During 45°-flexion of the hip joint, actions on the pelvis and integral values of abdominal muscle groups were measured by maintaining SLR at 3 different angles of hip joint abduction (0°, 15°, and 30°) to evaluate the relationship between the two. The results of this study suggest that rotating and anteverting actions occur on the pelvic side ipsilateral of SLR when the SLR is held at 30°-abduction of the hip joint in healthy volunteers. In addition, integral values of the abdominal scalenus ipsi- and contralateral of SLR and those of the rectus muscle of the abdomen ipsilateral of SLR obtained by maintaining SLR at 30°-abduction of the hip joint were significantly larger than those obtained at 0°-abduction of the hip joint (p<0.05). Integral values of the rectus muscle of the abdomen contralateral of SLR increase with the angle of hip joint abduction. These results suggest that attention should be focused on hip joint abduction angles during SLR exercise to increase the activity of the entire abdominal muscle groups.
