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 goalkeeper's save, and a defender's interception, at four specific moments during performance: (1) assisting attacker's ball reception and (2) moment of passing, (3) shooter's ball reception, and (4), shot on goal. Statistical analysis showed that when a goal was scored, the defender's 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.     

Teamwork in sport: a theoretical and integrative review

A commonly held belief in sports is the need for team members to be able to work well together in order for that team to be successful. Despite this assumption, research in the field of sport psychology has yet to formally or sufficiently conceptualize what is meant by teamwork. In this theoretical and integrative review, we draw from the extant organizational psychology and team development literature to present a multidimensional conceptual framework of teamwork in sport. We provide a working definition of teamwork in sport and discuss how teamwork sits within a broader model of team effectiveness. We conclude by providing an overview of salient research avenues on teamwork and team effectiveness in sport, which have potential implications for guiding interventions with sports teams.     

Dynamics of the basketball shot with application to the free throw

Abstract

A completely general three-dimensional dynamic model is presented for the motion of basketball shots that may contact the rim, the backboard, the bridge between the rim and board, and possibly the board and the bridge simultaneously. Non-linear ordinary differential equations with six degrees of freedom describe the ball angular velocity and ball centre position. The model includes radial ball compliance and damping and contains five sub-models: purely gravitational flight, and ball – rim, ball – bridge, ball – board, and ball – bridge – board contact. Each contact sub-model has both slipping and non-slipping motions. Switching between the sub-models depends on the reaction force at, and velocity of, the contact point. Although the model can be used to study shots from any point on the court, we here use it to study the sets of free throw release angle, velocity, angular velocity, and lateral deviation angle that result in success (capture), as well as underhand free throws and those using an under-inflated ball. Free throw shots with larger backspin, lower inflation pressures, and underhand release conditions are shown to result in larger capture percentages.     

基于SD的船舶敏捷制造项目进度管理模型研究

针对传统项目管理方法的不足,提出利用系统动力学方法来研究船舶敏捷制造项目的进度管理问题.通过传统项目管理方法与系统动力学方法的比较,证明利用系统动力学研究船舶敏捷制造项目进度管理的可行性和必要性,然后确定建模边界,构建因果关系图,对其中的反馈关系进行详细分析,得到四种反馈回路,进而对系统做进一步分析,建立船舶敏捷制造项目进度管理系统的系统动力学模型,最后通过实例仿真对模型进行有效性验证.     

基于组织身份领地维护与拓展的企业竞争行为研究

在组织身份与身份领地概念的界定基础上,分析组织身份领地对企业竞争行为的影响,最后结合组织身份领地维护与拓展的权衡视角,通过对诺基亚和柯达两大公司对于组织身份领地维护与拓展成败的案例分析,深入探析创新环境下企业竞争行为的选择.     

创新资源视角的创新型城市内在成长动力研究

选取上海市1995～2010年的时间序列数据,综合运用因子分析、单位根检验、协整检验、Granger因果关系检验、脉冲响应函数进行深入研究。研究发现,创新型城市成长的内在驱动因素主要靠创新财力资源,其次是创新知识资源,最后是创新人力资源;创新型城市成长有利于创新资源的积聚。提出了保持创新型城市持久成长动力的政策建议。     

Information-governing dynamics of attacker–defender interactions in youth rugby union

Abstract

Previous work on dynamics of interpersonal interactions in 1 vs. 1 sub-phases of basketball has identified changes in interpersonal distance between an attacker and defender as a potential control parameter for influencing organizational states of attacker–defender dyads. Other studies have reported the constraining effect of relative velocity between an attacker and defender in 1 vs. 1 dyads. To evaluate the relationship between these candidate control parameters, we compared the impact of both interpersonal distance and relative velocity on the pattern-forming dynamics of attacker–defender dyads in the sport of rugby union. Results revealed that when interpersonal distance achieved a critical value of less than 4 m, and relative velocity values increased or were maintained above 1 m · s^?1, a successful outcome (i.e. clean attempt) for an attacker was predicted. Alternatively, when values of relative velocity suddenly decreased below this threshold, at the same critical value of interpersonal distance, a successful outcome for the defender was predicted. Data demonstrated how the coupling of these two potential, nested control parameters moved the dyadic system to phase transitions, characterized as a try or a tackle. Observations suggested that relative velocity increased its influence on the organization of attacker–defender dyads in rugby union over time as spatial proximity to the try line increased.     

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.     

Analysis of lower limb internal kinetics and electromyography in elite race walking

Abstract

The aim of this study was to analyse lower limb joint moments, powers and electromyography patterns in elite race walking. Twenty international male and female race walkers performed at their competitive pace in a laboratory setting. The collection of ground reaction forces (1000 Hz) was synchronised with two-dimensional high-speed videography (100 Hz) and electromyography of seven lower limb muscles (1000 Hz). As well as measuring key performance variables such as speed and stride length, normalised joint moments and powers were calculated. The rule in race walking which requires the knee to be extended from initial contact to midstance effectively made the knee redundant during stance with regard to energy generation. Instead, the leg functioned as a rigid lever which affected the role of the hip and ankle joints. The main contributors to energy generation were the hip extensors during late swing and early stance, and the ankle plantarflexors during late stance. The restricted functioning of the knee during stance meant that the importance of the swing leg in contributing to forward momentum was increased. The knee flexors underwent a phase of great energy absorption during the swing phase and this could increase the risk of injury to the hamstring muscles.