Level of competition influences overhead athletes' shoulder internal rotation range of motion in the side-lying position.

BACKGROUND

A common impairment present in overhead athletes is decreased internal rotation (IR) range of motion (ROM). The supine position has typically been utilized for measuring IR ROM, but a side-lying position has demonstrated better reliability. There is, however, a paucity of reported values for this side-lying position in overhead athletes, as well as any impact on IR ROM across levels of athletic competition. Hypotheses for this study were: (1) dominant shoulder IR ROM would significantly decrease as level of competition increased; (2) dominant and nondominant IR ROM would be significantly different between the 2 positions, with the side-lying position yielding the least amount of IR ROM; and (3) the dominant shoulder would have significantly less IR ROM than the nondominant shoulder for both positions.

METHODS

Two measurements of passive IR ROM on the dominant and nondominant shoulder were gathered in a side-lying and supine position in 176 National Collegiate Athletic Association Division I (DI), III, and recreational overhead athletes.

RESULTS

The dominant shoulder mean IR ROM values for the side-lying and supine positions were 40.0° ± 10.1° and 54.5° ± 11.6°, respectively; paired t-tests revealed this difference was statistically significant (P < .0001). An analysis of variance (F2,173 = 5.02, P = .007) and post hoc tests revealed that the dominant shoulder side-lying IR ROM value of 35.2° ± 8.5° in DI athletes was significantly smaller than either DIII (40.9° ± 11.5°; P = .005) or recreational athletes (41.5° ± 8.1°; P = .008). In addition, the side-lying position had a higher interrater [intraclass correlation coefficients(2,k) = 0.91; 95% confidence interval 0.83-0.96)] and range of intrarater reliability across raters [intraclass correlation coefficients(1,1): 0.87-0.97; 95% confidence interval 0.79-0.99)]. No sex differences were noted for either position.

CONCLUSION

The side-lying position yielded significantly smaller IR ROM values compared to the supine position. The average IR ROM for the side-lying position for the dominant and nondominant shoulder in asymptomatic overhead athletes was 40° and 53°, respectively. National Collegiate Athletic Association DI athletes had a significantly smaller dominant-shoulder side-lying IR ROM value of 35°.