Internal rotation and scapular position differences: A comparison of collegiate and high school baseball players

Abstract

Context: Conditions such as labral and rotator cuff injuries have been linked with decreases in glenohumeral internalrotation and increases in external-rotation motion. Also, decreased glenohumeral internal rotation is strongly associated with scapular dyskinesis. Objective: To compare healthy collegiate and high school baseball players' glenohumeral joint range of motion and scapular position. Design: Cross-sectional study. Setting: Institutional research laboratory. Patients or Other Participants: Thirty-one male National Collegiate Athletic Association Division I collegiate (age = 20.23 ± 1.17 years, height = 186.24 ± 5.73 cm, mass = 92.01 ± 7.68 kg) and 21 male high school baseball players (age = 16.57 ± 0.76 years, height = 180.58 ± 6.01 cm, mass = 79.09 ± 11.51 kg). Main Outcome Measure(s): Glenohumeral internal and external rotation and scapular upward rotation were measured with a digital inclinometer. Scapular protraction was measured with a vernier caliper. All variables except scapular upward rotation were calculated as the difference between the dominant and nondominant sides. Results: Collegiate baseball players had more glenohumeral internal-rotation deficit (4.80°, P = .028) and total motion deficit (5.73°, P = .009) and less glenohumeral external-rotation gain (3.00°, P = .028) than high school players. Collegiate baseball players had less scapular upward rotation than high school players at the 906 (4.12°, P = .015, versus 3.00°, P = .025) and 120° (4.00°, P = .007, versus 3.40°, P = .005) positions. The scapular protraction difference was greater in collegiate baseball players than in high school players in the hands-on-hips and 906 positions (0.77 cm, P = .021, and 1.4 cm, P = .001). Conclusions: When comparing high school with collegiate baseball players, these data suggest that glenohumeral internalrotation deficit and scapular position change as the level of competition increases. © by the National Athletic Trainers' Association, Inc.