The Influence of Posterior Shoulder Tightness on Shoulder Range of Motion in Pitchers with Glenohumeral Internal Rotation Deficit

Abstract

Background and Purpose: Overhead athletes display dominant shoulder glenohumeral internal rotational deficit (GIRD). Several authors suggest that GIRD is the seminal event in the cascade of adaptations that occur before overuse injuries at the shoulder. But the relationship of posterior shoulder tightness on development of GIRD is not clear. Thus, the purpose of this study was to examine the influence of posterior shoulder tightness on shoulder range of motion (ROM) in pitchers with GIRD. Methods: Shoulder ROM and posterior shoulder tightness were measured in 35 asymptomatic collegiate baseball pitchers. Both shoulder external rotation(ER) and internal rotation (IR) ROM were assessed using a standard goniometric. Bilateral posterior shoulder tightness was assessed by measuring glenohumeral horizontal adduction with the participant lying supine. Pitchers were classified as having GIRD if their throwing shoulder displayed an IR loss ≥ 20° compared with nonthrowing shoulder. In addition, total rotational motion was analyzed (IR + ER). Results: Pitchers with GIRD displayed significantly greater posterior shoulder tightness in their dominant shoulder as compared with those without GIRD (GIRD = 13.71° ± 1.76°, no GIRD = 20.29° ± 3.65°; p = 0.001). There was moderate positive association between IR ROM and posterior shoulder tightness for pitchers with GIRD (R = 0.501; p = 0.04). Pitchers with GIRD display a significant alteration in ROM (IR = 56.12° ± 7.11°, ER = 120.00° ± 6.12°; p ＜ .01) when compared with pitchers without GIRD (IR = 68.36° ± 10.36°, ER = 110.29° ± 8.98°). Conclusions: Pitchers with GIRD displayed greater dominant posterior shoulder tightness as compared with pitchers without GIRD. Pitchers with greater posterior shoulder tightness appear to be more susceptible to restrict ROM and altered glenohumeral kinematics. Clinical Relevance: Early detection and assessment are important in diagnosing GIRD. Besides treatment of GIRD might included posterior shoulder stretch exercise; IR flexibility program; posture training and strengthening to increase ER musculature.