title: Understanding mismatches in body size, speed and power among adolescent rugby union players.
abstract: OBJECTIVE
  With adolescent sport increasingly challenged by mismatches in size, new strategies are important to maximize participation. The objectives were to (1) improve the understanding of mismatches in physical size, speed and power in adolescent rugby union players, (2) explore associations between size and performance with demographic, playing-history, and injury profiles, and (3) explore the applicability of existing criteria for age/body mass-based dispensation (playing-down) strategies.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Four hundred and eighty-five male community rugby union players were recruited from three Australian states selected to represent community-based U12, U13, U14 and U15 players. Body mass, stature, speed (10, 30, and 40 m sprints) and lower-leg power (relative peak power and relative peak force) were measured. Independent student t-tests, linear regressions and Chi square analyses were undertaken.
  
  
  RESULTS
  Mean values in age groups for size, speed and power masked considerable overlap in the ranges within specific age groups of adolescent rugby players. Only a small proportion of players (approximately 5%) shared the highest and lowest tertiles for speed, relative peak power and body mass. Physical size was not related to injury. The mean body mass of current community rugby union players was above the 75th percentile on normative growth-charts.
  
  
  CONCLUSIONS
  The notion that bigger, faster, and more powerful characteristics occur simultaneously in adolescent rugby players was not supported in the present study. Current practices in body mass-based criteria for playing down an age group lack a sufficient evidence for decision-making. Dispensation solely based on body mass may not address mismatch in junior rugby union.
authors: School of Exercise Science, Australian Catholic University, Melbourne, Victoria, Australia.
authors: Lyndon M
authors: LM
authors: Krause
authors: School of Exercise Science, Australian Catholic University, Melbourne, Victoria, Australia.
authors: Geraldine A
authors: GA
authors: Naughton
authors: Australian Rugby Union, Australia.
authors: Greg
authors: G
authors: Denny
authors: Australian Rugby Union, Australia.
authors: Declan
authors: D
authors: Patton
authors: School of Exercise Science, Australian Catholic University, Strathfield, New South Wales, Australia.
authors: Tim
authors: T
authors: Hartwig
authors: School of Exercise Science, Australian Catholic University, Brisbane, Queensland, Australia. Electronic address: tim_gabbett@yahoo.com.au.
authors: Tim J
authors: TJ
authors: Gabbett
mesh_terms: D000293:Adolescent; D054874:Athletic Performance; D001827:Body Height; D001835:Body Weight; D002648:Child; D003430:Cross-Sectional Studies; D005538:Football / Q000145:classification / Q000293:injuries / Q000502:physiology*; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D012420:Running / Q000502:physiology*
keywords: Ethnic groups; Football; Performance; Physiology; Sport; Youth