Moline, M., Laudner, K., & Meister, K. (2008). Correlation between external shoulder rotation strength and posterior shoulder range of motion in professional baseball players. ACSM 55th Annual Meeting Indianapolis. Presentation number 2498.

"Posterior shoulder tightness is a common trait among overhead athletes, such as baseball players, and has been linked with the development of restricted shoulder range of motion (ROM) and several pathologies. This tightness is hypothesized to be the result of the cumulative trauma placed on the posterior shoulder during the deceleration phase of the throwing motion. In addition to the posterior shoulder capsule’s role in absorbing this force, the shoulder external rotators also eccentrically decelerate the arm after ball release and therefore may aide in the dissipation of this force".

This study determined if a relationship exists between shoulder external rotation strength and glenohumeral internal rotation or horizontal adduction range of motion in a group of professional baseball players (20 pitchers and 25 position players) with no recent history of upper extremity pathology. External shoulder rotation isometric strength was measured with a hand-held digital dynamometer in the prone position, with the shoulder and elbow in 90° of abduction and flexion, respectively. Glenohumeral internal rotation and horizontal adduction range of motion were measured using a digital inclinometer in the supine position with the scapula stabilized.

Mean external shoulder rotation strength showed virtually no relationship with both mean glenohumeral internal rotation and horizontal adduction range of motion.

Implication. There is no relationship between shoulder external rotation strength and posterior shoulder range of motion among baseball players. Routine stretching may be more beneficial than preventative strengthening of the dynamic restraints for decreasing posterior shoulder tightness and decreasing the risk of upper extremity injuries.

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