Effect of Hip Joint Position on Hip Abductor Muscle Activity during Lateral Step-up Exercises

抄録

[Purpose] This study examined the influences of different hip positions on electromyographic (EMG) activity of the hip abductor and the quadratus lumborum muscles during lateral step-up exercises. [Subjects] Fifteen healthy subjects (ten men and five women) participated in this study. [Methods] The subjects performed lateral step-up exercises in hip-neutral, internal rotation, and external rotation positions. EMG activity of the gluteus medius, tensor fascia latae, and the quadratus lumborum muscles was measured using surface electromyography during the exercises. EMG activity of each muscle in the three hip positions during lateral step-up exercises was analyzed using one-way repeated-measures analysis of variance. [Results] EMG activity of the gluteus medius muscle was significantly increased in the hip-neutral and internal rotation positions compared with the external rotation position during lateral step-up exercises (p<0.05). Significantly increased EMG activity of the tensor fascia latae muscle was observed in the hip internal rotation position compared with other hip positions. There was no significant difference in the activity of the quadratus lumborum among the three hip positions during lateral step-up exercises (p>0.05). [Conclusion] These findings indicate that maintaining the hip-neutral position could be used as an effective method to increase the activity of the gluteus medius during lateral step-up exercise.