Soft Tissue Glenohumeral Internal Rotation Deficit Revealed Detailed Musculoskeletal Factors of Baseball Players

Weng, Y-H, Huang, T-S, Chang, C-Y, Yang, J-L, Chen, W-S, and Lin, J-J. Soft tissue glenohumeral internal rotation deficit revealed detailed musculoskeletal factors of baseball players. J Strength Cond Res XX(X): 000-000, 2024-Glenohumeral internal rotation deficit (GIRD) remains contentious regarding its role in shoulder injuries. Soft tissue GIRD (ST-GIRD), reflecting soft tissue changes, may offer a more precise understanding of the injury mechanism. This study investigates correlations between ST-GIRD, self-perceived function/performance, and musculoskeletal factors in baseball players, comparing them with traditional GIRD measurements. Subjects completed the Kerlan-Jobe Orthopedic Clinic self-report questionnaire for function and performance. Soft tissue GIRD, adjusted for humeral retrotorsion, was calculated. Eighty baseball players from various levels were recruited. Kerlan-Jobe Orthopedic Clinic scores significantly correlated with ST-GIRD (r = 0.307, p = 0.046) but not with GIRD (r = 0.164, p = 0.161). Soft tissue GIRD significantly correlated with scapula root of spine alignment (r = -0.303, p = 0.023) but not with GIRD (r = -0.069, p = 0.614). Higher correlation coefficients were found between acromiohumeral distance and posterior capsule thickness with ST-GIRD (r = -0.241 and 0.236, respectively) than with GIRD (r = 0.183 and 0.122, respectively). Soft tissue GIRD offers more detailed musculoskeletal insights than GIRD, showing improved correlations with function/performance, scapular alignment, acromiohumeral distance, and posterior capsule thickness. This supports the notion that internal rotation deficiency is associated with increased posterior capsule thickness and decreased acromiohumeral distance. These results provide coaches and health care practitioners a more detailed way to monitor function and performance of baseball players.