Influence Of Aerobic Exercise Intensity On Post-exercise Cerebrovascular Function

Abstract

Peripheral vascular function is acutely improved, in an intensity dependent manner, following a single session of aerobic exercise. While previous studies have examined the effects of acute exercise on cerebrovascular function, the influence of exercise intensity on post-exercise cerebrovascular function remains unclear. PURPOSE: To determine the influence of aerobic exercise intensity on post-exercise cerebrovascular function. METHODS: Eleven participants (age: 27 ± 4 y; VO2max = 51 ± 8 mL/kg/min; men = 4, women = 7) completed 2 study days, in a randomized order, in which they either walked at 30% VO2max for 30 min (WALK) or ran at 70% VO2max for 30 min (RUN). Cerebrovascular reactivity to hypercapnia (CVR) was measured pre and 30 min post-exercise. Middle cerebral artery velocity (MCAv), mean arterial pressure (MAP), and end-tidal CO2 (ETCO2) were continuously monitored during the hypercapnia protocol. Cerebrovascular conductance index (CVCi) was calculated as MCAv/MAP. CVR was calculated as the slope between the percent changes in MCAv or CVCi and ETCO2. RESULTS: During WALK and RUN, there was no difference in MCAv from pre to post-exercise (p ≥ 0.05 for both), despite a significant post-exercise reduction in ETCO2 (WALK: pre = 42 ± 3 mmHg, post = 40 ± 2 mmHg; RUN: pre = 41 ± 3 mmHg, post = 40 ± 3 mmHg; p < 0.05 for both). While WALK had no significant change in MAP and CVCi from pre to post-exercise (p ≥ 0.05 for both), RUN had a significant decrease in MAP and increase in CVCi (MAP: pre = 95 ± 13 mmHg, post = 85 ± 8 mmHg; CVCi: pre = 0.67 ± 0.14 cm/s/mmHg, post = 0.80 ± 0.12 cm/s/mmHg; p < 0.05 for both). There was no significant change in MCAv CVR or CVCi CVR from pre to post-exercise for WALK (p ≥ 0.05 for both); however, there was a decline in both MCAv CVR and CVCi CVR from pre to post-exercise during RUN (MCAv CVR: pre = 1.7 ± 0.5 AU, post = 1.3 ± 0.4 AU; CVCi CVR: pre = 1.3 ± 0.5 AU, post = 0.9 ± 0.4 AU; p < 0.05 for both). Finally, there was no significant difference in the magnitude of change in MCAv CVR and CVCi CVR from pre to post-exercise between the study days (p ≥ 0.05 for both). CONCLUSION: Exercise intensity influences post-exercise cerebrovascular hemodynamics and function as RUN, but not WALK, had a significant increase in CVCi and a reduced MCAv CVR and CVCi CVR from pre to post-exercise. Supported by UW-Madison’s Fall Research Competition, NHLBI 118154