[Purpose]We examined the deep abdominis muscle activity with the movement of the lower limb on condition that the hip-joint was flexed, using an electrode of Fine wire electromyography (EMG). [Method]For a healthy male, an electrode of Fine wire EMG was inserted into the right obliquus internus abdominis muscle and right transversus abdominis muscle. Measurements were achieved on condition of flexed hip-joint at supine position, or seated position(on the balloon), or inflating a balloon with seated position. The movements of both lower limbs were followed with resistant or non-resisitant exercises. [Results]The activities of Fine wire EMG on the deep abdominis muscle increased by resistant exercises. The contribution for the stability of the trunk on the deep abdominis muscle was affected by position of the limb or gravity. The transversus abdominis muscle may have an action, which bends the trunk to lateral side. [Conclusions]The deep abdominis muscle may affect the posture with the movement of the lower limb, and change the muscle activity, therefore, may concern with the foundation of the movement of the lower limb. However, we guess that the contribution for the stability of the trunk on the deep abdominis muscle was affected by position of the limb or gravity.
