인문학
사회과학
자연과학
공학
의약학
농수해양학
예술체육학
복합학
DBpia AI
AI 에이전트
AI 아이디어
AI 리더
AI 뷰어
Citeasy
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지원사업
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커뮤니티
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초록·키워드
This study investigated whether the concentric muscle action is enhanced by a preceding eccentric muscle action in a stretch-shortening cycle(SSC) and the pre-stretch angle condition can have an effect on jump height during vertical jumping. Twelve subjects randomly performed maximum vertical jump with a countermovement jump(CMJ) and a squat jump(SJ) at different knee angles(30° <60° <90°). Kistler force platform, a Lafayette EMG system and a video motion analysis system synchronized by timing device were used to record(200Hz) the vertical jumping motion. The video film was digitized and kinematic variables were calculated. The integrated EMG activities from gastrocnemius and rectus femoris were collected and normalized with a maximum voluntary contraction. The ground reaction force was normalized to the body weight(BW) The results showed that CMJ with preceding eccentric action led to greater jump height than SJ under 60° and 90° conditions(not 30°). The jump hight was increased as the pre-stretch angles(30° <60° <90°) increased. The maximum VGRF and EI showed no difference between CMJ and SJ, however EI was increased as the pre-strecth angles increased. The IEMG activity was higher during the positive work phase in the stretch-shortening cycle(CMG) than in the pure concentric action(SJ), and this IEMG was increased as the pre-stretch angles increased(30°~ 90 ° ). These results indicated that a greater jump height can be achieved in CMJ than in SJ, however a countermovement does not always induce the stretch- shortening cycle if the range of motion is short and does not allow a sufficient stretching.
본문·목차
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