title: The Effect of Head Impact Location on Day of Diagnosed Concussion in College Football.
abstract: Scientists and clinicians have attempted to identify and understand biomechanical factors that influence concussion likelihood. The effect of impact frequency to a given head location before the concussion has not been evaluated. The purpose of this study was to compare the frequency of impacts to a given head location on days of diagnosed concussion to the frequency of impacts to a given head location before kinematically matched nonconcussive impacts.
  
  
  
  Head impact data were gathered from 33 Division I National Collegiate Athletic Association football players. Twenty-four concussions were identified and matched with impacts of similar kinematic and injury criterion values (linear acceleration, rotational acceleration, Gadd severity index, and head injury criterion) that occurred during the same event type (game, practice, or scrimmage). In addition, these same matching criteria were used to match all players to the closest kinematic/same player group. All impacts within a session before the impact of interest (concussive or matched impact) were analyzed.
  
  
  
  On days of diagnosed concussion, the concussive group sustained a lower percentage of impacts to the front of the head (34.5%) and a greater frequency of impacts to the sides (19.6%) and top (18.9%) of the head (χ(3) = 10.23, P = 0.017) as compared with the matched nonconcussive group (front = 42.5%, sides = 16.6%, top = 14.0%). No significant difference in frequency was found in impacts to the back of the head.
  
  
  
  It may be more difficult to mitigate concussive forces sustained in impacts to the top and sides of the head than the front of the head. These findings fall in line with previous research demonstrating that reduced impact magnitudes may lessen concussion risk. Studying appropriate training paradigms to develop safer playing techniques on the field is warranted.
authors.affiliation: 1Department of Exercise and Sport Science, Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, The University of North Carolina, Chapel Hill, NC; and 2Curriculum in Human Movement Science, Department of Allied Health Sciences, School of Medicine, The University of North Carolina, Chapel Hill, NC.
authors.forename: Steven
authors.initials: S
authors.lastname: Liao
authors.forename: Robert C
authors.initials: RC
authors.lastname: Lynall
authors.forename: Jason P
authors.initials: JP
authors.lastname: Mihalik
mesh_terms: D000054:Acceleration; D001696:Biomechanical Phenomena; D001924:Brain Concussion / Q000175:diagnosis*; D005538:Football / Q000293:injuries*; D006257:Head / Q000473:pathology*; D006801:Humans; D014495:Universities; D055815:Young Adult