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

Abstract

Background Eccentric contractions (ECCs) cause muscle damage. In addition, we showed that ECCs induce nerve dysfunction and damage with rats and human. Purpose We aimed to evaluate motor nerve conduction velocity (MCV) for flexor pollicis brevis muscle (FPBM) after ECCs. Methods Twelve men (years, 19.8 ± 1.7 years; height, 172.4 ± 7.0 cm; weight, 64.0 ± 8.6 kg) 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 5 days 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. Results Decreases in MVC immediately (−32.9%) to 5 days 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 2 days (5.0 cm) after ECCs compared with before ECCs and CON (P < .05). Also, MCV after ECCs delayed significantly from immediately (−36.4%), 1, 2, and 5 days after ECCs compared with CON (P < .05), while no significant change in M‐wave amplitude was observed over time for both ECCs and CON. Conclusion The present study showed that ECCs of the FPBM cause a significant delay in MCV of median nerve.

Immediate and short-term effects of eccentric muscle contractions on structural, morphological, mechanical, functional and physiological properties of peripheral nerves: A protocol for a systematic review and meta-analysis

“…Consistent with these animal studies findings, it has been shown that eccentric contractions induce a temporary reduction on nerve function in healthy individuals [16][17][18][19]. Therefore, delays in motor and sensory NCV of the median nerve were observed following 100 eccentric contractions of the flexor pollicis brevis muscle [16,17]. Furthermore, an acute reduction (i.e., -27%) in muscle fiber conduction velocity was observed after 50 repeated maximal eccentric contractions of the elbow flexors, at 2 hours post-exercise [14].…”

“…Therefore, consecutive bouts of eccentric contractions with fast angular velocity cause severe nerve properties alterations, and thus impairing skeletal muscle function. Consistent with these animal studies findings, it has been shown that eccentric contractions induce a temporary reduction on nerve function in healthy individuals [16][17][18][19]. Therefore, delays in motor and sensory NCV of the median nerve were observed following 100 eccentric contractions of the flexor pollicis brevis muscle [16,17].…”

“…However, recent investigations have focused on the acute effects of eccentric contractions on peripheral nerve properties. Several authors have shown acute changes in structural and functional properties of peripheral nerves in both animals [14,15] and humans [16][17][18][19]. Thus, animal studies revealed myelin sheath damage, observed after 20 eccentric contractions of the plantar flexors with fast angular velocity (180˚/s) [14].…”

Neurodynamics: is tension contentious?

“…It is believed that sudden stretching trauma has the potential to be more damaging compared to more gradual tension applied within appropriate limits [ 67 ]. For example, fast eccentric muscle contractions have been shown to induce functional and structural damage in interfacing animal [ 82 , 83 ] and human [ 84 ] nerves. Clinically, neurodynamic techniques are typically promoted to be performed as dynamic techniques rather than sustained or static holds [ 85 , 86 ].…”