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

Abstract

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, VO2max: 55.5 ± 4.7 ml·kg−1·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 (ΔMCAvT/ΔMAPT) for each squat transition. Then, we compared averaged ΔMCAvT/ΔMAPT during MAP increases and decreases. Before HIIT, ΔMCAvT/ΔMAPT was comparable between MAP increases and decreases during 0.05 Hz repeated squat‐stands (p = 0.518). During 0.10 Hz repeated squat‐stands, ΔMCAvT/ΔMAPT was lower during MAP increases versus decreases (0.87 ± 0.17 vs. 0.99 ± 0.23 cm·s−1·mmHg−1, p = 0.030). Following HIIT, ΔMCAvT/ΔMAPT was superior during MAP increases over decreases during 0.05 Hz repeated squat‐stands (0.97 ± 0.38 vs. 0.77 ± 0.35 cm·s−1·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.

Lower dynamic cerebral autoregulation following acute bout of low-volume high-intensity interval exercise in chronic stroke compared to healthy adults

“…19,58,59 Previous studies have shown that dCA at rest 20 and during repetitive squat-stands [58][59][60] was less efficient at regulating decreases in MAP in comparison with MAP increases, and HIIT may exacerbate this directional sensitivity in healthy adults. 61 It is unknown whether individuals post-stroke have lesser dCA sensitivity to decreasing MAP compared to CON, however, this could potentially explain the differences between groups found immediately following HIIT. However, when forcing blood pressure to decrease using a single sit-to-stand following HIIT, we did not find any differences in the cerebral pressure-flow relationship in individuals post-stroke.…”