Luís Vilar

The Role of Ecological Dynamics in Analysing Performance in Team Sports

Performance analysis is a subdiscipline of sports sciences and one-approach, notational analysis, has been used to objectively audit and describe behaviours of performers during different subphases of play, providing additional information for practitioners to improve future sports performance. Recent criticisms of these methods have suggested the need for a sound theoretical rationale to explain performance behaviours, not just describe them. The aim of this article was to show how ecological dynamics provides a valid theoretical explanation of performance in team sports by explaining the formation of successful and unsuccessful patterns of play, based on symmetrybreaking processes emerging from functional interactions between players and the performance environment. We offer the view that ecological dynamics is an upgrade to more operational methods of performance analysis that merely document statistics of competitive performance. In support of our arguments, we refer to exemplar data on competitive performance in team sports that have revealed functional interpersonal interactions between attackers and defenders, based on variations in the spatial positioning of performers relative to each other in critical performance areas, such as the scoring zones. Implications of this perspective are also considered for practice task design and sport development programmes.

Interpersonal coordination and ball dynamics in futsal (indoor football).

Here, we report an investigation of the patterned movement behavior of players for a specific sub-phase of the game of futsal, namely when the goalkeeper for the attacking team is substituted with an extra outfield player. The movement trajectories of the ball and players were recorded in both lateral and longitudinal directions and investigated using relative phase analysis. Some differences in phase relations between different playing dyads were noted, indicating specificity of phase attractions, or otherwise, for certain players. In general terms, the defenders demonstrated strong in-phase attractions with the ball and with each other, whereas weaker phase attractions, indicated by increased relative phase variability, were observed for the attackers and ball, as well as between attackers themselves. These results demonstrate different coordination dynamics for the defending and attacking dyads, from which we interpret evidence for different playing sub-systems consistent with different team objectives linked together in an overarching game structure. In keeping with dynamical systems theory for complex systems, we view this sub-phase of futsal as being characterized by coordinated behavior patterns that emerge as a result of self-organizing processes. These dynamic patterns are generated within functional constraints, with players and teams exerting mutual influence on each other.

How small-sided and conditioned games enhance acquisition of movement and decision-making skills

This article summarizes research from an ecological dynamics program of work on team sports exemplifying how small-sided and conditioned games (SSCG) can enhance skill acquisition and decision-making processes during training. The data highlighted show how constraints of different SSCG can facilitate emergence of continuous interpersonal coordination tendencies during practice to benefit team game players.

Practice task design in team sports: representativeness enhanced by increasing opportunities for action.

Abstract This study investigated effects of manipulating the number of action possibilities in a futsal passing task to understand the representativeness of practice tasks designs. Eight male senior futsal players performed a passing task in which uncertainty on passing direction for the player in possession of the ball was increased in four conditions and compared with passing data from a competitive match. Performance during a passing task and competitive futsal performance was compared using ball speed and passing accuracy data. Ball speed data were analysed by approximate entropy (ApEn) to capture their regularity in each of the four conditions and during competitive performance. Significantly high levels of regularity were observed in predetermined passes in comparison with emergent passes (i.e., passes with high number of possibilities for action). Similar results for ball speed regularity were observed between practice tasks with a high number of possibilities for action (i.e., emergent passes) and competitive performance. Similar results were observed for passing accuracy in practice tasks with a high number of possibilities for action compared to competitive performance. Increases in the number of action possibilities during practice improved action fidelity of tasks in relation to competitive performance.

Science of winning soccer: Emergent pattern-forming dynamics in association football

Quantitative analysis is increasingly being used in team sports to better understand performance in these stylized, delineated, complex social systems. Here, the authors provide a first step toward understanding the pattern-forming dynamics that emerge from collective offensive and defensive behavior in team sports. The authors propose a novel method of analysis that captures how teams occupy sub-areas of the field as the ball changes location. The authors use this method to analyze a game of association football (soccer) based upon a hypothesis that local player numerical dominance is key to defensive stability and offensive opportunity. The authors find that the teams consistently allocated more players than their opponents in sub-areas of play closer to their own goal. This is consistent with a predominantly defensive strategy intended to prevent yielding even a single goal. The authors also find differences between the two teams’ strategies: while both adopted the same distribution of defensive, midfield, and attacking players (a 4: 3: 3 system of play), one team was significantly more effective in maintaining both defensive and offensive numerical dominance for defensive stability and offensive opportunity. That team indeed won the match with an advantage of one goal (2 to 1) but the analysis shows the advantage in play was more pervasive than the single goal victory would indicate. The proposed focus on the local dynamics of team collective behavior is distinct from the traditional focus on individual player capability. It supports a broader view in which specific player abilities contribute within the context of the dynamics of multiplayer team coordination and coaching strategy. By applying this complex system analysis to association football, the authors can understand how players’ and teams’ strategies result in successful and unsuccessful relationships between teammates and opponents in the area of play.

The influence of pitch dimensions on performance during small-sided and conditioned soccer games

Abstract This study examined the influence of pitch dimensions in small-sided soccer games in shaping opportunities for performers to maintain ball possession, pass to teammates and shoot at goal. Fifteen amateur standard male participants (M = 21.87, σ = 1.96 years) played 5 v 5 small-sided soccer games in three varying pitch conditions (28 m × 14 m, 40 m × 20 m and 52 m × 26 m). Thirty sequences of play in each condition were selected for digitisation using TACTO software, allowing the capture of bi-dimensional displacement coordinate data of all players and the ball. The values of interpersonal distance between all attackers and immediate defenders and the relative distances of defenders to intercept a shot and a pass were computed as dependent variables. Results showed existence of fewer opportunities to maintain ball possession on smaller pitches, compared to medium and larger pitches. Conversely, the different dimensions set to the pitch did not influence opportunities for players to shoot at goal, or to perform passes to other teammates. By examining the specific spatial–temporal relationships of players and key-task constraints, the data from this study explain how effects of manipulating pitch dimensions of small-sided games might enhance opportunities for acquiring specific movement and decision-making skills.

Spatial-temporal constraints on decision-making during shooting performance in the team sport of futsal

Abstract In this paper we examined the influence of opposing players constraining the decision-making of an attacker during shooting performance in futsal. Performance during 10 competitive matches was recorded and examined from the moment a shot was taken until the ball was intercepted or entered the goal in sequences of play: ending in a goal, a goalkeepers save, or an interception by the nearest defender. The variables under scrutiny in this study were (i) the distance of each player to the balls trajectory, (ii) the time for the ball to arrive at that same point (i.e. the interception point), and (iii), the required movement velocity of the nearest defender and the goalkeeper to intercept the ball. Results showed that values of distance from a defender and goalkeeper to the interception points were significantly lower when they intercepted the ball. The time of ball arrival at the interception point of the defender was also lower when the ball was intercepted. The required velocities of the nearest outfield defender and the goalkeeper to intercept the ball were significantly lower during plays in which they intercepted the ball, than in plays in which the ball was not intercepted. Our results suggest that researchers and practitioners should consider simultaneously both space and time in analysis of interceptive actions in team sports. The required movement velocities of the opponents to intercept the ball are reliable spatial-temporal variables constraining decision-making during shooting performance in team sports like futsal.

Interpersonal coordination tendencies supporting the creation/prevention of goal scoring opportunities in futsal

Abstract Research on 1vs1 sub-phases in team sports has shown how one player coordinates his/her actions with his/her opponent and the location of a target/goal to attain performance objectives. In this study, we extended this approach to analysis of 5vs5 competitive performance in the team sport of futsal to provide a performance analysis framework that explains how players coordinate their actions to create/prevent opportunities to score goals. For this purpose, we recorded all 10 futsal matches of the 2009 Lusophony Games held in Lisbon. We analysed the displacement trajectories of a shooting attacker and marking defender in plays ending in a goal, a goalkeepers save, and a defenders interception, at four specific moments during performance: (1) assisting attackers ball reception and (2) moment of passing, (3) shooters ball reception, and (4), shot on goal. Statistical analysis showed that when a goal was scored, the defenders angle to the goal and to the attacker tended to decrease, the attacker was able to move to the same distance to the goal alongside the defender, and the attacker was closer to the defender and moving at the same velocity (at least) as the defender. This study identified emergent patterns of coordination between attackers and defenders under key competitive task constraints, such as the location of the goal, which supported successful performance in futsal.

Coordination tendencies are shaped by attacker and defender interactions with the goal and the ball in futsal.

This study examined how the location of the goal and ball constrained the interpersonal coordination tendencies emerging of attacker-defender dyadic systems in team sports. Additionally, we analysed how the positioning of defenders constrained the emergent coordination tendencies between the ball carrier and supporting teammates. To investigate these tendencies in team sports, ten futsal games were filmed to observe inter-individual interactions. Movement trajectories of players and ball were digitized during 52 outfield attacker-defender interactions involving thirteen goal-scoring sequences. Relative phase was used as a measure to express participant coordination tendencies in these dyadic systems (in-phase or symmetry - 0°; anti-phase or anti-symmetry - 180°). Stable in-phase patterns of coordination emerged between specific values of an attackers distances to defenders and the goal (19% frequency from 0° to 29° of phase relations) and between specific values of distances of ball carriers to defenders and teammates (14% frequency from 0° to 29° of phase relations). A stable pattern of coordination of -60° emerged between values of an attackers distances to defenders and the ball (18% frequency from 0° to 29° of phase relations). Distances of attackers to the goal and ball, and distances of ball carriers to defenders, seemed to be coupled in a specific manner to guide interpersonal coordination tendencies between players during competitive performance in the team sport of futsal.

Tactical performance changes with equal vs unequal numbers of players in small-sided football games

This study investigated the effects of equal (GK+4-vs-4+GK) and unequal (GK+4-vs-3+GK) numbers of outfield players on tactical behaviour of players and teams in small-sided football games. Thirty sequences of play without transitions in ball possession captured from six games of five minutes duration were selected for analysis from each game condition. The movement trajectories of players, teams and ball were expressed using polar coordinates referenced on centre location of the defending goal. Tactical performance was expressed by the degree of coupling of players and teams as indicated by the relative phase for different dyad combinations and by spatial-temporal relations between players and teams using various kinematic metrics. Results showed stronger couplings in the defending dyads, defending player ball pairs and the defending team and ball (p < 0.05) for the unequal numbers game condition. Also, decreased distances between players to their team geometric centre, decreased surface areas but increased distances between team geometric centres was observed for unequal playing numbers (p<0.05). Thus, results demonstrated that numerical advantage for the attacking team changed the tactical performances of the defending and attacking players and teams, particularly the former. Knowledge on this matter provides support for coaches manipulating small-sided football games for training purposes.