Functional Significance of Sit-to-stand by Hip Abduction with External Rotation Angle

Abstract

The principal aim of this study was to analyze the effects of differences in hip abduction and external rotation angles on sit-to-stand (STS) movements. Hip abduction and external rotation angles of 0 deg (closed legs parallel to each other) and 45 deg (open legs) of 27 healthy participants were compared. Analysis parameters were the center of pressure, the ground reaction force, and the activities of fourteen muscles using surface electromyography. The center of pressure parameter revealed that standing with open legs requires less anterior-posterior displacement during STS movement. The open leg movement showed that ground reaction force differed slightly for right and left sides. Muscle activity of the erector spinae and tibialis anterior decreased with the STS movement with open legs. In contrast, muscle activity of the adductor longus and the biceps femoris increased.