title: Factors affecting children and adolescents 50 meter performance in freestyle swimming.
abstract: BACKGROUND
  This study investigated which factors influence performance in a short distance swimming test (50-meters) in adolescent swimmers.
  
  
  METHODS
  Freestyle 50-meter personal best time (PBT) was registered for 67 swimmers (14.3±2.2 y; 46 males). Handgrip (HG), standing broad jump (SBJ), isometric knee-extension (KE), time to run 30 meters (V30m), maximal estimated oxygen-consumption (VO2max), swimming-technique (CTE), height, weight, fat mass, body fat percentage (BF%) and fat-free mass (FFM) were measured. Variables that presented correlation with PBT were further examined using multiple linear regressions.
  
  
  RESULTS
  PBT was correlated with SBJ, VO2max, HG, KE, CTE, Weight, Height, FFM, BF% and swimming hours per week (SHW). Multiple linear regressions showed that PBT was associated to Height, V30m, CTE and SBJ. Sex and age did not modify these associations.
  
  
  CONCLUSIONS
  PBT was found to be mainly associated with height, an anthropometric variable. SBJ and V30m, both fitness-related variables, highly influenced by muscle fiber type were also predictors, suggesting that for short distances physiological factors might be determinant to performance. Age modified predictive values suggesting that this is also a key factor to performance, and thus competitions during adolescence should be organized according to year of birth rather than by age category.
authors.affiliation: GENUD Research Group, University of Zaragoza, Zaragoza, Spain.|Faculty of Health and Sport Sciences (FCSD), Department of Physiatry and Nursing, University of Zaragoza, Huesca, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Gomez-Bruton
authors.affiliation: GENUD Research Group, University of Zaragoza, Zaragoza, Spain.|Faculty of Health and Sport Sciences (FCSD), Department of Physiatry and Nursing, University of Zaragoza, Huesca, Spain.
authors.forename: Angel
authors.initials: A
authors.lastname: Matute-Llorente
authors.affiliation: GENUD Research Group, University of Zaragoza, Zaragoza, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Pardos-Mainer
authors.affiliation: GENUD Research Group, University of Zaragoza, Zaragoza, Spain.|Faculty of Health and Sport Sciences (FCSD), Department of Physiatry and Nursing, University of Zaragoza, Huesca, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Gonzalez-Aguero
authors.affiliation: GENUD Research Group, University of Zaragoza, Zaragoza, Spain.|Centro Universitario de la Defensa, Zaragoza, Spain.
authors.forename: Alba
authors.initials: A
authors.lastname: Gomez-Cabello
authors.affiliation: GENUD Research Group, University of Zaragoza, Zaragoza, Spain.|Faculty of Health and Sport Sciences (FCSD), Department of Physiatry and Nursing, University of Zaragoza, Huesca, Spain.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Casajus
authors.affiliation: GENUD Research Group, University of Zaragoza, Zaragoza, Spain - gervicen@unizar.es.|Faculty of Health and Sport Sciences (FCSD), Department of Physiatry and Nursing, University of Zaragoza, Huesca, Spain.
authors.forename: German
authors.initials: G
authors.lastname: Vicente-Rodriguez
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D016014:Linear Models; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D013550:Swimming / Q000502:physiology*