UBC Theses and Dissertations

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UBC Theses and Dissertations

A comprehensive investigation of repetitive head impacts (heading) on brain activity and biomechanics in varsity women's soccer Kenny, Rebecca A


Soccer players are exposed to a high number of repetitive head impacts (RHIs), which have been hypothesized to lead to cumulative brain trauma. Studies have utilized a variety of methods to estimate exposure to RHIs including self-report, direct observation, modified video analysis and head impact sensors. Such measurements have previously only been done for select events and participants or have relied heavily on memory leading to potential sampling bias and limited understanding of total exposure. Additionally, due to methodological inconsistencies and sex-based differences, previous research has remained inconclusive on potential brain function and health-related changes due to RHIs. This dissertation contains five interconnected studies on female athletes. The first uses encephalography (EEG) and health-related metrics to compare non-contact athletes to soccer players with and without concussions. This chapter establishes that while soccer players without a concussion demonstrate differences to non-contact athletes, they do not demonstrate significant changes compared to soccer players with a concussion. The next chapter demonstrates that soccer players routinely overestimate the number of head impacts experienced in both games and practices. We establish the unreliability of self-report to estimate exposure and suggest video data be used to objectively quantify absolute head exposure. The third chapter is a comprehensive analysis of three years’ worth of video footage to quantify heading frequency. We demonstrate significant inter-player variability withing a single team and demonstrate the necessity of including training sessions, in addition to games, when representing player RHI exposure levels. The fourth chapter quantifies the magnitude of individual head impacts through custom fitted mouthpieces with an accelerometer and gyroscope. We demonstrate which impact scenarios produce the highest kinematics and therefore, which scenarios may pose higher risk. Chapter three and four illustrate the need to study both frequency and magnitude of RHI in research. The final chapter revisits the use of EEG and health-related metrics to evaluate the influence of heading on brain function and behaviour. We demonstrate a potential dose-response between the number of head impacts and resulting changes. Results from these studies contribute to the growing scientific knowledge surrounding RHIs and sets a structure for future quantification of RHIs.

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