Contrasting Learning Psychology Theories Applied to the Teaching-Learning-Training Process of Tactics in Soccer.

Research in sport pedagogy and its applied recommendations are still characterized by a contrast between the different learning theories from psychology. Traditional theories and their corresponding approaches to the specific case of teaching and learning "how to play [team sports like soccer]" are subject to compatibilities and incompatibilities. We discuss how behaviorism as an approach to teaching the game shows more incompatibilities with the nature of tactical actions when compared to constructivism. As coaches strive to teach the game and make their players and team perform, we argue that teaching the game requires teaching approaches that will help develop their way to play (i.e., tactical behavior) without taking away their autonomy and adaptiveness. The teaching-learning-training process for playing the game should then be conducted to harmonize the characteristics of the contents, the context, and the individual(s) at hand. We provide two illustrated examples and portray how the recommended approaches fit key contents of the game that are observed in the tactical behavior. We finally argue that the coherent design of games provides minimal conditions to teaching approaches, and that such a design should be a priority when elaborating the learning activities along the player development process. As a conclusion, the interactionist theory is the one that best serves the teaching of the game and the development of tactical behavior. We therefore defend that its principles can help coaches tailor their own strategy to teach the game with the many tools.

Body Physique, Body Composition, Physical Performance, Technical and Tactical Skills, Psychological Development, and Club Characteristics of Young Male Portuguese Soccer Players: The INEX Study.

Youth soccer performance is multifaceted, includes physical growth, biological maturation, and physical fitness, and is linked to the sporting environment to which the players are exposed. We aim to describe age-related associations in body physique, body composition, physical performance technical and tactical skills, psychological and club characteristics of male soccer players aged 12 to 14 years. A total of 157 male soccer players clustered into three age-cohorts (12, 13 and 14 years) were recruited from six soccer clubs. Anthropometric, body composition and body physique, biological maturation, physical performance, skill/game proficiency data, psychological characteristics, and clubs' characteristics were collected. Group means were compared using analysis of variance and covariance. Fourteen years old players were significantly taller, heavier, leaner, faster, stronger, and technically more skilled than their younger peers (p < 0.05). Differences in physical performance and technical skills (p < 0.05) were found between age groups when adjusting for confounders of soccer training and biological maturation. No significant differences (p > 0.05) between age groups were found in psychological domains. Our findings suggest that age, biological maturation, and training volume are key factors influencing young soccer players' performance and development. Further, clubs' conditions provide players with ample resources for their success in training and competition.

Multivariate Exploratory Comparative Analysis of LaLiga Teams: Principal Component Analysis.

The use of principal component analysis (PCA) provides information about the main characteristics of teams, based on a set of indicators, instead of displaying individualized information for each of these indicators. In this work we have considered reducing an extensive data matrix to improve interpretation, using PCA. Subsequently, with new components and with multiple linear regression, we have carried out a comparative analysis between the best and bottom teams of LaLiga. The sample consisted of the matches corresponding to the 2015/16, 2016/17 and 2017/18 seasons. The results showed that the best teams were characterized and differentiated from bottom teams in the realization of a greater number of successful passes and in the execution of a greater number of dynamic offensive transitions. The bottom teams were characterized by executing more defensive than offensive actions, showing fewer number of goals and a greater ball possession time in the final third of the field. Goals, ball possession time in the final third of the field, number of effective shots and crosses are the main discriminating performance factors of football. This information allows us to increase knowledge about the key performance indicators (KPI) in football.

Motor Performance in Male Youth Soccer Players: A Systematic Review of Longitudinal Studies.

The aim of this systematic review was to identify and synthesize the available information regarding longitudinal data addressing young soccer players' motor performance changes. Following the Preferred Reporting Items for Systematic and Meta-analyses (PRISMA) statement, literature searches were performed in three databases: PubMed, ISI Web of Science and SCOPUS. The following descriptors were used: football, soccer, youth, young, player, athlete, physical performance, motor performance, longitudinal. The inclusion criteria were original articles in English with longitudinal data of young males (aged 10-18 years), with the aim to investigate motor performance serial changes. The initial search returned 211 records, and the final sample comprised 32 papers. These papers covered the European continent, and used mixed and pure longitudinal design with variation in sample size and age range. The reviewed studies tended to use different tests to assess the motor performance and aimed to identify changes in motor performance in several ways. In general, they indicated motor performance improvements with age, with a marked influence of biological maturity, body composition, and training stimuli. This review highlights the need for coaches and stakeholders to consider players' motor performance over time whilst considering biological maturation, biological characteristics, and training stimuli.

Talent Development in Sport Requires Athlete Enrichment: Contemporary Insights from a Nonlinear Pedagogy and the Athletic Skills Model.

Traditional talent identification and development programs have sought to identify and select the most promising children as athletes of the future, to provide them with specialised training and preparation for expert performance in sport from an early age. Traditional models of talent identification and development tend to be linear, emphasising the numbers of hours spent in specialised training. However, major concerns have been raised by evidence emerging on psycho-emotional and physical issues with early specialisation programmes, and negative associations with wellbeing and mental health. More contemporary models of talent development emphasise a deep integration of specialised training with more general enrichment of athleticism. This integrative process enhances self-regulation processes of perception and action, as well as emotional control and social interactions, all of which underpin sports performance at elite and sub-elite levels. Here, we discuss insights and principles of contemporary models of pedagogy, such as Nonlinear Pedagogy (NLP) and the Athletic Skills Model (ASM), which offer valuable frameworks for talent development. We conclude by considering implications of adopting such principles for developing athlete functionality in specific performance environments.

Tactical Behaviour of Youth Soccer Players: Differences Depending on Task Constraint Modification, Age and Skill Level.

This study aimed to investigate: i) how Small-Sided and Conditioned Games based on different representation and exaggeration modification strategies, from the Teaching Games for Understanding pedagogical principles, affected team performance and exploratory behaviour; and ii) how teams and players of different ages and skill levels were affected by the use of these different modification strategies. In total, forty-eight youth male soccer players participated in the study (U15, n = 24 mean age = 13.06 ± 1.53 years; U17, n = 24 mean age = 16.89 ± 0.11 years). In both categories, players were organized into three groups according to their tactical efficiency level (Group 01 = High Skilled Players (HSP), Group 02 = Intermediate Skilled Players (ISP), and Group 03 = Low Skilled Players (LSP)). The HSP and LSP groups performed two types of Gk+4vs4+Gk Small-Sided and Conditioned Games (SSCGs) based on different representation and exaggeration modification strategies. The first type of SSCGs was modified by structural constraints (Structural SSCG) and the second type was modified by rule manipulation (Manipulation SSCG). Team performance and exploratory behaviour were analysed through the Offensive Sequences Characterization System and Lag Sequential Analysis, respectively. SSCG modification strategies affected differently tactical performance and exploratory behaviour of teams composed of players of different skill levels. It was found that SSCG modification strategy through rule manipulation provided players and teams with a higher level of difficulty, compromising their performance and inhibiting exploratory behaviour. This information is crucial to practitioners wishing to apply more appropriate pedagogical strategies to improve a specific tactical problem using a player-centred and game-based approach.

How do Elite Soccer Teams Perform to Ball Recovery? Effects of Tactical Modelling and Contextual Variables on the Defensive Patterns of Play.

Researchers in soccer match analysis have been using limited procedures to express the dynamics of the game and mainly focus on the attack. Therefore, the aims of this paper were to detect the successful teams' ball recovery defensive patterns of play and study the influence of tactical modelling, halves, match status, opponent quality and stage competition on those patterns. The sample consisted of 1323 situations of defensive ball possession of the semi-finalist teams from the 2014 FIFA World Cup play-offs, which was collected by a valid and reliable observational instrument (Soccer-Defence). The Kruskal-Wallis H, Mann-Whitney U, Chi-square, Z-, multinomial logistic regression tests and sequential analysis (p < .05; z > 1.96) were used accordingly to test the differences and associations among and within teams of tactical modelling, tactical-technical behaviours and contextual variables to ball recovery. We found that among teams ball recovery differed in duration; H(3) = 14.958, p = .002. Germany were more likely to perform ball recovery by the goalkeeper than Argentina (p = .04; OR = 0.47) or the Netherlands (p < .05; OR = 0.50). Nevertheless, Brazil was the least likely to concede a shot off goal. Teams facing lower-ranked opponents were 0.63 times less likely to perform ball recovery by interception (p <.001). Additionally, sequential analysis illustrated that teams varied between central and lateral high-pressure zones before ball recovery in lower zones of the field. Finally, coaches could use such findings to design training exercises, create their own style of play, and set strategies.

The Arrowhead Agility Test: Reliability, Minimum Detectable Change, and Practical Applications in Soccer Players.

Rago, V, Brito, J, Figueiredo, P, Ermidis, G, Barreira, D, and Rebelo, A. The arrowhead agility test: Reliability, minimum detectable change, and practical applications in soccer players. J Strength Cond Res 34(2): 483-494, 2020-Four independent studies were conducted to examine the utility of the arrowhead agility test (AAT) to measure change of direction (COD) capacity in soccer players, specifically, (a) intersession reliability and minimum detectable change (n = 24); (b) power-dependent abilities associated with AAT performance (n = 56); and (c) fatigue sensitivity (n = 20); differences between competitive levels and age groups (n = 264). Irrespective of the AAT outcome measure (skillful side, less-skillful side, sum of both), intersession reliability and the ability to detect changes in performance were good (ICC = 0.80-0.83; CV = 1.25-2.21%; smallest worthwhile change, 0.06-0.12 >SEM, 0.01-0.03) except for the asymmetry index. A 15-m sprint explained a significant amount of variance in COD (p < 0.01; R = 0.42). Arrowhead agility test performance did not change from the prematch toward half time (p = 0.21). However, reduced COD performance was observed after an intense period in the second half and after the game, compared with prematch and half-time performance (p < 0.05; effect size [ES] = -0.85 to 0.42). Irrespective of age group, national players were more agile than regional players (p < 0.05; ES = -1.97 to -0.36). Moreover, independently of their competitive level, senior and U18 players had a better performance than U16 (p < 0.05; ES = -2.33 to -0.84), whereas no significant differences were observed between senior and U18. Percentiles were also reported in the results. The AAT is reliable to measure COD in soccer players. The test may simultaneously encompass 15-m sprint testing but should be implemented independently to countermovement jump. Furthermore, the test is sensitive to match-induced fatigue during the second half and discriminates players from different competitive levels.

Methods to collect and interpret external training load using microtechnology incorporating GPS in professional football: a systematic review.

The aim of this article was to systematically review the methods adopted to collect and interpret external training load (ETL) using microtechnology incorporating global positioning system (GPS). The main deficiencies identified concerned the non-collection of match ETL, and the non-consideration of potential confounders (e.g. playing position, fitness level, starting status or session content). Also, complementary training (individual/reconditioning) and pre-match warm-up were rarely quantified. To provide a full picture of the training demands, ETL was commonly complemented by internal training load monitoring with the rating of perceived exertion predominantly adopted instead of heart rate recordings. Continuous data collection and interpretation of ETL data in professional football vary widely between observational studies, possibly reflecting the actual procedures adopted in practical settings. Evidence about continuous ETL monitoring in female players, and female as well as male goalkeepers is lacking.

A multilevel hypernetworks approach to capture meso-level synchronisation processes in football.

Understanding team behaviours in sports performance requires understanding the interdependencies established between their levels of complexity (micro-meso-macro). Previously, most studies examined interactions emerging at micro- and macro-levels, thus neglecting those emerging at a meso-level (reveals connections between player and team levels, depicted by the emergence of coordination in specific sub-groups of players-simplices during performance). We addressed this issue using the multilevel hypernetworks approach, adopting a cluster-phase method, to record player-simplice synchronies in two performance conditions where the number, size and location of goals were manipulated (first-condition: 6 × 6 + 4 mini-goals; second-condition: Gk + 6 × 6 + Gk). We investigated meso-level coordination tendencies, as a function of ball-possession (attacking/defending), field-direction (longitudinal/lateral) and teams (Team A/Team B). Generally, large synergistic relations and more stable patterns were observed in the longitudinal direction of the field than the lateral direction for both teams, and for both game phases in the first condition. The second condition displayed higher synchronies and more stable patterns in the lateral direction than the longitudinal plane for both teams, and for both game phases. Results suggest: (i) usefulness of hypernetworks in assessing synchronisation of teams at a meso-level; (ii) coaches may consider manipulating these task constraints to develop levels of local synchronies within teams.

Changing Rules and Configurations During Soccer Small-Sided and Conditioned Games. How Does It Impact Teams' Tactical Behavior?

The present study aimed to investigate how team's tactical behavior varies within and between age categories in different Small-Sided and Conditioned Games' configurations and conditions. Twenty non-elite youth male soccer players (U15, n = 10, mean age = 13.5 ± 1.2 years; U17, n = 10, mean age = 16.3 ± 0.5 years) were selected. Thirty-six Small-Sided and Conditioned Games (SSCG) were played in both categories, namely three Representative SSCG (R-SSCG), three Maintaining Ball Possession Games (MBPG) and three Progression to Target Games (PTG) performed for each configuration (Gk+3vs3+Gk and Gk+4vs4+Gk). Teams' tactical behavior was analyzed based on simple and composite performance indicators, as well as through Lag Sequential Analysis. Rules manipulation and SSCG configurations influenced teams' tactical behavior on both categories, but in different ways. Teams composed by younger players presented greater difficulties in MBPG played in smaller games configuration, while Gk+4vs4+Gk configuration can be used to enhance teams' tactical performance of younger players in R-SSCG and MBPG conditions. Moreover, increasing rules manipulations appeared to negatively impact on teams' exploratory behavior. Therefore, practitioners should carefully manipulate key constraints to adapt task demands to players' age category and training session's goals in order to enhance tactical performance.

How Does the Adjustment of Training Task Difficulty Level Influence Tactical Behavior in Soccer?

Purpose: This study aimed to investigate if player tactical skill level and age category influence team performance and player exploratory behavior in tasks with different difficulty levels. Method: In total, 48 youth male soccer players participated in the study (U15, n = 24, mean age = 13.06 ± 1.53 years; U17, n = 24, mean age = 16.89 ± 0.11 years). Player tactical skills were evaluated through the System of Tactical Assessment in Soccer (FUT-SAT), allowing them to be organized into three groups according to tactical efficiency: Higher tactical skill level (Group 01), Intermediate tactical skill level (Group 02), and Lower tactical skill level (Group 03). Next, Group 01 and Group 03 of both categories performed six Small-Sided and Conditioned Games (SSCG) each, namely three High difficulty SSCGs and three Low difficulty SSCGs. Team performance and players' exploratory behavior were analyzed through the Offensive Sequences Characterization System and Lag Sequential Analysis, respectively. Results: We found that team performance and players' exploratory behavior were influenced both by the age and tactical skill level of the players, as well as by task difficulty level. Conclusion: Therefore, in an attempt to improve player performance, practitioners must carefully manipulate key task constraints to adapt training task difficulty levels to player age and tactical skill level.

Variability of activity profile during medium-sided games in professional soccer.

BACKGROUND: In Southern European countries it is very frequent to perform medium-sized games (MSG) as last training drill. We analyzed the individual variability and changes in activity patterns during MSG throughout the preseason. METHODS: Activity profile during MSGs (10v10+goalkeepers, duration: 10-min, field length: 50 m, width: 90 m, area per player: 204.5 m2) was quantified using a GPS in 14 professional male players (6 defenders, 5 midfielders 5 and attackers). RESULTS: Inter-individual variability was higher for high-intensity (HIR), very-high speed (VHS), maximum acceleration (Accmax) and maximum deceleration (Decmax) distance (CV=25.2 to 43.3%), compared to total distance (TD), total acceleration (Acctot) and total deceleration (Dectot) distance (CV= 8.3 to 18.3%). Defenders showed higher variability in TD, HIR, VHS, Acctot and Dectot (ES= 1.30 to 11.28) compared to the other field positions, whereas attackers showed higher variability in HIR, VHS Accmax and Decmax (ES=-4.92 to 2.07) than other the field positions. Variability in TD regularly increased (ES= -2.13 to -0.91) towards the end of the preseason, while HIR and VHS variability tended to increase over the 3rd and the 4th preseason week (ES=-0.94 to -3.05). However, the behavior of variability across the preseason period was more unpredictable for Acctot and Dectot, both decreasing in the 3rd week (ES= 0.70 to 1.20), while Decmax increased in the 4th week (ES=-0.91±0.59). CONCLUSIONS: During MSGs, individual variability of activity differs among field positions, and tends to increase with either speed or acceleration intensity, underlining the need of an individualized approach for training load monitoring.

Switching between pitch surfaces: practical applications and future perspectives for soccer training.

INTRODUCTION: Soccer training and completion is conventionally practiced on natural grass (NG) or artificial turf (AT). Recently, AT pitches for training/competition, and of unstable surfaces for injury prevention training has increased. Therefore, soccer players are frequently exposed to variations in pitch surface during either training or competition. These ground changes may impact physical and physiological responses, adaptations as well as the injury. The aim of this review was to summarize the acute physical and physiological responses, chronic adaptations, and injury risk associated with exercising on different pitch surfaces in soccer. EVIDENCE ACQUISITION: Eligible studies were published in English, had pitch surface as an independent variable, and had physical, physiological or epidemiological information as outcome variables. Specific data extracted from the articles included the training response, training adaptations or injury outcomes according to different pitch surfaces. A total of 224 studies were retrieved from a literature search. EVIDENCE SYNTHESIS: Twenty articles met the inclusion criteria: 9 for acute physical and physiological responses, 2 for training adaptations and 9 for injury assessment. The literature lacks consistent evidence regarding the effects of pitch surface on performance and health outcomes in soccer players. However, it seems that occasionally switching training surfaces seems a valuable strategy for focusing on specific musculoskeletal queries and enhancing players' fitness. For instance, sand training may be occasionally proposed as complementary training strategy, given the recruitment of additional musculature probably not involved on firmer surfaces, but the possible training-induced adaptations of non-conventional soccer surfaces (e.g., sand) might potentially result into a negative transfer on AT or NG. CONCLUSIONS: Since the specific physical demands of soccer can differ between surfaces, coaches should resort to the use of non-traditional surfaces with parsimony, emphasizing the specific surface-related motor tasks, normally observed on natural grass or artificial turf. Further studies are required to better understand the physiological effects induced by systematic surface-specific training, or switching between pitch surfaces.

Is Football players' performance influenced by the quality of opposition? Application of the golden index formula in Club Atlético de Madrid 2016/2017

Aim: In this study, we sought to analyze the influence of the quality of opposition on players' performance of Club Atlético de Madrid (ATM) 2016/2017. For that, the Golden Index (GI) formula was applied to identify and rank the Golden Players of ATM when playing against opponents of different quality levels. Methods: GI formula variables were collected through notational analysis and three global adjacency matrices were constructed to record all successful ball-passing actions performed. Next, the matrices were imported to SocNetV to collect the network centrality metrics. To uniformize each variable, the statistical standardization technique was applied to all variables. ATM opponents were classified into three groups: high-level (n=4), medium-level (n=2) and low-level (n=2), according to their classification in La Liga and participation in the final stage of UEFA Champions League 2016/2017. Results: Koke was considered the Golden Player playing against high-level teams, while opposing low-level opponents he was ranked as second. Against medium- and low-level teams, Antoine Griezmann was considered the Golden Player, but was not classified in the three first positions against high-level opponents. Yannick Carrasco and Filipe Luís were ranked in the second and third positions, respectively, when playing against high- and medium-level opponents. Also, Saúl Ñíguez obtained the third higher index against low-level teams. Conclusions: This study evidenced that players' individual performance is influenced by the quality of the opposition. Additionally, the GI formula proved to be a potent tool in analyzing player's performance in attacking plays in Football.(AU)

Análise dos principais fatores epidemiológicos relacionados ao suicídio em uma cidade no interior do Ceará, Brasil / Analysis of the main epidemiological factors related to suicide in a town of Ceará country-side, Brazil

Introdução: o município de Iguatu, localizado no interior do estado do Ceará no Nordeste brasileiro, é popularmente conhecido pelo alto número de pessoas que cometem suicídio. No entanto, até o presente momento, não existe um estudo que confirme essa crença popular e analise o perfil dos suicidas. Objetivo: este trabalho avaliou a incidência e o perfil dos suicidas, no município do Iguatu, para obtenção de dados que tornem possíveis ações de prevenção. Metodologia: trata-se de um estudo retrospectivo e transversal de natureza descritiva sobre óbitos por suicídio coletados sob autorização da coordenação de vigilância epidemiológica com dados fornecidos pela Secretaria de Saúde no Município do Iguatu entre os anos de 2006 a 2015. As variáveis analisadas foram sexo, idade, estado civil, raça, escolaridade, ocupação e causas de óbito por suicídio. Foi realizada análise dos dados e esses apresentados em tabelas e gráficos. Resultados: o número de causas externas de mortalidade foi de setecentos e vinte, sendo setenta e dois casos de morte por suicídio. As pessoas que cometeram suicídio eram principalmente homens (78%), de coloração parda (73,5%) e faixa etária predominante entre 20 a 29 anos de idade (27,8%) e estado civil solteiro (43%) ou casado (41,7%). Nenhum apresentava nível superior completo, e a maioria tinha como ocupação a produção agrícola (36,1%). As principais causas de morte foram por enforcamento (59,7%) e uso de pesticidas (23,6%). Conclusão: o perfil dos suicidas é composto por homens de cor parda, sem nível superior completo, produtores agrícolas, adultos jovens e solteiros. O Iguatu apresenta uma alta incidência de suicídio, e as pessoas se matam mais por enforcamento e autointoxicação por pesticidas.(AU)

Introduction: The city of Iguatu, located in the state of Ceará in the Brazilian Northeast, is popularly known for its high numbers of people committing suicide. However, to the present moment, there is no work that confirms this popular belief and analyzes the profile of suicides. Objective: Evaluate the incidence and the profile of suicidal in the city of Iguatu, aiming to discuss preventive actions. Methods: Retrospective, cross-sectional and descriptive study of deaths by suicide collected with the authorization of the coordination of epidemiological surveillance as public data in Iguatu, between 2006 and 2015. The analyzed variables were: gender, age, marital status, race, schooling, occupation and causes of death by suicide. Descriptive analysis of the data was performed in tables and graphs from Excell 2011. Results: The number of external mortality causes was seven hundred and twenty, with seventy-two cases of death by suicide. The people who committed suicide were mainly men (78%), brown coloration (73.5%) and the predominant age group between 20 and 29 years old (27.8%). The predominant marital status was single (43%), but followed closely by people who were married (41.7%). None had a complete upper level, and the majority had agricultural production as the occupation (36.1%). The main causes of death were intentional self-harm by hanging, strangulation and suffocation (59.7%) and pesticide autointoxication. Conclusion: The profile of people who committed suicide is predominantly composed of brown colored males, under graduated people, agricultural producers, young adults and single. The city of Iguatu town shows a high incidence of suicide and the most used kinds of killing are by hanging and pesticide autointoxication.(AU)

Influence of opponent standard on activity profile and fatigue development during preseasonal friendly soccer matches: a team study.

We examined the influence of competitive standard of the opponent on activity profile and fatigue during preseason friendly soccer matches. Time motion analysis was performed in a male professional soccer team (N = 14) during six friendly games played against professional, semi-professional and amateur-level opponents (PL, SPL and AL). The reference team covered higher acceleration distance, acceleration and deceleration > 2 m· s-2 distance against PL than AL (ES = 0.77 to 0.91). Acceleration and deceleration distance > 2 m· s-2 was also higher (ES = 0.66 to 0.84) against SPL than AL. Greater decreases in total distance, distance> 16 km· h-1 and > 22 km· h-1, total acceleration and deceleration, acceleration and deceleration distance > 2 m· s-2 (ES = 0.84 to 2.20) were also observed during PL compared to AL opponent. Playing against a stronger opponent seems to be more physically demanding, with special emphasis on events related with change of velocity (accelerations and decelerations). Declines in physical performance appear more evident against a higher opponent.

Small-sided soccer games on sand are more physically demanding but less technically specific compared to games on artificial turf.

BACKGROUND: The use of sand has been suggested as fitness-enhancing surface in field-based team sports. However, concerns have arisen in regard whether physical responses associated to sand training are sport-specific. We compared physical and technical demands during small-sided soccer games (4 vs. 4 + goalkeeper; SSGs) played on artificial turf and on sand. METHODS: Movement patterns, rating of perceived exertion (RPE) and technical parameters were obtained from eight adult male soccerers (20.1±1.0 years, 176±4 cm and 70.1±2.0 kg) using Global Positioning Systems, Visual Analogue Scale questionnaires, and notational analysis. RESULTS: High-intensity actions (high intensity running, high intensity activities), low changes of speed, as well as peak and average speed were higher on artificial turf (P<0.05; effect sizes (ES) 0.41 to 0.82). In contrast, time spent by jogging as well as high and maximum changes of speed was higher on sand (P<0.05; ES: 0.59 to 0.82). Moreover, players perceived more demanding to play on sand (P<0.05; ES=0.72). Rating of successful actions was higher during turf SSGs than sand SSGs (P<0.05; ES: 0.44 to 0.73), whereas actions requiring lifting the ball were higher on sand (P<0.05; ES: 0.47 to 0.50). CONCLUSIONS: The use of sand can be considered as complemental to on-turf soccer training, when the training goal is to tax lower limb muscle strength or to require high-ball situations. Nonetheless, sand training is not appropriate when the achievement of maximal speed is desired. Further research should clarify the suitability of sand training within soccer conditioning programs.

Influence of pitch length on inter- and intra-team behaviors in youth soccer / Influencia de la longitud del campo en los comportamientos inter e intra -equipo en jóvenes jugadores de fútbol

Tactical behavior could be affected by changes in small-sided game (SSG) formats. The aim of the present study was to analyze the influence of different pitch lengths during 7-a-side SSGs played by young football players. Fourteen male soccer players in each age group (13 and 14 years old, U13 and U14 teams) were divided in two teams of seven players who played four SSGs of 7 minutes, interspersed with 4 minutes of passive recovery. The only modification to the SSG format was pitch length: 60 m (SSG60), 50 m (SSG50), 40 m (SSG40), and 30 m (SSG30), while the width of the field was kept constant at 40 m. The variables used to characterize collective behavior were grouped in a) intra-team variables, namely, team length (L), team width (W), effective area of team play or convex hull (CH), and stretch index (SI); and b) inter-team variables, namely distance between centroids (DC), length of both teams (L2), width of both teams (W2), convex hull of both teams (CH2), and stretch index of both teams (SI2). Our results revealed different intra and inter-team behaviors according to SSG format and player age. L, CH, SI, DC, L2, CH2, and SI2 all increased with increasing pitch length, while W and W2 showed only minimal changes. The differences were greater in the U13 group, suggesting that younger players were more likely to vary their collective behavior in response to changes to pitch length, inter-task, particularly in the longer pitches (SSG50 and SSG60). Conversely, using the analysis of the entropy, greater unpredictability of tactical behavior was observed in the U14 group, intra-task, compared with the U13 group. Overall, the findings suggest that responses to task constraints, such as modifications to pitch length and accordingly relative area of play, are dependent on age (experience, skill) and this is something coaches should consider when designing SSGs to develop team tactics (AU)

El comportamiento táctico puede verse afectado por los cambios en los formatos de juegos reducidos (SSG). El objetivo del presente estudio fue analizar la influencia de diferentes longitudes del terreno de juego en formatos SSG-de-7 jugadores en jóvenes futbolistas. 14 jugadores masculinos de fútbol en cada grupo de edad (13 y 14 años, U13 y U14, respectivamente) se dividieron en dos equipos de siete jugadores, quienes jugaron en cuatro SSGs de 7 minutos de duración, intercalados con 4 minutos de recuperación pasiva. La única modificación en el formato SSG fue longitud del terreno: 60 m (SSG60), 50 m (SSG50), 40 m (SSG40) y 30 m (SSG30), mientras que la anchura del campo de 40 m se mantuvo constante. Las variables utilizadas para caracterizar el comportamiento colectivo se agruparon en: a) variables intra-equipo, es decir, la longitud del equipo (L), ancho del equipo (W), el área efectiva de juego del equipo o convex hull (CH), y el strech index (SI); y b) las variables inter-equipo, es decir, la distancia entre los centroides (DC), la longitud de los dos equipos (L2), la anchura de los dos equipos (W2), envolvente convexa de los dos equipos (CH2), y el índice de estiramiento de los dos equipos (SI2). Los resultados revelan diferentes comportamientos intra e inter-equipo de acuerdo al formato de SSG y la edad del jugador. Las variables L, CH, SI, DC, L2, CH2, y SI2 aumentaron con el incremento en longitud del terreno, mientras que W y W2 mostraron sólo cambios mínimos. Las diferencias fueron mayores en el grupo U13, lo que sugiere que los jugadores más jóvenes fueron más propensos a variar su comportamiento colectivo en respuesta a los cambios de alargar el terreno de juego, inter-tarea, especilamente en los campos más largos (SSG50 y SSG60). Por el contrario, utilizando el análisis de la entropía, mayor imprevisibilidad de comportamiento del equipo se observó en el grupo U14, intra-tarea, en comparación con el grupo U13. En general, los resultados sugieren que las respuestas a la limitación de las tareas, tales como la modificación de la longitud del espacio y el espacio relativo de juego, son dependientes de la edad (experiencia, habilidad) y esto es algo que los entrenadores deben tener en cuenta al diseñar los SSGs para desarrollar comportameintos tácticos colectivos (AU)