From motion to deformation: a large-scale study of concussive versus non-concussive head acceleration events and brain strains in Canadian university football.

Abstract

Sport-related concussion arises from complex brain loading during head acceleration events (HAEs). However, tissue-level responses in Canadian university football remain poorly characterized. This study quantified head kinematics and finite element-derived brain strain in concussive and non-concussive HAEs. Helmet-mounted sensors recorded linear acceleration and rotational velocity during games and practices from 250 players across seven seasons (2013-2019). Medically diagnosed concussions (n = 45) were identified, and causative HAEs determined through expert consensus of available data. A set of 180 HAEs was selected to represent non-concussive HAEs based on linear and rotational severity distributions. Time series data were applied to a validated 50th percentile male finite element head model to compute 95th percentile maximum principal strain (MPS95), and multi-threshold cumulative strain damage measure (CSDM). Concussive HAEs exhibited significantly higher kinematics than non-concussive events, with median linear acceleration of 83.51 versus 27.71 g and rotational velocity of 24.58 versus 9.87 rad/s. These kinematics produced greater brain deformation across all regions, with median concussive MPS95 of 0.10 to 0.29 versus 0.08 to 0.11 in non-concussive events, and CSDM elevated across all thresholds. The largest relative strain increases were observed in the cerebellum, corpus callosum, and brainstem. Overlap between concussive and non-concussive HAEs persisted across kinematic and strain metrics, emphasizing the probabilistic nature of concussion. These results establish the first population-specific biomechanical concussion reference data in Canadian university football, demonstrating that concussive HAEs produce higher head kinematics and corresponding regional and whole-brain strain, providing a foundation for injury modeling, computational validation, and concussion risk function development.