title: High injury incidence in adolescent female soccer.
abstract: BACKGROUND
  Previous studies report varying rates of time-loss injuries in adolescent female soccer, ranging from 2.4 to 5.3 per 1000 athlete-exposures or 2.5 to 3.7 per 1000 hours of exposure. However, these studies collected data using traditional injury reports from coaches or medical staff, with methods that significantly underestimate injury rates compared with players' self-reports.
  
  
  OBJECTIVE
  The primary aim was to investigate the injury incidence in adolescent female soccer using self-reports via mobile telephone text messaging. The secondary aim was to explore the association between soccer exposure, playing level, and injury risk.
  
  
  METHODS
  Descriptive epidemiology study and cohort study; Level of evidence, 2 and 3.
  
  
  METHODS
  During a full adolescent female soccer season in Denmark (February-June 2012), a population-based sample of 498 girls aged 15 to 18 years was included in the prospective registration of injuries. All players were enrolled on a team participating in Danish Football Association series. Soccer injuries and exposure were reported weekly by answers to standardized text message questions, followed by individual injury interviews. Soccer exposure and playing levels were chosen a priori as the only independent variables of interest in the risk factor analyses. Injury rates and relative risks were estimated using Poisson regression. Generalized estimation equations were used to take into account that players were clustered within teams.
  
  
  RESULTS
  There were 498 players who sustained a total of 424 soccer injuries. The incidence of injuries was 15.3 (95% CI, 13.1-17.8), the incidence of time-loss injuries was 9.7 (95% CI, 8.2-11.4), and the incidence of severe injuries was 1.1 (95% CI, 0.7-1.6) per 1000 hours of soccer exposure. Higher average exposure in injury-free weeks was associated with a lower injury risk (P value for trend <.001), and players with low exposure (≤1 h/wk) were 3 to 10 times more likely to sustain a time-loss injury compared with other players (P < .01). Playing level was not associated with the risk of time-loss injuries (P = .18).
  
  
  CONCLUSIONS
  The injury incidence in adolescent female soccer is high, and this includes many severe injuries. Players with low soccer participation (≤1 h/wk) have a significantly higher injury risk compared with players participating more frequently.
authors.affiliation: Sports Orthopaedic Research Center-Copenhagen, Arthroscopic Centre Amager, Copenhagen University Hospital, Amager-Hvidovre, Denmark School of Physiotherapy, Institute of Rehabilitation and Nutrition, Faculty of Health and Technology, Metropolitan University College, Copenhagen, Denmark mikkelbek@gmail.com.
authors.forename: Mikkel Bek
authors.initials: MB
authors.lastname: Clausen
authors.affiliation: Sports Orthopaedic Research Center-Copenhagen, Arthroscopic Centre Amager, Copenhagen University Hospital, Amager-Hvidovre, Denmark School of Physiotherapy, Institute of Rehabilitation and Nutrition, Faculty of Health and Technology, Metropolitan University College, Copenhagen, Denmark Gait Analysis Laboratory, Copenhagen University Hospital, Hvidovre, Denmark.
authors.forename: Mette Kreutzfeldt
authors.initials: MK
authors.lastname: Zebis
authors.affiliation: Section of Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark.
authors.forename: Merete
authors.initials: M
authors.lastname: Møller
authors.affiliation: Section of Human Physiology, Department of Nutrition, Exercise and Sports, Copenhagen Centre for Team Sport and Health, University of Copenhagen, Copenhagen, Denmark Sport and Health Sciences, College of Life and Environmental Sciences, St Luke's Campus, University of Exeter, Exeter, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Krustrup
authors.affiliation: Sports Orthopaedic Research Center-Copenhagen, Arthroscopic Centre Amager, Copenhagen University Hospital, Amager-Hvidovre, Denmark.
authors.forename: Per
authors.initials: P
authors.lastname: Hölmich
authors.affiliation: Sport Medicine Clinic, Department of Orthopaedics, Hospital of Lillebaelt, Institute of Regional Health Service Research and Center for Research in Childhood Health, Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Wedderkopp
authors.affiliation: National Research Centre for the Working Environment, Copenhagen, Denmark.
authors.forename: Lars Louis
authors.initials: LL
authors.lastname: Andersen
authors.affiliation: Department of Biostatistics, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Karl Bang
authors.initials: KB
authors.lastname: Christensen
authors.affiliation: Sports Orthopaedic Research Center-Copenhagen, Arthroscopic Centre Amager, Copenhagen University Hospital, Amager-Hvidovre, Denmark.
authors.forename: Kristian
authors.initials: K
authors.lastname: Thorborg
mesh_terms: D000293:Adolescent; D001265:Athletic Injuries / Q000453:epidemiology*; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D015601:Injury Severity Score; D011446:Prospective Studies; D012307:Risk Factors; D012916:Soccer / Q000293:injuries*
keywords: incidence; injury; soccer; text messaging