Sport Sciences

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 direc-
tions and investigated using relative phase analysis. Some differ-
ences 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 differ-
ent coordination dynamics for the defending and attacking dyads,
from which we interpret evidence for different playing sub-sys-
tems 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.

In 2009, Kannekens and colleagues evaluated the development of tactical skills of elite youth football players using a method based on verbal reports. Results showed no improvements in players’ tactical skills over the years of their longitudinal study. These results are based on an erroneous assumption that tactical skills and verbalizations about tactical skills are equivalent. This note comprises an explanation of why verbal reports are not a valid measure of tactical skills.

The main goal of performance analysis in team sports has been the identification of data frequencies or sequences of actions in a temporal line, based on the assemblage of numerous discrete variables. This focus may be
deemed as not displaying the foremost team sport feature, i.e., the dynamics of the interaction between two teams. In order to better understand the dynamic patterns of the game, the methods commonly applied must be furthered in a functional perspective. Underpinned in the Ecological Dynamics approach to decision making in sport, this paper regards performance analysis as a process of synthesis and parsimonious explanation of game’s functional nature. Accordingly, we argue the importance of the following three aspects: i) game must be viewed considering different levels of analysis;
ii) there is a functional role of variability in players’ behaviour that must be included in the analysis; iii) human behaviour is better understood if we consider how the dynamics reflects individual and collective perceptual-action couplings.

Background and objective. In the last years, several motion analysis methods have been developed without considering representative contexts for sports performance. The purpose of this paper was to explain and underscore a straightforward method to measure human behavior in these contexts.
Material and methods. Procedures combining manual video tracking (with TACTO device) and bidimensional reconstruction (through direct linear transformation) using a single camera were used in order to capture kinematic data required to compute collective variable(s) and control parameter(s).
These procedures were applied to a 1vs1 association football task as an illustrative subphase of team sports and will be presented in a tutorial fashion.
Results. Preliminary analysis of distance and velocity data identified a collective variable (difference between the distance of the attacker and the defender to a target defensive area) and two nested control parameters (interpersonal distance and relative velocity).
Conclusions. Findings demonstrated that the complementary use of TACTO software and direct linear transformation permit to capture and reconstruct complex human actions in their context in a low dimensional space (information reduction)

Objectives: This study aimed to explain how defenders intercept the trajectory of a passing ball by understanding how they coupled their actions to critical information sources in a competitive performance
setting in team sports.
Design: Time series data on movement displacements of fifteen senior male futsal performers were recorded and digitized during nine competitive futsal games.
Method: Performance was recorded by a digital camera and digitized with TACTO software. The spatial etemporal dynamics of performers during ten intercepted and ten non-intercepted passes were compared. Time to ball interception was calculated by the difference between the time of each defender to an interception point in ball trajectory and the time of the ball’s arrival at the same interception point.
Initial distances between defenders and ball and velocity data of defenders and ball over time were also recorded.
Results: Time to ball interception revealed positive values when passes were not intercepted, and negative to zero values when passes were intercepted. At the moment of pass initiation defenders’
distances to the ball constrained their possibilities for successful interception. Analysis of defenders’ adaptations to the environment revealed that continuous changes in the defenders’ velocities constrained their success of the interception.
Conclusions: Intercepted passes seemed to be influenced by the continuous regulation of a defender’s velocity relative to the ball’s trajectory. Time to ball interception is a variable that captured the emergent functional behaviours of players attempting to intercept the trajectory of a pass in the team sport of
futsal.

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. 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. 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. 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. 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.

Previous research on coordination dynamics of 1 vs. 1 sub-phases in team sports has reported stable emergent patterns of coordination in the displacement trajectories of attackers and defenders. The aim of this study was to use attacker–defender interactions in competitive team match-play to investigate how the locations of the goal and ball constrain the pattern-forming dynamics of attacker–defender dyadic systems. Ten high-level futsal matches were filmed and 13 goal sequences selected for analysis. Displacements of the players and the ball were filmed and digitized from 52 attacker–defender dyadic system interactions. Results showed that, although attackers and defenders exhibited similar angular orientations to the goal, the latter always remained closer to the goal than attackers. Observations revealed that in-phase patterns of coordination emerged from changes to both the distances and angles of attackers and defenders to the goal. Attackers always remained closer to the ball than defenders, while the latter exhibited a lower angle to the ball than attackers. A pattern of in-phase coordination modes emerged between the attackers and defenders' distances and angles to the ball. This study helps us to understand interpersonal interactions in team sports by explaining how attackers and defenders use information about their relative positioning to the goal and the ball to perform successfully.

Neste estudo tivemos como objectivo investigar se o processo decisional surge através de um processo relacional “on-line” entre indivíduos e ambiente para a concretização de um objectivo. Para tal, utilizámos 35 situações de passe numa tarefa de Futsal onde avaliámos como evolui o contexto decisional até ao momento do passe. Neste estudo utilizámos como variáveis as distâncias interpessoais entre jogadores, as suas velocidades instantâneas e a fase relativa entre as referidas distâncias. Como resultados, verificámos que entre o momento de recepção da bola até à realização do passe, existe uma convergência nas distâncias entre os jogadores para um valor estável e uma divergência das suas velocidades. Estes resultados sugerem que a decisão para passar emerge face à afinação perceptual do indivíduo com bola à informação relevante do ambiente. Esta afinação permite a exploração e detecção de affordances, para passar a bola, definidas por uma janela espácio-temporal entre os jogadores.

La reciente aplicación de las teorías de la complejidad a la actividad física nos obliga a reconsiderar los métodos que a menudo se utilizan en los procesos de enseñanza-aprendizaje en la educación física. En este artículo, se presenta un ejemplo de aplicación concreta al fútbol, considerando que los procesos relacionados con la toma de decisiones que se producen son fruto de la auto-organización del alumnado con el contexto en
el cual se produce la práctica. En lugar de pretender estabilizar comportamientos, mediante la comúnmente denominada automatización, se buscará un método más acorde con el objetivo real del juego, que será justamente la desestabilización de los comportamientos del oponente.
El alumnado necesitará explorar el contexto e interactuar con él para resolver lo que demanda cada situación única. Para ello, se propone una progresión en tres fases con ejemplos de tareas concretas. En la primera, se explorarán las posibilidades de juego, creando situaciones representativas que permitan una gran variedad de comportamientos para conseguir el objetivo. En la segunda, se pretenderá la adaptación de las acciones a la información que se recibe. Por último, en la tercera, se maximizarán todas las posibilidades para conseguir un determinado objetivo.

This report investigated the behavioural dynamics of teams in futsal game practice when the goalkeeper of the attacking team is substituted for an extra outfield player. To this end, the lateral and longitudinal displacements of the ball and both teams, as well as their kinematics expressed in angles and radial distances from the centre of goal, were obtained and subjected to relative phase analysis. The results demonstrated (a) stronger phase relations with the ball for the defending team than the attacking team for both coordinate systems, (b) phase relations between each team and ball, and, to a lesser extent, between teams themselves, produced greater stabilities in the lateral (side-to-side) direction than the longitudinal (forward-backward) direction, and (c) phase attractions were most pronounced for the defending team and ball when using angles as a measure of association, indicating ball position and goal location as key informational constraints for futsal game behaviour. These findings advance understanding of self-organizing sports game dynamics with implications for sports practice.

This study investigated the influence of interpersonal coordination tendencies on performance outcomes of 1-vs-1 sub-phases in youth soccer. Eight male developing soccer players (11.8±0.4 yrs; training experience: 3.6±1.1 yrs) performed an in situ simulation of 1-vs-1 sub-phase of soccer. Data from 82 trials were obtained with motion-analysis techniques, and relative phase used to measure the space-time coordination tendencies of attacker-defender dyads. Approximate entropy (ApEn) was then used to quantify the unpredictability of interpersonal interactions over trials. Results revealed how different modes of interpersonal coordination emerging from attacker-defender dyads influenced the 1-vs-1 performance outcomes. High levels of space-time synchronisation (47%) and unpredictability in interpersonal coordination processes (ApEn: 0.91±0.34) were identified as key features of an attacking player’s success. A lead-lag relation attributed to a defending player (34% in -30º bin) and a more predictable coordination mode (ApEn: 0.65±0.27, p < .001), demonstrated the coordination tendencies underlying the success of defending players in 1-vs-1 sub-phases. These findings revealed how the mutual influence of each player on the behaviour of dyadic systems shaped emergent performance outcomes.