Abstract
BACKGROUMD: Alteration in scapular medial border displacement often observed as scapular winging, can affect the force couples of the rotator cuff muscles and thereby shoulder function. The relationship between scapular medial border displacement and shoulder internal and external rotator muscle function in the baseball player-throwing arm has not been studied.
OBJECTIVE: The purpose of the study was to determine if any relationship exists between the amounts of scapular medial border displacement measured at rest and during the sitting hand press up test position and shoulder internal and external rotator muscular strength in Division III baseball players throwing arm.
METHODS: A total of 51 Division III baseball players volunteered for the study. Scapular medial border displacement was measured with a standardized posterior scapular displacement measurement tool in two positions, the resting and the sitting hand press-up position. Isokinetic strength of concentric internal rotation (IR) and external rotation (ER) peak torque and time to peak torque for each subject were measured using 3 maximal testing repetitions at 60°/s.
RESULTS: The results of the study showed a linear relationship between the amount of scapular medial border displacement and concentric IR strength and also in time to peak torque. However, no linear relationships were observed between scapular medial border displacement and other isokinetic strength variables.
CONCLUSIONS: Scapular medial border displacement produced during a loaded state influences shoulder internal rotatory strength. This may bear on rehabilitation and strengthening exercises in terms of focusing on proper scapular position and subsequent muscular balance to optimize shoulder function.