Motor unit recruitment strategies of the vastus lateralis according to sex

Despite men exhibiting greater muscle strength than women it remains unclear if there are sex- based differences in muscle recruitment strategies e.g. motor unit (MU) recruitment and modulation of firing rate with increasing force. These differences may explain underrepresentation of women and mixed-sex cohorts in studies of neuromuscular function. Twenty-nine healthy male and thirty-one healthy female participants (18-35 years) were studied. Intramuscular electromyography was used to record individual motor unit potentials (MUPs) and near fibre MUPs from the vastus lateralis (VL) during 10% and 25% maximum isometric voluntary contractions (MVC), and spike-triggered averaging was used to obtain motor unit number estimates (MUNE) of the VL. Multilevel mixed-effects linear regression models were used to investigate the effects of sex and contraction levels. Men exhibited greater muscle strength (p