ABSTRACT

　It is known that muscle relaxation of one muscle induces temporal reduction inforce level of the other muscle. Furthermore, many previous study investigated thattranscranial direct current stimulation （tDCS） induced increase in training efficiencyfor motor learning.　In the present study, we investigated the effect of tDCS on theprimary motor cortex during 3 days’ training including muscle relaxation. Thirtyhealthy participants were divided into 3 groups （without stimulation, with anodalstimulation and with cathodal stimulation）， and they sustained isometric contractionof their right finger. Then participants simultaneously performed muscle relaxationof shoulder adduction immediately after audio cue from 50% MVC of isometriccontraction for 30 times in each day. Participants performed the task for three dayswith 2 -10 days interval. As a result, sustained force level of finger contraction wastemporally decreased by muscle relaxation of shoulder. However, changes in its effectdue to the 3 days' training without stimulation was not observed. Likewise, no changesin its effect were observed in both anodal and cathodal groups. Present study revealed that different mechanism might be involved in motor learning process for musclerelaxation compared to that of muscle contraction.

DECENTE SPORTS SCIENCE Vol.40/The DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE