International concern regarding the association between repetitive neurotrauma in sport and long term concerns with ageing continues. While previous studies have reported older (i.e. over 50 years) our study describes corticomotor changes across the lifespan between retired contact sport athletes, between the ages of 30 and 70 years. Retired athletes, minimum five years retired, (n=152; 48.6+/-9.0 years) and age-matched controls (n=72; 47.8+/-9.5 years) were assessed using single and paired-pulse transcranial magnetic stimulation (TMS) for active motor threshold (aMT), motor evoked potential and cortical silent period duration (expressed as MEP:cSP ratio), and short- and long-interval intracortical inhibition (SICI and LICI). Age-matched controls showed significant moderate correlations for MEP:cSP ratios at 130% (rho=0.48), 150% (rho=0.49)and 170% aMT (rho=0.42; all p<0.001) and significant but small negative correlation for SICI (rho=-0.27; p=0.030), and moderate negative correlation for LICI (rho=-0.43; p<0.001). Further, group-wise correlation analysis shows significant stronger corelations (all p<0.05) in the control for each variable than in the retired players. This study is the first to characterise corticomotor differences between retired athletes and age matched controls across the lifespan. in those with a history of repetitive head trauma and provides a foundation for further work to utilise TMS as a prodromal marker useful in supplementing neuropsychological assessment for traumatic encephalopathy syndrome which currently lacks physiological biomarkers.

This research received no external funding, nor any support for the work. A.J.P. has previously received partial research funding from the Erasmus+ strategic partnerships program (2019-1-IE01-KA202-051555), Sports Health Check Charity (Australia), Australian Football League, Impact Technologies Inc., and Samsung Corporation, and is remunerated for expert advice to medicolegal practices. A.J.P is also a honorary director of the Concussion Legacy Foundation Austrlaia. No other author has any declaration of interest.

This study did not receive any funding

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Ethical approval for all protocols were given by the La Trobe University Human Research Ethics Committee (Human Ethics Committee approval number 18005) conforming to the guidelines set out by the Declaration of Helsinki.

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All data produced in the present study are available upon reasonable request to the authors