【論文摘要】The Influence of Glenohumeral Internal Rotation Deficit on Pitching Biomechanics in Elite High School Baseball Pitchers

【論文摘要】盂肱關節內轉缺失對高中棒球投手投球生物力學之影響

翁義軒(Yi-Hsuan Weng) ； 黃崇舜(Tsun-Shun Huang) ； 黃正雅(Cheng-Ya Huang) ； 陳星宇(Hsing-Yu Chen) ； 蔡鏞申(Yung-Shen Tsai) ； 林居正(Jiu-Jenq Lin)

《物理治療》 45卷4期 (2020/12) Pp. 295-295

https://doi.org/10.6215/FJPT.202012.O01

摘要

Background and Purpose: Glenohumeral internal rotation deficit (GIRD) is believed to be a potential risk factor contributing to shoulder injury. Additionally, research has reported that it is associated with altered scapular kinematics. However, it is unclear whether these alterations and changes in muscle activities are related to fastball pitching in pitchers with and without symptom. The objectives of this study were to compare the scapular kinematics and associated muscular activities during fastball pitching in baseball pitchers with and without GIRD and GIRD baseball pitchers with and without symptom. Methods: Thirty-three high school baseball pitchers were recruited for 3 groups (11 pitchers per group), asymptomatic baseball pitchers without GIRD (AwG), asymptomatic baseball pitchers with GIRD (AG), and symptomatic baseball pitchers with GIRD (SG). During fast ball pitching, the scapular kinematics (upward/downward rotation, anterior/posterior tilt, external/internal rotation) and associated muscle activation (upper trapezius, lower trapezius, serratus anterior, anterior deltoid, biceps brachii, and triceps brachii) were recorded by three-dimensional electromagnetic motion analysis and electromyography. Results: GIRD baseball pitchers had increased scapular anterior tilt (AG = 6.8-18.4°, p ＜ 0.01 and SG = 14.5°, p = 0.009, respectively) compared to baseball pitchers without GIRD (AwG). Increased triceps brachii and serratus anterior muscular activity (9.9%, p = 0.015; 30.8%, p = 0.006, respectively) were also found in GIRD baseball pitchers (AG) compared to baseball pitchers without GIRD (AwG). Additionally, GIRD baseball pitchers with symptom (SG) had decreased triceps brachii and serratus anterior muscular activity (37.8%, p = 0.016; 4.8-30.2%, p ＜ 0.01, respectively) compared to GIRD baseball pitchers without symptom (AG). Conclusion: GIRD and symptom showed different effect on scapular kinematics and associated muscular activities during fastball pitching. Increased scapular anterior tilt and serratus anterior, triceps brachii muscle activity during pitching were characterized in GIRD pitchers while decreased serratus anterior, triceps brachii muscle activity during pitching were characterized in GIRD with symptom. Clinical Relevance: GIRD pitchers had specific characteristics during fastball pitching, like altered scapular anterior tilt and serratus anterior, triceps brachii muscle activity. These changes may be related to further symptomatic development. On the other hand, serratus anterior and triceps brachii muscle activity are important to consider in the rehabilitation of symptomatic GIRD pitchers.