Effects of Different Hip Rotations on Gluteus Medius and Tensor Fasciae Latae Muscle Activity During Isometric Side-Lying Hip Abduction.

Gluteus medius (Gmed) weakness is connected to some lower extremity injuries. Individuals with Gmed weakness might compensate by activating the tensor fasciae latae (TFL). Different hip rotations in the transverse plane may affect Gmed and TFL muscle activity during isometric side-lying hip abduction (SHA). In light of this the authors conducted this study so they might compare Gmed and TFL muscle activity and the Gmed/TFL muscle activity ratio during SHA exercise with three different hip rotations. The study was conducted at the university research laboratory and consisted of 20 healthy, university students. Participants executed isometric hip abductions: frontal SHA with neutral hip (frontal SHA-N), frontal SHA with hip medial rotation (frontal SHA-MR), and frontal SHA with hip lateral rotation (frontal SHA-LR).  Surface electromyography measured the activity of the Gmed and the TFL. A one-way repeated-measures analysis of variance (ANOVA) assessed the statistical significance of Gmed and TFL muscle activity. When there was a significant difference, a Bonferroni adjustment was performed.

The study found that frontal SHA-MR showed significantly more Gmed muscle activation than frontal SHA-N (P = .000) or frontal SHA-LR (P = .015). Frontal SHA-LR showed significantly greater TFL muscle activation than frontal SHA-N (P = .002). Frontal SHA-MR also resulted in a substantially higher Gmed/TFL muscle activity ratio than frontal SHA-N (P = .004) or frontal SHA-LR (P = .000), and frontal SHA-N was significantly higher than frontal SHA-LR (P = .000). Conclusions: Frontal SHA-MR results in greater Gmed muscle activation and a higher Gmed/TFL muscle ratio.