Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Kinesiology

Supervisor

Heath, Matthew

Abstract

A single bout of exercise improves executive function (EF); however, the physiological mechanism(s) contributing to this benefit are unclear. One candidate mechanism for the benefit is an exercised-mediated increase in cerebral blood flow (CBF) that improves neural efficiency. In my thesis, I conducted two experiments to assess the relationship between an increase in CBF and EF. In Experiment 1, I examined passive exercise, and in Experiment 2, I examined a 2.5% hypercapnic environment given that both interventions increase CBF independent of the metabolic demands of volitional muscle activity. Experiment 1 indicated that passive exercise increased CBF and was associated with a postexercise EF benefit. In Experiment 2, result showed that a hypercapnic environment increased CBF but did not lead to improved EF. As such, my thesis indicates that an increase in CBF does not impart a unitary EF benefit.

Summary for Lay Audience

Executive function represents a set of mental processes that supports activities of daily living. Notably, a single bout of exercise improves executive function, and this benefit has been linked to an exercise-based increase in blood flow to the brain. To better evaluate the relationship between brain blood flow and executive function, my thesis examined whether an increase in cerebral blood flow independent of the metabolic demands of exercise improves executive function. In Experiment 1, I examined brain blood flow and executive function in a passive exercise condition; that is, exercise wherein participants’’ limbs were moved via an external force (i.e., a mechanically driven stationary bike). In Experiment 2, participants inhaled a higher-than-atmospheric concentration of carbon dioxide given that it provides a well-defined increase in brain blood flow. Results from Experiment 1 indicated that passive exercise increased brain blood flow and provided a post-intervention executive function benefit, whereas results from Experiment 2 found that a higher-than-atmospheric concentration of carbon dioxide increased brain blood flow but did not benefit executive function. Accordingly, an increase in brain blood flow may only represent one of several mechanisms contributing to a postexercise executive function benefit.

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