ID 263 – Effects of short-term vibration on mixed nerve silent period

Abstract

Aim Following the electrical stimulation of mixed nerve during voluntary muscle contraction, temporarily suppressed EMG activation called mixt nerve silent period (MNSP). MNSP is interrupted by several bursts; first one is segmental reflex (SR) and others known as a long-loop reflexes(LLR). Vibration has been shown suppress the segmental H-reflex amplitude by increasing Ia afferent discharge. In this study, our aim was to provide insight into SR characteristics and the effects of vibration on other parameters. Method Eleven healthy volunteer (5 women, 33.36 ± 5.35 years) included the study. Vibration was applied for 2 min at 100 Hz with repositioning amplitude of 1 mm on right forearm. Median nerve stimulated at wrist during thumb abduction and MNSP recorded at baseline, during and after the vibration application. Latencies of SR, LLR and MNSP and amplitudes of SR and LLR compared for each session. Results Average SR and LLR amplitudes, MNSP durations before, during and after vibration were found as (1093.36 ± 606.16/877.22 ± 390.37/863.0 ± 604.51), (561.17 ± 353.8/1363.92 ± 1242.78/1100.0 ± 901.65) and (108.6 ± 12.41/113.55 ± 21.35/100.47 ± 18.03) respectively. MNSP durations, SR and LLR latencies were not significantly different between sessions. While SR amplitude tended to decrease, LLRA tended to increase. Conclusion Present study demonstrated that short-therm vibration is not effective on MNSP parameters. Our results may support that SR share similar characteristics with HR.