title: Aerobic endurance performance does not determine the professional career of elite youth soccer players.
abstract: BACKGROUND
  Physical characteristics have been widely analyzed in order to understand why some soccer players are more successful than others. Therefore, the aims of this study were: 1) to describe the evolution of aerobic endurance performance across 18 years in a Spanish elite soccer academy; 2) to know if the playing position could affect physical testing performance; and 3) to look into the alleged impact of this factor on the professional career of soccer players.
  
  
  METHODS
  We considered 162 players belonging to the reserve team of an elite Spanish soccer club from 1994 to 2012. The percentage of players that played in the reserve team for at least five matches in Third Division (2nd B) and later promoted to the Spanish First or Second Division was 32%. The participants were classified in three six-year periods and according to their highest competitive level attained until the 2014/2015 season and their regular tactical position. All the players performed a four-stage submaximal intermittent running test with the running speeds 12 km/h (10 min), 13 km/h (10 min), 14 km/h (10 min), and 15 km/h (5 min) in order to assess the individual velocities associated with a [La]b of 3 mmol/L (i.e., V3).
  
  
  RESULTS
  No differences (P>0.05) in aerobic fitness were found between the three six-year periods groups (P>0.05), between the tactical positions nor among the competitive levels attained.
  
  
  CONCLUSIONS
  These findings indicate that aerobic endurance performance (i.e., V3) is not a pertinent trait when identifying players from different seasons, tactical positions and competitive levels.
authors.affiliation: Faculty of Education and Sport, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain - daniel.castillo@ehu.es.
authors.forename: Daniel
authors.initials: D
authors.lastname: Castillo
authors.affiliation: Faculty of Education and Sport, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain.
authors.forename: Asier
authors.initials: A
authors.lastname: Los Arcos
authors.affiliation: Faculty of Education and Sport, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain.
authors.forename: Raúl
authors.initials: R
authors.lastname: Martínez-Santos
mesh_terms: D000124:Achievement; D000293:Adolescent; D000332:Aerobiosis; D054874:Athletic Performance / Q000191:economics; D006801:Humans; D008297:Male; D010807:Physical Endurance; D012420:Running; D012621:Seasons; D012916:Soccer / Q000191:economics / Q000502:physiology*; D055815:Young Adult