外乱刺激に対する予測の可否が体幹筋の筋活動に与える影響

Abstract

This study investigated the modulation of trunk muscle activity with the expectation of sudden perturbations in ten healthy male volunteers. The activities of the internal and external abdominal oblique, rectus abdominal, multifidus and thoracic and lumbar erector spinae muscles were measured using surface electromyography. Unexpected and expected perturbations were applied to the trunk by sudden loading. The subject was instructed to maintain his initial standing position. The results showed that the activation of the multifidus and lumbar and thoracic erector spinae muscles was increased significantly more in the expected condition than in the unexpected condition in anticipation of postural adjustment. The activation of the multifidus and lumbar erector spinae muscles was increased significantly more than 150 msec before the perturbations, while that of the thoracic erector spinae muscles was increased significantly, 50 msec before the perturbations. The increased activation of the multifidus and lumbar erector spinae muscles appears to be a mechanism designed to improve the stability of the trunk through stiffening of the entire segment during forward loading.