Bernstein(1967)提出動作是由不同身體單位協調共動而成，動作形成初期由凍結自由度、經解放自由度，最後利用反作用力以達成動作表現的增進，Newell(1986)亦提出限制觀點以及動作變異性探討動作的協調型態。本研究旨在驗證個體限制是否會造成動作結果改善，以及限制個體部分力學自由度對動作過程變異性和結果變異性的影響。邀集8位實驗參加者（平均年齡20.1±2.2歲），採用A-B-A'的實驗流程，階段B介入實驗操弄，同時也採用限制組與無限制組的實驗設計。自變項為肘關節限制之有無，依變項為飛鏢投擲結果的成績表現、出手速度、與出手角度之間的關係比較。每位實驗參加者總共投擲飛鏢150次，以10台紅外線攝影機進行拍攝與資料收集，並以Vicon Nexus的軟體分析出手速度、角度，統計使用2（組別）×3（階段）混合設計二因子變異數分析(two-way ANOVA)，階段因子為重覆量數。結果發現在肢段限制後得分下降，出手速度與矢狀面出手角度產生消長的現象，並且當肘關節限制時，個體動作結果變異性顯著大於未受肘限制情境。本研究結論為手肘關節被限制時，會改變投擲動作之過程表現與結果表現，而肘關節限制前後，呈現不同的動作表現。

This study was designed to examine the performance and the degrees of freedom changed by the constraint form the elbow joint to identify the relationship between process and product variability. Eight male adult subjects (age: 20.1±2.2 years) were participated in this study. The A-B-A' design was employed and the elbow was constrained as the experiment manipulation during the stage B. The control and experimental groups performed the same darting-throwing movements. The performance outcome, velocity and angle of the dart when departing from the participant's hand were measured as dependent variable. One hundred and fifty throwing trials in three stages were recorded from 10 infrared-ray cameras. A 2 (constraint) × 3 (stages) mixed design ANOVA with stage factors as repeated measures was used for the statistical analysis. The results showed that decreased scores and tradeoffs between the darts' velocity and angles after constraint, but the product variability was improved after elbow constraint. It was concluded that the throwing performance and process changed with the elbow constrained. After releasing the elbow constraint, the coordination differed from that of without constraint.