Cross-education Of The Repeated-bout Effect After Unilateral Eccentric Exercise With And Without Mirror Visual Feedback

CROSS-EDUCATION OF THE REPEATED BOUT EFFECT AFTER UNILATERAL ECCENTRIC EXERCISE WITH AND WITHOUT MIRROR VISUAL FEEDBACKChinguun Khurelbaatar1, Richard Yang1,2, Michael A. Bemben1, Daniel Larson1, Christopher D. Black1, FACSM1University of Oklahoma, Norman, Oklahoma; 2University of Oklahoma-Health Sciences Center, Oklahoma City, Oklahoma There is evidence of cross-education of the repeated-bout effect (RBE) to the undamaged contralateral limb; but it is reduced in magnitude compared to what is observed in the ipsilateral limb. Mirror visual feedback (MVF) has been shown to augment the degree of cross-education observed with unilateral strength training, thus it is plausible MVF might augment cross-education of the RBE. PURPOSE: Therefore, the purpose of this study was to investigate if MVF could enhance the contralateral RBE following unilateral eccentric exercise. METHODS: Twenty-eight participants performed 3 sets of maximal eccentric contractions with the elbow flexors on an isokinetic dynamometer with their dominant arm. They were then randomized into 3 groups: 1) control (CON), 2) no mirror (NM), and 3) mirror (MIR). CON performed a second bout of eccentric exercise two week later, again with their dominant arm. The NM and MIR each performed the second bout 1 week later. In the MIR group a mirror was placed along the midline of the body such that it created the illusion of bilateral exercise. Muscle damage was quantified using maximal isometric strength (MVC), range-of-motion (ROM) of the elbow flexors, and ratings of muscle soreness (DOMS). EMG was also recorded from the elbow flexors and extensors during each bout of eccentric exercise. RESULTS: CON (-26 ± 11 vs. -11 ± 11%) and NM (-39 ± 18 vs. -28 ± 13%) showed a RBE for change in MVC 48-hours after exercise (p < 0.02). MIR showed no change (-26 ± 21 vs. -24 ± 20%; p = 0.70). Similar patterns were observed for DOMS with CON (41 ± 20 vs. 17 ± 7) and NM (64 ± 24 vs. 53 ± 27) showing a RBE (p < 0.04) but not for MIR (49 ± 28 vs. 42 ± 29; p = 0.11). No differences were observed in ROM or EMG RMS across all groups between bouts (p > 0.05). CONCLUSIONS: Our findings that MVF did not result in a contralateral RBE and therefore did not augment this effect compared to the NM group.