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.