Internal Rotation Deficits Affect Scapular Positioning in Baseball Players

Stephen J. Thomas MEd, ATC, Kathleen A. Swanik PhD, ATC, Charles B. Swanik PhD, ATC, John D. Kelly IV MD
Clinical Research
Volume 468, Issue 6 / June , 2009

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Abstract

Background

Anecdotal evidence suggests an association between glenohumeral internal rotation deficits (GIRD) and scapular dysfunction, an observable alteration in the normal position or motion of the scapula in relation to the thoracic cage.

Questions/purposes

We therefore hypothesized players with GIRD (15° or greater) will have decreased dominant arm scapular upward rotation and increased scapular protraction compared with baseball players with GIRD (14° or less).

Methods

We studied 43 baseball players with no current shoulder or elbow symptoms; 22 had GIRD 15° or greater and 21 had GIRD 14° or less. We measured glenohumeral internal rotation supine with the scapula stabilized. Scapular upward rotation was tested at rest; 60°, 90°, and 120° abduction in the scapular plane; and scapular protraction at 0°, hands on hips, and 90° abduction in the scapular plane.

Results

The GIRD (15° or greater) group had less scapular upward rotation at 60° (3.58), 90° (5.01), and 120° (2.63) in the dominant arm. Scapular protraction at 90° (0.88 cm) also was greater in the dominant arm of the GIRD (15° or greater) group.

Conclusions

Baseball players with more GIRD have alterations to the position and motion of their scapula. A dual goal of minimizing GIRD and strengthening the scapular stabilizers may be warranted in this population.

Level of Evidence

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

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