Investigating the influence of head kinematics on head injury metrics and factors to consider for football helmet design.

This article investigates the relationships between head kinematics, impact severity metrics, and overall football helmet performance using four NFL helmet models tested according to the NFL helmet testing protocol. It evaluates the Head Acceleration Response Metric (HARM), which combines the Head Injury Criterion (HIC) and Diffuse Axonal Multi-Axis General Evaluation (DAMAGE) metrics, emphasizing that DAMAGE, a rotational injury metric, correlates more strongly with HARM than HIC, a translational metric, across all impact locations. Peak resultant angular velocity (PRAV) was identified as the best predictor of HARM overall, particularly at facemask and rear impact sites, while HIC showed the strongest correlation to HARM at side, side upper, and oblique front locations, highlighting the importance of both translational and rotational kinematics depending on impact site. The study underscores the influence of impact duration on HIC and suggests that helmet design improvements should consider location-specific kinematic factors to enhance protective performance.