Eccentric contraction-induced muscle damage in human flexor pollicis brevis is accompanied by impairment of motor nerve.

Abstract

Eccentric contractions (ECCs) cause muscle damage. In addition, we showed that ECCs induce nerve dysfunction and damage with rats and human. We aimed to evaluate motor nerve conduction velocity (MCV) for flexor pollicis brevis muscle (FPBM) after ECCs. Twelve men (years, 19.8±1.7years; height, 172.4±7.0cm; weight, 64.0±8.6kg) performed maximal 100 ECCs on their FPBM of non-dominant hands with torque dynamometer. The dominant hands were control (CON). Maximal voluntary contraction (MVC), range of motion (ROM), DOMS, and MCV were assessed before, immediately post, and 1, 2, and 5days after ECCs. MCV was calculated as the distance by stimulation divided by the latencies of the waveforms generated. Values were statistically analyzed by two-way ANOVA, and the significance level was set at P<.05. Decreases in MVC immediately (-32.9%) to 5days after ECCs were significantly greater (P<.05) than for the CON group. ROM showed a significant decrease immediately (-21.6%) after ECCs compared with before ECCs and CON group (P<.05). DOMS after ECCs increased at 1 and 2days (5.0cm) after ECCs compared with before ECCs and CON (P<.05). Also, MCV after ECCs delayed significantly from immediately (-36.4%), 1, 2, and 5days after ECCs compared with CON (P<.05), while no significant change in M-wave amplitude was observed over time for both ECCs and CON. The present study showed that ECCs of the FPBM cause a significant delay in MCV of median nerve.