No effect of short term cross-education training on concentric contralateral shoulder strength

Abstract

BACKGROUND: The ability to train unilaterally and experience contralateral strength gains, a phenomenon known as cross-education, has been well documented in the lower extremity but not the upper. Additionally, short-term training of one to two weeks has shown neural adaptations in strength. OBJECT IVE: To examine the effects of a short-term cross-education strength-training program on contralateral shoulder strength. METHODS: Twenty-seven healthy college students (age: 21.37 ± 2.02 years; height: 167.85 ± 7.63 cm; mass: 74.42 ± 16.73 kg) were randomly assigned to either an experimental (n= 13) or control group (n= 14). All participants completed a pre and post-test separated by two weeks. Testing consisted of 6 maximal repetitions of shoulder internal/external rotation, at each of three speeds (60 and 180∘/s). The experimental group underwent right arm unilateral training (3 × 10 repetitions at all 3 speeds) two times a week for the next two weeks on the same dynamometer. Control group did not train. RESULTS: A 2 × 2 × 2 × 2 (time × arm × speed × group) ANOVA revealed no significant interactions by group, however there main effects of time and arm. For internal rotation, peak moment was significantly greater in the right arm and at 60∘/s, and average power was significantly greater in the right arm and at 180∘/s. For external rotation; peak moment, average power and total work, were significantly greater in the right arm and at 60∘/s. CONCLUSIONS: Short-term cross education training showed no increase in contralateral shoulder strength. Therefore, short-term cross education strength training should not be considered a useful tool in shoulder rehabilitation at this time. However, future research should investigate contrasting training programs.