title: Skeletal age in youth soccer players: implication for age verification.
abstract: OBJECTIVE
  To evaluate variation in skeletal age (SA) within single-year chronological age (CA) groups of soccer players aged 11 to 17 years in the context of using SA for age verification in age-group competitions.
  
  
  METHODS
  Cross sectional.
  
  
  METHODS
  Regional and elite youth soccer programs.
  
  
  METHODS
  Five hundred ninety-two male players from Portugal and Spain.
  
  
  METHODS
  Skeletal age assessed with the Fels method.
  
  
  METHODS
  Skeletal age and maturity status (late, average, early, or mature).
  
  
  RESULTS
  Chronological age and SA overlapped in players aged 11 to 12 years, but SA was advanced relative to CA in players aged 14 to 16 years. The majority of players between 11 and 12 years of age were on time in skeletal maturity and percentages of late and early maturers did not differ. The majority of players between 13 and 14 years of age were also on time, but early maturers were 4 times more frequent than late maturers. Percentages of late maturers were low among players aged 14 to 16 years. Among 200 players aged 15 to 16 years, 80 (40%) were advanced in SA by > 1 year and 27 (14%) were skeletally mature, whereas among 23 players aged 17 years, 9 (39%) were skeletally mature.
  
  
  CONCLUSIONS
  Among adolescent soccer player, boys advanced in SA for CA are overrepresented and those later in SA for CA are underrepresented with increasing CA. If Fels SA was used to verify CA in this sample of youth for under-17 competition, 36 skeletally mature players aged 15 to 17 years (16%) would be disqualified. The results for this sample of male soccer players question the utility of SA or magnetic resonance imaging as a valid estimate of CA in youth sport competitions.
authors.affiliation: Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas, USA. rmalina@skyconnect.net
authors.forename: Robert M
authors.initials: RM
authors.lastname: Malina
authors.forename: Maria Eugenia
authors.initials: ME
authors.lastname: Peña Reyes
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Figueiredo
authors.forename: Manuel J
authors.initials: MJ
authors.lastname: Coelho E Silva
authors.forename: Luis
authors.initials: L
authors.lastname: Horta
authors.forename: Rui
authors.initials: R
authors.lastname: Miller
authors.forename: Manuel
authors.initials: M
authors.lastname: Chamorro
authors.forename: Luis
authors.initials: L
authors.lastname: Serratosa
authors.forename: Francisco
authors.initials: F
authors.lastname: Morate
mesh_terms: D000293:Adolescent; D000365:Age Determination by Skeleton; D056352:Athletes; D001846:Bone Development; D002648:Child; D003430:Cross-Sectional Studies; D006132:Growth Plate / Q000254:growth & development; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011174:Portugal; D012916:Soccer / Q000502:physiology*; D013030:Spain