2019 Volume 40 Pages 65-71
It is known that muscle relaxation of one muscle induces temporal reduction in force level of the other muscle. Furthermore, many previous study investigated that transcranial direct current stimulation （tDCS） induced increase in training efficiency for motor learning.In the present study, we investigated the effect of tDCS on the primary motor cortex during 3 days’ training including muscle relaxation. Thirty healthy participants were divided into 3 groups （without stimulation, with anodal stimulation and with cathodal stimulation）， and they sustained isometric contraction of their right finger. Then participants simultaneously performed muscle relaxation of shoulder adduction immediately after audio cue from 50% MVC of isometric contraction for 30 times in each day. Participants performed the task for three days with 2 -10 days interval. As a result, sustained force level of finger contraction was temporally decreased by muscle relaxation of shoulder. However, changes in its effect due to the 3 days' training without stimulation was not observed. Likewise, no changes in its effect were observed in both anodal and cathodal groups. Present study revealed that different mechanism might be involved in motor learning process for muscle relaxation compared to that of muscle contraction.
