Effects of Isometric Hip Abduction using an Elastic-band on Muscle Activation in the Gluteus Maximus, Hamstring, and Erector Spinae during Forward Bending and Return Task

Background : Trunk bending requires coordination of the pelvis and hip joints and activation of the gluteal and lower extremity muscles. The gluteus maximus (GM) is an important muscle for trunk bending task and repeated trunk extension increases erector spinae (ES) muscle activity, and these extensors exhibit muscle activity opposite that of the gluteal muscles at a given lumbo-pelvic angle. Elastic band placed around the legs was found to increase GM muscle activity during exercise. Previous studies have compared GM, ES, and HS muscle activities during flexion movements. However, there is no study that applies elastic band during trunk forward bending and compared the activity of the GM, ES and HS muscles. Objectives : The purpose of this study was to investigate muscle activity in the gluteus maximus (GM), erector spinae (ES), and hamstring (HS), as well as hip joint angle during trunk forward bending in a hip abduction exercise using an elastic band. Methods Fourteen healthy women were recruited. Surface electromyographic activity was recorded from the GM, HS, and ES muscles, and hip joint angle was measured using Image J during trunk forward bending while performing a hip abduction exercise using an elastic band. Results : The hip joint angle during the forward bending movement increased significantly when an elastic band was used compared to when it was not. Muscle activity in the GM increased significantly, whereas that in the HS decreased significantly, with the elastic-band intervention. No significant change in ES muscle activity was observed with the band. Conclusions : During trunk forward bending with isometric hip abduction using an elastic band could be beneficial to promote hip joint movement and GM muscle relative to HS muscle activity.