Effect of Knee Flexion Angle on Squat Jump Performance

Abstract

Muscular function adaptations and movement capacities differ among individuals. However, there is uncertainty about squat depth and squat-jump performance. Hence, the study aimed to investigate the effect of knee flexion angle on the squat jump performance. 15 Asian females $(24\pm 2$ years, $163\pm 3\mathrm{c}\mathrm{m}$, and $54\pm 5\mathrm{k}\mathrm{g}$) performed squat jumps at the knee flexion angle of $60^{\circ}, 75^{\circ}, 90^{\circ}$, 1050, and 1200. Flight time, peak speed, peak propulsive force, maximum concentric power, and flight height during the propulsive phase were measured using the BTS G-Walk® system. The results revealed that increasing knee flexion angle corresponded to a significant decrease in flight time, peak speed, and flight height but an increase in propulsive peak force $(p\lt .05)$. The highest maximum concentric power was observed at 750. Flight time $(r^{2}=.854,\ p\lt .05)$ and peak speed $(r^{2}=.849,p\lt 05)$ were significantly correlated to flight height. Results indicated that optimal squat jump performance was observed at the knee flexion angle of600 while flight time and peak speed were good predictors of squat jump performance.