Abstract
[Purpose] The purpose of this study was to clarify the muscle activities and joint angles of standing up motion with thoracolumbar spine flexed, reproducing the humpback posture of the elderly. [Subjects] The subjects were ten healthy adult males. [Methods] Electromyography (EMG) and joint angles of the lower leg, captured by a video camera, were studied during standing up motion from the sitting position under the conditions of: normal posture, thoracolumbar flexion of 20˚, and thoracolumbar flexion of 40˚. We calculated the average amplitude of the relative EMG value and noted the order of EMG activities in the lower leg, as well as the forward tilt angle of the trunk and lower leg. [Results] Compared to normal posture, the average amplitude of the relative EMG value of the tibialis anterior muscle (TA), and the forward tilt angle of both the trunk and lower leg during standing with thoracolumbar flexion of 40˚ were significantly increased. In addition, TA activity started significantly earlier than in the other muscles. [Conclusion] The results suggest thoracolumbar flexion influences the muscle activity of TA and the forward tilt angle of the lower leg.
