The present study aimed to investigate whether the form and amount of declarative tactical knowledge (DTK) and procedural tactical knowledge (PTK) influence cognitive effort during soccer performance among young players. We assessed 36 male players from a Brazilian first-division soccer club; participants averaged 14.89 ( SD = 1.42) years of age. We evaluated DTK from video simulation tests and PTK through the System of Tactical Assessment in Soccer. We assessed cognitive effort by measures of pupil diameter using Mobile Eye Tracking-XG while players viewed soccer video scenes and made game-related play decisions. After the assessment of tactical knowledge, we categorized the sample according to players’ tactical knowledge into participants with higher and lower PTK and higher and lower DTK. Subsequently, we examined the both PTK and DTK groups on cognitive effort. Our results suggest that tactical knowledge influences cognitive effort in that players with higher PTK and DTK displayed less cognitive effort during soccer performance tasks. In conclusion, we observed that PTK and DTK influenced the cognitive effort younger soccer players expended while viewing soccer scenes and making soccer performance decisions.

Purpose. the aim of the study was to verify the effect of mental fatigue on tactical actions quality and the intensity of covered distance in soccer players. Methods. Six U-15 male soccer players participated in this study (14.7 ± 0.59 years of age). For data collection, the FUtSAt and GPSports® (SPI-HPU) systems were applied. to induce mental fatigue, the Stroop task was used for 20 minutes. the individuals were evaluated in 2 conditions: mental fatigue and control (with and without the Stroop task). Statistical analysis was performed with the Kolmogorov-Smirnov test, t-test, and Wilcoxon test. Results. the results displayed significant differences in actions related to principles of balance (p = 0.02), defensive unity (p < 0.01), and total defensive actions (p = 0.02), as well as in the covered distance in intensity related to zones 3 (p = 0.03) and 6 (p < 0.01). In mental fatigue, the players revealed a decrease in tactical action quality referring to movements that aimed at numerical stability in relations of opposition and at defending in unity and in block, and covered greater distances in zones 3 and 6. Conclusions. Mental fatigue modified the players' movement dynamics on the pitch with reference to the quality of tactical actions and covered distance intensity.

Could the Human Development Index and Birth-Date of the players influence the climbing up to higher performance in Soccer?Abstract: The present study verifies the possible influence of the human development index (HDI) and the birth-date (BD) on the climb up to higher performance in sports, considering Brazilian football context. The sample comprised all 643 players from 20 teams of the Premier Football League in Brazil. The data were collected from official website of Brazilian National Federation, United Nations Development Programme and Brazilian Institute of Geography and Statistics. Descriptive analysis, Kolmogorov-Smirnov test, chi-square test (²), Pearson correlation and Kruskall-Wallis H test were carried out. The level of significance was set at α=0.05. The results suggested that contextual factors associated with size and HDI of birth-place and birthdate contribute to the achievement of the Premier Football League. Thus, players were born in the first months of the year and in cities with medium or higher HDI had more conditions to climb up the elite level of Brazilian Football.

RESUMOO objetivo do estudo foi comparar a eficiência do comportamento tático entre os jogadores de futebol de diferentes categorias etárias. A amostra foi composta por 400 jogadores divididos em quatro categorias (sub-11, sub-13, sub-15 e sub-17), que realizaram no total 23.855 ações táticas. Para avaliação da eficiência do comportamento tático dos jogadores foi utilizado o FUT-SAT. Para o tratamento estatístico, foram realizadas análises descritivas, os testes Kolmogorov-Smirnov, Kruskal-Wallis, Mann-Whitney e foi considerado um nível de significância de p<0,05. Os resultados indicam que a eficiência do comportamento tático tende a aumentar ao longo do tempo, com exceção da categoria Sub-15 que apresenta uma queda acentuada em relação às demais. Assim é possível concluir que existem variações na eficiência do comportamento tático de jogadores de futebol de diferentes categorias etárias. Palavras-chave: Futebol. Comportamento tático. Categorias etárias. ABSTRACTThe aim of this study was to compare the tactical behavior efficiency between soccer players from different age levels. The sample comprised 400 players from four age groups , who performed 23,855 tactical actions. Players' tactical behavior efficiency was assessed through FUT-SAT. Statistical procedures included descriptive analysis and the tests Kolmogorov-Smirnov, Kruskal-Wallis and Mann-Whitney. The significance level adopted was p<0.05. Results indicated that the tactical behavior efficiency tends to increase over time, except for the U-15 age level, that displayed an accentuated drop in relation to the others. It is concluded that the efficiency of tactical behavior of the players in soccer displayed differences across different age levels.

The aim of the study was to investigate the relationship between tactical performance, somatic maturity, and functional capabilities in young soccer players. Study participants were 48 soccer players (14.80 ± 1.5 years) belonging to an extension project at the State University of Maringa - Brazil. Anthropometric measurements of body mass, body height, and sitting height were carried out. The number of years to peak height velocity (PHV) was used as an index of maturation. Evaluations of functional fitness included the following tests: sit-and-reach, Yo-Yo Intermittent Recovery Test Level 1, handgrip test, modified abdominal test, and vertical jumps (Counter Movement Jump and Jump Squat). Tactical performance was assessed through the System of Tactical Assessment in Soccer (FUT-SAT). Multiple Linear Regression models were used to estimate the relative contributions of functional and maturational capacities to tactical performance. The results indicated weak associations between the tactical performance indices and somatic maturity, functional capacity, and anthropometric attributes (r < 0.40). The Yo-Yo Test contributed to 36% of the defensive tactic performance variation in the under 13 category. These results suggest that the level of maturity, growth status, and functional fitness have limited impact on tactical performance of young soccer players.

Fatigue in soccer players is traditionally investigated based on neuromuscular and metabolic factors. However, given that soccer is one of the sports that has the highest cognitive demand, it is believed that players' performance might also be influenced by the high levels of attention, and frequent decision-making required in soccer. This systematic review aimed to verify the effects of mental fatigue on physical, technical, tactical and cognitive performance of soccer players. We searched in the electronic databases Pubmed, Web of Science and Scopus, for articles published up to 30 April 2018. We included articles that used a protocol of mental fatigue through cognitive tasks performed prior to a physical or cognitive task related to soccer. Only studies that presented an experimental design with the control condition (without mental fatigue) and the experimental condition (with mental fatigue) were selected. A total of six articles met the inclusion criteria, one study by backward reference search and other through the authors' indication. The results showed smaller distances covered in physical tests, while the effects of mental fatigue on physical performance in small-sided games were not clear. In technical tests, there were more penalties in passes and less accuracy and speed when kicking the ball when players were in conditions of mental fatigue. Regarding the tactical variables, it was found that mental fatigue had a detrimental effect on the synchronization between team players and on individual tactical performance in defensive actions. In cognitive tests, based on video recordings of game play, negative effects on the players' speed and accuracy of decision-making were observed. According to the results of the literature search, it can be inferred that mental fatigue is a factor that has a negative influence on soccer performance. Level of evidence II; Systematic review.

-Aim:The aim of this research is to identify the mechanisms that lead soccer players to make quality tactical decisions, and how these mechanisms evolve over time. Methods: Ninety male youth players training in a professional club in Brazil were submitted to a soccer video test which consists in making tactical decisions when the image freezes. These participants were divided in five groups with 18 players in each of following age levels: Under-11, Under-13, Under-15, Under-17 and Under-20. The dominant statements of verbal reports were distributed in categories that reflect key mechanisms. The frequency of correct tactical answers was calculated for each statement types and Standard Residuals (e) were calculated to verify the influence of the mechanisms on the quality of tactical decision for each age level. Results: Results revealed that evaluation statement was related to accurate tactical decisions from Under-15 age level. Conclusion: In conclusion, evaluation of perceived information makes better decision makers.

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