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Abstract Aim: This study investigated the adaptations of football teams as hierarchically organised open systems. In this type of system, the collective and individual behaviours are characterised by consistency and variability, respectively. Methods: Five professional men's football matches in the under-20 category were analysed. The team's centroid as a measure of the system's macrostructure and the distance from each player to the team's centroid (a measure of the system's microstructure) were obtained from the players' x and y coordinates of displacement on the soccer field. Cluster analyses were run using Ward's minimum variance method with Euclidean distance. Results: (i) teams showed consistency and variability in their macro- and microstructures, respectively; (ii) there was a correlation between attack and defence patterns in most game sequences; (iii) goals were scored when teams modified their macro and/or microstructure. Conclusion: Football teams showed correspondence in attack-defense patterns with macro-consistency and micro-variability throughout the match. Despite this, there was no relationship between the foregoing patterns and game outcomes. Goals were scored after changes in the team's structure.

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ABSTRACT This study examined the information constraining volleyball blockers' decision-making as they attempted to anticipate an opponent's shot. The role of the ball flight information emerging from the interaction between the digger and the setter was investigated. In the first experiment a kinematic analysis of the ball trajectory was run in order to determine its influence on setter's action. In the second experiment players were asked to predict the block location by watching a video involving (i) the complete ball flight or (ii) only the final ball flight. It was verified that the setting occurred more frequently to the outside hitter when setter was far from the net (experiment 1). In addition, it was found that the ball flight information and the setter position guided the blockers anticipation (experiment 2). These findings suggest that the passing information can provide support for blocking anticipation in specific situations in which the ball flight was characterised by high altitudes.

RESUMO O presente estudo examinou a informação que constrange a tomada de decisão dos bloqueadores no jogo de voleibol, referente à antecipação da jogada adversária. Foi investigado o papel da informação do voo da bola, que emerge da interação entre o passador e o levantador. No primeiro experimento foi feita análise cinemática da trajetória da bola para determinar sua influência na ação do levantador. No segundo experimento jogadores tinham que prever o local em que ocorreria o bloqueio, após assistir a dois tipos de vídeo que continham: (i) o voo completo da bola ou (ii) apenas o voo final da bola. Verificou-se que o levantamento ocorreu mais frequentemente para o jogador da posição 2, quando o levantador estava mais distante da rede (experimento 1). Adicionalmente, verificou-se que a informação de voo da bola e a posição do levantador guiaram a antecipação dos bloqueadores em algumas situações (experimento 2). Os achados sugerem que a informação do passe pode fornecer suporte para a antecipação de bloqueadores em situações específicas, nas quais o voo da bola seja caracterizado por grandes alturas.

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RESUMO

This study investigated how changes in the focus of instruction might affect the learning by individuals who are not trained dancers of a complex classical ballet movement, the pirouette. Seventy-two volunteer college students were divided into six groups according to the focus of instruction: (1.) head, (2.) arms, (3.) trunk, (4.) knees, (5.) feet, and (6.) controls. In the acquisition phase, all groups performed 160 trials, over 2 consecutive days. At the beginning of each day, they received verbal instruction regarding some of the general principles involved in performance of the pirouette and viewed a video that illustrated those principles. Each group (head, arms, etc., exclusive of controls) was then given specific directions for controlling focus on its body part while performing the movement. After a week, all participants were asked to complete a retention test, with no additional instruction. The trials were videotaped with two cameras (frontally and laterally), and the results were analyzed by 10 specially trained examiners, utilizing Movement Pattern and Error of Performance measures. They revealed that all groups improved in the acquisition phase, and the improvement was maintained in the retention test. No differences were revealed between groups. It was concluded that generalized instruction in basic principles of the movement was more effective than focus on specific body parts in the teaching and learning of the pirouette.

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