Cerebrovascular Reactivity to Hypocapnia Following Maximal Sprint Exercise Is Better Maintained in Females than Males

Background/Objectives: Despite increasing interest in high-intensity exercise and cerebrovascular function, the effects of maximal sprint exercise on cerebrovascular reactivity (CVR), a key indicator of vascular health, remain unclear. Methods: This study investigated the acute effects of a 30-s all-out cycling sprint (Wingate Anaerobic Test, WAnT), on CVR to hypocapnia in 24 healthy young adults (12 males). Following familiarisation and a $\dot{\mathrm{V}}$O_2max test, participants completed an experimental session where CVR was assessed at rest and 30 min post-WAnT. CVR was evaluated using a 1-min voluntary hyperventilation protocol (25 breaths·min⁻¹), with middle cerebral artery blood velocity (MCAv) measured via transcranial Doppler ultrasound and end-tidal CO₂ (P_ETCO₂) recorded breath-by-breath. CVR was calculated as the absolute change in MCAv per 1 mmHg change in P_ETCO₂ from the final 10 s of hyperventilation. Results: Resting MCAv and P_ETCO₂ were significantly reduced post-WAnT (p < 0.01 and p < 0.001 respectively). Consequently, the reductions in MCAv and P_ETCO₂ during hyperventilation were attenuated after exercise in both males and females (p < 0.01 and p < 0.001 respectively). Despite these changes, CVR remained unaltered in both sexes following WAnT (males: 1.79 ± 0.35 vs. 1.59 ± 0.26 cm·s⁻¹·mmHg⁻¹, p = 0.09; females: 2.01 ± 0.44 vs. 2.01 ± 0.46 cm·s⁻¹·mmHg⁻¹, p = 0.97). However, post-exercise CVR was significantly lower in males than females, despite no baseline sex differences (p = 0.01). Conclusions: Cerebrovascular reactivity to hypocapnia is preserved 30 min after a single bout of maximal sprint exercise in healthy young adults. Notably, females demonstrated a more favorable maintenance of CVR post-exercise compared to males, suggesting potential sex differences in CVR following maximal sprint exercise.