緒論：本研究之目的是比較有無肩關節內轉角度缺損投手之投球手與非投球手肩關 節內/外轉活動度及肩部穩定性之差異，以及了解肩關節穩定性與活動度之間的關係。方 法：共有15 位大學甲組投手參與 (8 位肩關節內轉角度缺損者及7 位肩關節內轉角度正 常者)，使用關節角度計評估投手投球手與非投球手之肩關節內轉、外轉、及內轉加外轉 全角度之主動活動度，以及使用測力板測試單肘側邊支撐肩部穩定性測試。以無母數 Mann-Whitney U test 分析兩獨立組別的投球手與非投球手之肩關節活動度及肩關節穩定 性數值之差異，及皮爾森積差相關與簡單線性迴歸分析投球手的肩關節活動度與肩關節 穩定性之關係。結果：肩關節活動度測量中，缺損組在投球手的肩外轉角度比正常組大 (p = .04)，其餘關節活動度並未有差異 (p > .05)；肩關節穩定性測量中，擺盪面積呈現缺損 組比正常組大 (p = .04)，顯示缺損組有較差的肩關節穩定性，而擺盪距離與擺盪速度則 無差異。肩關節擺盪距離及擺盪速度與肩內轉角度呈現中度負相關 (p = .03)，且可以迴 歸公式y = -0.038x+56.903 使用肩內轉角度預測肩關節的穩定性 (x：肩關節內轉角度；y： 肩擺盪距離；R2 = 0.309, F (1,13) = 5.825, p = .03)。結論：肩內轉角度缺損投手在肩外轉 角度較大、肩部穩定性較差，且當投手的肩內轉活動度增加，肩關節穩定性隨之增加。

Introduction: Shoulder pain and instability often occurs in baseball pitchers. The shoulder pain and instability may come from the glenohumeral internal rotation deficit (GIRD). The purpose of this study was to compare the difference and relationship of shoulder range of motion (ROM) and shoulder stability between pitchers with and without GIRD. Methods: Fifteen pitchers participated in this study (8 pitchers with GIRD and 7 pitchers without GIRD). The shoulder internal / external rotation, and shoulder total range were measured by using goniometer for both arms. The Zebris force platform was used to assess the shoulder stability with using lateral single elbow supports dynamic stability test. The non-parametric Mann-Whitney U test was used to compare the difference between pitchers with and without GIRD. Pearson’s coefficient of correlation and simple linear regression was used to analyze the relationship between shoulder range of motion and stability. Results: The result was showed that the pitchers with GIRD symptom had more laxity in shoulder external rotation than pitchers without GIRD in throwing arm (p < .05), and no significant different was found in others measurement of shoulder ROM. Pitcher with appearing GIRD was found to have poor shoulder stability (p < .05) when comparing with pitcher who has no GIRD symptom. The moderated negative relationships were found among sway path length, velocity of shoulder stability test and shoulder internal rotation ROM (p < .05). The regression formation: y=-0.038x+56.903 (x: shoulder internal rotation ROM; y: sway path length of shoulder stability test). It was meant that the shoulder internal rotation deficit could predict the shoulder stability. Conclusion: It had relieved that the pitchers with GIRD symptom has more laxity degree in shoulder external rotation and poor shoulder stability. It is also showed more ROM of shoulder internal rotation, more shoulder stability.