老年人立定垂直跳動作中下肢動力學參數之時宜特徵

The timing characteristics about the kinetically parameters in elderly during countermovement jump

目的：分析老年人立定垂直跳時下肢關節的活動角度與動力學參數之時宜表現。方法：青年與老扯男性各七名為研究對象，進行下蹲跳動作。一高速攝影機與一測力板同步。以肢段鏈模式得動力學參數。獨立樣本t-test檢測兩組間各角度參數；時宜參數採重複量數單因子變異分析，並以重複量數t-test進行試後比較。Purpose: To investigate the aging effect on movement skill by comparing the differences of range of motion (ROM) and timing of kinetic parameters in countermovement jump. Methods: Seven young males and seven elderly males were recruited as subjects for this study. A high-speed camera and a force plate were synchronized to collect the biomechanical parameters. The net muscle joint moments were calculated by using inverse dynamics process. Student's t-test was used to test the ROM differences of two age groups. One-way ANOVA was used to test the timing of kinetically parameters. Statistical significance was set at α= .05. Results: The elderly group had less range of motion in preparatory crouch at the hip joint. In addition, the elderly group had less displacement of hip, knee, and ankle angle in the propulsive phase. The timing characteristics about the dynamical parameters showed that there were different muscle activity patterns between two groups. At the hip joint, the elderly group didn't have concentric contraction in the flexors, and allotted longer time for extensors to contract eccentrically. The elderly group allotted less time for extensors to contract concentrically at the knee and hip joints. The proximal-distal sequence was not observed at the start initial time of extensors' concentric contraction of lower limbs in the elderly. Conclusion: During countermovement jump, the elderly adjust the hip strategy to control balance in preparatory crouch. This might result in simultaneous muscle activation, and inadequate extension of the lower limbs during the propulsive phase. These might affect the CG projection angle and deteriorate postural stability at take off.