Characterising biomechanical and situational aspects of high magnitude subconcussive impacts in Canadian collegiate football.

The objective of this study was to characterise high magnitude subconcussive impacts in Canadian football to identify injurious relationships between player/game-based characteristics, impact magnitude, and frequency. Eighty-one male university-level football players were equipped with helmet accelerometers to capture peak linear acceleration (PLA), impact frequency, and helmet impact location. Impacts with PLA ≥ 60 g were included in this analysis. Video footage from 15 games over three seasons was analysed to characterise aspects of play including play type, position, closing distance, tackling versus blocking, and impact. Impacts occurring at the left outside boundary of the field resulted in significantly higher linear accelerations. Impacts with a closing distance of ≥10 yards resulted in higher PLA compared to <10 yards and occurred most frequently in run plays. Helmet-to-body impacts generated significantly higher PLA compared to helmet-to-helmet, though helmet-to-helmet occurred more often. Players being tackled sustained significantly higher PLAs than those blocking. The results of this work suggest that the left outside boundary is an area of importance for spotters looking to identify high-risk impacts. Further, rules regarding offensive backfield running starts could be adjusted to decrease the risk of impact after a larger closing distance.