THE COMPARISON OF WORK INTENSITY AND EXERCISE PERFORMANCE BETWEEN

This experiment is to investigate the kinematic and dynamic variables of drop jumps (DJ) in order to understand the differences on force and sport performance between two different stretch amplitudes of SSC movements. The short-stretch DJ and long-stretch DJ were performed by 11 subjects of jumpers and sprinters with average ages 23.18±2.64 years, heights 173.0±4.03cm and weights 64.31±5.97kg. AMIT force-platform and Penny electrical goniometer were used to record ground reaction forces and angular displacements. The short-stretch DJ endured larger work intensity of initial eccentric phase at the 25ms and PK2, developed larger force and loading rate at the end of prestretch and enhanced concentric average force. Although the long-stretch DJ didn’t develop larger forces during concentric and concentric phases, it had a longer supporting time that helped to increase the momentum and ended up with the higher flight-height. When we practice SSC exercise with the intent to increase the concentric force, the method of short-stretch DJ should be adopted. If the purpose is to jump higher, the longstretch DJ is recommended