title: Allometric modelling of peak oxygen uptake in male soccer players of 8-18 years of age.
abstract: BACKGROUND
  Peak oxygen uptake (VO2peak) is routinely scaled as mL O2 per kilogram body mass despite theoretical and statistical limitations of using ratios.
  
  
  OBJECTIVE
  To examine the contribution of maturity status and body size descriptors to age-associated inter-individual variability in VO2peak and to present static allometric models to normalize VO2peak in male youth soccer players.
  
  
  METHODS
  Total body and estimates of total and regional lean mass were measured with dual energy X-ray absorptiometry in a cross-sectional sample of Portuguese male soccer players. The sample was divided into three age groups for analysis: 8-12 years, 13-15 years and 16-18 years. VO2peak was estimated using an incremental maximal exercise test on a motorized treadmill. Static allometric models were used to normalize VO2peak.
  
  
  RESULTS
  The independent variables with the best statistical fit explained 72% in the younger group (lean body mass: k = 1.07), 52% in mid-adolescent players (lean body mass: k = 0.93) and 31% in the older group (body mass: k = 0.51) of variance in VO2peak. The inclusion of the exponential term pubertal status marginally increased the explained variance in VO2peak (adjusted R(2 )= 36-75%) and provided statistical adjustments to the size descriptors coefficients.
  
  
  CONCLUSIONS
  The allometric coefficients and exponents evidenced the varying inter-relationship among size descriptors and maturity status with aerobic fitness from early to late-adolescence. Lean body mass, lean lower limbs mass and body mass combined with pubertal status explain most of the inter-individual variability in VO2peak among youth soccer players.
authors.affiliation: Faculty of Sport Sciences and Physical Education, University of Coimbra , Coimbra , Portugal .
authors.forename: João
authors.initials: J
authors.lastname: Valente-Dos-Santos
authors.forename: Manuel J
authors.initials: MJ
authors.lastname: Coelho-E-Silva
authors.forename: Óscar M
authors.initials: ÓM
authors.lastname: Tavares
authors.forename: João
authors.initials: J
authors.lastname: Brito
authors.forename: André
authors.initials: A
authors.lastname: Seabra
authors.forename: António
authors.initials: A
authors.lastname: Rebelo
authors.forename: Lauren B
authors.initials: LB
authors.lastname: Sherar
authors.forename: Marije T
authors.initials: MT
authors.lastname: Elferink-Gemser
authors.forename: Robert M
authors.initials: RM
authors.lastname: Malina
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D056352:Athletes; D001823:Body Composition; D049628:Body Size; D002648:Child; D003430:Cross-Sectional Studies; D005080:Exercise Test; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D011174:Portugal; D012916:Soccer
keywords: Aerobic fitness; body composition; growth; static allometry; youth athletes