THREE-DIMENSIONAL DYNAMIC ANALYSIS FOR THE LOWER EXTREMITY DURING FASTBALL BASEBALL PITCH

Abstract

Five collegiate baseball pitchers, who have different types of delivery, were videotaped and analyzed using three-dimensional videography and ground reaction force (GRF) anaysis. Just before stride foot contact, a peak vertical GRF of 1.28 BW for pivot foot was produced, resulting from the joint torques for the knee and hip extensors. A peak forward GRF of 0.67 BW also appeared. This GRF may result in the ankle plantar flexors. Immediately after stride foot contact, the joint torques of hip’s extension, abduction and internal rotation, knee’s extension and valgus, ankle’s plantar flexion for the striding leg were generated in order to resist the resultant of vertical and backward GRFs.