Effects of manipulations of player numbers vs. field dimensions on inter-individual coordination during small-sided games in youth football

The relative space per player formulated in small-sided and conditioned games can be manipulated either by promoting variations in player numbers or by modifying field dimensions. In this study we analysed how the same relative spaces per player, obtained through manipulations of player numbers and field dimensions, influenced inter-individual coordination. The positional data (GPS, 10 Hz) of 24 U-15 yrs performing in three different relative spaces per player (118, 133 and 152m2) was used. Inter-individual behavioural measures included: (i) effective relative space per player, (ii) radius of free movement; (iii) numerical relations inside each player’s relative space per player; and (iv) players’ spatial distribution variability. Magnitude-based inferences were used to analyse the practical significance of the selected variables. Results showed that manipulations of player numbers elicited more free space in the vicinity of each player. However, more advantageous numerical relations adjacent to each individual player and broader individual spatial distributions on field were observed during manipulations of field dimensions. These findings highlight the complex nature of performance behaviours captured by the co-adaptation of players to surrounding spatial constraints. Sport pedagogists should carefully evaluate the use of player numbers and field dimensions as strategies to simulate constraints of specific game contexts

KINANTHROPOMETRIC PROFILE OF PORTUGUESE WATER POLO PLAYERS

Our purpose was to describe physical and training background characteristics of Water Polo players and compare them according to their specialized playing positions. The International Working Group of Kinanthropometry guidelines were followed. A one-way unvaried measure ANOVA with Bonferroni post hoc was used to develop a multiple comparisons procedure between the specialized playing positions (α=0.05). It was concluded that the center players presented tendency for the highest values in 8 of the 10 parameters studied. Center backs are older than the drivers and center forwards have a higher BMI than the wingers and the goalkeepers. The somatotype is balanced mesomorph. Center forwards and Drivers tend to get closer endomorphy when compared with the remaining positions

A multilevel hypernetworks approach to capture properties of team synergies at higher complexity levels.

Previous work has sought to explain team coordination using insights from theories of synergy formation in collective systems. Under this theoretical rationale, players are conceptualised as independent degrees of freedom, whose interactions can become coupled to produce team synergies, guided by shared affordances. Previous conceptualisation from this perspective has identified key properties of synergies, the measurement of which can reveal important aspects of team dynamics. However, some team properties have been measured through implementation of a variety of methods, while others have only been loosely addressed. Here, we show how multilevel hypernetworks comprise an innovative methodological framework that can successfully capture key properties of synergies, clarifying conceptual issues concerning team collective behaviours based on team synergy formation. Therefore, this study investigated whether different synergy properties could be operationally related utilising hypernetworks. Thus, we constructed a multilevel model composed of three levels of analysis. Level N captured changes in tactical configurations of teams during competitive performance. While Team A changed from an initial 1-4-3-3 to a 1-4-4-2 tactical configuration, Team B altered the dynamics of the midfielders. At Level N + 1, the 2 vs. 1 (1 vs. 2) and 1 vs. 1 were the most frequently emerging simplices, both behind and ahead of the ball line for both competing teams. Level N + 2 allowed us to identify the prominent players (a6, a8, a12, a13) and their interactions, within and between simplices, before a goal was scored. These findings showed that different synergy properties can be assessed through hypernetworks, which can provide a coherent theoretical understanding of competitive team performance

Influence of situational variables, team formation and playing position on match running performance and social network analysis of Brazilian professional soccer players

The purpose of this study was to investigate the independent and interactive effects of situational variables, opposition team formation, and playing position on running performance and network analysis in Brazilian professional soccer players (n=22). Global Positioning System technology was used to determine total distance covered, mean speed, maximum running speed, and distance covered in six speed ranges. Social network analysis was used to assess interpersonal coordination (team interactions characterized as successful passes (n=3033) between teammates). Observations of match running performance (n=129), and network analysis (n=108) were obtained. The main results were: (i) no interactive effects between team formation and playing position were observed for running and network variables (unclear to possibly); (ii) matches played at home or against ‘weaker’ opponents presented greater running demands and individual/global metrics of network analysis (likely to almost certain); (iii) match outcome demonstrated influence only for running performance; matches in which the reference team won resulted in higher values than in lost matches; (iv) when the reference team competed in 1˗4˗4˗2 formation, this resulted in greater running demands than 1˗4˗2˗3˗1 formation (likely to almost certain); (v) reduced values of running performance variables were reported in central defenders compared to other positions. Central/external midfielders reported greater closeness/betweenness centrality, out-degree and eigenvector compared to central/external defenders and forwards (likely to almost certain). The results from this study provide practical information to potentially impact on physical, tactical and technical training

Field dimension and skill level constrain team tactical behaviours in small-sided and conditioned games in football

This study analysed the influence of field dimension and players’ skill level on collective tactical behaviours during small-sided and conditioned games (SSCGs). Positioning and displacement data were collected using global positioning systems (15 Hz) during SSCGs (Gk+4 v. 4+Gk) played by two groups of participants (NLP- national-level and RLP-regional-level players) on different field dimensions (small: 36.8 × 23.8 m; intermediate: 47.3 × 30.6 and large: 57.8 × 37.4 m). Team tactical performance was assessed through established dynamic team variables (effective playing space, playing length per width ratio and team separateness) and nonlinear signal processing techniques (sample entropy of distances to nearest opponents and the teams’ centroids’ mutual information). Results showed that the effective playing space and team separateness increased significantly with pitch size regardless of participant skill level (P < 0.001, η2 = 0.78 and P < 0.001, η2 = 0.65, respectively). Playing length per width ratio increased with pitch size for the NLP but was maintained at a relatively constant level by RLP across treatments indicating different playing shapes. There was significantly more irregularity in distances to nearest opponents for the NLP in small (P = 0.003) and intermediate fields (P = 0.01). Findings suggest that tactical behaviours in SSCGs are constrained by field size and skill level, which need to be considered by coaches when designing training practices

Effects of pitch size and skill level on tactical behaviours of Association Football players during small-sided and conditioned games

In Association Football, the study of variability in players' movement trajectories during performance can provide insights on tactical behaviours. This study aimed to analyse the movement variability present in: i) the players' actions zones and ii), distances travelled over time, considered as a player's positional spatial reference. Additionally, we investigated whether the movement variability characteristics of players from different skill levels varied. Two groups of U-17 yrs players of different performance levels (national and regional) performed in three small-sided games with varying pitch dimensions (small, intermediate and large). Linear and non-linear analyses were used to capture the magnitude and structure of their movement variability. Results showed that increases in pitch size resulted in more restricted action zones and higher distance values from personal spatial positional references for both groups. National-level players were more sensitive to pitch modifications and displayed more variability than regional-level players in the small and intermediate pitches. These findings advance understanding about individual tactical behaviours in Association Football and have implications for training design, using pitch size manipulation

Back pain in Portuguese schoolchildren: prevalence and risk factors

2 Centre of Research, Education, Innovation and Intervention In Sport, Faculty of Sport, University of Porto, Portugal Background: Regarding children aged _10 years, only a few international studies were conducted to determine the prevalence of and risk factors for back pain. Although other studies on the older Portuguese children point to prevalence between 17% and 39%, none exists for this specific age-group. Thus, the aim of this study was conducted to establish the prevalence of and risk factors for back pain in schoolchildren aged 7–10 years. Methods: A cross-sectional survey among 637 children was conducted. A self-rating questionnaire was used to verify prevalence and duration of back pain, life habits, school absence, medical treatments or limitation of activities. For posture assessment, photographic records with a bio-photogrammetric analysis were used to obtain data about head, acromion and pelvic alignment, horizontal alignment of the scapulae, vertical alignment of the trunk and vertical body alignment. Results: Postural problems were found in 25.4% of the children, especially in the 8- and 9-year-old groups. Back pain occurs in 12.7% with the highest values among the 7- and 10-year-old children. The probability of back pain increased 7 times when the children presented a history of school absences, 4.3 times when they experienced sleeping difficulties, 4.4 times when school furniture was uncomfortable, 4.7 times if the children perceived an occurrence of parental back pain and 2.5 times when children presented incorrect posture. Conclusions: The combination of school absences, parental pain, sleeping difficulties, inappropriate school furniture and postural deviations at the sagittal and frontal planes seem to prove the multifactorial aetiology of back pain

Team sports performance analysed through the lens of social network theory: implications for research and practice

This paper discusses how social network analyses and graph theory can be implemented in team sports performance analyses to evaluate individual (micro) and collective (macro) performance data, and how to use this information for designing practice tasks. Moreover, we briefly outline possible limitations of social network studies and provide suggestions for future research. Instead of cataloguing discrete events or player actions, it has been argued that researchers need to consider the synergistic interpersonal processes emerging between teammates in competitive performance environments. Theoretical assumptions on team coordination prompted the emergence of innovative, theoretically-driven methods for assessing collective team sport behaviours. Here, we contribute to this theoretical and practical debate by conceptualising sports teams as complex social networks. From this perspective, players are viewed as network nodes, connected through relevant information variables (e.g., a ball passing action), sustaining complex patterns of interaction between teammates (e.g., a ball passing network). Specialized tools and metrics related to graph theory could be applied to evaluate structural and topological properties of interpersonal interactions of teammates, complementing more traditional analysis methods. This innovative methodology moves beyond use of common notation analysis methods, providing a richer understanding of the complexity of interpersonal interactions sustaining collective team sports performance. The proposed approach provides practical applications for coaches, performance analysts, practitioners and researchers by establishing social network analyses as a useful approach for capturing the emergent properties of interactions between players in sports teams