Hand-held dynamometer testing of the internal and external rotator musculature based on selected positions to establish normative data and unilateral ratios.

摘要

HYPOTHESIS: Objective documentation is needed of shoulder internal and external rotator strength using hand-held dynamometry in selected positions commonly used in a clinic. We compared strength measures and unilateral ratios between gender, limbs (dominant, nondominant), and 3 testing positions. We hypothesized that men would be stronger than women, the dominant shoulder would be stronger than the nondominant shoulder, and the seated neutral (0 degrees adduction) and seated 30 degrees abduction, 30 degrees scaption, 30 degrees diagonal (30 degrees -30 degrees -30 degrees ) positions would be stronger than the prone at 90 degrees -90 degrees position. MATERIALS AND METHODS: Three positions (prone at 90 degrees , seated at neutral, and seated at 30 degrees -30 degrees -30 degrees ) were evaluated in 181 individuals using hand-held dynamometry. Three separate 3-factor (limb by position by gender) analyses of variance were conducted on internal rotation, external rotation, and unilateral ratios. RESULTS: Although the dominant limb was significantly stronger (P < .001) than the nondominant for internal rotation, there was no difference for external rotation. The external rotators demonstrated significantly greater strength in the prone at 90 degrees position compared with the seated at neutral (P = .001) and seated at 30 degrees -30 degrees -30 degrees (P = .002) positions. The internal rotators demonstrated significantly greater (P = .036) strength in the neutral position than in the prone at 90 degrees position for the women. The unilateral ratio of external rotators/internal rotators ranged from 86% to 99%. For the women, the prone at 90 degrees ratio was significantly greater than seated at neutral (P = .001) and seated at 30 degrees -30 degrees -30 degrees (P = .001) positions. Moderate strength relationships (r = 0.506 to 0.572) were revealed between body mass and all strength measures. DISCUSSION: The results of this study provide evidence to interpret normative data, bilateral comparisons and unilateral ratios of the internal/external rotators in the 3 selected positions. CONCLUSION: Because there are no differences between the seated at neutral and 30 degrees -30 degrees -30 degrees positions and the advantages it offers, we recommend the 30 degrees -30 degrees -30 degrees position for testing and the initiation of rehabilitation.