Using the Split Squat to Potentiate Bilateral and Unilateral Jump Performance

Research Review: Using The Split Squat To Potentiate Bilateral And Unilateral Jump Performance

By Sean Butler BS, CSCS, CES, DPT Student

Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Bishop, CJ., Tarrant, J., Jarvis, PT. and Turner, AN (2017). Using the split squat to potentiate bilateral and unilateral jump performance. The Journal of Strength & Conditioning Research, 31(8), 2216-2222. ABSTRACT

Why is this study relevant: Post-activation potentiation (PAP) is a phenomenon in which a muscle's force is acutely increased as a result of its contractile history (1). Research appears to imply that while fatiguing muscle contractions may impair performance, non-fatiguing muscle contractions may enhance performance (2). Much of the research investigates the use of high-load conditioning exercises to maximize motor unit recruitment and elicit a PAP response (3-5). This 2017 study is noteworthy, as it investigated the role of bodyweight and lightly loaded unilateral split squats to elicit PAP and enhance bilateral and unilateral jump performance. The findings of this study support the use of bodyweight and low load split squats for eliciting PAP and enhancing bilateral jump performance.

Caption: Dr. Brookbush teaching an upright lunge.

Upright Lunge

Study Summary

Study Design	Quasi-experimental, cross-over design
Level of Evidence	IIB Evidence from at least one other type of quasi-experimental study
Participant Characteristics	Demographics 12 semiprofessional rugby players Age (± standard deviation, in years): 22.3 +/- 1.4 Height: 1.84 +/- .05 m Mass: 92.4 +/- 9.6 kg All participants had > 3 years resistance training experience, and were familiar with both bilateral/unilateral countermovement and broad jumps All participants played in the English National League Inclusion Criteria: N/A Exclusion Criteria: N/A
Methodology	Testing occurred on 2 separate days with 48 hours of rest in between testing All participants performed a standardized warm up: Including a 4-minute slow jog, 3 x 20 m shuttle runs followed by dynamic stretches intended to mobilize the joints of the lower body Participants then performed baseline jumps, 2 of each variation for a total of 12: 2 bilateral countermovement and 2 broad jumps 2 dominant leg unilateral countermovement and 2 broad jump 2 non-dominant leg unilateral countermovement and 2 broad jump) Participants hands remained on their hips during all jump variations as a way to standardize the tests 30 seconds of rest were given between jumps of the same variation, and 3 minutes of rest were given between variations. 5 minutes of rest were given following baseline jump testing Then, participants performed split squat interventions. Bodyweight split squats was used on the first testing day and a 30kg weight vest was added to the split squat intervention on the second testing day 2 sets of 10 reps were used in both conditions After 5 minutes of rest were given following the split squat intervention, participants proceeded to retest the 12 jumps in the same order as baseline testing
Data Collection and Analysis	Vertical jump height was calculated using the iPhone app “My Jump”. This app has been validated to be reliable (6). The broad jump variations were measured by jumping next to a tape measure. The distance was determined by measuring the rear-most part of the heel to the nearest millimeter Changes in jump performance were analyzed with a 2x2 repeated measures ANOVA for each dependent variable Cohen’s d effect sizes were calculated for magnitude of change in jump performance by subtracting pre-test mean from post-test mean and dividing by standard deviation
Outcome Measures	The only outcome measures were jump performance. Results described below.
Results	Baseline data was normally distributed (p > 0.05) Countermovement and broad jump performance increased significantly with both bodyweight and loaded conditions Countermovement jump - ANOVA identified a significant interaction effect of condition and time. Bonferroni post hoc analysis identified significance between time points for both the bodyweight condition and the weighted vest condition. Broad jump - ANOVA identified a significant interaction effect of condition and time. Bonferroni post hoc analysis identified significance between time points for both the bodyweight condition and the weighted vest condition. Non-significant performance improvements occurred in both the single-leg countermovement and single-leg broad jump. Single leg countermovement jump - ANOVA identified no significant interaction effect of condition and time for either the dominant limb or the nondominant limb. Single leg broad jump - ANOVA identified no significant interaction effect of condition and time for either the dominant limb or the nondominant limb.
Our Conclusions	Both bodyweight and loaded split squats improve countermovement and broad jump performance when adequate rest is given. Human movement professionals should recommend both bodyweight and lightly loaded (<30 kg) split squats to enhance performance before and during plyometric training.
Researchers' Conclusions	Heavy loads are not the only way to obtain potentiation. The use of a bodyweight exercise serves as a practical way for athletes to improve performance before practice, and potentially competition.

Review & Commentary:

This study provides evidence that the use of bodyweight split squats may elicit post-activation potentiation (PAP) and improve bilateral jump performance. This offers human movement professionals the opportunity to enhance performance in equipment-limited situations. Further research is needed to compare body-weight and high load PAP protocols.

This study had several strengths, including:

This study adds an easily applicable protocol to the human movement professionals repertoire; a bodyweight lunge can be done with or without equipment in most training environments.
Repeated measures design allows athletes to act as their own control group. This design aids in accounting for confounding variables such as sleep, nutrition, training experience, genetics, etc., making it a great design for the professional athletic population.
All warm ups, jump order, and rest time intervals were standardized. Rest time is especially important since PAP is dependent on fatigue dissipation (7, 8).

Weaknesses that should be noted prior to clinical integration of the findings:

A small sample size (n=12) of semiprofessional rugby players makes the results less generalizable.
The study used a 30kg load for all participants, resulting in varied stimulus relative to bodyweight. Future research should consider using “relative load”.
The study tested four variables in the same session, which may have resulted in fatigue during the jumps performed later in the testing sequence.

Why This Study is Important:

To our knowledge, this study is the first to demonstrate that a bodyweight (as well as "vest loaded") exercise is capable of inducing a post-activation potentiation response in bilateral jump performance. This is an interesting addition to the protocols used in prior research that have demonstrated the effect of high load training on PAP and jump performance. Further research is needed to determine the ideal load and range of loads appropriate for PAP protocols, and research should also attempt to address why unilateral jump performance was unaffected.

How the Findings Apply to Practice:

Human movement professionals should consider the use of bodyweight or "vest loaded" lunges as an "less or no equipment" alternative to high load training to induce PAP before power training programs. This study suggests that the alternative is specific to bilateral jump performance, implying that bodyweight or vest loaded lunges should not be used to enhance unilateral jump performance.

Related to Brookbush Institute Content

While much of the research on PAP uses heavy, bilateral movement patterns (7-10), this study demonstrates that bodyweight may be sufficient. This alternative may be used in routines comprised of bilateral power movements, including the routines comprised of resistance exercise/power exercise supersets that are promoted by the National Academy of Sports Medicine and Brookbush Institute during the highest intensity phases of a periodized programs. The convenience of a "little to no equipment option" includes using this type of training in home gyms, on the field or court or during exercise programs outdoors. Further, this may extend the possibility of using a form of PAP supersets with a population that should not be exposed to the stress of a 1 - 5 repetition max strength set. For example, lunges followed by squat jumps can be safely performed by a much larger population than those who can perform a 3 rep max back squat followed by 24" box jumps .

Below are videos related to the exercises in the study.

Static Lunge

Static Lunge to Row

Single Leg Box Jump

Bilateral Box Jump

Bibliography:

Robbins, D. W. (2005). Postactivation potentiation and its practical applicability: a brief review. Journal of Strength and Conditioning Research,19(2), 453.
Lorenz, D. (2011). Postactivation potentiation: An introduction. International Journal of Sports Physical Therapy, 6(3), 234.
Scott, D. J., Ditroilo, M., & Marshall, P. (2016). Complex training: The effect of exercise selection and training status on post-activation potentiation in rugby league players. Journal of strength and conditioning research.
Cuenca-Fernández, F., López-Contreras, G., & Arellano, R. (2015). Effect on swimming start performance of two types of activation protocols: lunge and YoYo squat. The Journal of Strength & Conditioning Research, 29(3), 647-655.
Kilduff, L. P., Cunningham, D. J., Owen, N. J., West, D. J., Bracken, R. M., & Cook, C. J. (2011). Effect of postactivation potentiation on swimming starts in international sprint swimmers. The Journal of Strength & Conditioning Research, 25(9), 2418-2423.
Balsalobre-Fernández, C., Glaister, M., & Lockey, R. A. (2015). The validity and reliability of an iPhone app for measuring vertical jump performance. Journal of sports sciences, 33(15), 1574-1579.
Kilduff, L. P., Bevan, H. R., Kingsley, M. I., Owen, N. J., Bennett, M. A., Bunce, P. J., … & Cunningham, D. J. (2007). Postactivation potentiation in professional rugby players: Optimal recovery. Journal of Strength and Conditioning Research, 21(4), 1134.
Kilduff, L. P., Owen, N., Bevan, H., Bennett, M., Kingsley, M. I., & Cunningham, D. (2008). Influence of recovery time on post-activation potentiation in professional rugby players. Journal of Sports Sciences, 26(8), 795-802.
Esformes, J. I., Cameron, N., & Bampouras, T. M. (2010). Postactivation potentiation following different modes of exercise. The Journal of Strength & Conditioning Research, 24(7), 1911-1916.
Esformes, J., & Bampouras, T. (2013). Effect of back squat depth on lower-body postactivation potentiation. Journal of Strength and Conditioning Research, 27(11), 2997-3000

Questions, comments, and criticisms are welcomed and encouraged -

Using the Split Squat to Potentiate Bilateral and Unilateral Jump Performance

Research Review: Using The Split Squat To Potentiate Bilateral And Unilateral Jump Performance

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