Rotational Head Kinematics in Football Impacts: An Injury Risk Function for Concussion

TLDR

Recent studies link sports‑related concussions to neurodegenerative risk, underscoring the need for accurate head‑impact tolerance metrics based on kinematic parameters that reflect the brain’s inertial response. This study aims to characterize the rotational kinematics of concussive head impacts using a large dataset of football player head accelerations. Head accelerations were recorded from 335 instrumented helmets during play, yielding 300,977 sub‑concussive and 57 concussive impact events. Concussive impacts exhibited mean rotational acceleration of 5,022 rad/s² and velocity of 22.3 rad/s, compared to 1,230 rad/s² and 5.5 rad/s for sub‑concussive events, and an injury‑risk curve identified 6,383 rad/s² at 28.3 rad/s as the 50 % concussion threshold, offering insights into biomechanics and prevention.

Abstract

Abstract Recent research has suggested a possible link between sports-related concussions and neurodegenerative processes, highlighting the importance of developing methods to accurately quantify head impact tolerance. The use of kinematic parameters of the head to predict brain injury has been suggested because they are indicative of the inertial response of the brain. The objective of this study is to characterize the rotational kinematics of the head associated with concussive impacts using a large head acceleration dataset collected from human subjects. The helmets of 335 football players were instrumented with accelerometer arrays that measured head acceleration following head impacts sustained during play, resulting in data for 300,977 sub-concussive and 57 concussive head impacts. The average sub-concussive impact had a rotational acceleration of 1230 rad/s 2 and a rotational velocity of 5.5 rad/s, while the average concussive impact had a rotational acceleration of 5022 rad/s 2 and a rotational velocity of 22.3 rad/s. An injury risk curve was developed and a nominal injury value of 6383 rad/s 2 associated with 28.3 rad/s represents 50% risk of concussion. These data provide an increased understanding of the biomechanics associated with concussion and they provide critical insight into injury mechanisms, human tolerance to mechanical stimuli, and injury prevention techniques.