Fig. 11. The sensitivity of jumping performance to variations in the magnitudes of the iliosacral extensor torque and the hindlimb torques examined using model 4. The torque pattern in Fig. 9 was used to drive the forward dynamics, and individual torques were scaled in amplitude by a factor of 0.80-1.20. HR, hip external rotation torque; HA, hip adduction torque; HE, hip extensor torque; KE, knee extensor torque; AE, ankle extensor torque; IE, iliosacral extensor torque. The take-off angle (trajectory of the center of mass, COM) was most sensitive to variations in the amplitude of the hip external rotation torque (i.e. the range of take-off angles was largest when HR was scaled from 0.80 to 1.20 of its base value). The horizontal velocity V_H was most sensitive to variations in the hip extensor torque. The vertical velocity V_V was most sensitive to variations in the hip external rotation torque and the knee extensor torque.