Intermuscular Coordination of Men vs Women
A squat-to-exhaustion study reveals differences in muscle coordination patterns between sexes.
A recent study published in Scientific Reports examined how the leg and back muscles synchronise and integrate as a network during a squat test performed to exhaustion. Women showed stronger, more stable inter-muscular coordination throughout the test. Men showed weaker but more adaptable inter-muscular coordination and lasted longer on average, though the performance gap was not statistically significant. The findings suggest that how muscles coordinate at a network level may help explain sex-based differences in fatigue, injury risk, and training response.
Aim
Researchers wanted to understand how the leg and back muscles synchronise and integrate as an inter-muscular network during a squat test performed to exhaustion, and whether that coordination differs between men and women. A secondary aim was to examine how the temporal variability of those inter-muscular interactions changes over the course of the test, something that had not been studied before in this context.
Methods
38 healthy young adults participated: 11 males (average age 21.9 years) and 27 females (average age 22.5 years). All were sport science students who exercised regularly but were not competitive athletes.
Participants performed a bodyweight back squat to exhaustion at a controlled 3-seconds-down, 3-seconds-up tempo, regulated by a metronome. Exhaustion was defined as the inability to maintain that tempo for three consecutive repetitions.
Surface electromyography (sEMG) sensors were placed on four muscles: the left and right vastus lateralis and the left and right erector spinae. Researchers used a novel analytical method called Amplitude-Amplitude Cross-Frequency Coupling (ACFC) to measure how the inter-muscular coordination between different frequency bands in these muscles changed throughout the test.
Results
Men lasted an average of 673 seconds; women averaged 465 seconds. This difference was not statistically significant.
Despite performing for less time, women showed stronger average inter-muscular coordination across nearly all muscle pairings. In the cross-body muscle pairs, such as the right leg with the left back, women showed 20 to 30% stronger inter-muscular coordination.