Affiliations: [a] Oregon Health and Science University, Portland, OR, USA | [b] Department of Sport Rehabilitation, Kookmin University, Seoul, Korea | [c] Oregon State University, Corvallis, OR, USA
Note: [] Corresponding author: Junggi Hong, Department of Sport
Rehabilitation, Kookmin University, Seoul, Korea. Tel.: +82 2 910 5826; Fax:
+82 2 910 4789; E-mail: hongjunggi@gmail.com
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.
