title: Epidemiology of concussion in sport: a literature review.
abstract: OBJECTIVE
  The purpose of this study was to summarize sport concussion incidence data, identify sports that present higher injury frequency, reveal the degree of risk in some lesser-known sports, and outline specific details within the sports literature that raise additional concerns, such as helmet-to-helmet contact and player positions that experience frequent impact.
  
  
  METHODS
  A systematic literature review of Pub Med using keyword search on injury, concussion, and sports was performed through May 2012. Abstracts were identified, selections were made based upon inclusion criteria, and full-length articles were obtained. Additional articles were considered following review of reference sections. Articles were reviewed and tabulated according to sport.
  
  
  RESULTS
  Two hundred eighty-nine articles were screened, and 62 articles were reviewed. The overall incidence of concussion in sport ranged from 0.1 to 21.5 per 1000 athletic exposures. The lowest incidence was reported in swimming and diving. Concussion incidence was highest in Canadian junior ice hockey, but elevated incidence in American football remains a concern because of the large number of participants.
  
  
  CONCLUSIONS
  The literature reviewed included incidence of concussion on the field of play under real-world conditions and influenced by the current culture of sport. The studies examined in this article show that there is risk of concussion in nearly every sport. Some sports have higher concussion frequency than others, which may depend upon the forces and roles of the positions played in these sports. Younger athletes have a higher incidence of concussion, and female incidence is greater than male in many comparable sports. Headgear may reduce concussion in some sports but may also give athletes a false sense of protection.
authors.affiliation: Clinical Lead, Chiropractic Clinic, Naval Hospital Camp Lejeune, Camp Lejeune, NC.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Clay
authors.affiliation: Staff Clinician, Bodies in Balance Physical Therapy, Wilmington, NC.
authors.forename: Kari L
authors.initials: KL
authors.lastname: Glover
authors.affiliation: Staff Clinician, Inter-Disciplinary Pain Management Clinic, Madigan Army Medical Center, Fort Lewis, WA.
authors.forename: Duane T
authors.initials: DT
authors.lastname: Lowe
keywords: Concussion; Epidemiology; Incidence; Sport; Traumatic brain injury