Author(s): EUM, Y., Institution: BAEKSEOK UNIVERSITY, Country: KOREA, SOUTH, Abstract-ID: 247

INTRODUCTION:
The gluteus medius (GMed) plays a critical role in pelvic stability and frontal-plane control during functional movements. Weakness or delayed activation of the GMed is often associated with compensatory overactivation of the tensor fasciae latae (TFL), which may contribute to altered lower-extremity alignment and increased injury risk. Although many rehabilitation studies have focused on maximizing GMed activation, evaluating absolute muscle activity alone may not adequately explain inter-muscular coordination or compensatory strategies. Furthermore, neuromuscular activation patterns may differ between males and females due to anatomical and neuromuscular factors. Therefore, this study aimed to examine sex-related differences in EMG activation patterns of the GMed and TFL during commonly prescribed rehabilitation exercises for GMed strengthening.
METHODS:
Twenty-six healthy adults (13 males and 13 females) participated in this cross-sectional study. Surface electromyographic (EMG) signals were recorded from the GMed and TFL using a wireless EMG system during the performance of ten lower-extremity rehabilitation exercises commonly used to strengthen the GMed. Electrode placement followed SENIAM recommendations. All EMG signals were normalized to maximum voluntary isometric contraction (MVIC) values. Mean normalized EMG amplitudes (%MVIC) were calculated, and the relative activation ratio between the two muscles (GMed/TFL) was computed to assess selective muscle activation. A two-way mixed repeated-measures ANOVA (sex × exercise) was used for statistical analysis.
RESULTS:
FL activation was significantly higher in females than in males during the clam shell, side-lying hip abduction, knee side plank with hip abduction (supporting and elevated leg), and lateral band walk exercises (p < .05). GMed activation was significantly greater in females during the side-lying hip abduction, knee side plank with hip abduction (supporting and elevated leg), lateral band walk, pelvic drop, and single-leg squat exercises (p < .05). No significant sex differences were observed in the GMed/TFL ratio across most exercises. However, males demonstrated a significantly higher GMed/TFL ratio during the clam shell exercise (p < .05), whereas females exhibited a significantly higher ratio during the side plank with hip abduction (supporting and elevated leg) (p < .05).
CONCLUSION:
Females may require greater neuromuscular activation to meet the same relative task demands, aligning with prior reports of sex differences in motor unit recruitment and firing strategies. Notably, even when absolute gluteus medius (GMed) activation was comparable between sexes, the GMed/tensor fasciae latae (TFL) ratio differed in selected exercises, indicating sex-specific coordination patterns that are not captured by absolute EMG alone. Overall, these findings suggest that both activation magnitude and inter-muscular coordination should be considered when selecting and evaluating GMed-strengthening exercises.