title: Injuries in children with extra physical education in primary schools.
abstract: OBJECTIVE
  (1) Examine the influence of extra physical education (EPE) on the number of musculoskeletal injuries in public schools accounting for organized sports participation (OSP) outside school. (2) Examine the major injury subgroup: growth-related overuse (GRO) through the overuse-related injury group.
  
  
  METHODS
  A longitudinal controlled school-based study among Danish public schools. At baseline, 1216 children participated age 6.2-12.4 yr. Six schools (701 children) with EPE and four control schools (515 children) were followed up with weekly automated mobile phone text messages for information on musculoskeletal problems and OSP. Health care personnel diagnosed the children according to the World Health Organization's International Classification of Diseases, Tenth Revision. Data were analyzed using a two-part zero-inflated negative binomial (ZINB) regression model.
  
  
  RESULTS
  School type had no influence on the odds of sustaining an injury but increased the probability of sustaining a higher injury count for children with injuries, with total injuries by a factor of 1.29 (95% confidence interval [CI] = 1.07-1.56), overuse by a factor of 1.29 (95% CI = 1.06-1.55), and GRO by a factor of 1.38 (95% CI = 1.02-1.80). Weekly mean OSP decreased the odds of belonging to the group of children with no injuries, by a factor of 0.29 (95% CI = 0.14-0.58), 0.26 (95% CI = 0.14-0.48), and 0.17 (95% CI = 0.06-0.52) for total, overuse, and GRO, respectively. OSP also increased the probability of sustaining a higher injury count for children with injuries by a factor of 1.11 (95% CI = 1.02-1.22), 1.10 (95% CI = 1.00-1.22), and 1.14 (95% CI = 1.00-1.30), respectively.
  
  
  CONCLUSIONS
  Children enrolled in EPE schools with high OSP have the highest odds of injury and a high probability of sustaining a higher injury count compared to their peers at schools with normal PE. Special attention should be assigned to these children during compulsory PE.
authors.affiliation: 1Centre of Research in Childhood Health, Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, DENMARK; 2Department of Sports Medicine, The Norwegian School of Sport Sciences, Oslo, NORWAY; 3National Institute of Public Health, University of Southern Denmark, Copenhagen, DENMARK; 4Sport Medicine Clinic, Orthopedic Department, Hospital of Lillebaelt, Odense, DENMARK; and 5Institute of Regional Health Services Research, University of Southern Denmark, Odense, DENMARK.
authors.forename: Christina Trifonov
authors.initials: CT
authors.lastname: Rexen
authors.forename: Lars Bo
authors.initials: LB
authors.lastname: Andersen
authors.forename: Annette Kjær
authors.initials: AK
authors.lastname: Ersbøll
authors.forename: Eva
authors.initials: E
authors.lastname: Jespersen
authors.forename: Claudia
authors.initials: C
authors.lastname: Franz
authors.forename: Niels
authors.initials: N
authors.lastname: Wedderkopp
mesh_terms: D001265:Athletic Injuries / Q000453:epidemiology*; D001842:Bone and Bones / Q000293:injuries; D002648:Child; D012090:Cumulative Trauma Disorders / Q000453:epidemiology; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D018482:Muscle, Skeletal / Q000293:injuries; D010806:Physical Education and Training; D012307:Risk Factors; D012574:Schools