本研究之主要目的是要藉由三度空問動作分析系統及兩塊測力板，探討平擊及上旋兩種不同發球方式中，下肢之踝、膝、髖關節、骨盆和軀幹之三維運動學之變化，並結合測力板量測地面反作用力，計算出壓力中心後分析其與身體質量中心所形成的力矩，以探討身體的運動特性，並進一步深入的了解下肢各關節在發球動作中之助益及扮演之角色。六位男性的全能型網球選手為本研究之受試者。利用HIRES三度空間動作分析系統，收集各受試者發球時的肢體運動軌跡影像資料(120 Hz)，及兩塊Kistler測力板，讓受試者雙足各放在一塊測力板上，量取發球時雙腳之地面反作用力(1000 Hz)。研究結果發現：在平擊及上旋發球中，最主要的差異在於上旋發球較平擊發球產生更多側屈力矩，而此力矩的產生最主要的貢獻來自於身體軀幹的側屈，此外，在三維運動學資料中，上旋發球較平擊發球於加速期時產生較多的膝關節彎曲，同時在骨盆產生較多的後傾，如此可幫助增加發球時之動量產生及傳遞。

The serve is the most important technique in tennis and is usually classified into three patterns: flat serve, spin serve and slice serve. However, the ground reaction force (GRF) and its effects on body movements between different serve patterns are rarely known. The purpose of this study was to investigate 3D kinematics data of the trunk and lower extremities and their moment about the whole body center of mass (COM) during a flat serve and a spin serve in three phases (wind-up, cocking, acceleration). The HiRES Expert Vision motion system with six cameras was used to quantitatively collect the trajectories of the reflective markers at a sampling rate of 120 Hz while the subject performed a tennis serve. Twenty-one markers were placed on selected anatomic landmarks to define the position of each body segment. A 13-segment model was used to calculate the whole body center of mass. Two Kistler forceplates were used to measure the GRF for each leg at 1000Hz, respectively. Six Taiwan national tennis representatives were recruited for this study. The results showed that the moment of COM around Y (mediolateral)-axis was different for flat and spin serves, especially in the acceleration phase. It also can be conformed from the 3D kinematics results of trunk with greater lateral flexion during spin serve. Besides, the spin serve generated greater knee flexion and pelvis posterior tilt in the acceleration phase. The power of different serves was mainly from the movement of trunk rotation and bending.