Impact Mitigation in Modern Football Helmets: Advances and Limitations of Position-Specific Designs.

It has been established that repetitive head impacts lead to the accrual of changes in brain function, structure, and chemistry. The helmet is the primary piece of protective equipment for participants in American football. The first helmets were constructed from leather. Plastic helmets with chin straps were developed in the 1950s, but testing standards were not developed until 1973. While those standards resulted in improved padding materials, previous work demonstrated that modern helmets mitigate translational accelerations better than rotational accelerations, especially on a helmet's Rear Aspect. The goal of this study was to detail the methodology used to examine the impact mitigation of football helmets with differing energy dissipation mechanisms, including position-specific helmets. The experiments were integrated within a dimensional analysis framework to yield a technique that makes it possible to simultaneously evaluate translational and rotational accelerations due to quantified impact loads at multiple locations around the helmet. Despite improvements in the overall impact mitigation of one of the helmets tested here, in general, they did not achieve their design goals.