The effect of initial knee angle on oncentric-only squat jump performance

Document Type

Journal Article

Publication Title

Research Quarterly for Exercise and Sport

Publisher

Routledge

Place of Publication

United States

School

School of Medical and Health Sciences

RAS ID

26433

Comments

Mitchell, L. J., Argus, C. K., Taylor, K. L., Sheppard, J. M., & Chapman, D. W. (2017). The effect of initial knee angle on concentric-only squat jump performance. Research Quarterly for Exercise and Sport, 88(2), 184-192. https://doi.org/10.1080/02701367.2017.1293777

Abstract

Purpose: There is uncertainty as to which knee angle during a squat jump (SJ) produces maximal jump performance. Importantly, understanding this information will aid in determining appropriate ratios for assessment and monitoring of the explosive characteristics of athletes. Method: This study compared SJ performance across different knee angles—90º, 100º, 110º, 120º, 130º, and a self-selected depth—for jump height and other kinetic characteristics. For comparison between SJ and an unconstrained dynamic movement, participants also performed a countermovement jump from a self-selected depth. Thirteen participants (Mage = 25.4 ± 3.5 years, Mheight = 1.8 ± 0.06 m, Mweight = 79.8 ± 9.5 kg) were recruited and tested for their SJ performance. Results: In the SJ, maximal jump height (35.4 ± 4.6 cm) was produced using a self-selected knee angle (98.7 ± 11.2°). Differences between 90°, 100°, and self-selected knee angles for jump height were trivial (ES ± 90% CL = 90°–100° 0.23 ± 0.12, 90°–SS −0.04 ± 0.12, 100°–SS −0.27 ± 0.20; 0.5–2.4 cm) and not statistically different. Differences between all other knee angles for jump height ranged from 3.8 ± 2.0 cm (mean ± 90% CL) to 16.6 ± 2.2 cm. A similar outcome to jump height was observed for velocity, force relative to body weight, and impulse for the assessed knee angles. Conclusions: For young physically active adult men, the use of a self-selected depth in the SJ results in optimal performance and has only a trivial difference to a constrained knee angle of either 90° or 100°

DOI

10.1080/02701367.2017.1293777

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