Sex-differences in neuromuscular control of hip abductors during isometric submaximal tasks.

Background: One key focus in the literature is the need to better understand how males and females perform neuromuscular control, which requires consideration of muscle morphology, as it may change neural drive during force production. Although previous studies focused on muscles around the knee and ankle, it is crucial to explore the behavior of other muscles, such as the hip abductors, since many lower limb conditions more common in females have been associated with alterations in hip muscles.

Research Questions: Are electromyography (EMG) variables (amplitude and low- and high frequency bands) of hip abductors during submaximal isometric tasks different between males and females? How is muscle size associated with EMG responses during these tasks?

Methods: Thirty-six participants (males, n = 18; females, n = 18) had muscle and subcutaneous thickness of gluteus medius (GMed) and tensor fascia latae (TFL) measured. They then performed an estimated one-repetition maximum (1RM) test in a side-lying hip abduction exercise, followed by two 10-s submaximal tasks: (i) side-lying hip abduction with 50 % 1RM and (ii) with 20 % 1RM. GMed and TFL EMG amplitude and frequency bands (low and high frequency components) were analyzed.

Results: Females had higher GMed EMG amplitude, lower low-frequency, and higher high-frequency components than males in both tasks (p = 0.001-0.040). No differences were observed in TFL EMG variables. Greater GMed thickness was associated with lower amplitudes in the 50 % 1RM task (r = - 0.35; p = 0.03), while greater TFL thickness was associated with lower low-frequency [20 % 1RM: r = - 0.70; p = 0.002; 50 %-1RM: r = - 0.65; p = 0.005] and higher high-frequency components [20 % 1RM: r = 0.74; p = 0.001; 50 %-1RM: r = 0.76; p < 0.001] only in females.

Significance: Males and females employ different neuromuscular control strategies, which vary among the synergists for hip abduction.