Evaluation of three on-the-field non-assisted Posterior Shoulder Stretches in Collegiate Baseball Pitchers

Introduction: Shoulder musculoskeletal adaptations commonly occur in baseball pitchers due to repetitive throwing and extremely high shoulder velocities. Some observed adaptations include posterior shoulder tightness (PST) and glenohumeral internal rotation deficit (GIRD). The static capsular structures and dynamic muscles of the shoulder that are responsible for controlling normal glenohumeral arthrokinematics, must be properly stretched for normal shoulder movement. It is speculated that appropriate posterior shoulder stretching of the glenohumeral joint can decrease the amount of PST in an overhead athlete, help minimize the risk of developing shoulder pathologies, and increase the ability of the overhead athlete to perform. The purpose of this study was to evaluate three on-the-field posterior shoulder stretches among collegiate baseball pitchers. It was hypothesized that the standing sleeper stretch at 90º, sleeper stretch at 45º, and the horizontal cross arm stretch would create acute ROM differences and provide scapular stabilization for increasing shoulder IR ROM and decreasing PST. Methods: Glenohumeral ROM, PST, and scapular kinematics were measured in 15 male collegiate pitchers. All subjects were free of shoulder pain. Each subject performed one posterior shoulder stretch during 3 individual sessions. Glenohumeral ROM and PST were measured using an inclinometer/anthropometer, pre and post stretch while scapular kinematics were assessed using an electromagnetic tracking device during each stretch. Results: The results of this study show that stretching created significant acute increases in glenohumeral IR (p<.0001) and decreases in supine PST (p<.0001) and side-lying PST (p=.012). There were no significant differences between stretches for IR (p=.919), ER (p=.494), Supine PST (p=.536), and Side-lying PST (p=.177). The five scapular kinematic values showed no significant differences among stretches when compared for scapular upward rotation (p=0.066), external rotation (p=0.077), posterior tilting (p=0.101), protraction (p=0.221), and elevation (p=0.228). Conclusions: This study has demonstrated that performing a posterior shoulder stretch for a single session of 3 repeated 30 seconds is adequate to significantly increase acute GH IR ROM and decrease PST. Sufficient scapular stabilization can be achieved when the standing sleeper stretch at 90º, standing sleeper stretch at 45º, and the standing horizontal cross arm stretch are performed correctly