Neurovascular coupling and cerebrovascular hemodynamics are modified by exercise training status at different stages of maturation during youth

Neurovascular coupling (NVC) is mediated via nitric oxide signaling, which is independently influenced by sex hormones and exercise training. Whether exercise training differentially modifies NVC pre- versus postpuberty, where levels of circulating sex hormones will differ greatly within and between sexes, remains to be determined. Therefore, we investigated the influence of exercise training status on resting intracranial hemodynamics and NVC at different stages of maturation. Posterior and middle cerebral artery velocities (PCA(v) and MCA(v)) and pulsatility index (PCA(PI) and MCA(PI)) were assessed via transcranial Doppler ultrasound at rest and during visual NVC stimuli. N = 121 exercise-trained (males, n = 32; females, n = 32) and untrained (males, n = 28; females, n = 29) participants were characterized as pre (males, n = 33; females, n = 29)- or post (males, n = 27; females, n = 32)-peak height velocity (PHV). Exercise-trained youth demonstrated higher resting MCA(v) (P = 0.010). Maturity and training status did not affect the Delta PCA(v) and Delta MCA(v) during NVC. However, pre-PHV untrained males (19.4 +/- 13.5 vs. 6.8 +/- 6.0%; P <= 0.001) and females (19.3 +/- 10.8 vs. 6.4 +/- 7.1%; P <= 0.001) had a higher Delta PCA(PI) during NVC than post-PHV untrained counterparts, whereas the Delta PCA(PI) was similar in pre- and post-PHV trained youth. Pre-PHV untrained males (19.4 +/- 13.5 vs. 7.9 +/- 6.0%; P <= 0.001) and females (19.3 +/- 10.8 vs. 11.1 +/- 7.3%; P = 0.016) also had a larger Delta PCA(PI) than their pre-PHV trained counterparts during NVC, but the Delta PCA(PI) was similar in trained and untrained post-PHV youth. Collectively, our data indicate that exercise training elevates regional cerebral blood velocities during youth, but training-mediated adaptations in NVC are only attainable during early stages of adolescence. Therefore, childhood provides a unique opportunity for exercise-mediated adaptations in NVC.