Association between downhill mountain bike racing and neurophysiological indices of sensory, attentional and cognitive processing in youth athletes

Background: There is growing concern over potential neurological impairment associated with accumulation of repetitive head acceleration events (HAE) in sport, particularly during periods of neurological vulnerability, including youth. Despite the high volume of HAEs sustained during downhill mountain biking, it is currently unknown downhill mountain biking is associated with neural function in youth. Thus, the purpose of this study was to investigate the association between exposure to downhill mountain bike racing and sensory, attentional, and cognitive processing in youth using N100, P300 and N400 Event related Potentials (ERPs). Methods: Fifteen participants (6 female, 9 male; ages 15-24 years) contributed 38 ERP observations at baseline timepoints and following up to 5 days of elite downhill mountain bike competition. Results: Conditional linear regression models demonstrated that the average marginal difference in N400 amplitude in measures taken post-mountain bike exposure was 1.26 μV (95% CI: -2.16, -0.36; p = 0.006) less than before riding. N400 latency, P300 amplitude and latency, and N100 amplitude and latency were unchanged from baseline by days (range: 1-4) of mountain biking (all p > 0.26). Conclusion: In agreement with studies in hockey and football, our results showed that participation in downhill mountain biking is associated with acute cognitive neural processing impairments. The contribution of exercise, focus and HAEs to these impairments is unclear. This study expands the growing evidence of neural processing impairments occurring acutely following sport participation to the understudied sport of downhill mountain biking.