Potential of M-Wave Elicited by Double Pulse for Muscle Fatigue Evaluation in Intermittent Muscle Activation by Functional Electrical Stimulation for Motor Rehabilitation.

Naoto Miura,Takashi Watanabe

doi:10.1155/2016/6957287

Abstract

Clinical studies on application of functional electrical stimulation (FES) to motor rehabilitation have been increasing. However, muscle fatigue appears early in the course of repetitive movement production training by FES. Although M-wave variables were suggested to be reliable indices of muscle fatigue in long lasting constant electrical stimulation under the isometric condition, the ability of M-wave needs more studies under intermittent stimulation condition, because the intervals between electrical stimulations help recovery of muscle activation level. In this paper, M-waves elicited by double pulses were examined in muscle fatigue evaluation during repetitive movements considering rehabilitation training with surface electrical stimulation. M-waves were measured under the two conditions of repetitive stimulation: knee extension force production under the isometric condition and the dynamic movement condition by knee joint angle control. Amplitude of M-wave elicited by the 2nd pulse of a double pulse decreased during muscle fatigue in both measurement conditions, while the change in M-waves elicited by single pulses in a stimulation burst was not relevant to muscle fatigue in repeated activation with stimulation interval of 1 s. Fatigue index obtained from M-waves elicited by 2nd pulses was suggested to provide good estimation of muscle fatigue during repetitive movements with FES.

Highlights

Functional electrical stimulation (FES) has been studied clinically as an application to an orthotic and therapeutic aid in rehabilitation of upper and lower limb motor functions [1,2,3,4]
This study demonstrated that M-waves elicited by the 2nd pulses of double pulses would be effective in muscle fatigue evaluation for repetitive movements in rehabilitation training using FES, while the M-wave obtained from single pulse was not sensitive to detect muscle fatigue
M-waves elicited by double pulses were measured under the conditions of repeated intermittent stimulation for training with FES, which were force production under the isometric condition and joint angle control based on cycle-to-cycle control under the dynamic movement condition

Summary

Introduction

Functional electrical stimulation (FES) has been studied clinically as an application to an orthotic and therapeutic aid in rehabilitation of upper and lower limb motor functions [1,2,3,4]. Peak-to-peak amplitude of M-wave has been found to be a reliable muscle fatigue indicator that characterizes FES-produced force in continuous constant stimulation [8,9,10,11]. In a gait rehabilitation exercise for motor paralysis, paralyzed leg muscles are activated repeatedly with time interval in accordance with the preprogrammed muscle activation pattern that mimics normal gait [2, 6, 12]. In such rehabilitation training, electrical stimulation pulses are applied to muscles intermittently. The time interval between movement productions by electrical stimulation is considered to rest the electrically stimulated muscle and increases activity of the muscle, which

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