Long-Term Cumulative Effects of Repeated Concussions in Cyclists: A Neurophysiological and Sensorimotor Study

<b>Objectives</b>: Sports-related concussion (SRC) is mostly associated with contact and combat sports. However, emerging evidence suggest that cyclists are also at risk of repeated concussion injury. Moreover, long-term neurophysiological outcomes in cycling cohorts remain underexplored. This novel study investigated the long-term effect of repetitive concussions in cyclists. Road, mountain biking (MTB), and BMX riders with a history of concussions and self-reported persistent symptoms were assess for neurophysiology and cognitive-motor performance compared to previously concussed cyclists with no ongoing symptoms. Both groups were compared to age-matched with controls. <b>Methods</b>: Using a cross-sectional between-group design, 25 cyclists with a history of concussions (15 symptomatic, 10 asymptomatic) and 20 controls completed symptom reporting, cognitive and balance assessments (SCAT5), sensorimotor testing using vibrotactile stimulation, and neurophysiological assessments via transcranial magnetic stimulation (TMS). <b>Results</b>: Symptomatic cyclists reported a higher number of concussions compared to asymptomatic cyclists (<i>p</i> = 0.041). Cognitive testing revealed large effects (<i>d</i> > 1.0), with impaired concentration in symptomatic cyclists compared to controls (<i>p</i> = 0.005). Motor assessments demonstrated large effects (<i>d</i> > 1.0), with slower tandem gait times (<i>p</i> < 0.001) and greater errors (<i>p</i> = 0.02) in the symptomatic group. Sensorimotor testing indicated slowed simple reaction times (<i>p</i> = 0.001) and poorer temporal order judgement <i>(p</i> = 0.038). TMS showed large effects (<i>d</i> > 1.0) in increased cortical inhibition in the symptomatic group, with prolong cortical silent periods (<i>p</i> < 0.05) and large effects (<i>d</i> > 1.0), and reduced short interval intracortical inhibition (<i>p</i> = 0.001) compared to asymptomatic cyclists and controls. <b>Conclusions</b>: Cyclists reporting persistent symptoms showed greater cortical inhibition and impaired cognitive-motor performance, consistent with findings in contact sport athletes. These results suggest that repeated concussions in cycling carry risk of chronic neurophysiological alterations. Cycling disciplines should consider more rigorous concussion identification protocols and stricter management strategies to mitigate persistent and long-term consequences.