Variable Heights Influence Lower Extremity Biomechanics and Reactive Strength Index during Drop Jump: An Experimental Study of Male High Jumpers

Introduction. This study finds the lower limbs' reactive strength index and biomechanical parameters on variable heights. Objective. This research aims to reveal the effects of drop height on lower limbs' reactive strength index and biomechanical parameters. Methods. Two AMTI force platforms and Vicon motion capture system were used to collect kinematic and dynamic signals of the lower limbs. Results. The drop height had significant effects on peak vertical ground reaction force and peak vertical ground reaction force in the extension phase, lower limbs' support moment, eccentric power of the hip joint, eccentric power of the knee joint, eccentric power of the ankle joint, and concentric power of the hip joint. The drop height had no significant effects on the reactive strength index. Reactive strength index (RSI) had no significant correlations with the personal best of high jumpers. The optimal loading height for the maximum reactive strength index was 0.45 m. Conclusion. The optimal loading height for the reactive strength index can be used for explosive power training and lower extremity injury prevention.