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Cumulative effects of sports-related subconcussive hits on response inhibition Bryk, Kelsey Nicole

Abstract

Whereas it has been demonstrated that sustaining multiple concussions can detrimentally affect neurophysiologic health and cognitive abilities, there is no consensus on the cumulative effect of repetitive subconcussive head impacts in contact sports. Subconcussive hits are head impacts that are typically less forceful than concussive impacts. They occur much more frequently, and do not produce obvious or immediate clinical symptoms. The global objective of this research was to investigate how cumulative exposure to repetitive subconcussive hits, as experienced through participation in one season of competitive American football, affects response inhibition, one of many executive functions of the brain. In addition, accelerometers were used to collect biomechanical data to determine the cumulative number and magnitude of these repetitive head impacts and relate this to changes in response inhibition. Response inhibition was probed with the use of a complex neurocognitive sensorimotor KINARM hit-and-avoid task. This required the subject to use robotic arms to respond to virtual targets while avoiding multiple distractors presented simultaneously on a 2D virtual screen. The results showed a significant difference between the contact and non-contact sport athletes from pre-season to post-season, and therefore support this hypothesis. In addition, it was hypothesized that contact-sport athletes who experienced a greater cumulative number of head impacts over a season would show significantly poorer performance on the task of response inhibition compared to the contact-sport athletes who experienced a lesser cumulative number of head impacts. It was also hypothesized that contact-sport athletes who experienced a greater cumulative magnitude of head impacts over a season would show significantly greater poorer performance on the task of response inhibition compared to those athletes who experienced a lesser cumulative magnitude over the season. Interestingly, the results fail to support this hypothesis, and instead appear to support the opposite hypothesis. The findings from this thesis indicate that experiencing a season’s worth of subconcussive hits does appear to affect the specific executive function of response inhibition in contact-sport athletes, however other factors besides head impact data may play an important role in these adverse effects.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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