Contralateral Repeated Bout Effect of Elbow Flexors Not Observed in Young Women

Abstract

Previous studies have reported that a prior bout of damaging exercise with one limb attenuated the magnitude of muscle damage in the subsequent damaging exercise with the contralateral limb, a phenomenon called contralateral repeated bout effect (CL-RBE). To our knowledge, these studies involved either exclusively men or a mixture of both sexes. PURPOSE: To determine whether contralateral repeated bout effect of elbow flexors exists in women. METHODS: Twelve healthy women (20.9 ± 2.5 yrs) performed two bouts of 45 maximal eccentric contractions (ECC) of elbow flexors separated by 14 days. The isokinetic muscle strength (60°/sec) was measured pre-exercise, immediately post-exercise, and at 24 and 48 h post-exercise. Limb girth, range of motion (ROM), and muscle soreness were measured pre-exercise, and at 24 and 48 h post-exercise. Surface Electromyography (EMG) was recorded during both exercise bouts from the biceps brachii muscle. Data of all variables were analyzed using two-way repeated measures ANOVA (Bout × Time) except that of median frequency of EMG which was analyzed via paired t-test. RESULTS: The isokinetic strength was significantly reduced after the eccentric exercise for both bout 1 (-19.3 ± 17.4%, P < 0.01) and bout 2 (-15.3 ± 15.2%, P < 0.01). Significant main effects of time were also observed for muscle soreness and ROM. Limb girth did not change significantly after either exercise bout. There were no significant differences between bouts for all the measured variables. CONCLUSION: The CL-RBE of elbow flexors was not evident in healthy young women, which is probably because the magnitude of the muscle damage induced by the first exercise bout was not sufficient to induce protective adaptation for the contralateral arm in the second bout.