Characterization of the Biomechanical and Situational Aspects of High Magnitude Subconcussive Impacts in Canadian University Football

Abstract

Background: Subconcussive impacts are asymptomatic head impacts that induce alterations in the brain after repetitive exposure. Understanding factors that lead to higher magnitude or frequency of subconcussive head impacts in Canadian football is crucial for the development of harm reduction and prevention strategies. Purpose: The objective of this study was to characterize high magnitude subconcussive impacts in Canadian football to identify injurious relationships between player and game-based characteristics, impact magnitude, and frequency. Methods: Eighty-one male university-level football players were equipped with helmet accelerometers to capture linear acceleration (LA), impact frequency, and helmet impact location. Impacts with LA ≥60g were included in the analysis. Video footage from 15 games over three seasons was analyzed to characterize aspects of play including play type, position, closing distance, player technique, tackling versus blocking, and impact type (helmet-to-helmet/body/ground) during these high magnitude impacts. Results: A total of 570 impacts were included in the analysis with a mean LA of 83.44 ± 23.60g. Impacts with a closing distance of ≥10 yards resulted in higher LA compared to <10 yards and occurred most frequently in run plays. Small skill players experienced significantly higher LA than linemen. Helmet-to-body impacts generated significantly higher LA compared to helmet-to-helmet, though helmet-to-helmet occurred more often. Impacts with poor technique had higher LA and occurred more frequently in tackling versus blocking impacts. Conclusion: The results of this work suggest that rules regarding offensive backfield running starts could be adjusted to decrease the risk of impact after a larger closing distance. Behavioral modifications and coaching approaches aimed at improving tackling technique could decrease exposure to high magnitude impacts at the level of the individual player.