Influence of high‐intensity interval training to exhaustion on the directional sensitivity of the cerebral pressure‐flow relationship in young endurance‐trained men

We previously reported subtle dynamic cerebral autoregulation (dCA) alterations following 6 weeks of high-intensity interval training (HIIT) to exhaustion using transfer function analysis (TFA) on forced mean arterial pressure (MAP) oscillations in young endurance-trained men. However, accumulating evidence suggests the cerebrovasculature better buffers cerebral blood flow changes when MAP acutely increases compared to when MAP acutely decreases. Whether HIIT affects the directional sensitivity of the cerebral pressure-flow relationship in these athletes is unknown. In 18 endurance-trained men (age: 27 +/- 6 years, VO(2)max: 55.5 +/- 4.7 ml center dot kg(-1)center dot min(-1)), we evaluated the impact of 6 weeks of HIIT to exhaustion on dCA directionality using induced MAP oscillations during 5-min 0.05 and 0.10 Hz repeated squat-stands. We calculated time-adjusted changes in middle cerebral artery mean blood velocity (MCAv) per change in MAP (Delta MCAv(T)/Delta MAP(T)) for each squat transition. Then, we compared averaged Delta MCAv(T)/Delta MAP(T) during MAP increases and decreases. Before HIIT, Delta MCAv(T)/Delta MAP(T) was comparable between MAP increases and decreases during 0.05 Hz repeated squat-stands (p = 0.518). During 0.10 Hz repeated squat-stands, Delta MCAv(T)/Delta MAP(T) was lower during MAP increases versus decreases (0.87 +/- 0.17 vs. 0.99 +/- 0.23 cm center dot s(-1)center dot mmHg(-1), p = 0.030). Following HIIT, Delta MCAv(T)/Delta MAP(T) was superior during MAP increases over decreases during 0.05 Hz repeated squat-stands (0.97 +/- 0.38 vs. 0.77 +/- 0.35 cm center dot s(-1)center dot mmHg(-1), p = 0.002). During 0.10 Hz repeated squat-stands, dCA directional sensitivity disappeared (p = 0.359). These results suggest the potential for HIIT to influence the directional sensitivity of the cerebral pressure-flow relationship in young endurance-trained men.