THE INTERRELATIONSHIP OF JOINT STIFFNESS IN DROP JUMP UNDER DIFFERENT CONDITIONS: A SINGLE-SUBJECT DESIGN

The purpose of this study was to examine the relationship between leg stiffness and joint stiffness in the various conditions of drop jump. A women’s athlete was recruited as the subject and asked to perform drop jump from different height of box to another box in different horizontal distance between them. The leg stiffness is influenced on the contact time and relates to knee and ankle joint stiffness. The change in leg length is greater at great horizontal distance and peak ground reaction force is greater at higher box of jump off and up. The contact time was also related to the horizontal distance and to the knee and ankle joint stiffness, peak ankle joint torque and minimum knee joint angle. These might suggest that leg stiffness influenced by ankle and knee joint stiffness due to peak ankle joint torque and knee joint angular displacement to adjust the conditions of drop jump