Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Kinesiology

Supervisor

Heath, Matthew

2nd Supervisor

Nagamatsu, Lindsay

Co-Supervisor

Abstract

A single bout of aerobic exercise improves executive function (EF) and is a benefit, in part, attributed to an increase in cerebral blood flow (CBF). It is, however, unknown whether a postexercise EF benefit mitigates mental fatigue (MF). My thesis assessed EF prior to and following separate 20-min conditions of active and passive cycle ergometry and a non- exercise control. Subsequently, a 20-min psychomotor vigilance task (PVT) was employed to determine whether the exercise intervention(s) decreased susceptibility to MF. Transcranial Doppler ultrasound was used throughout the protocol to estimate exercise- and PVT-based changes in CBF. Both exercise conditions increased CBF and produced a postexercise EF benefit. In turn, the PVT decreased CBF and increased subjective and objective measures of MF; however, frequentist and Bayesian statistics indicated the preceding exercise condition did not ameliorate these changes. Accordingly, exercise did not provide a neuroprotective mechanism mitigating MF in a sustained vigilance task.

Summary for Lay Audience

Executive function refers to cognitive processes that regulate activities of daily living. A single bout of volitional aerobic exercise (i.e., active exercise) provides a ‘boost’ to executive function and is a benefit that has been linked to an exercise-based increase in brain blood flow. Passive exercise, wherein movement is generated via an external force (e.g., mechanically driven stationary bike) provides a similar postexercise executive function benefit and associated increase in brain blood flow. In contrast, mental fatigue impairs executive function and is associated with a reduction in brain blood flow. It is, however, unknown whether passive and active exercise lessen the performance decline experienced during a mental fatigue inducing task and whether this is linked to the documented postexercise executive function benefit. Accordingly, I had participants complete an executive function task prior to and immediately following separate conditions involving 20 minutes of passive and active stationary bike riding as well as a non-exercise control condition. Subsequently, participants completed a 20-min psychomotor vigilance task (PVT) to determine whether a postexercise executive function benefit mitigates subjective and objective measures of mental fatigue. As well, transcranial Doppler ultrasound was used to measure middle cerebral artery velocity to determine potential links between brain blood flow with exercise, executive function and mental fatigue. As expected, both exercise conditions increased brain blood flow and improved executive function. Notably, completing an exercise condition in advance of the PVT did not mitigate subjective and objective measures of mental fatigue or an associated decrease in brain blood flow. Accordingly, my findings demonstrate that passive and active exercise provide a selective benefit to executive function that does not extend to reducing a mental fatigue-induced performance decline.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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