緒論：臺灣目前已經邁向高齡化社會，對於中老年人即將邁入老年，其日常生活能 力的減低，進而造成跌倒風險增加，許多研究指出太極拳可以增進下肢肌力，並指出立 定垂直跳爲常用且有效測量下肢肌力的方法，因此本研究目的爲比較有長期規律太極拳 運動之中老年人與健康中老年人，在立定垂直跳動作時下肢生物力學參數是否有差異。 方法：以每組12名，共24位中老年人爲研究對象，在一年内皆無下肢段病史，其中太 極拳組包含5位男性7位女性（年齡：60.67±2.71歲、身高：162.25 ±8.16公分、體重： 64.79±11.09公斤），健康中老人組包含5位男性7位女性（年齡：62.33± 1.61歲、身高： 157.67 ± 8.55 公分、體重：60.75 ± 8.08 公斤），使用 10 台 Vicon Motion System 紅外線攝 影機（250 Hz)、2塊Kistler測力板（1000 Hz)及Vicon Nexus軟體同步擷取立定垂直跳 時運動學及動力學參數，使用Visual 3D軟體進行計算，之後進行標準化處理，所得資料 使用獨立樣本t檢定進行統計分析，顯著水準爲a = .05。結果：研究分析顯示騰空期時， 太極拳組跳躍高度明顯高於健康中老人組；起跳期時，在最大起跳速率、離地瞬間速率、 最大髖關節力矩與最大髋關節功率方面，皆爲太極拳組顯著大於健康中老人組。結論： 因太極拳組跳躍高度明顯較大，可推論太極拳組的下肢肌力大於健康中老人組，原因爲 起跳期髖關節力矩和功率優於健康中老人組，顯示太極拳運動可有效減緩髖關節部位的 力矩和功率退化，因此建議中老年人可規劃長期的從事太極拳運動。

Introduction: Taiwan is becoming an aging society. As the middle-aged elderly grow old, they become less capable of performing daily activities, which causes an increase in the risk of tripping. Many studies indicated that Tai Chi exercise can improve lower-extremity muscle strength. Standing vertical jump is a common and effective way of measuring lower-extremity muscle strength. Therefore, the purpose of the study was to investigate biomechanical effects of Tai-Chi exercise on the lower-extremity in middle-aged elders during countermovement jump. Methods: Twelve middle-aged elders with regular Tai Chi exercise experience (5 males and 7 females，age: 60.67 ± 2.71 years old，height: 162.25 ± 8.16 cm，Weight: 64.79 土 11.09 kg) and twelve healthy middle-aged elders (5 males and 7 females, age: 62.33 ± 1.61 years old, height: 157.67 ± 8.55 cm, weight: 60.75 ± 8.08 kg) participated in this study. Ten Vicon Motion System cameras (250 Hz)? two Kistler force plates (1000 Hz) and Vicon Nexus software were used simultaneously to capture the kinematic and dynamic parameters of standing vertical jumps. Visual 3D software was used for calculations. Independent samples t-test was performed for statistical analysis (a = .05). Results: Study analysis showed that jump height in the Tai Chi group was significantly higher than control group. The maximum velocity, peak hip moment, and peak hip power during the take-off phase, as well as the maximum velocity at take-off in Tai Chi group were also greater than the control group. Conclusion: Since the jvimp height of Tai Chi group was significantly higher (p < .05), it was inferred that the lower-extremity muscle strength of the Tai Chi group was stronger than the control group. This might be due to the maximum moment and power of the hip joint in the Tai Chi group were better than the control group. It showed that practicing Tai Chi exercise could effectively slow down the degeneration of the moment and power at the hip joint. Therefore, middle-aged elders were recommended to engage in long-term Tai Chi exercise.