title: Concussion in professional football: helmet testing to assess impact performance--part 11.
abstract: OBJECTIVE
  National Football League (NFL) concussions occur at an impact velocity of 9.3 +/- 1.9 m/s (20.8 +/- 4.2 mph) oblique on the facemask, side, and back of the helmet. There is a need for new testing to evaluate helmet performance for impacts causing concussion. This study provides background on new testing methods that form a basis for supplemental National Operating Committee on Standards for Athletic Equipment (NOCSAE) helmet standards.
  
  
  METHODS
  First, pendulum impacts were used to simulate 7.4 and 9.3 m/s impacts causing concussion in NFL players. An instrumented Hybrid III head was helmeted and supported on the neck, which was fixed to a sliding table for frontal and lateral impacts. Second, a linear pneumatic impactor was used to evaluate helmets at 9.3 m/s and an elite impact condition at 11.2 m/s. The upper torso of the Hybrid III dummy was used. It allowed interactions with shoulder pads and other equipment. The severity of the head responses was measured by a severity index, translational and rotational acceleration, and other biomechanical responses. High-speed videos of the helmet kinematics were also recorded. The tests were evaluated for their similarity to conditions causing NFL concussions. Finally, a new linear impactor was developed for use by NOCSAE.
  
  
  RESULTS
  The pendulum test closely simulated the conditions causing concussion in NFL players. Newer helmet designs and padding reduced the risk of concussion in 7.4 and 9.3 m/s impacts oblique on the facemask and lateral on the helmet shell. The linear impactor provided a broader speed range for helmet testing and more interactions with safety equipment. NOCSAE has prepared a draft supplemental standard for the 7.4 and 9.3 m/s impacts using a newly designed pneumatic impactor. No helmet designs currently address the elite impact condition at 11.2 m/s, as padding bottoms out and head responses dramatically increase.
  
  
  CONCLUSIONS
  The proposed NOCSAE standard is the first to address helmet performance in reducing concussion risks in football. Helmet performance has improved with thicker padding and fuller coverage by the shell. However, there remains a challenge for innovative designs that reduce risks in the 11.2 m/s elite impact condition.
authors.affiliation: Mild Traumatic Brain Injury Committee, National Football League, New York, New York, USA.
authors.forename: Elliot J
authors.initials: EJ
authors.lastname: Pellman
authors.forename: David C
authors.initials: DC
authors.lastname: Viano
authors.forename: Chris
authors.initials: C
authors.lastname: Withnall
authors.forename: Nick
authors.initials: N
authors.lastname: Shewchenko
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Bir
authors.forename: P David
authors.initials: PD
authors.lastname: Halstead
mesh_terms: D001696:Biomechanical Phenomena; D001924:Brain Concussion / Q000209:etiology* / Q000517:prevention & control*; D004867:Equipment Design; D005538:Football; D006040:Goals; D006260:Head Protective Devices / Q000592:standards*; D006801:Humans; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods*