title: Descriptive Characteristics of Concussions in National Football League Games, 2010-2011 to 2013-2014.
abstract: BACKGROUND
  Despite a high reported incidence rate of concussion, little is known about the on-field characteristics of injurious head impacts in National Football League (NFL) games.
  
  
  OBJECTIVE
  To characterize on-field features (location, player position, and time during game) and biomechanical features (anticipation status, closing distance, impact location and type) associated with concussions in NFL games over a 4-season period (2010-2011 to 2013-2014).
  
  
  METHODS
  Descriptive epidemiology study.
  
  
  METHODS
  We analyzed video of a subset of reported, in-game concussions for the 2010-2011 to 2013-2014 seasons. These videos represented a sample of injuries that were diagnosed and reported on the same day and that could be clearly associated with an in-game collision as captured on video. We determined anticipation status, closing distance, impact location on the injured player's helmet, and impact type (helmet-to-helmet, helmet-to-body, or helmet-to-ground). Associations between these variables were analyzed by use of descriptive statistics and tests of association.
  
  
  RESULTS
  A total of 871 diagnosed concussions were reported as occurring during NFL preseason, regular season, and postseason games for the 2010-2011, 2011-2012, 2012-2013, and 2013-2014 seasons. A total of 1324 games were played during this period, giving a concussion incidence rate of 0.658 per game (95% CI, 0.61-0.70). From the video-reviewed subset (n = 429; 49.3%), the majority of injurious impacts occurred with good anticipation (57.3%) and <10 yards of closing distance (59.0%). An association was found between anticipation status and play type ([Formula: see text] = 27.398, P < .001), largely because injuries occurring on pass plays were more likely to be poorly anticipated than injuries during run plays (43.0% vs 21.4%; [Formula: see text] = 14.78, P < .001). Kick returns had the greatest proportion of well-anticipated impacts (78%) and the greatest proportion of impacts with ≥10 yards of closing distance (80%). The type of impact was approximately equally divided between helmet-to-helmet, helmet-to-body, and helmet-to-ground types. The impact location was broadly distributed over the helmet of the injured player.
  
  
  CONCLUSIONS
  In-game concussions in the NFL occurred through a diverse variety of mechanisms, surprisingly tended to be well-anticipated, and, also surprisingly, occurred with <10 yards of closing distance. The impacts causing concussion were broadly distributed over the helmet. More concussions occurred during the second half of game play, but we do not have evidence to explain this finding.
authors.affiliation: Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, North Carolina, USA.|Curriculum in Human Movement Science, Department of Allied Health Sciences, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Clark
authors.affiliation: Department of Clinical and Health Psychology, Neuropsychology College of Public Health and Health Professions, University of Florida, Gainesville, Florida, USA.
authors.forename: Breton M
authors.initials: BM
authors.lastname: Asken
authors.affiliation: Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, North Carolina, USA.|Injury Prevention Research Center, University of North Carolina, Chapel Hill, North Carolina, USA.|Department of Epidemiology, University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Marshall
authors.affiliation: Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, North Carolina, USA.|Curriculum in Human Movement Science, Department of Allied Health Sciences, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA.|Injury Prevention Research Center, University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Guskiewicz
mesh_terms: D059031:Anticipation, Psychological; D001924:Brain Concussion / Q000453:epidemiology* / Q000209:etiology; D005538:Football / Q000293:injuries*; D006260:Head Protective Devices; D006801:Humans; D015994:Incidence; D008297:Male; D013997:Time Factors; D013996:Time and Motion Studies; D014481:United States / Q000453:epidemiology
keywords: American football; National Football League; concussion; head impacts