目的：棒球投手慣用側手臂常有肩後軟組織緊繃現象，可能影響到肩關節的運動學與肩胛骨的姿勢。然而，此機制仍然不清楚。因此，本研究旨在探討肩後軟組織緊繃對盂肱關節旋轉活動度和肩胛骨姿勢的影響。方法：共有二十位體育大學的棒球投手（17位右投手；3位左投手）參與本研究。測量項目包括兩側盂肱關節水平內收活動度與內旋及外旋和整體旋轉角度。此外肩胛骨姿勢測量有肩胛骨前突和側邊移動距離包括自然姿勢及雙手在髖關節與盂肱關節外展90度。結果：投手慣用側手臂比非慣用側有較小的水平內收與內旋及整體旋轉角度（＜0.05）。此外，慣用側手臂水平內收活動度與內旋及整體旋轉角度及肩胛骨前突姿勢呈顯著負相關（r=-0.48, -0.56, -0.49, P＜0.05）。結論：肩後軟組織緊繃曹限制盂肱關節內旋與整體旋轉角度且會增加肩胛骨前突姿勢，因此，早期介入肩胛骨周邊軟組織的放鬆技術與伸展運動，可以維持良好柔軟度並避免投手運動傷害產生。

Objectives. Posterior shoulder soft tissue tightness of the dominant shoulder might affect glenohumeral rotation range of motion (ROM) and change of scapular kinematics in baseball pitchers. However, the mechanism through which it does this is still not clear. Therefore, the purpose of this study was to investigate the effects of the posterior soft tissue tightness of the dominant shoulder on glenohumeral rotation ROM and scapular position. Methods. Twenty healthy collegiate baseball pitchers were included in the study. (right-arm dominant, =17, left-arm dominant, =3). Bilateral glenohumeral internal rotation (IR), external rotation, total rotation ROM and horizontal adduction ROM were measured. Scapular positions were measured according to bilateral scapular protraction posture and lateral scapular slider performed in three different positions, including neutral, hands on hips, and abduction 90°. Results. The dominant shoulder had less glenohumeral horizontal adduction ROM, IR ROM, and total rotation ROM (P＜.05). We found a significant negative correlation between glenohumeral adduction ROM, IR ROM, total rotation ROM, and scapular protraction, (all P＜0.05). Conclusion. Posterior shoulder soft tissue tightness limited glenohumeral IR ROM, total rotation ROM and increased scapular protraction position. Therefore, an early program making use of release techniques and stretching exercise applied to peri-scapular soft tissue may help these patients maintain flexibility and prevent risk of further sport injury.