One-week cocoa flavanol intake increases prefrontal cortex oxygenation at rest and during moderate-intensity exercise in normoxia and hypoxia.

Introduction: During exercise in hypoxia, O2 delivery to brain and muscle is compromised and oxidative stress is elicited. Cocoa flavanols (CF) have antioxidant capacities and can increase blood flow by stimulating endothelial function. We aimed to examine the effects of 7-day CF intake on oxidative stress, nitric oxide production and tissue oxygenation in response to exercise in hypoxia (14.3% O2). Methods: In a randomized, double blind, cross-over study, 14 well-trained male cyclists completed 4 trials: exercise in normoxia or hypoxia, after 7-day CF or placebo intake. Flow-mediated dilation (FMD) was measured before intake of the last dose CF or placebo. One hundred minutes later, 20-minute steady-state (SS, 45% VO2max) and 20-minute time trial (TT) (cycling) were performed. Blood samples were taken. Prefrontal and muscular oxygenation were assessed by near-infrared spectroscopy. Results: At baseline, FMD was increased by CF. Hypoxia increased exercise-induced elevations in lipid peroxidation and antio...