title: Changes in practice task constraints shape decision-making behaviours of team games players.
abstract: OBJECTIVE
  This study examined the effects of manipulating relative positioning between defenders (initial distance apart) on emergent decision-making and actions in a 1 vs. 2 rugby union performance sub-phase.
  
  
  METHODS
  Twelve experienced youth players performed 80 trials of a 1 (attacker) vs. 2 (defenders) practice task in which the starting distance between defenders was systematically decreased.
  
  
  METHODS
  Movement displacement trajectories of participants were video recorded to obtain 2D positional data. The independent variable was the starting distance between defenders and dependent variables were: (i) performance outcome (try or tackle), (ii) mean speed of all players during performance, and (iii), time between the first crossover and the end of the trial. Repeated measures ANOVA was used to compare the effects of different starting distances on performance.
  
  
  RESULTS
  Shorter starting distances between defenders were associated with a higher frequency of effective tackle outcomes, lower mean speeds of all participants, and a greater time period between the first crossover and the end of the trial.
  
  
  CONCLUSIONS
  Decision-making behaviours emerged as a function of changes in participants' spatial location during performance. This observation supports the importance of manipulating key spatial-temporal variables in designing representative practice task constraints that induce functional player-environment interactions in team sports training.
authors.affiliation: Faculty of Human Kinetics, Technical University of Lisbon, Cruz Quebrada, Portugal. advcorreia@fmh.utl.pt
authors.forename: Vanda
authors.initials: V
authors.lastname: Correia
authors.forename: Duarte
authors.initials: D
authors.lastname: Araújo
authors.forename: Ricardo
authors.initials: R
authors.lastname: Duarte
authors.forename: Bruno
authors.initials: B
authors.lastname: Travassos
authors.forename: Pedro
authors.initials: P
authors.lastname: Passos
authors.forename: Keith
authors.initials: K
authors.lastname: Davids
mesh_terms: D000293:Adolescent; D054874:Athletic Performance / Q000523:psychology; D003657:Decision Making; D005538:Football / Q000523:psychology*; D006801:Humans; D008297:Male; D013647:Task Performance and Analysis; D014741:Video Recording