Assessment of shoulder strength in professional baseball pitchers.

STUDY DESIGN A bilateral comparison of strength and range of motion testing in professional baseball pitchers. OBJECTIVE We studied 39 professional male baseball pitchers to determine if the shoulder used for throwing was weaker or had less passive range of motion, compared to the nondominant arm. BACKGROUND Shoulder muscle weakness has been proposed as a possible risk factor for developing injury. Therefore, objective quantification of the strength of glenohumeral and scapular rotator muscle groups should be studied in a population of professional baseball pitchers. METHODS AND MEASURES Passive internal and external range of motion was bilaterally measured at 90 degrees of abduction. Muscle strength of the following muscles was measured bilaterally with a hand-held dynamometer: external and internal glenohumeral rotators, supraspinatus, middle trapezius, lower trapezius, and serratus anterior. RESULTS Passive external rotation of the glenohumeral joint at 90 degrees of abduction on the pitching side was significantly greater than on the nonpitching side. Passive internal rotation range of motion on the nonpitching side was significantly greater than on the pitching side. The pitching arm's internal rotators, when tested in abduction, were significantly stronger than the nonpitching arm. The nonpitching arm's external rotators in the plane of the scapula, and in abduction, were significantly greater than those of the pitching arm. The pitching arm's middle and lower trapezius muscles were significantly stronger than those of the nonpitching arm. CONCLUSION The range of motion and strength characteristics measured in this study can assist clinicians in evaluating athletes who use overhead throwing motions.