Different Hip Rotations Influence Hip Abductor Muscles Activity During Side-lying Isometric Hip Abduction in Subjects With Gluteus Medius Weakness

다국어 초록 (Multilingual Abstract)

Gluteus medius (Gmed) weakness is related to several lower extremity injuries. People with Gmed weakness often compensate by activating the tensor fasciae latae (TFL). A dominant TFL can force hip medial rotation and lateral patellar displacement, which can cause related patellofemoral pain. Meanwhile, the Gmed and gluteus maximus (Gmax) control excessive hip medial rotation and adduction of the hip during a gait. Different hip rotations in the transverse plane may affect Gmax, Gmed, and TFL muscle activity through side-lying hip abduction (SHA). The aim of this study was to establish the effects of different hip rotations on Gmax, Gmed, and TFL muscle activity and the muscle activity ratio of the Gmax/TFL, Gmed/TFL, and Gmed/Gmax during isometric SHA in subjects with Gmed weakness.
The study recruited nineteen subjects with Gmed weakness. Subjects performed isometric SHA: frontal SHA with neutral hip (SHA-N), frontal SHA with hip medial rotation (SHA-MR), and frontal SHA with hip lateral rotation (SHA-LR). Surface electromyography measured the activity of the Gmax, Gmed, and TFL. A one-way repeated-measures analysis of variance (ANOVA) assessed the statistical significance of Gmax, Gmed, and TFL muscle activity. A significant difference prompted a Bonferroni adjustment.
Gmed muscle activity was significantly greater in SHA-MR than in SHA-N. TFL muscle activity was significantly greater in SHA-LR than in SHA-N. The Gmed/TFL and Gmed/Gmax muscle activity ratios were also significantly greater in SHA-MR than in SHA-N or SHA-LR.
SHA-MR is the most effective exercise for greater Gmed muscle activation and a higher Gmed/TFL muscle activity ratio among three SHA exercises.