The modulation of corticospinal excitability and inhibition following acute resistance exercise in males and females

OBJECTIVE: The acute responses to resistance training (RT) between males and females are poorly understood, especially from a neural perspective. Therefore, we aimed to compare the corticospinal and intracortical responses during fatigue and recovery following RT. METHODS: Twenty-two participants (12M, 10F) completed one-session of RT (3 × 12 repetition maximum) unilateral leg extensions with 60 s recovery. Single- and paired-pulse transcranial magnetic stimulation measured changes in the motor-evoked potential (MEP), corticospinal silent period (CSP), CSP/MEP ratio, and intracortical facilitation/inhibition (ICF, SICI). The maximal compound wave (MMAX) measured peripheral excitability of the rectus femoris (RF) and maximal voluntary isometric contraction (MVIC) neuromuscular function of the leg extensors. Measures were taken immediately post, 30 min, 1 and 6 h post-training. RESULTS: A significantly greater increase in MEP/MMAX ratio (p = .005) was observed for females immediately post-training compared to males. While no sex differences in MEP/MMAX ratio was observed at 30 min and 1 h post-training, a greater MEP/MMAX ratio for males was observed at 30 min (p < .001), which remained elevated up until 1 h post-training for males when compared to baseline (p = .003). CSP trended to decrease for males compared to females immediately post-training (d = 1.93). MVIC was decreased post-training for males; 14.22% and females; 14.16% (P < .001), with MMAX reduced at 30 min for both groups (P < .001). No differences in the CSP/MEP ratio, SICI or ICF were observed (P > .05). CONCLUSION: The net output of corticospinal excitability is similar between males and females during fatigue. However, the mechanism in which this is modulated (increased MEP, decreased CSP) appears to be sex-specific.