During muscle contractions, women and men show different patterns of nerve signal activity in specific thigh muscles: women have higher nerve firing rates in the outer thigh muscle at low and...

We analyzed the available research and found that men and women appear to differ in how their nerves activate certain leg muscles during exercise. Specifically, women tend to have higher nerve firing rates in the outer thigh muscle—called the vastus lateralis—at low and moderate effort levels, and also in more powerful motor units when pushing harder. In contrast, men show higher firing rates in the inner thigh muscle—called the vastus medialis—especially during the early stages of muscle activation, regardless of how hard they’re working [1]. These differences were observed across multiple studies examining nerve signal patterns during muscle contractions, with no studies contradicting these findings [2]. The evidence we’ve reviewed suggests that these patterns aren’t the same across all muscles or all intensities. For example, at lower effort levels, women’s nerves fire more frequently in the vastus lateralis, but men’s nerves fire more in the vastus medialis during initial activation. This points to a difference in how neural control is distributed between the sexes, depending on which muscle is involved and how much force is needed. We didn’t find evidence that these differences apply to all muscles or all types of movement—only to specific muscles in the thigh during exercise. What we’ve found so far doesn’t tell us why these differences exist, or whether they affect performance, fatigue, or injury risk. But it does suggest that the nervous system may organize muscle activation differently in men and women, at least in certain leg muscles under specific conditions. In everyday terms: when men and women work out, their bodies may turn on their thigh muscles in slightly different ways—especially in the early or moderate stages of effort. This doesn’t mean one is better or stronger, just that the signals from the brain to the muscles may follow different patterns.