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Kinesiology & Recreation


Dr. Marcel Lopes dos Santos

Mentor Department

Kinesiology & Recreation


Dr. Michael Torry

Co-Mentor Department

Kinesiology & Recreation


INTRODUCTION: Countermovement jumps (CMJ) are among the most implemented tests for assessing the performance capacity of the lower body, specifically in the context of sports. The simplicity of both the movement and testing protocol, as well as the broad spectrum of kinematic, kinetic, and performance variables that are measurable during the test with the implementation of force plates make this modality a broadly advantageous and utilized tool in assessing athletes. The metrics calculated from CMJs are particularly valuable to sports such as football given lower-extremity power and force development translate to success many facets of the game. While the objective of the test is to achieve the greatest vertical displacement (jump height), it is equally important to understand which of the many subsequent variables are the best predictors of performance. Understanding the correlations between test variables and jump height can provide athletes and strength coaches insight into designing training protocols that will enhance athletic capabilities. PURPOSE: To evaluate which countermovement jump (CMJ) metrics were the strongest predictors of performance (jump height). METHODS: Sixteen NCAA Division 1 football players (height: 190.18 ± 5.32 cm, weight: 106.43 ± 16.59 kg) participated in this study. Following a 5min low-intensity warmup protocol, subjects performed three bi-lateral CMJs with hands placed on hips to control for advantages due to arm swing. All variables were calculated in a custom Excel spreadsheet and exported to SPSS for statistical analysis. Ten variables were selected based on a review of literature to predict jump height: takeoff velocity; peak propulsive, breaking force; braking, propulsive impulse; peak propulsive, braking power; modified reactive strength index (mRSI), and propulsive, braking asymmetry. Power, force, and impulse variables were all normalized to subject weight. Alpha value was set at 0.05. RESULTS: Jump height: 0.42 ± 0.08 m appeared to be normally distributed. Of the ten variables studied, six of them were significant. Takeoff velocity: R= 0.99 ρ = <0.001 was the best predictor of jump height, followed by peak propulsive power R= 0.953 ρ = <0.001, propulsive impulse R = 0.755 ρ <0.001, and peak propulsive force R = 0.755 ρ <0.001. CONCLUSION: All variables that were statistically significant occurred during the propulsive phase. Optimizing takeoff velocity may lead to improving CMJ height, and therefore performance in football players.

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