人體的運動現象大部分是多肢段的開放性動力鏈系統，而在投擲類的動作技術中，所參與的肢段都是以〞近端－遠端〞這樣的順序形式來表現．這個多肢段的順序原理學者常常以各肢段的線速度，關節角速度肢段角速度等來進行描述，但有關於這個動作過程中，外在表現（運動學）與內在原因（動力學）之間的關係則較少探究其因．本研究的目的為探討排球扣球的手臂揮擺動作中，上肢的連結系統之間的交互作用關係，以排球扣球的揮臂動作而言，是屬於不含其他運動用具（implement）的多肢段運動系統，所以是一項探討〞近端－遠端〞多肢段運動系統的基本論題．本研究以動力學正過程理論以及拉格朗日（Lagrangian）運動方程建立兩肢段的簡化動作模式，並假設這個揮臂動作是在一個二維平面上運動．最後的非線性微分方程組，我們以MATHEMATICA 數學軟體進行數值求解，將兩位受試者皂實驗揮臂動作過程的運動學初始值以及肢段參數帶入方程中，再以調整模式中各肢段力矩的值，去逼近受試者擊球瞬間的邊界值，而觀察於比較兩者之間的關係，結論以下列兩點簡述：1.在簡化模式中，遠端肢段的角速度最大值（ｗ　d-max）以及遠端肢段末端的線速度（Ｖ d-max）都同時發生在兩肢段成一直線時．2.在實際的動作過程中，ｗ　dmax　和Ｖ　d-max都出現在擊球前，而簡化模式中，　ｗd-max 和Ｖd-max 則出現在擊球後且過程中以漸增的形式表現．在同樣的初始值與擊球時的邊界值而言，模式的過程式以一種漸進的形式表現，以能量觀點來說，是一種較有效率的過程．

Sport is full of examples of motions with open-linked and multi-segment systems. The motions of segments participating in arm-swing (or throwing)skills are generally sequenced in a proximal-to-distal fashion. The prupose of segments during the action of arm-swing phase of volleyball spike. The arm-swing phase of volleyball spike is a multi-segment system withour any implement, so it was a basic example to help explain the proximal-to-distal sequential pattern of the motion by kinetics. The forward dynamicswas used to the modeling of the action, and the Lagrangian Equtions of Motion are applied on it. Assuming the motion system with two segments was moving in two-dimensional plane. The final differential equations of Lagrange's equations were nonlinera, and could not be solved by exactly solution. The numerical method of Mathematica software was used to get the numerical solution. The initial conditions and segmental constants from the experimental motions that demonstrated by two male elite spikers from national team were used to substitute into the equations of motions. Then approximate to the borndary condition of impact event of arm-swing phase by changing the moments of each segment. After comparing modeling and real motion, the conclusions could be described as following:1.In modeling, the maximum angular velocity of distal segment（ｗd-max）and the maximum linear velocity of the endpoint of distal segment（Ｖd-max）are appear at the time when two segments get straight.2.In experimental process of the swing phase, ｗd-max and Ｖd-max both appeared prior to impact. But in modeling,ｗd-max and Ｖd-max both appeared after impact event.With the same initial conditional and boundary conditions, the process of the model exhibit more effective then that of experimental motion.