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:青年與老年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按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。α=.05。結果:老年組在關節角度的表現上顯示曬關節前屈 下蹲較少與下肢關節蛙伸不足。在動力學時宜的表現上顯示競與膝關節肌群活動型態明顯的與青年組不同，其幌關節屈服a群無向心收縮、仲肌群離心收縮時間較長而向心收縮時間較短;膝關節仲肌群向心收縮的時間較少;且下肢關節伸肌群開始向心收縮的時宜無近一遠端之順序性。結論:年長者在進行動態性多關節動作時，改變下蹲時有寬關節參與策略以維平衡，使E登仲的協調改變、離地瞬間未充分蛙伸，然其為維持下蹲動作之穩定卻影響離地瞬間的身體姿勢，不利於離地動作之穩定。

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 atα= .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.