Influence of Cognitive Challenges During Exercise on Post‐Exercise Cerebrovascular Function

Abstract

Peripheral vascular function is acutely improved following a single session of aerobic exercise. This improvement is likely due to increased blood flow during aerobic exercise. Cognitive activity and aerobic exercise both acutely increase cerebral blood flow, and while previous studies have examined the influence of acute exercise on post‐exercise cerebrovascular function, the effects of increased cognitive activity during exercise on post‐exercise cerebrovascular function remains unclear. Therefore, the purpose of this study was to examine the influence of increased cognitive activity during aerobic exercise on post‐exercise cerebrovascular function. We hypothesized that performing cognitive challenges during exercise would result in greater post‐exercise cerebrovascular function. METHODS: Ten participants (age: 27 ± 5 y; VO2max = 53 ± 10 mL/kg/min; men = 5, women = 5) completed 2 study days, in a randomized order, in which they either walked at 30% VO2max for 30 min (WALK) or walked at 30% VO2max for 30 min while completing N‐back cognitive tasks (WALK+COG). Cerebrovascular reactivity to hypercapnia (CVR) was measured pre‐ and 90 min post‐exercise as a measure of cerebrovascular function. 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 changes in MCAv or CVCi and ETCO2. RESULTS: During WALK and WALK+COG, 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 = 43 ± 2 mmHg, post = 41 ± 3 mmHg; WALK+COG: pre = 41 ± 4 mmHg, post = 40 ± 3 mmHg; p < 0.05 for both). While WALK had no significant change in MAP from pre‐ to post‐exercise (p = 0.10), WALK+COG had a significant increase in MAP (pre = 88 ± 18 mmHg, post = 98 ± 14 mmHg; p = 0.01). Both WALK and WALK+COG had a decrease in CVCi from pre‐ to post‐exercise (WALK: pre = 0.70 ± 0.15 cm/s/mmHg, post = 0.65 ± 0.17 cm/s/mmHg; WALK+COG: pre = 0.75 ± 0.15 cm/s/mmHg, post = 0.66 ± 0.14 cm/s/mmHg; p < 0.05 for both). There was no significant change in CVR from pre‐ to post‐exercise during either study days (assessed as MCAv or CVCi; p ≥ 0.05 for both). Finally, there was no significant difference in the magnitude of change in CVR from pre‐ to post‐exercise between the study days (assessed as MCAv or CVCi; p ≥ 0.05 for both). CONCLUSION: Cognitive challenges during exercise did not influence post‐exercise cerebrovascular function. Despite this finding, cognitive challenges during walking may influence resting systemic hemodynamics, as it resulted in an increased post‐exercise MAP compared with walking alone.