title: The Ability of American Football Helmets to Manage Linear Acceleration With Repeated High-Energy Impacts.
abstract: BACKGROUND
  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.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  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.
authors.affiliation: University of Ottawa, Ontario, Canada.
authors.forename: Janie
authors.initials: J
authors.lastname: Cournoyer
authors.affiliation: University of Ottawa, Ontario, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Post
authors.affiliation: University of Ottawa, Ontario, Canada.
authors.forename: Philippe
authors.initials: P
authors.lastname: Rousseau
authors.affiliation: University of Ottawa, Ontario, Canada.
authors.forename: Blaine
authors.initials: B
authors.lastname: Hoshizaki
mesh_terms: D000054:Acceleration; D001930:Brain Injuries / Q000209:etiology; D005538:Football / Q000293:injuries; D006260:Head Protective Devices / Q000592:standards*; D006801:Humans; D008422:Materials Testing; D055595:Mechanical Phenomena; D012307:Risk Factors; D014481:United States
keywords: education; head injuries; material fatigue