Doctor of Philosophy (PhD)
Kinesiology and Physical Education
Faculty of Science
Visual attention is challenged in everyday environments with exposure to busy urban scenes and access to advancing technology. In addition, high performance sport consists of unique neurocognitive and visual demands that may distinguish cognitive functioning of an experienced athlete from the general population (Faubert, 2013; Hüttermann & Memmert, 2014; van Paridon et al., 2022). In strategic team sports, such as rugby and ice hockey, athletes must quickly process constantly-evolving visual scenes and make accurate decisions to perform successful motor actions while under high levels of physical stress (Dubois et al., 2017; van Paridon et al., 2022). The ability to attend to and perceive complex visual information with additional balance and exertion demands may become compromised if an athlete sustains a sport-related concussion (SRC). A SRC is a traumatic brain injury that results in functional neurological impairments that may impact various aspects of sport performance, including cognition, vision, balance, and exercise tolerance (Broglio et al., 2009; Leddy et al., 2011; Master et al., 2016; Patricios et al., 2023; Powers et al., 2014). The following dissertation explored how previous experience (competitive sport participation and SRC) and task-related factors (balance and physical exertion) influence performance on a custom dynamic visual acuity (DVA) task in young adults.
In the first two studies, participants completed a dynamic visual acuity (DVA) task that compared, 1) varsity athletes and students from the general population and 2) varsity athletes with and without recent SRC, during different balance (standing and treadmill walking) and exertion conditions (low-intensity and moderate-intensity). The DVA task has two motion types (random walk (RW) and horizontal (H)) and is scored as the log of the minimum angle of resolution (logMAR), that is measured using an inverse scale based on the smallest target size recognized at a specified viewing distance. The effect of balance and exertion demands were analyzed by calculating a change in DVA score from seated position. The last two studies examined DVA and balance control while standing between athletes with and without recent SRC, during resting conditions, as well as before and after completing a vigorous-intensity treadmill running protocol. DVA performance was calculating using a difference from resting DVA score post-exercise and comparing RT across all time conditions. In Study 3 and Study 4, balance control was analyzed as the root mean square of centre of pressure displacement (dCOP) and variability of the high frequency COP (COPhigh) at a cut-off of 4Hz.
The results of Study 1 revealed that athletes are better at dividing attention between the DVA task during different balance and exertion conditions from seated compared to the general population during RW-motion. In Study 2, the DVA task was also sensitive to differences in DVA score from seated between athletes with and without recent history of SRC during standing and walking conditions based on spatial-temporal characteristics of DVA motion types. Overall, both athletes with SRC and students from the general population exhibited a speed-accuracy trade-off during RW-motion conditions, demonstrated by a worse relative change in DVA score from seated as responses became faster during more challenging conditions. Further, balance analysis in Study 3, revealed that athletes with recent SRC history prioritized maintaining balance with a worse change in DVA while standing. In Study 4, a vigorous treadmill running protocol seemed to facilitate DVA performance as both groups maintained performance with faster response times following exercise. However, changes in response time manifested differently following exercise between groups, such that athletes with SRC responded more slowly beyond 10-minutes of recovery.
The overall findings from this dissertation revealed that the individual experience and task-related factors do have different modulating effects on DVA for young adults. By increasing task demands (balance and physical exertion), the DVA task may further distinguish young adult athletes from the general student population. Further, recent history of SRC negatively impacted DVA performance and balance control similarly to the general population. The results suggest that the expectations for athletes with SRC should not be the same as the general population on the DVA task, such that persisting impairments may remain undetected. For rehabilitation purposes, exercise may independently help facilitate visual processing and cognitive functions for athletes with recent SRC, rather than concurrently while performing the DVA task. Overall, a DVA assessment in dual-task conditions that quantifies multiple clinical domains may be more sensitive to persisting impairments and help mitigate subsequent musculoskeletal injury risk for athletes following SRC.
Mitchell, Katelyn, "Examining modulating factors of dynamic visual acuity in young adults and athletes with and without recent concussion history." (2024). Theses and Dissertations (Comprehensive). 2612.
Available for download on Friday, October 30, 2026