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Original Research

Acute Performance Enhancement Following Squats Combined With Elastic Bands on Short Sprint and Vertical Jump Height in Female Athletes

Krčmár, Matúš; Krčmárová, Bohumila; Bakaľár, Igor; Šimonek, Jaromír

Author Information
Journal of Strength and Conditioning Research: February 2021 - Volume 35 - Issue 2 - p 318-324
doi: 10.1519/JSC.0000000000003881
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Abstract

Introduction

Short-term or acutely improved physical performance through the neuromuscular system is known as postactivation potentiation (PAP) (24) or by a new term PAPE that refers to postactivation performance enhancement (9). To date, there have been a number of potential mechanisms proposed to explain this phenomenon (5,15,26,32,33). In short, among all of the potential mechanisms (e.g., myosin light chain phosphorylation, muscle temperature, muscle blood flow/water content, muscle pH, muscle activation, and muscle-tendon stiffness) PAP can be still largely explained by myosin light chain phosphorylation but still with a minor contribution of the other aforementioned mechanisms (5).

For clarity, the term PAPE will be used as performance enhancement is the goal of this article. Several research studies have examined the efficacy of different PAPE protocols, whereas some found significant improvements in muscular strength (3), running speed (6,22), vertical jump performance (22,33), isometric force (17); however, some did not find any changes in running speed and vertical jump height (30,36). These conflicting results could be explained by factors such as the specific conditioning activity used, the rest interval between the conditioning activity and the performance activity, and the training status of the subjects, and these factors should reflect the choice of PAPE protocol used (33,35).

Interestingly, only a few studies examined the acute effects of PAPE including variable resistance by using elastic bands (25,37). The rationale for using of elastic bands is based on several factors, including increasing muscular activity during the eccentric phase with a better transition to concentric and thus possibly an increased rate of force development (27), overcoming the sticking point (16), and potentially accelerate or overload the top of the range of motion (23). For instance, Wallace et al. (34) examined the effect of a back squat with elastic bands where 35 and 20% of the total load at 60 and 85% of 1 repetition maximum (1RM), respectively, was provided by elastic bands. A significant increase (p < 0.05) in peak power and peak force was observed mainly when the higher total load (85% of 1RM with 20% provided by elastic bands) was used. However, when similar protocols were applied with the intention to elicit PAPE effects, it seems that it can positively improve short sprint performance (37), peak power, peak force, vertical jump height (25), and broad jump distance (28). For instance, Wyland et al. (37) examined the effects of back squats with elastic bands on 9.1-m sprint time. Significant improvements (p = 0.002) were recorded after performing back squat accompanied with elastic bands 4 minutes after the last set of PAPE. Also, significant improvements after incorporating elastic bands to back squat and deadlift PAPE protocols were seen in rugby players in the standing broad jump distance (28).

Based on previous research, most studies were performed on men, and no study has addressed the application of PAPE with elastic resistance in trained women. Furthermore, PAPE protocols and set-rep configuration used in this study (the relative load 85% of 1RM with 3 sets and 4 reps with or without elastic resistance) were chosen based on previous studies (35) because it seems to be optimal volume and intensity to achieve PAPE. Short sprint distances were performed with the intention to potentially avoid more demanding testing such as maximal running speed, whereas repeating this type of test may also act as a confounding factor/potentiating stimulus. Although previous authors have not identified any sex effects with female athletes using PAPE protocols, no previous research have used elastic bands in the conditioning protocols.

Methods

Experimental Approach to the Problem

A randomized repeated-measures design was implemented. Subjects visited the laboratory 6 times. During the first visit, 1RM in the back squat was performed. The second visit, after 72 hours of rest, subjects performed technical familiarization where adjustment of elastic bands was performed. This was performed by using a force plate device to achieve 20 or 30% of total resistance coming from the bands by measuring vertical ground reaction forces at the top of the back squat range of motion (i.e., the comparable average load to the isoinertial load at 85% of 1RM). Thereafter, subjects performed isoinertial (ISO), variable 20 (BAND20), variable 30 (BAND30), and control (CON) conditioning PAPE protocols on separate days with at least 72 hours of rest between sessions. Short sprint performance over 3, 5, and 10-m as well as squat jump (SJ) and countermovement vertical jump height (CMJ) were measured before as well as 5 and 10 minutes after the last set of parallel back squat with individualized isoinertial, variable, or control conditioning (Figure 1). Strong verbal encouragement to the athletes was given during each PAPE protocol across all sets and tests.

Figure 1.
Figure 1.:
Schematic illustration of study design.

Subjects

Fourteen female athletes (None of the subjects was under 18 years old; age: 22 ± 2.3 years; body mass [BM]: 66.2 ± 6.2 kg; 1.78 ± 6 m; back squat relative 1RM: 1.96 ± 0.14 kg·kg−1 BM; training experience: 5 ± 2 years; ± SD) volunteered to participate in this study; of whom 7 were volleyball players, 2 track and field athletes, 1 handball and 1 soccer player, and 3 CrossFit athletes. Inclusion criteria consisted of the following: (a) no actual and recent neuromuscular injuries, (b) no cardiovascular disease, and (c) no orthopedical limitations that could affect health and also the results of the measurements. At the beginning of the study, 20 subjects were enrolled, but because of missing one or more PAPE sessions due to injury during their matches or inability to produce maximal performance as a consequence of menstrual cycle they were excluded. All stimulants (e.g., caffeine) were prohibited on the day of all experimental procedures. Subjects were informed about the study design, potential benefits, and research-related risks. All subjects signed a written informed consent form. This study was approved by the Institutional Review Board of the Constantine the Philosopher University in Nitra in Slovakia ethics committee and conducted according to the Declaration of Helsinki.

Procedures

All physical tests, PAPE, and control protocols were performed in the same laboratory with controlled temperature and humidity as well as the same squat rack and running surface.

One Repetition Maximum Test

Back squat 1RM was performed in a controlled manner with 2 spotters on both sides of the barbell. Squat depth was set at a knee joint angle of 85–90° (full extension = 180° knee angle) controlled with a goniometer, and this was also the same depth that was used in the PAPE protocols. At first, subjects performed 3 repetitions at 50, 70, and 80% of self-predicted 1RM. This approach was preceded by an individual warm-up. After performing 3 repetitions on each load, subjects then attempted the predicted 1RM load. When the subject successfully completed the lift, the load was raised by 5 kg, and, conversely, when they failed to lift the selected load, 5 kg was decreased before the subsequent trial. The successful trial with the greatest load was recorded as 1RM. The maximal number of trials that were allowed to reach 1RM was 5 (3 trials were sufficient for most athletes). The rest interval between maximal trials was 4–5 minutes. All testing was performed using a standard Olympic barbell.

Adjustment of Elastic Bands

Adjustment of elastic bands was based on the studies by Wallace et al. (34) and Baker (2). The subject stood on a force plate where barbell height was measured in fully extended posture. It was estimated that 85% of 1RM will be used in the PAPE protocols with 20% (BAND20) and 30% (BAND30) of total resistance coming from bands. Resistance produced by elastic bands (10 and 15% of total elastic resistance) was removed from the loaded barbell so that lighter total resistance was obtained at the bottom position of the back squat and heavier total resistance was obtained at the top of the back squat. When comparing PAPE protocols, it was important to normalize this load to achieve the same average vertical force as during the isoinertial trials. Vertical force during the back squat was measured using a 2D force plate (Fitro Force Plate, Bratislava, Slovakia). Before each measurement, the force plate was calibrated according to the manufacturer's instructions. The elastic bands used (Power Gears, Bratislava, Slovakia) were new, so there were no modifications of their elasticity and stiffness due to prolonged usage. Different bands and their adjustment on the rack were individually tailored for each athlete depending on their strength level and height (Figure 2).

Figure 2.
Figure 2.:
Back squat with elastic bands adjustment depending on required tension individually for each athlete. A) Top back squat position and (B) bottom back squat position.

Postactivation Performance Enhancement Protocols

On 4 separate days, different PAPE protocols were applied in a randomized order with at least 48–72 hours of rest between each test session. Postactivation performance enhancement protocols consisted of isoinertial protocol (ISO), variable 20 (BAND20), and variable 30 (BAND30) where subjects performed 3 sets of 4 repetitions of the back squat using a load of 85% of 1RM (ISO) or 85% of 1RM where 20% (BAND20) or 30% (BAND30) of the total load was accompanied by elastic bands. The rest interval between sets was 2 minutes. During the control protocol (CON), subjects performed the same testing but only maintained low-level physical activity (walking) for a similar duration as the PAPE protocols (i.e., 5 minutes +5 minutes for retesting). Before baseline testing and the application of all PAPE and CON protocols, all subjects performed a standardized warm-up. The standardized warm-up consisted of initial cycling on a stationary bicycle ergometer with a load set at 1 W per kilogram of subject's BM (Elevation Series Lifecycle, LifeFitness). Subjects cycled for 6 minutes, and after that mobilization exercises were performed, which included foam rolling of calves, hamstrings, glutes, quadriceps, and back muscles. Rolling occurred for a duration of 20 seconds per muscle in 1 set. After foam rolling, subjects performed dynamic stretching exercises that mimic PAPE protocols and tests as well as included movements of shoulders, back, hips, knees, and ankles. Dynamic stretching took place for a duration of 8 minutes. In addition, this warm-up procedure was based on the athletes' own experiences, and they use a similar approach in their own training routines. Such a warm-up was intended to ensure that it did not include unfamiliar exercise nor have a negative impact on the resultant physical performance.

Physical Performance Tests

Standard physical performance tests were selected to determine the potential effects of PAPE protocols. Squat jump and CMJ tests were selected to measure the explosive vertical ability of the lower limbs. Both tests were performed with hands placed on the hips and with the intention to jump as high as possible. All subjects performed 2–3 trials, and the best trial was recorded for further analysis. Thirty seconds of rest was allowed between individual jumps in both variations. During the SJ testing, subjects were also asked to lower their hip until a knee angle 85–90° was achieved and remain in this position for 2–3 seconds before executing vertical jumps. No countermovement before the execution of jump was permitted. During the CMJ, the depth was self-selected. All jumps were performed on a force plate (Fitro Force Plate) with a sampling frequency of 1,000 Hz with an absolute value of 5 N used to identify both takeoff and landing during the jump. Vertical jump height was calculated by using flight time (the period between takeoff and contact after landing). Time in the air was then used in the following equation: jump height = FT2 × g/8. Data showed good and excellent intrasession test-retest reliability expressed by an intraclass correlation coefficient (ICC) (ICCSJ = 0.80, ICCCMJ = 0.90). Short sprint distances over 3, 5, and 10-m were performed from a standing stationary position, which was consistent across the trials and testing sessions. The front foot was placed first behind the starting line. Subjects were notified of the time limit to begin each sprint, but they started on their own initiative. A self-selected start was chosen to avoid any reaction time discrepancies such as false start or stress-related factors that could affect the results. All distances were measured simultaneously as split times. A maximum of 2–3 trials was allowed with a maximum of 40 seconds rest between trials. The best time was recorded for further analysis. All the measures of short sprint performance were performed using an infrared system (Witty, Microgate, Bolzano, Italy) with ICC ranging from 0.85 to 0.91. Timing gates were positioned at hip height individually for each athlete. The order of performance tests was randomized to control for cofounding effects of repeated testing during all PAPE protocols throughout the study.

Statistical Analyses

Traditional methods were used to determine mean values and SDs. The Shapiro-Wilk test was used to assess the normality of the distribution of the data. All data showed normal distribution. A 2-way repeated measures analysis of variance with 4 conditions (ISO, CON, BAND20, and BAND30) and 3 times (pretesting, post 5 minutes, and post 10 minutes) was performed, with Bonferroni post hoc correction where appropriate. Effect sizes are described by Hedges g (14), whereby <0.2–0.49 is a small effect, 0.5–0.79 is a moderate effect, and ≥0.8 is a large effect. The Pearson correlation coefficient r was calculated to assess relative changes in performance after PAPE protocols in relation to baseline (calculated from the best performance characteristics from both times of posttesting). A priori G*Power analysis revealed that there is an 82% chance of rejecting the null hypothesis of no significant effect of the interaction with 10 subjects in each condition (12). Alpha was set at ≤0.05. All the analyses were performed using the Jamovi project (2020) jamovi (Version 1.2) [Computer Software]. Retrieved from https://www.jamovi.org.

Results

Significant condition × time interaction was observed in 3-m sprint time (p < 0.001). Post hoc analysis revealed that only the BAND30 group significantly improved from pretesting to post 5 minutes (p < 0.001, g = 0.89) and pretesting to post 10 minutes (p < 0.001, g = 0.65). Significant condition × time interaction was also observed in 5-m sprint time (p < 0.001). Significant improvements were seen after ISO from pretesting to post 5 minutes (p = 0.03, g = 0.42) and after BAND30 from pretesting to post 5 minutes (p < 0.001, g = 0.65) and pretesting to post 10 minutes (p < 0.001, g = 0.73). Significant differences in 5-m sprint times were observed for BAND20 and BAND30 compared with CON at post 5 minutes (p < 0.01, g = 1.69–1.19) and also at post 10 minutes (p < 0.01, g = 1.69–1.41). In 10-m sprint time, significant condition × time interaction was observed (p < 0.001). Post hoc analysis revealed that all PAPE protocols significantly improved performance from pretesting to post 5 minutes (ISO: p = 0.01, g = 0.23; BAND20: p = 0.02, g = 0.58) and ISO from pretesting to post 10 minutes (p = 0.03, g = 0.36). Only BAND30 significantly improved at both testing times with p < 0.01 (g = 0.61–0.43). When comparing conditions, the only significant difference at both posttesting times were noted between BAND20 and CON (p < 0.01, g = 1.92–1.93).

In SJ, significant condition × time interaction was observed (p < 0.001). All PAPE protocols significantly (p < 0.01) improved SJ height from pretesting to post 5 minutes (ISO: g = 0.68, BAND20: g = 0.85, BAND30: g = 0.76) and pretesting to post 10 minutes (ISO: g = 0.44, BAND20: g = 0.75, BAND30: g = 0.40). A significant difference between protocols was noted only when comparing BAND30 and CON at both testing times (p < 0.01). A similar trend was seen also in CMJ height where all PAPE significantly (p < 0.01) improved from pretesting to post 5 minutes (ISO: g = 0.47, BAND20: g = 0.76, BAND30: g = 1.05) and pretesting to post 10 minutes (ISO: g = 0.23, BAND20: g = 0.61, BAND30: g = 0.98) except ISO (where improvements occurred only pretesting to post 5 minutes) (p < 0.01). In this case, all PAPE protocols showed significantly larger increases in CMJ height compared with CON at both times of posttesting (p < 0.01). No significant differences were noted between PAPE protocols at any pretesting and posttesting times. All data are presented in Table 1.

Table 1. - Shows neuromuscular performance (mean ± SD and 95% CI) before and after potentiating protocols.*
Protocol/Outcome Isoinertial BAND 20
Pre Post 5 Post 10 Pre Post 5 Post 10
CMJ (cm) 31.7 ± 3.8 (29.9–33.6) 33.6 ± 4.0‡‖ (31.7–35.4) 32.6 ± 3.7 (30.7–34.5)‖ 30.8 ± 2.9 (28.9–32.6) 33.1 ± 3.0‡‖ (31.3–35.0) 32.6 ± 2.8.3‡‖ (30.7–34.5)
SJ (cm) 27.5 ± 2.4 (25.9–29.1) 29.3 ± 2.7‡ (27.6–30.9) 28.5 ± 2.0 (26.9–30.1) 28.1 ± 2.3 (26.5–29.7) 30.3 ± 2.7‡ (28.7–32.0) 30.0 ± 2.6 (28.4–31.6)
3 m (s) 0.86 ± 0.06 (0.82–0.89) 0.84 ± 0.07 (0.80–0.87) 0.85 ± 0.07 (0.81–0.88) 0.84 ± 0.04 (0.80–0.87) 0.82 ± 0.04 (0.78–0.85) 0.83 ± 0.04 (0.79–0.86)
5 m (s) 1.26 ± 0.07 (1.23–1.29) 1.23 ± 0.07† (1.20–1.26) 1.23 ± 0.07 (1.20–1.27) 1.23 ± 0.03 (1.20–1.27) 1.21 ± 0.03‖ (1.18–1.25) 1.21 ± 0.03‖ (1.18–1.25)
10 m (s) 2.13 ± 0.08 (2.09–2.17) 2.10 ± 0.08‡ (2.06–2.14) 2.10 ± 0.08† (2.06–2.14) 2.07 ± 0.03 (2.03–2.11) 2.04 ± 0.05†‖ (2.00–2.08) 2.06 ± 0.05‖ (2.02–2.10)
Protocol/Outcome BAND 30 Control
Pre Post 5 Post 10 Pre Post 5 Post 10
CMJ (cm) 30.2 ± 2.8 (28.3–32.1) 33.5 ± 2.3‡‖ (31.6–35.4) 33.3 ± 3.3‡‖ (31.4–35.1) 30.2 ± 3.5 (28.4–32.1) 28.6 ± 2.8 (26.8–30.5)‡ 29.1 ± 2.8 (27.3–31.0)‡
SJ (cm) 30.3 ± 3.7 (28.7–32.0) 33.4 ± 4.2‡‖ (31.8–35.0) 31.9 ± 4.0‖ (30.3–33.5) 27.5 ± 2.5 (25.9–29.2) 27.0 ± 2.4 (25.4–28.7) 27.3 ± 2.3 (25.6–28.9)
3 m (s) 0.87 ± 0.06 (0.82–0.89) 0.81 ± 0.07‡ (0.77–0.84) 0.83 ± 0.06‡ (0.78–0.85) 0.85 ± 0.06 (0.81–0.87) 0.86 ± 0.06 (0.82–0.89)‡ 0.86 ± 0.06 (0.83–0.89)†
5 m (s) 1.26 ± 0.08 (1.24–1.30) 1.21 ± 0.07‡‖ (1.18–1.24) 1.21 ± 0.05‡‖ (1.18–1.24) 1.28 ± 0.06 (1.25–1.31) 1.29 ± 0.06 (1.26–1.32)† 1.30 ± 0.06 (1.26–1.33)‡
10 m (s) 2.17 ± 0.10 (2.13–2.21) 2.11 ± 0.09‡ (2.08–2.16) 2.13 ± 0.08‡ (2.09–2.17) 2.13 ± 0.07 (2.09–2.16) 2.16 ± 0.07 (2.12–2.20)‡ 2.17 ± 0.06 (2.13–2.21)‡
*CI = confidence interval; CMJ = countermovement jump; Isoinertial = protocol where standard 85% 1RM was used, BAND20 = protocol where 20% of the total load coming from elastic bands, BAND30 = protocol where 30% of the total load coming from elastic bands; Pre = pretesting; Post 5 = posttesting after 5 minutes of rest; Post 10 = posttesting after 10 minutes of rest.
p < 0.05, ‡p < 0.01 compared with pre-training; §p < 0.05, ‖p < 0.01 compared with control; ¶p < 0.05, #p < 0.01 baseline differences (no baseline differences between protocols were noted).

Only 2 statistically significant associations were detected between baseline 1RM and relative changes after PAPE protocols (Figure 3).

Figure 3.
Figure 3.:
Associations between baseline 1RM and relative changes in 10-m sprint time in BAND20 (A) and 3-m sprint time in ISO (B). 1RM = 1 repetition maximum.

Discussion

The purpose of this study was to evaluate acute performance enhancement after back squat with an isoinertial load and different elastic band resistances on short sprint and vertical jump performance in female athletes. The results of this study suggest using elastic bands as a potential method to optimize PAPE effects in female athletes. All PAPE protocols significantly improved physical performance; however, a small advantage was observed from elastic band protocols. Because there were no electromyography (EMG) or other methods used to assess potential mechanisms in this study, only previously mentioned mechanisms and factors (5,26) to explain PAPE effects can be considered.

A significant improvement in 3-m sprint time was recorded only after the BAND30 protocol at both posttesting times. These results are somewhat unique because no study yet examined the acute effects of PAPE on such a short distance. A possible explanation could lie in the fact that the BAND30 protocol led to higher total resistance at the top of the squat. This may have affected the early acceleration distance because it is known that immediately during the starting speed there is a powerful extension of hips, knees, and ankles, which corresponds to the optimal performance in this short phase of the acceleration (10). However, it should be noted that this result may be a type I error due to the relatively small sample size in this study.

Similar results were recorded in 5-m sprint time where the BAND30 protocol significantly improved 5-m sprint time during both posttesting times (p < 0.01, g = 0.65–0.73), but also, the ISO protocol significantly improved performance (p < 0.05) over this distance with a small effect size (g = 0.42). Effects of back squat PAPE on 5-m sprint time have been examined frequently in the literature in male athletes with contrasting results; some studies show significant improvements (4) and some not (8). Interestingly, to the best of our knowledge, only one study examined effects of PAPE (after assisted sprints) over short distances of 5-m and 10-m sprint split times in female athletes (20). A significant improvement was observed only over 5 m. Unfortunately, it is difficult to compare our study with that of Nealer et al. (20) because of the greatly different PAPE protocols used. However, in 10-m sprint time, all PAPE groups significantly improved in this study. In this case, studies more frequently assess this distance using comparable PAPE protocols to ours but mostly in the male population (4,18,21,30), observing similar improvements. Concerning the acute effect of variable resistance, only one study (37) examined the effect of back squat with and without elastic bands; again in a male population. Wyland et al. (37) found a significant improvement in 9.1-m sprint time after performing back squat with elastic band-based resistance and no changes after traditional resistance. However, it should be noted that in the study by Wyland et al. (37) they used 30% of elastic resistance without removing an equivalent load from the barbell, which is in contrast to our study. In this case, one could assume that subjects performed back squat with higher intensity or volume load that may have influenced the potentiating effect in their study (37). When comparing PAPE protocols in our study, we did not find any significant differences between the protocols at either 5 or 10 minutes posttesting times. However, there was a positive trend for the BAND 30 protocol, which significantly enhanced sprint speed over all distances with higher effect sizes compared with the other protocols.

When analyzing SJ and CMJ height, we observed significant improvements after all PAPE protocols at both posttesting times, but there were no differences between the protocols. However, when baseline and the best vertical height from either 5 or 10 minutes posttesting were analyzed, we observed a significant difference between BAND30 and ISO (p < 0.01, g = 1.08) in favor of the BAND30 protocol in SJ height. When analyzing the current literature, there are only a few studies that examined women, and there were no significant improvements in CMJ or SJ in these studies (29,36). However, in some studies, significant improvements in jump performance were noted (1,19), but in one study another test (standing long jump) rather than CMJ or SJ was used, (1) and in another there was a mixed group with no clear effects of PAPE in female athletes (11). Only one study examined the effect of the back squat by using elastic band resistance (25). The authors observed significant improvements (p ≤ 0.05) in peak power, jump height, and accompanying EMG activity when rest intervals were individualized. Although we did not directly assess EMG or muscular power variables during our PAPE conditions, the significant improvements observed in SJ height in favor of BAND30 condition may have been due to enhanced muscle activity accompanied by higher power output during the execution of the jumps.

In regards of abovementioned studies with conflicting findings in CMJ and SJ in women, it seems that perhaps the main factor is an existing strength level of the athletes; where subjects' 1RM to BM ratio was about 1.1–1.5 in the study by Sygulla and Fountaine (29) compared with an average of 1.96 in our study. Interestingly, when the authors (29) selected the strongest subjects from their study (1RM: BM ratio >1.44) they markedly improved jump height and muscular power as well. The assertion that athletes must have a sufficient strength level to benefit from PAPE protocols is also partly supported by our identified associations of 1RM and relative increases in 3-m (r = −0.56, p = 0.03, n = 14) and 10-m sprint (r = −0.66, p = 0.01, n = 14).

Several factors, in addition to the existing strength level (35), could increase the likelihood of achieving acute performance enhancement. Appropriate rest intervals can affect the magnitude of PAPE effects, where interval 0–12 minutes seem optimal (13), and also PAPE protocols should exhibit a similar movement pattern to the selected tests/activity (8) and include multiple sets per exercise (35). Collectively, we can assume that abovementioned factors positively affect PAPE in general, and therefore were considered during the execution of our study design.

The originality of this study lies in the fact that complex PAPE protocols including different adjustments of elastic band resistance were applied in female athletes. As noted above, these trained athletes are regularly measured in the tests examined in this study, and almost each of them has experience with PAPE protocols from practice, which can lead to marked differences when comparing with other studies. Interestingly, there is some evidence that PAPE effects can be trainable/modified over 10 or more weeks depending on the individual athlete (31,33), possibly indicating that experienced athletes can acquire beneficial PAPE effects with a greater magnitude regardless of sex. The influence of an increase in strength affecting the response to PAPE protocols can be partially supported by the study by Chiu et al. (7), whereas highly trained women (with hypertrophied type IIa fibers) would likely see the effects of PAPE more than untrained/slightly trained women.

Limitations of this study include the absence of EMG measurements that could indicate potential mechanisms responsible for the achieved improvements. Another possible limitation could be the low number of subjects and their varied sport specializations. Nevertheless, according to a priori our study attained the minimum number of subjects necessary. Regarding different sport specialization in this study, one could argue that it is a somewhat heterogeneous group, but we intended to enroll as many subjects as possible with an emphasis on actual strength level, experience with testing procedures, and PAPE application. Another limitation can also be the absence of real-time measures of velocity and power during the PAPE protocols, which would potentially show differences between the isoinertial PAPE protocol compared with the variable (BAND20 and BAND30) protocols. We are aware of this limitation, and it is not certain that our variable protocols increased velocity and power output during the back squat as it was observed in previous studies (34).

Practical Applications

The originality of this study lies in the fact that PAPE protocols including variable resistance with different resistance band adjustments were applied in female athletes because there is a significant gap in the literature in this population. Our results suggest that coaches who work with female athletes may incorporate PAPE protocols to enhance short sprint performance and vertical jump height. Application of PAPE protocols with variable resistance in team-sports athletes (for instance volleyball players) may be suitable before and during the quarters, whereas at that time there is a window of opportunity to perform potentiating exercise. In addition, application of such protocols may be also suitable during the training session (individual as well as team-sport athletes), where coaches frequently use a combination of heavy-to-light load during the contrast strength training sessions, and application of PAPE protocols with variable resistance could be beneficial to power development of their athletes. However, these protocols are best used in already strength-trained and experienced (PAPE protocols) female athletes if a significant effect is to be expected. Regarding using variable resistance, it seems that adjustments where 30% of the total load comes from the elastic bands could be an advantage in this population because we observed trends for best improvements after this protocol (i.e., greater effect sizes and SJ height after BAND30 compared with the ISO protocol).

Acknowledgments

The authors of the study would like to thanks all subjects who participated in this study.

References

1. Ah Sue R, Adams KJ, DeBeliso M. Optimal timing for post-activation potentiation in women collegiate volleyball players. Sports (Basel) 4: 27, 2016.
2. Baker D. Using strength platforms for explosive performance. Part II: developing athletic capacity. In: High Performance Training for Sports. Joyce D, Lewindon D, eds. Champaign, IL: Human Kinetics, 2014. pp. 127–144.
3. Beato M, Stiff A, Coratella G. Effects of postactivation potentiation after an eccentric overload bout on countermovement jump and lower-limb muscle strength. J Strength Cond Res 2019. doi: 10.1519/JSC.0000000000003005. Epub ahead of print.
4. Bevan RH, Cunningham DJ, Tooley EP, et al. Influence of postactivation potentiation on sprinting performance in professional rugby players. J Strength Cond Res 24: 701–705, 2010.
5. Blazevich JB, Babault N. Post-activation potentiation versus post-activation performance enhancement in humans: Historical perspective, underlying mechanisms, and current issues. Front Physiol 10: 1359, 2019.
6. Chatzopoulos DE, Michailidis CJ, Giannakos AK, et al. Postactivation potentiation effects after heavy resistance exercise on running speed. J Strength Cond Res 21: 1278–1281, 2007.
7. Chiu LZ, Fry AC, Schilling BK, Johnson EJ, Weiss LW. Neuromuscular fatigue and potentiation following two successive high intensity resistance exercise sessions. Eur J Appl Physiol 92: 385–392, 2004.
8. Crewther BT, Kilduff LP, Cook CJ, et al. The acute potentiating effects of back squats on athlete performance. J Strength Cond Res 25: 3319–3325, 2011.
9. Cuenca-Fernández F, Smith IC, Jordan MJ, et al. Nonlocalized postactivation performance enhancement (PAPE) effects in trained athletes: A pilot study. Appl Physiol Nutr Metab 42: 1122–1125, 2017.
10. Delecluse C. Influence of strength training on sprint running performance. Current findings and implications for training. Sports Med 24: 147–156, 1997.
11. Evetovich TK, Conley DS, McCawley PF. Postactivation potentiation enhances upper- and lower-body athletic performance in collegiate male and female athletes. J Strength Cond Res 29: 336–342, 2015.
12. Faul F, Erdfelder E, Lang AG, Buchner A. G*Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods 39: 175–191, 2007.
13. Gouvêa AL, Fernandes IA, César EP, Silva WAB, Gomes PSC. The effects of rest intervals on jumping performance: A meta-analysis on post-activation potentiation studies. J Sports Sci 31: 459–467, 2013.
14. Hedges LV, Olkin I. Estimation of a single effect size: Parametric and nonparametric methods. In: Statistical Methods for Meta-Analysis. San Diego, CA: Academic Press, 1985. pp. 76–104.
15. Hodgson M, Docherty D, Robbins D. Post-activation potentiation: Underlying physiology and implications for motor performance. Sports Med 35: 585–595, 2005.
16. Kompf J, Arandjelović O. Understanding and overcoming the sticking point in resistance exercise. Sports Med 46: 751–762, 2016.
17. Lima LC, Oliveira FB, Oliveira TP, et al. Postactivation potentiation biases maximal isometric strength assessment. Biomed Res Int 2014: 126961, 2014
18. McBride JM, Nimphius S, Erickson TM. The acute effects of heavy-load and loaded countermovement jumps on sprint performance. J Strength Cond Res 19: 893–897, 2005.
19. McCann MR, Flanagan SP. The effects of exercise selection and rest interval on postactivation potentiation of vertical jump performance. J Strength Cond Res 24: 1285–1291, 2010.
20. Nealer AL, Dunnick DD, Malyszek KK, et al. Influence of rest intervals after assisted sprinting on bodyweight sprint times in female collegiate soccer players. J Strength Cond Res 3: 88–94, 2017.
21. Nickerson BS, Mangine GT, Williams TD, Martinez IA. Effect of cluster set warm-up configurations on sprint performance in collegiate male soccer players. Appl Physiol Nutr Metab 43: 625–630, 2018.
22. Petisco C, Ramirez-Campillo R, Hernández D, et al. Post-activation potentiation: Effects of different conditioning intensities on measures of physical fitness in male young professional soccer players. Front Psychol 10: 1167, 2019.
23. Rhea MR, Kenn JG, Dermody BM. Alterations in speed of squat movement and the use of accommodated resistance among college athletes training for power. J Strength Cond Res 23: 2645–2650, 2009.
24. Robbins DW. Postactivation potentiation and its practical applicability: A brief review. J Strength Cond Res 19: 453–458, 2005.
25. Scott DJ, Ditroilo M, Marshall P. Effect of accommodating resistance on the postactivation potentiation response in rugby league players. J Strength Cond Res 32: 2510–2520, 2018.
26. Seitz LB, Trajano GS, Dal Maso F, Haff GG, Blazevich AJ. Postactivation potentiation during voluntary contractions after continued knee extensor task-specific practice. Appl Physiol Nutr Metab 40: 230–237, 2015.
27. Soria-Gila MA, Chirosa IJ, Bautista IJ, Baena S, Chirosa LJ. Effects of variable resistance training on maximal strength: A meta-analysis. J Strength Cond Res 29: 3260–3270, 2015.
28. Strokosch A, Louit L, Seitz L, Clarke R, Hughes JD. Impact of accommodating resistance in potentiating horizontal-jump performance in professional rugby league players. Int J Sports Physiol Perform 13: 1223–1229, 2018.
29. Sygulla KS, Fountaine CJ. Acute post-activation potentiation effects in NCAA division ii female athletes. Int J Exerc Sci 7: 212–219, 2014.
30. Till KA, Cooke C. The effects of postactivation potentiation on sprint and jump performance of male academy soccer players. J Strength Cond Res 23: 1960–1967, 2009.
31. Tsimachidis C, Patikas D, Galazoulas C, Bassa E, Kotzamanidis C. The post-activation potentiation effect on sprint performance after combined resistance/sprint training in junior basketball players. J Sports Sci 31: 1117–1124, 2013.
32. Vandenboom R. Modulation of skeletal muscle contraction by myosin phosphorylation. Compr Physiol 7: 171–212, 2016.
33. Walker S, Ahtiainen JP, Häkkinen K. Acute neuromuscular and hormonal responses during contrast loading: Effect of 11 weeks of contrast training. Scand J Med Sci Sports 20: 226–234, 2010.
34. Wallace BJ, Winchester JB, McGuigan MR. Effects of elastic bands on force and power characteristics during the back squat exercise. J Strength Cond Res 20: 268–272, 2006.
35. Wilson JM, Duncan NM, Marin PJ, et al. Meta-analysis of postactivation potentiation and power: Effects of conditioning activity, volume, gender, rest periods, and training status. J Strength Cond Res 27: 854–859, 2013.
36. Witmer CA, Davis SE, Moir GL. The acute effects of back squats on vertical jump performance in men and women. J Sports Sci Med 9: 206–213, 2010.
37. Wyland TP, Van Dorin JD, Reyes GF. Postactivation potentiation effects from accommodating resistance combined with heavy back squats on short sprint performance. J Strength Cond Res 29: 3115–3123, 2015.
Keywords:

muscular power; variable resistance; postactivation potentiation

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