Postexercise executive function benefits and cerebral blood flow: in the lab and at home

Benjamin Tari, The University of Western Ontario

Abstract

A single bout of aerobic exercise improves executive function; however, the mechanism, or mechanisms, supporting this improvement remain unclear. One candidate mechanism is an exercise-mediated increase in cerebral blood flow (CBF) that enhances the efficiency of executive-related frontoparietal networks. To evaluate the link between exercise, CBF and executive function, three separate experiments were conducted. In the first study, separate 10-min sessions of moderate-to-heavy-intensity aerobic exercise, and a hypercapnic environment (i.e., 5% CO₂) were implemented. The hypercapnic condition was included because it increases CBF independent of the metabolic demands of exercise. The second study investigated whether exercise intensity-specific changes in CBF differentially influence the magnitude of a postexercise executive function benefit. Accordingly, I measured CBF in conditions wherein participants completed separate 10-min sessions of light- (i.e., 25 Watts: W), moderate- (i.e., 80% estimated lactate threshold: LT), and heavy-intensity (i.e., 15% of the difference between LT and V̇O_2peak) aerobic exercise. The third study measured CBF during separate passive and active light-intensity exercise conditions and evaluated putative immediate and sustained executive function benefits. My final study (i.e., Study 4) was developed to meet the challenges associated with COVID-related research restrictions and hence developed and evaluated an at-home tablet-based assessment of postexercise executive function. The first three studies demonstrated that an increase in CBF independent of the metabolic demands of exercise was associated with a postexercise improvement in executive function. The fourth study demonstrated that an at-home executive function assessment provides a reliable means to identify single bout postexercise benefits to executive function. The findings from my dissertation provide further evidence indicating that CBF is a candidate mechanism supporting postexercise executive function and demonstrate the utility of a novel executive function assessment that may be implemented in populations that are demo- and geographically under-represented in exercise neuroscience research.