過肩運動包括所有的投擲運動項目以及游泳、排球及網球等。這些運動項目的運動員需要有均衡的內轉肌群及外轉肌群之肌力，來幫助維持肩關節之穩定性及達到最佳之運動表現。人們亦相信肌力與傷害有很大的關係，不少研究顯示肩關節的肌力不均衡是導致肩關節傷害的一大主因，因此，本研究之目的為利用等速肌力測驗儀來評估過肩運動員的肩關節肌力。二十九位過肩運動員參與本研究，接受60°、180°及300°／秒三種不同角速度的等速收縮肌力（最大肌力及功）測驗。測驗採平躺，肩關節外展90°及肘關節彎曲90°的關節組合角度為正中位置。研究結果發現男女選手的內轉肌群肌力均較外轉肌群之肌力高。雖然統計上不具明顯差異，但外轉肌／內轉肌之肌力比值有隨著角速度的增快而變大的趨勢。本研究結果也顯示不管是內轉肌群或外轉肌群，男選手的肌力很明顯的均較女選手高，但當比較三個不同角速度的外轉肌／內轉肌之肌力比值時，男、女的肌力比值則非常相近似。

Overhead sports include all forms of throwing type sports, and swimming, volleyball and tennis etc. Athletes in this field require balanced muscular strength between external and internal muscle group in order to achieve their peak performance. People also believe that muscular strength is highly related to the risk of sports injury and researches showed that the imbalance of muscular strength with in shoulder is one of the major factors that leads to shoulder injury. Therefore, the purpose of this study was to evaluate overhead sport athletes in shoulder muscular strength and the strength ratio of external/internal using Cybex 6000 Isokinetic dynamometry. Twenty-nine physical education students who were specialized in overhead sports participated in this study. Testing was performed in the supine position, arm abducted to 90° in frontal plane. Three speeds were taken into account: 60° ,180° and 300° per second respectively. The results of this study showed that both male and female athletes had higher internal strength than external strength, and the strength ration of external/internal was increased as speed increased, although it was not statistically significant. Result also showed that all male athletes had significantly higher shoulder strength both internal and external among all three different speeds when compared with female athletes (p<0.001). However, the ratios of external/internal strength were similar at all speeds between male and female athletes.