New Strategies for Controlling Pelvic Transverse Rotation and Selective Activation of Hip Muscles during Prone Hip Extension with Knee Flexion

Background : Prone hip extension with knee flexion (PHEKF) is a commonly used exercise for strengthening the gluteal muscles. However, PHEKF exercise is associated with a risk of increased hamstring and erector spinae activities, lumbar rotation to compensate for gluteal muscle weakness. Therefore, PHEKEF with isometric hip 30 abduction was evaluated in this study using Thera-Band to reduce pelvic transverse rotation compensation and effectively strengthen gluteal muscle strength. Objectives : The purpose of this study was to investigate the activity of the gluteus maximus (GMax), gluteus medius (GMed), erector spinae (ES) and hamstring (HAM) muscles and pelvic transverse rotation during PHEKF in three conditions. Methods : Fifteen healthy women participated in the study. The pelvic transverse rotation was measured using a smart phone-based measurement tool. The surface electromyography was attached the GMax, GMed, ES and HAM muscles. Then, the maximum voluntary isometric contraction was measured. The PHEKF exercise was performed in three different conditions (PHEKF, PHEKF with 30º hip abduction, and PHEKF with 30º isometric hip abduction [IHA]) by randomly. A one-way repeated measures ANOVA was performed to determine the difference in pelvic transverse rotation angle and muscle activity between the condition. Results : The GMax and GMed amplitudes were highest in PHEKF with 30° IHA, followed by 30º and 0° hip abduction during PHEKF (GMax, p < 0.001; GMed, p < 0.001). HAM and ipsilateral ES amplitudes were not significantly different among the three conditions (ipsilateral ES, p = 0.268; HAM, p = 0.577). In the pelvic transverse rotation angle and contralateral ES, the PHEKF with 30° IHA showed significantly lower than PHEKE with 30° abduction (the pelvic transverse rotation angle, p < 0.05; contralateral ES, p < 0.05). Conclusions : The results of these studies can examine that the PHEK with 30º IHA was effective to control pelvic transverse rotation and increase the contribution of the selective muscles activities of GMax and GMed muscles.