Abstract—Functional electrical stimulation (FES) is an effective tool for rehabilitation. However the decrease of induced muscle contraction is one of the limitations of using FES in clinical therapy. The purpose of this study is to improve the evoked tension by periodical shifting of stimulating pair of electrode on the same muscle. We applied the time shifting stimulation (TSS) to biceps brachii to validate its effect. Two pairs of surface electrodes were placed over biceps brachii’s motor point. Motor point moves depending on muscle contraction, so the electrode pairs were set to stimulate the motor point in elbow flexion posture and extension posture respectively. TSS changed the stimulating pair of electrode periodically from the distal pair to the proximal pair with 0.5 seconds offset. For comparison, simultaneous stimulation (SS) that stimulated two pairs of electrodes at the same time was conducted. The improvement of maintenance of muscle contraction was assessed by the angle of motion induced by FES. Ten healthy male subjects performed in both TSS and SS experiments in which 180 contractions were induced by FES in 15 minutes. 1 week rest was taken between the stimulation methods. As a result, TSS realized significantly larger angle of motion than SS. The effect of TSS on angle of motion maintained for 15 minutes. The results suggest that TSS may cause less fatigue than SS. The effectiveness of TSS can be contributed by stimulating motor point periodically. Because motor point moves from distal position to proximal position in response to the muscle contraction, TSS may apply stimulation to motor point effectively.

Index Terms—Functional electrical stimulation, muscle fatigue, biceps brachii, motor point, multi-channel electrode.

Rintaro Kamihira, Misato Kasuya, Shunta Togo, and Masao Sugi are with Graduate School of Informatics and Engineering, the University of Electro-Communications, Tokyo, Japan (email: yokoi@mce.uec.ac.jp).
Yinlai Jiang and Hiroshi Yokoi are with Brain Science Inspired Life Support Research Center, the University of Electro-Communications, Tokyo, Japan. They are also with Graduate School of Informatics and Engineering, the University of Electro-Communications, Tokyo, Japan.

Cite: Rintaro Kamihira, Misato Kasuya, Yinlai Jiang Shunta Togo, Masao Sugi, Hiroshi Yokoi, "Maintenance of Muscle Contraction Improves during Dynamic Exercise by Multi-channel Functional Electrical Stimulation with Time Shifting Stimulation," International Journal of Bioscience, Biochemistry and Bioinformatics vol. 7, no. 1, pp. 33-40, 2017.