探討排球踏併跳動作中，先行腳與跟隨腳之運動學與動力學現象的差異，以提供教學與訓練一參考之依據。方法：以11名國立東華大學排球特優級選手為受試對象進行踏併跳動作，以一台MegaSpeed高速攝影機(120Hz)及AMTI三軸測力板(1200Hz)同步擷取跳躍過程中下肢運動學與動力學資料。以相依樣本t-test檢驗踏併跳先行腳與跟隨腳之運動生物力學特性的差異。結果：相較於踏併跳跟隨腳，先行腳有較長的下蹲期與制動期時間。在關節屈曲角位移方面，先行腳的膝與髖關節皆大於跟隨腳；關節蹬伸角位移方面，先行腳之踝、膝與髖關節皆大於跟隨腳。動力學之結果發現，先行腳較跟隨腳產生較大的標準化總衝量值，在蹬伸期跟隨腳較先行腳產生較大的最大垂直地面反作用力，且峰值出現的時間亦較早，而跟隨腳產生的快速肌力指數(speed strength index, SSI)也較先行腳大。結論與建議：踏併跳是一非雙邊對稱之動作技術，先行腳具較慢的下蹲與制動，故牽張反射與彈性能再利用效果不大，其技術上或許是產生較大的向心收縮力量之能力更重於牽張反射肌力與爆發力，其可藉由不具SSC之動作進行訓練，如蹲踞跳。而跟隨腳之動作則為一快速制動蹬伸的淺蹲跳動作，牽張反射肌力與爆發力之特性對跟隨腳之動作技術尤其重要，其可藉由具SSC之動作進行訓練，如增強式訓練。

Purpose: The purpose of this study was to investigate the differences of the kinematic and kinetic properties between the lead leg and the trail leg during step-close jump. Methods: Eleven varsity volleyball players were selected to participate and to perform step-close jump. Lower extremity kinematics and ground reaction forces during landing in step-close jump task were recorded by using the MegaSpeed camera and AMTI force plate synchronous. All data were analyzed by using the repeated t-test to evaluate whether the differed significantly between the lead leg and the trail leg. Results: Our research indicated that a longer squatting phase and a breaking phase are required for the lead leg in comparison to the trail leg. The angular displacement of flexion of the knee and the hip joints for the lead leg are greater than those for the trail leg. The trail leg not only generated greater vertical ground reaction force but also reached its peak value sooner than the lead leg during the extending phase. The speed strength index derived from the lead leg was higher than that from the trail leg. Conclusions: The step-close jump is an asymmetric technique for jumping, leading to distinct requirements for both legs in terms of movements and muscle strength. To be specific, the stretch reflex and reutilization of elastic energy matter less due to the fact that the lead leg required a longer squatting phase and breaking phase. Technically speaking, for the lead leg, the capability of producing concentric contraction was more relevant in this regard. Such capability can be developed through non-SSC movements such as squat jumps. On the contrary, the capabilities of generated stretch reflex and reutilized elastic energy were more important for the trail leg. Unlike the lead leg, these capabilities can be trained through SSC movements such as plyometric training.