目的：主要探討三級跳遠選手下肢起跳腿與擺動腿動作對成績表現之影響。方法：以五部每秒60張畫面的攝影機（Canon ZR-60），拍攝九十二年全國運動會男女三級跳遠決賽各八位選手為受試者，以Dempster（1955）建立14個肢段、21個關節點的人體模型，透過Kwon3D動作分析器實施二度空間的影片分析。結果與結論：一、肌肉反應係數男女三個階段均未達到相關意義。二、女子騰跳與躍跳階段較小的腿部勁度，可增加階段距離表現（r=-0.716，r=-0.848，p< .05）。三、男子在騰跳與女子在跨跳階段較小的膝關節勁度將有利於階段距離獲得（r=-0.715，r=-0.821 , p< .05）。四、髖關節並不是選手在支撐階段緩衝垂直力量的關節。五、擺動腿角速度僅女子在躍跳緩衝與蹬伸階段與實跳距離達顯著相關意義，快速的擺動角速度將有利於成績表現（r=0.727，r=0.850 P< .05）。六、起跳腿與擺動腿夾角變化在三個階段均未達到顯著相關意義。建議：加強擺動腿訓練將有利於垂直速度的獲得，提高成績表現。

　　Purpose: The purpose of this study is to explore the influence of the motions of takeoff legs and free legs on the performance. Method : This study used five cameras with a speed of 60 frames per second to record the jumpers performance in the 2003 National Games Competition. According the Dempster model(1955) to record 14-segments and 21-joint points on the jumper's performance through the Kwon3D analysis software to analyze the dates. Result and Conc1usion: The data of competitions were computed. According to the results, the conc1usions are as following: 1. The muscle response coefficients in the three phases are not significantly correlated. 2. The less leg stiffness during hop and jump phase, the longer the phase distance in females(r=-0. 716, r=-0.848, p < .05). 3. A lower degree of knee angular stiffness is beneficial to achieving greater phase distance during male's Hop phase and female's step phase(r=-0.715, r=-0.821 , p< .05). 4. The jumpers do not use the hip joint to alleviate the vertical force during support phase. 5. The actual distance is significantly correlated with the speed of free legs only for females during the Jump-buffer and Pressing phases; in other words, a higher speed of the free legs results in better performance(r=0. 727, r=0.850 P < .05). 6. Changes in the intersection angle of the takeoff leg and free leg do not reach significance in all three phases. Suggest: It is suggest that strengthen the training of free leg will good for acquirement of vertical speed to promote sport performance.