech University; and 3 University 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
1 St. Mary's University; 2 Cardiff Metropolitan University; 3 University of Gloucestershire; and 4 Cincinnati 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
1 Brown University; and 2 Rhode 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
1 Montana State University—Northern; 2 Tennessee State University; and 3 Idaho 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
1 Appalachian State University; and 2 University 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
1 Catawba College; 2 University of Alabama; 3 University of Montevallo; and 4 Pacific 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 R 2 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 (R 2 = 0.252); Quarterbacks (R 2 = 0.326); Tight Ends (R 2 = 0.979); Offensive Linemen (R 2 = 0.144); Wide Receivers (R 2 = 0.212); Defensive Linemen (R 2 = 0.317); Linebackers (R 2 = 0.705); and Defensive Backs (R 2 = 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 R 2 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
1 Louisiana Tech University; and 2 University 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
1 Human Performance Laboratory, California State University Fullerton, Fullerton, California; and 2 Department 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
1 Sale Sharks RUFC; and 2 University 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 (R 2) 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 (R 2) 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
1 University of Houston—Clear Lake; and 2 University 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
1 Adams State University; and 2 Canadian 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
1 Human Performance Laboratory, California State University, Fullerton, California; 2 Department of Kinesiology, Center for Sport Performance, California State University, Fullerton, California; and 3 Human 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
1 Human Performance Laboratory, California State University, Fullerton, California; and 2 Department 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
1 Human Performance Laboratory, California State University, Fullerton, California; and 2 Department 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
1 University of Alabama; and 2 Catawba 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
1 Univsersity of Alabama; and 2 St. 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
1 University of Wisconsin—La Crosse; 2 George Mason University; and 3 Texas 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
1 Texas Christian University; 2 University of Wisconsin—La Crosse; and 3 George 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
1 Providence Hospital; and 2 University 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 ma