The purpose of this research is to investigate how the kinematic factors during the horse (table) contact phase influence the post-flight performance in handspring vaulting. A six-segment planar simulation model comprising the lower arm, upper arm, head-trunk, thigh, shank, and foot was customized to an elite gymnast. The body segment parameters, maximum joint torques, and initial kinematic parameters from video analysis of the subject are required for the optimal matching computer simulation. The model was able to match a handspring vault after adjusting the visco-elastic characteristics of the arm-horse interface and joint activation time histories. The model was then used to determine the key factors which influence performance by varying the initial conditions. The objective function was the vertical velocity of the body center of mass at takeoff. The results suggest that smaller wrist angle, greater wrist angular velocity, straighter elbow, greater shoulder angular velocity, greater maximum shoulder torque, and smaller hip angle at horse contact were crucial in achieving the optimal performance. Compared with the five-segment model with a visco-elastic shoulder of a previous study, the six-segment model without a visco-elastic shoulder could still closely match the real performance, and better mimic the actual pushing movement of the arms.
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