Head trauma that occurs during sporting events is responsible for an increasing number of emergency department visits in Canada and is associated with an increased risk of developing neurodegenerative diseases. While head injury in American football has been extensively studied, it cannot be extrapolated to non-helmeted sports. Approximately 265 million people are actively participating in soccer and many are 18 years of age and younger. Soccer is unique in that players use their head to redirect the ball;​ however, the effects of cumulative purposeful soccer heading on brain health are unknown. Accordingly, the objective of this thesis was to quantify head impact magnitudes that female youth soccer players sustain during games and evaluate their influence on electrophysiological functioning both at rest and exercise. This was achieved through three research projects that studied female youth soccer players for an entire soccer season and investigated repetitive soccer heading using methodological equipment including, game video analysis, headbands instrumented with wireless microsensors, as well as electroencephalogram (EEG) recordings. Results indicated that the median number of headers experienced during a single game was one, while the maximum is nine, and minimum is zero (Chapter 2). Furthermore, player age is positively associated with an increasing number of purposeful soccer headers, but there is no association between head impact location and game scenario (Chapter 2). Chapter 3 reveals that game scenario and head impact location significantly affect both linear head acceleration and rotational head velocity magnitudes. As an initial attempt to detect neurocognitive change (Chapter 4), EEG recordings revealed a statistically significant increase in EEG power during exercise compared to rest at each EEG frequency band (Alpha1, Alpha2, Beta1, Beta2, Theta). These differences were amplified when cumulative number of headers were considered, but only for Alpha1, Alpha2 and Beta2. In conclusion, this thesis shows cumulative soccer heading experienced by female youth soccer players could lead to neurocognitive changes after one season of soccer. Furthermore, exercise may help to reveal sub-clinical brain changes due to cumulative soccer heading that are not shown at rest. These findings can help guide data-driven approaches to improve player safety in youth soccer.