THE ADJUSTMENT OF LEG STIFFNESS DURING DYNAMIC EXERCISE AND DOWNWARD STEPPING FOR ELDERLY
Keywords: elderly, stiffness, downward stepping, CMJ
AbstractThe purpose of the present study was to evaluate the ability of leg stiffness regulation during downward stepping and maximal Counter-Movement-Jump (CMJ) for the elderly. Ten healthy aged people (age: 68.6±5 years; height: 165.3±4.4cm; mass: 61.7±9.3kg) and 10 students (age: 24.3±2years; height: 171.5±4.6cm; mass: 65.9±8kg) volunteered as subjects. Kistler force platform (1200Hz) and Peak high-speed camera (120Hz) were used synchronously to record the ground reaction force and the kinematic parameters of the subjects performing CMJ and stepping down from different heights. The results revealed that the elderly group has a smaller joint range of motion and greater leg stiffness than the young group during stepping down. The force and the leg stiffness during CMJ were significantly smaller for the elderly. The leg stiffness during downward stepping is independent of dynamic leg stiffness during CMJ. With aging, the adjustment ability of leg stiffness for maximal dynamic voluntary contraction was decreased.
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