Examining the cumulative effect of repetitive head-impacts on the ability to inhibit a motor response

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ObjectiveTo examine how a season of sub-concussive head-impact exposures influence a measure of response-inhibition in contact-sport athletes.DesignProspective cohortSettingLaboratoryParticipantsTwenty-five contact-sport athletes (20.3±1.3 years) performed a response-inhibition task prior to and following the competitive season. Each player wore an adhesive accelerometer (X2Biosystems) during games. Players were excluded if they sustained a concussion during the season.InterventionsTo probe response-inhibition, an object hit-and-avoid sensorimotor task (KINARM) was performed. This 2.5 minute task entailed the successful hitting of two target shapes while avoiding six other distractor shapes. Players were divided into tertiles (high, medium, low; n=8) based on cumulative number of 20g+ head impacts, cumulative peak linear acceleration (cPLA), and cumulative peak rotational acceleration (cPRA). Comparisons of response-inhibition performance were made between high and low tertiles.Outcome measuresPre-post changes in number of targets hit, distractors hit, total cancelled movements towards pursued distractors (CPDs), and total task accuracy (percent) were recorded for the KINARM task.ResultsIndependent t-tests indicated no significant differences between the high and low tertiles on the KINARM task despite the high tertile group experiencing 4-times greater head impacts throughout the season. There was a trend for greater KINARM task improvement from pre-to-post-season in the bottom tertile, as reflected by the increase in CPDs in their post-season measures (cumulative number: p=0.06, CI=[−16.2148519, 0.7148519]).ConclusionsThese findings reveal that one season of repetitive sport-related head impacts does not appear to have a significant effect on an athlete’s ability to inhibit a motor response.Competing interestsAll authors have no competing interests to declare.

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