Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Neuroscience

Supervisor

Heath, Matthew

Abstract

Background: Impaired executive function (EF) is a primary sequela of sport-related concussion (SRC). Aerobic exercise below symptom exacerbation may improve post-SRC EF via increased cerebral blood flow (CBF). Objectives: To examine the impact of a single bout of sub-symptom threshold aerobic exercise on CBF and EF during SRC recovery. Methods: SRC participants (n = 16) and age- and sex-matched healthy controls (HC) completed 20-min of aerobic exercise at 80% of their heart rate threshold (HRt). Pre- and postexercise EF was assessed via antisaccades. Transcranial Doppler ultrasound (TCD) estimated exercise-mediated CBF changes. Results: SRC and HC participants showed an exercise-mediated increase in CBF (psConclusions:Sub-symptom threshold aerobic exercise increases CBF and improves inhibitory control following an SRC.

Summary for Lay Audience

Executive function (EF) is a collection of cognitive processes that support our ability to plan, focus attention, remember instructions, and complete multiple tasks. A brief bout of aerobic exercise improves EF, and this is – in part – attributed to an exercise-based increase in blood flow to the brain. In turn, persons who have experienced a sport-related concussion (SRC) show an impairment in EF and a decrease in blood flow to the brain. Notably, however, no work to date has examined whether a single bout of aerobic exercise improves EF in persons in the early stages of SRC recovery and whether the benefit is related to an increase in brain blood flow. Accordingly, my thesis investigated whether a single session of aerobic exercise, below a level that increases concussion symptoms, improves EF during early SRC recovery. I also explored if improvements in EF were related to increased blood flow to the brain during exercise. On an initial visit, 16 participants recovering from SRC performed an exercise test (via a stationary bike) to determine the heart rate threshold (HRt) at which their symptoms increased, or they voluntarily stopped due to exhaustion. On a separate day, SRC participants and healthy individuals of similar age and sex exercised on a stationary bike for 20 min at 80% of HRt. Blood flow to the brain was estimated by measuring its velocity in the middle cerebral artery. Participants completed an eye movement task (i.e., oculomotor assessment) before and after exercise that required them to “look away” from a target that appeared suddenly on a computer screen (i.e., antisaccade task). The antisaccade task was used because it provides a reliable basis to assess subtle changes in EF. SRC and healthy participants showed increased brain blood flow during exercise and demonstrated improved performance on the antisaccade task following exercise; however, the increase in brain blood flow and improvement in antisaccade performance were not related. As well, concussion symptoms in the SRC group did not increase immediately after exercise and were reduced 24 hours later. The results suggest that a personalized aerobic exercise program may help improve EF following an SRC.

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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