The Ability of American Football Helmets to Manage Linear Acceleration With Repeated High-Energy Impacts.

Context: Football players can receive up to 1400 head impacts per season, averaging 6.3 impacts per practice and 14.3 impacts per game. A decrease in the capacity of a helmet to manage linear acceleration with multiple impacts could increase the risk of traumatic brain injury.

Objective: To investigate the ability of football helmets to manage linear acceleration with multiple high-energy impacts.

Design: Descriptive laboratory study.

Setting: Laboratory.

Main Outcome Measure(s): We collected linear-acceleration data for 100 impacts at 6 locations on 4 helmets of different models currently used in football. Impacts 11 to 20 were compared with impacts 91 to 100 for each of the 6 locations.

Results: Linear acceleration was greater after multiple impacts (91-100) than after the first few impacts (11-20) for the front, front-boss, rear, and top locations. However, these differences are not clinically relevant as they do not affect the risk for head injury.

Conclusions: American football helmet performance deteriorated with multiple impacts, but this is unlikely to be a factor in head-injury causation during a game or over a season.