Sex Differences in Cognitive Stability: Response Variability Following Acute High-Intensity Functional Training

Acute exercise has been shown to enhance cognitive function such as inhibitory control, with aerobic and resistance exercises yielding significant benefits. High-Intensity Functional Training (HIFT), such as CrossFit®, combines high-intensity, multi-joint movements and has shown promise in improving working memory. However, its acute effects on inhibitory control, particularly regarding potential sex differences, remain unclear. PURPOSE: This study investigated the acute effects of a single CrossFit®-based HIFT session on inhibitory control in healthy young adults and examined potential sex differences in response execution. METHODS: Eighteen healthy college students (8 females, 10 males) completed two counterbalanced sessions: (1) HIFT exercise consisting of six CrossFit®-based exercises (e.g., burpees, snatch) performed in 20-second all-out intervals with 10-second rest, and (2) a seated reading control. Inhibitory control was assessed pre- and post-intervention using the Flanker Task. Data were analyzed using Linear Mixed Models to examine Response Accuracy (ACC), Reaction Time (RT), and Response Variability (SD of RT) across Sex (Male/Female), Time (Pre/Post), Treatment (HIFT/Control), and Congruency (Congruent/Incongruent). RESULTS: Accuracy remained high (>96%) across all conditions. A significant main effect of Congruency was found for RT (β=108.2 ms, pβ=39.9, p=0.012), whereas males maintained stable variability across conditions (p=0.206). CONCLUSIONS: A single bout of CrossFit® exercise did not significantly improve inhibitory control compared to rest. While both sexes demonstrated typical slowing during incongruent trials, females appeared more susceptible to increased response variability under higher cognitive loads. Future research should explore if chronic HIFT adaptations differ by sex.