目的：肩關節的疼痛常發生於過肩運動之運動員，過肩運動包括單側或雙側的運動模式，如游泳、網球。本研究目的是比較單側性（網球）與雙側性（游泳）過肩運動項目選手的肩關節活動角度。方法：實驗參與者共18名（7名雙側性運動項目選手及11名單側性運動項目選手），測量其肩彎曲、過度伸展、肩內轉／外轉、及水平內收，使用關節量角器進行測量，以相依樣本t檢定比較選手慣用與非慣用側之差異，並以獨立樣本t檢定分析單側性與雙側性過肩運動項目選手之差異。結果：雙側性過肩項目（游泳）的慣用側與非慣用側肩關節活動度經比較後並無顯著差異，兩側的關節活動度較均衡，但是單側性過肩項目（網球）的慣用側與非慣用側肩關節活動度測量中，外轉角度及水平內收角度慣用側大於非慣用側、內轉角度慣用側小於非慣用側；比較單側性與雙側性之肩關節活動度差異發現，慣用側除肩關節彎曲角度之外，其餘角度均達顯著差異，其中過度伸展、外轉、水平內收呈現單側性大於雙側性項目，內轉及旋轉全角度呈現雙側性大於單側性項目。結論：本研究顯示因單側性運動項目的特殊性（如網球）而導致肩部活動度的適應。

Purpose: Shoulder pain often occurs in overhead athletes. Overhead sports included unilateral or bilateral arms used, such as tennis or swim. The purpose of this study was to measure and compare the difference of shoulder range of motion (ROM) between healthy unilateral and bilateral shoulder used players. Methods: Eighteen overhead athletes participated in this study (7 bilateral and 11 unilateral shoulder used players). The shoulder flexion, hyperextension, internal/external rotation, and horizontal adduction were measured by using goniometer for both arms. Independent t-test was used to analyze the difference between unilateral and bilateral shoulder used players and paired T-test was used to compare the difference between their dominant and non-dominant shoulder respectively. Results: No significant difference was found in dominant and non-dominant shoulder comparison for bilateral shoulder used players (p>.05). However, we found the ROM of external rotation and horizontal adduction of dominant shoulder had larger degree than non-dominant side, the ROM of internal rotation of dominant shoulder was less than non-dominant shoulder. All ROM had showed significant difference, except shoulder flexion, when we compared the unilateral and bilateral shoulder used events players. Conclusions: We found the shoulder ROM adaptation in unilateral shoulder used players.