Peters, RyanBanman, Christopher James2024-05-022024-05-022024-04-29Banman, C. J. (2024). Electrical vestibular stimulation for probing the effect of combat sports on balance control (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/118614https://doi.org/10.11575/PRISM/43456Combat athletes are at a high risk for head injuries such as concussion. Recent work has uncovered that even repetitive head impacts (RHIs) may have lasting effects on cognitive, emotional, and motor function. This thesis will focus on the changes to vestibulospinal processing seen in combat athletes. Electrical vestibular stimulation (EVS) was used to evoke vestibulospinal reflexes, comparing the resulting responses between combat athletes and healthy sex/age matched controls. This is described through three separate chapters. First, I test the differences in electromyography (EMG) responses, then develop a novel EVS-induced postural sway thresholding technique, and finally investigate the EVS threshold differences between the fighters and controls. The experimental results of the first study demonstrated frequency-specific changes in vestibular sensitivity to EVS for combat athletes, via EMG responses. Combat athletes showed an increased sensitivity to low frequency EVS, and a decreased sensitivity to high frequency EVS, resulting in increased latencies on short and medium latency reflexes, scaling with increasing career RHI exposure. The second study presented shows that stochastic electric vestibular stimulation (SVS) can be used to determine EVS postural sway thresholds much lower than those that have previously been shown in the literature. The second study also shows that humans appear to be more sensitive to bipolar EVS than monopolar EVS. The third study found that combat athletes had lower EVS-induced sway thresholds using low frequency EVS than their matched controls. Taken together this thesis displays significant changes to vestibulospinal processing with increased RHI exposure in combat athletes.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Electrical Vestibular StimulationGalvanic Vestibular StimulationRepetitive Head ImpactBalanceVestibularCombat SportsPostural SwayVestibular ThresholdNeurosciencePhysiologydoctoral thesis