2017 Volume 32 Issue 3 Pages 443-447
[Purpose] Electromyography (EMG) was used to examine the activities of the muscles surrounding the hip joint which are involved in maintaining internal and external rotation in the sitting posture. [Subjects and Methods] The subjects were 10 healthy males, 20 lower limbs. EMG of the gluteus maximus upper fibers, gluteus medius, and tensor fasciae latae muscles was performed in the sitting posture. The activities during internal and external rotation of the hip joint at 10, 20, and 30° were compared among the angles. [Results] Integrated EMG of the gluteus maximus upper fibers at 30° of internal rotation was significantly greater those at 10 and 20° internal rotation. Integrated EMGs of the gluteus medius and tensor fasciae latae muscles at 30° internal rotation were significantly greater than those at 10° internal rotation. [Conclusion] The gluteus maximus upper fibers are involved in maintaining internal rotation at hip flexion of 90° without participating in the maintenance of external rotation.
