目的：探討國內優秀成棒投手的肩關節外旋與內旋、屈曲與伸展、外展與內收、肘關節屈曲與伸展、前臂旋後與旋前、腕關節屈曲與伸展之等速肌力與可投出最快球速之關係，並與國內外相關研究比較。方法：利用Biodex等速測力儀量測10位男性受測者肩、肘、前臂和腕關節在不同旋轉角速度下之向心等速肌力所能提供轉矩；另外，受測者在室內人工投手丘上以最大努力投球，利用Vicon 3D系統量測其所能投出之最快速球速。結果：只有肩關節伸展在角速度500和300°/s與球速有顯著正相關；達顯著負相關的有肘關節360°/s屈曲、腕關節150與210°/s屈曲；其餘皆無顯著相關。結論：在上肢肌力訓練上，再增加肩關節伸展方向肌力（如胸大肌、闊背肌等）可能有助於球速表現。而部分受測者可能太過著重肘、腕關節屈曲肌力之訓練，導致空有高肌力而無快球速之結果。受測者之大部分等速肌力雖顯著低於西方同層級投手，但球速相對來說卻不會低太多，可能是有其它的投球技巧（如軀幹扭轉及屈曲動作）的補償作用，值得再進一步探究。

Purpose: The purpose of this study was to investigate the relationship between the pitching speed and isokinetic strength for Taiwan elite adult male pitcher, and to compare these results with western and other Taiwanese adult pitchers. Method: 10 elite pitchers volunteered to participate this study. Biodex dynamometer was used to measure the isokinetic strengths of shoulder, elbow, forearm and wrist at different angular speeds of rotation. Pitchers pitched fast balls as fast as they can in lab, and the fastest speed for each pitcher was recorded for analysis. Results: For isokinetic strength, only the shoulder extension at high speed (300 and 500°/s) was positively relative to the ball speed; the wrist flexion at 360°/s and elbow flexion at 150 and 210°/s were negatively relative to the ball speed. Conclusion: The more efficiently pitchers train their shoulder extension, the faster ball speed they might pitch. Some pitchers in this study, who pitched more slowly, seemed to over-emphasize on the wrist and elbow flexion training. Comparing to the western pitchers in the same level, although the isokinetic strengths of Taiwan pitchers are significantly low, but the maximum pitched ball speed wasn't lower so much relative to the strength. It implies that Taiwan pitchers may have other skills for strength compensation, and deserve for further researches.