title: The older, the wider: On-field tactical behavior of elite-standard youth soccer players in small-sided games.
abstract: OBJECTIVE
  Young soccer players need excellent tactical skills to reach the top. Tactical behavior emerges through interactions between opposing teams. However, few studies have focused on on-field tactical behavior of teams with talented soccer players. Therefore, this study aimed to determine teams' tactical behavior during small-sided games in two age categories, Under-17 and Under-19.
  
  
  METHODS
  Positional data of thirty-nine elite-standard soccer players were collected during twenty-four small-sided games to calculate longitudinal and lateral inter-team distances, stretch indices and length per width ratios. Corresponding interaction patterns and game-to-game variability were also determined.
  
  
  RESULTS
  Under-19 showed a significantly larger lateral stretch index and a significantly lower length per width ratio compared with Under-17. Furthermore, teams of both age groups showed similar large proportions of in-phase behavior. Variability of tactical performance measures within and between games was similar for Under-17 and Under-19.
  
  
  CONCLUSIONS
  Variability within games seems to be functional for attacking teams for creating goal-scoring opportunities. In conclusion, the main difference was that Under-19 adopted a wider pitch dispersion than Under-17, represented by a larger lateral stretch index and smaller length per width ratio. Coach instructions and training exercises should be directed at exploiting pitch width to increase the pursuit of goal-scoring.
authors.affiliation: University of Groningen, University Medical Center Groningen, Center for Human Movement Sciences, A. Deusinglaan 1/P.O. Box 196, 9713 AV/9700 AD Groningen, The Netherlands. Electronic address: s.b.h.olthof@umcg.nl.
authors.forename: Sigrid B H
authors.initials: SB
authors.lastname: Olthof
authors.affiliation: University of Groningen, University Medical Center Groningen, Center for Human Movement Sciences, A. Deusinglaan 1/P.O. Box 196, 9713 AV/9700 AD Groningen, The Netherlands; Hanze University of Applied Sciences, School of Sports Studies, Zernikeplein 7/P.O. Box 70030, 9747 AS/9700 RM Groningen, The Netherlands; Football Club Groningen, Boumaboulevard 41, 9723 ZS Groningen, The Netherlands.
authors.forename: Wouter G P
authors.initials: WG
authors.lastname: Frencken
authors.affiliation: University of Groningen, University Medical Center Groningen, Center for Human Movement Sciences, A. Deusinglaan 1/P.O. Box 196, 9713 AV/9700 AD Groningen, The Netherlands; Hanze University of Applied Sciences, School of Sports Studies, Zernikeplein 7/P.O. Box 70030, 9747 AS/9700 RM Groningen, The Netherlands.
authors.forename: Koen A P M
authors.initials: KA
authors.lastname: Lemmink
mesh_terms: D000293:Adolescent; D000367:Age Factors; D056352:Athletes; D054874:Athletic Performance / Q000502:physiology*; D003071:Cognition; D006801:Humans; D008297:Male; D012916:Soccer; D013037:Spatial Behavior / Q000502:physiology
keywords: Dynamical systems; Football; Performance analysis; Tactics; Talent development