Trunk and hip electromyographic activity during single leg squat exercises do sex differences exist?

Area of Science:

• Biomechanics
• Exercise Physiology
• Rehabilitation Science

Background:

• Sex differences in lower extremity muscle activation are known during dynamic activities.
• Limited research exists on sex-based muscle activation differences during rehabilitation exercises.

Purpose of the Study:

• To investigate sex differences in trunk and hip muscle activation during four single leg squat (SLS) variations.
• To compare muscle activation amplitudes between males and females during SLS exercises.

Main Methods:

• Surface electromyography (EMG) measured abdominal obliques (AO), lumbar extensors (LE), gluteus maximus (GMX), and gluteus medius (GM) activity.
• Data were normalized to maximum voluntary isometric contractions (% MVIC).
• A 2x4 mixed-model ANOVA analyzed sex and exercise interaction effects.

Main Results:

• No significant interaction between sex and exercise type was found.
• Females exhibited significantly greater gluteus medius (GM) and lumbar extensor (LE) activation than males.
• Gluteus maximus (GMX) and abdominal obliques (AO) activation did not differ between sexes.

Conclusions:

• Muscle activation levels in the studied SLS exercises were generally insufficient for strength gains.
• Females demonstrated moderate GM activation, potentially beneficial for neuromuscular re-education.
• Males showed low GM activation, possibly inadequate for improving gluteus medius function; exercise modifications may be needed.