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

CONTEXT: Conditions such as labral and rotator cuff injuries have been linked with decreases in glenohumeral internal-rotation 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 degrees, P = .028) and total motion deficit (5.73 degrees, P = .009) and less glenohumeral external-rotation gain (3.00 degrees, P = .028) than high school players. Collegiate baseball players had less scapular upward rotation than high school players at the 90 degrees (4.12 degrees, P = .015, versus 3.00 degrees, P = .025) and 120 degrees (4.00 degrees, P = .007, versus 3.40 degrees, P = .005) positions. The scapular protraction difference was greater in collegiate baseball players than in high school players in the hands-on-hips and 90 degrees 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 internal-rotation deficit and scapular position change as the level of competition increases.