Sub-Concussive Head Impacts From Heading Footballs Do Not Acutely Alter Brain Excitability As Compared to a Control Group

Abstract Background Repeated sub-concussive head impacts are a growing brain health concern, but the possible mechanisms of trauma and plausible biomarkers remain elusive. One impediment is the lack of an experimental model to study the effects of sub-concussive head impacts on the brain. Objectives This work’s objective was to provide an experimental model to study the acute effects of sub-concussive head impacts on the brain. To do so, this study aimed to replicate previous work from Di Virgilio et al. (2016) showing that head impacts from heading footballs acutely alter brain excitability by increasing corticomotor inhibition. Methods Scores from the Rivermead Post-Concussion Questionnaire and measurements of cortical silent period (CSP) duration – obtained using transcranial magnetic stimulation to assess corticomotor inhibition in the central nervous system – were taken before and after participants performed 20 football headings (Headings; n = 30) or control (Control; n = 30). Results The results revealed increased headaches and dizziness symptoms in the Headings as compared to the Control group, revealing the qualitative experience of head impacts. The results then revealed that CSP duration similarly lengthened in both the Headings and Control groups, suggesting that head impacts did not cause the increased corticomotor inhibition. Conclusions The results show that head impacts from football headings did not acutely alter corticomotor inhibition as compared to a control group that did not experience head impacts, suggesting that excitability changes do not reflect acute sub-concussive brain injuries. Nonetheless, this work suggests that football headings can be used as an experimental model to study the effects of sub-concussive head impacts on brain health. Future work could use the present procedures to investigate additional biomarkers of brain injury.