Israel Teoldo da Costa^1,2,3, Júlio Garganta³, Pablo Juan Greco², Isabel Mesquita³ e José Afonso³

¹University Center of Belo Horizonte, UNI-BH, Belo Horizonte, MG-Brazil

²Federal University of Minas Gerais, UFMG, Belo Horizonte, MG-Brazil.

³Centre of Research, Education, Innovation and Intervention in Sport, CIFI²D, Faculty of Sport, University of Porto, FADEUP, Porto, Portugal.

CORRESPONDENCE

ABSTRACT

The aim of this study was to analyze tactical behaviours performed by youth Soccer players of different age groups according to ten core tactical principles of the game, in order to understand characteristics of each age group and their differences. The sample comprised a total of 300 youth Soccer players (60 U11, 60 U13, 60 U15, 60 U17 and 60 U20), who have performed 17,239 tactical actions. Three tactical measures were analyzed (number of tactical actions, efficiency of tactical behaviours and tactical performance indices). Kruskal-Wallis H and Whitney U tests were applied to compare the values of these measures. Data reliability was assured by the Kappa of Cohen index. The results indicated forty statistical differences relative to the number of tactical actions performed, thirty-two statistical differences relating the efficiency of tactical behaviours, and twenty statistical differences concerning tactical performance indices. In conclusion, it is possible to state that as the age group increased, the players had a greater participation in the game, namely through the performing of more tactical actions. In addition, the U15 and U17 groups presented no statistical differences in the efficiency of their tactical behaviours, and U17 and U20 groups exhibited the biggest differences in the tactical performance indices.

Avaliação dos princípios tácticos em jovens futebolistas de diferentes idades

RESUMO

O objetivo desse estudo consistiu na análise dos comportamentos táticos realizados por jovens jogadores de Futebol com base em dez princípios táticos fundamentais do jogo, de modo a verificar as características e as diferenças de cada grupo etário avaliado. A amostra foi constituída por 300 jovens jogadores (60 Sub-11, 60 Sub-13, 60 Sub-15, 60 Sub-17 e 60 Sub-20), que realizaram 17.239 ações táticas. Foram analisados três indicadores táticos (número de ações táticas, eficiência dos comportamentos táticos e índice de performance tática). Os testes de Kruskal-Wallis H e Whitney U foram utilizados para comparar os valores obtidos. A fiabilidade foi avaliada pelo índice de Kappa de Cohen. Dos resultados emergiram quarenta diferenças estatisticamente significativas para o número de ações táticas realizadas, trinta e duas para a eficiência dos comportamentos táticos e vinte para os índices de performance tática. Em suma, é possível afirmar que, à medida que o escalão etário aumentou, os jogadores demonstraram ter maior participação no jogo, nomeadamente realizando mais ações de jogo. Adicionalmente, os jogadores dos grupos Sub-15 e Sub-17 não apresentaram diferenças estatisticamente significativas em relação à eficiência dos seus comportamentos táticos, enquanto os grupos Sub-17 e Sub-20 exibiram as maiores diferenças com relação aos índices de performance tática.

Palavras-chave: futebol, performance tática, comportamento tático, escalões de formação

Introduction

The identification and promotion of talent in Soccer have received much attention of sport scientists, who have tried to describe some characteristics of expertise that can lead a young player to the highest level of performance^{(3, 40)}. Investigations that took into account the stages of sport participation have identified three different periods of formation, prior to the attainment of expert performance: the sampling years (6-12 years old), the specializing years (13-15 years old), and the investment years (more than 16 years old)^{(5, 8)}. To youth sport competition, the governing body of Soccer, FIFA (Fédération Internationale de Football Association), accredits international tournaments for players with ages between 15 and 21 years old. According to these stages, many Soccer Clubs have youth development programs that aim to provide conditions leading to the complete development of the abilities of athletes from early ages. In addition, many Soccer Clubs provide a specific training environment for players with distinguished skills from under 11 (U11) until under 20 years old (U20) groups, where they can practice activities in specific and systematic training programs to develop their soccer abilities towards fulfilling their potential⁽²⁸⁾. Probably, all these clubs provide excellent conditions for talented players from as early as 11 years old, believing that a 10-year commitment to a high level of training is the minimum requirement to reach the expert level^{(10, 18)}. Specifically in the context of Soccer, Helsen et al.⁽¹⁷⁾ found that around nine years into their career expert players increased both training duration and intensity and they suggested that this was a necessary requirement for reaching expert level performance, i.e., the international level of competition.

Moreover, as stated by Silva, Fernandes and Celani⁽³²⁾, each of the sports developmental stages has particularities and demands connected with game knowledge and learning. Baker and Côté⁽³⁾ claim that this ability to perceive essential information from the playing environment, to correctly interpret this information, and then to select the appropriate response is a key characteristic for expert performance in team ball sports. In the context of Soccer, researchers have highlighted that the high number of actions performed by the players without the ball raises the solicitations of the tactical abilities and cognitive skills underlying decision-making^{(12, 15, 26, 33)}. Hence, they suggest that teachers and coaches should use a training model underpinned in tactical features and basic guidelines in order to facilitate decision-making and collective organization. This way, the phases of training should follow and represent the demands of game situations on the organization and efficiency of the players’ movements, according to the team goals, in order to maximize their learning and performance^{(21, 43)}. Accordingly, it seems to make sense that the establishment of the training phases, preparation of training sessions and assessment of the development of player’s skills should be based on tactical principles, since they provide athletes the possibility to attain effective tactical solutions for game situations^{(14, 20, 35)}.

Methods

Sample

Three hundred youth Soccer players participate in the study [U11 (n=60), U13 (n=60), U15 (n=60), U17 (n=60) and U20(n=60)]. Furthermore, this study comprised the observation of 17,239 tactical actions (2,637 were performed by U-11 players, 3,306 by U-13 players, 3,480 by U-15 players, 3,988 by U-17 players and 3,828 by U-19 players). Data from throw-ins, free kicks and situations where the player did not move were not analyzed.

Procedures

Applied Method

The System of Tactical Assessment in Soccer (FUT-SAT), developed in the Centre for Team Sports Studies of the Faculty of Sport, University of Porto, was used to collect data⁽⁶⁾. This system considers two macro-categories, seven categories and 76 variables, and was designed to assess the tactical actions performed by the players (with and without the ball), according to ten core tactical principles of the Soccer game^{(7, 44)}. Additionally, the evaluation takes into account the action’s place and outcome (for details see Table 1).

Based on this information, three tactical measures were analyzed: the number of tactical actions performed by the players, the efficiency of tactical behaviours and the tactical performance indices. The assessment of efficiency of tactical behaviours was based on the degree to which the skill’s execution matches established criteria of mechanical execution⁽³¹⁾. To calculate the tactical performance indices, the efficiency of tactical behaviours was taken into account, as well as the field position where the actions took place and the obtained result, in agreement with the goal of the action, i.e., the effectiveness of the actions⁽³¹⁾.

The field test is designed in a space of 36 meters long by 27 meters wide, and requires the player to perform during four minutes (3 vs. 3 with goalkeepers). With the exception of the offside rule, all laws of the game are applied in the field test.

Data collection

Data for this study was gathered in four different clubs with directors’ permission. The players who were voluntarily involved in the study have regular participation in regional tournaments. Prior to the test, a brief explanation of its purposes was given to the players. The teams were formed randomly and the players were wearing numbered vests in order to facilitate their identification. A thirty-second period had been granted to familiarize players with the test, after which the game began.

Materials

The games were recorded with a digital camera (PANASONIC NV – DS35EG). The digital videos were then transferred to a laptop (LG model E500 CPU Intel T2370) via cable (IEEE 1394) and converted into “.avi” files. Software Utilius VS® and Soccer Analyzer® were used for data processing. The first software was utilized to register and save the tactical actions observed, while the second was built specifically for the FUT-SAT; it inserts special references in the video, allowing unerring evaluation of the position and movement of the players in the field.

Data Analysis

The second step involves the assessment, classification and registration of tactical actions analyzed during the first step. It is supported by a framework of tactical behaviour analysis of FUT-SAT and two software packages: Soccer Analyser® and Utilius VS®.

The third step involves the calculation of the variables’ scores, with reference to the test, through a system developed for Excel for Windows® (Figure 1). Through the insertion of data from the second step, this system allows the automatic calculation of all variables present in FUT-SAT.

Figure 1. System for calculation of test variables; developed for Excel for Windows®.

Statistical Analysis

Descriptive statistics (frequencies, means and standard deviations) were carried out to characterize the sample. The number of tactical actions performed by the players, the efficiency of tactical behaviours and the tactical performance indices obtained by five groups (U11 to U20) were compared using the Kruskal-Wallis H test. For the comparison of each pair of groups, Mann-Whitney U test was applied. The level of significance was set at p≤0.05.

To determine the reliability of the observation, the test-retest method was used to obtain the stability-reliability coefficient. Five observers were trained to review 2275 tactical actions, representing 13.2% of the sample. This percentage is above the value of reference (10%) recommended by the literature ⁽³⁴⁾. The results reveal inter-observers’ agreement coefficients between 0.81 (SD = 0.03) and 0.91 (SD = 0.02) and intra-observers’ agreement coefficients between 0.85 (SD = 0.02) and 0.92 (SD = 0.01). These values are above the conventional level of acceptance (0.61) ⁽²²⁾.

All statistical procedures were done using software EQS 6.1 and SPSS 17.0.

Results

Table 2 presents the means and standard deviations concerning tactical actions performed by players from all groups. The comparison among the groups indicated forty statistical differences. Only the “depth mobility” and “delay” principles exhibited no significant differences. The “concentration” principle presented the greatest number of differences among youth Soccer teams. The offensive and defensive principles more frequently performed by players from all groups were “width and length” and “defensive unity”, respectively. On the other hand, “defensive coverage” was the defensive principle least used by players. In the same order, “depth mobility” and “penetration” were the offensive principles less executed by U11 until U17 and U20 players.

Table 2. Tactical actions performed by players for each tactical principle of the game.

*Significant statistics differences (p≤0.05) between: ¹ U11 and U13: Penetration (Z=-2.44; p=0.015). Offensive Coverage (Z=-2.63; p=0.009). Width and Length (Z=-3.66; p<0.001). Balance (Z=-2.85; p=0.004). Concentration (Z=-2.67; p=0.007) and Defensive Unity (Z=-2.57; p=0.010). ² U11 and U15: Offensive Coverage (Z=-2.46; p=0.014). Width and Length (Z=-4.84; p<0.001). Balance (Z=-3.03; p=0.002). Concentration (Z=-2.83; p=0.005) and Defensive Unity (Z=-4.10; p<0.001). ³ U11 and U17: Offensive Coverage (Z=-2.98; p=0.003). Width and Length (Z=-5.55; p<0.001). Offensive Unity (Z=-3.58; p<0.001). Defensive Coverage (Z=-2.68; p=0.007). Balance (Z=-3.70; p<0.001). Concentration (Z=-6.74; p<0.001) and Defensive Unity (Z=-2.16; p=0.031). ⁴ U11 and U20: Penetration (Z=-3.71; p=0.002). Offensive Coverage (Z=-4.41; p<0.001). Width and Length (Z=-4.76; p<0.001). Offensive Unity (Z=-3.69; p<0.001). Defensive Coverage (Z=-5.62; p<0.001). Balance (Z=-2.30; p=0.021). Concentration (Z=-4.70; p<0.001) and Defensive Unity (Z=-3.21; p=0.001). ⁵ U13 and U17: Width and Length (Z=-2.10; p=0.036). Offensive Unity (Z=-3.04; p=0.002). Defensive Coverage (Z=-2.26; p=0.024) and Concentration (Z=-4.86; p<0.001). ⁶ U13 and U20: Offensive Unity (Z=-3.07; p=0.002). Defensive Coverage (Z=-5.36; p<0.001) and Concentration (Z=-2.35; p=0.019). ⁷ U15 and U17: Offensive Unity (Z=-2.49; p=0.013) and Concentration (Z=-5.01; p<0.001). ⁸ U15 and U20: Penetration (Z=-2.23; p=0.026). Offensive Unity (Z=-2.70; p=0.007). Defensive Coverage (Z=-3.69; p<0.001) and Concentration (Z=-2.40; p=0.016). ⁹ U17 and U20: Concentration (Z=-2.87; p=0.004).

Regarding the groups in study, it was verified that only U13 and U15 did not show statistical differences. All the other groups presented statistical differences concerning the quantity of tactical actions performed. The highest number of differences was observed between U11 and U20 groups, and the lowest number between U17 and U20 players. Globally, the statistical differences between the groups increased as the age difference broadened, i.e., U11 showed more differences when compared with U20 and less when contrasted with U13.

Table 3. Efficiency of tactical behaviours by groups for each tactical principle of the game.

*Significant statistics differences (p≤0.05) between: ¹ U11 and U13: Penetration (Z=-3.28; p=0.001). ² U11 and U15: Concentration (Z=-2.37; p=0.018) and Defensive Unity (Z=-3.94; p<0.001). ³ U11 and U17: Penetration (Z=-2.62; p=0.009). Width and Length (Z=-2.81; p=0.005). Offensive Unity (Z=-2.74; p=0.006). Concentration (Z=-3.62; p<0.001) and Defensive Unity (Z=-6.08; p<0.001). ⁴ U11 and U20: Penetration (Z=-3.20; p=0.001). Width and Length (Z=-2.87; p=0.004). Delay (Z=-2.35; p=0.019) and Defensive Coverage (Z=-3.36; p=0.001). ⁵ U13 and U15: Offensive Unity (Z=-2.13; p=0.033). Delay (Z=-2.13; p=0.034). Concentration (Z=-3.24; p=0.001) and Defensive Unity (Z=-2.96, p=0.003). ⁶ U13 and U17: Width and Length (Z=-2.61; p=0.009). Offensive Unity (Z=-3.00; p=0.003). Delay (Z=-1.98; p=0.048). Concentration (Z=-4.69; p<0.001) and Defensive Unity (Z=-5.19; p<0.001). ⁷ U13 and U20: Width and Length (Z=-2.64; p=0.008). Delay (Z=-3.06; p=0.002) and Defensive Coverage (Z=-2.38; p=0.017). ⁸ U15 and U20: Offensive Unity (Z=-1.98; p=0.048). Delay (Z=-1.98; p=0.048). Concentration (Z=-2.29; p=0.022) and Defensive Unity (Z=-4.03; p<0.001). ⁹ U17 and U20: Offensive Unity (Z=-2.98; p=0.003). Defensive Coverage (Z=-4.08; p<0.001). Concentration (Z=-3.81; p<0.001) and Defensive Unity (Z=-5.84; p<0.001).

It was also observed that all groups showed significant statistical differences on the rating of efficiency of tactical behaviours, except when comparing U15 with U17. The highest numbers of significant differences were placed in U17 group, with five differences to U11 and U13 groups, and four differences to U20, although it did not present any differences to U15.

Table 4 displays the tactical performance indices obtained by players in each tactical principle. The values showed that the players were heterogeneous concerning their performance. Comparing the performance indices among the groups, twenty statistical differences were found. These differences concern five of the ten core principles, namely two offensive principles and three defensive principles. In spite of being only two offensive principles (“offensive coverage” and “depth mobility”), they concentrated twelve statistical differences, while the other three defensive principles (“defensive coverage”, “balance” and “defensive unity”) presented eight differences. Moreover, the “depth mobility” principle had the lowest tactical performance indices (U11 to U20), and the “offensive coverage” (U11) and “width and length” (U13 to U20) principles had the highest values in the offensive phase. In the defensive phase, the “defensive unity” (U11 to U15) and “defensive coverage” (U17 and U20) principles presented the highest tactical performance indices, and “defensive coverage” (U11 to U15) and “delay” had the lowest ones. Significant differences among all groups were observed. The highest number of performance differences was observed in the comparison between U17 and U20 groups.

*Significant statistics differences (p≤0.05) between: ¹ U11 and U13: Depth Mobility (Z=-2.59; p=0.010). ² U11 and U15: Depth Mobility (Z=-2.17; p=0.030). ³ U11 and U17: Offensive Coverage (Z=-2.46; p=0.014) and Depth Mobility (Z=-3.11; p=0.002). ⁴ U11 and U20: Depth Mobility (Z=-5.00; p<0.001) and Defensive Coverage (Z=-3.37; p=0.001). ⁵ U13 and U15: Offensive Coverage (Z=-2.39; p=0.017). ⁶ U13 and U17: Offensive Coverage (Z=-5.00; p<0.001). ⁷ U13 and U20: Offensive Coverage (Z=-2.65; p=0.008). Defensive Coverage (Z=-2.85; p=0.004) and Balance (Z=-2.84; p=0.005). ⁸ U15 and U17: Offensive Coverage (Z=-3.12; p=0.002). ⁹ U15 and U20: Depth Mobility (Z=-2.69; p=0.007). Balance (Z=-3.26; p=0.001) and Defensive Unity (Z=-2.66; p=0.008). ¹⁰ U17 and U20: Offensive Coverage (Z=-2.88; p=0.004). Depth Mobility (Z=-3.30; p=0.001). Defensive Coverage (Z=-3.84; p<0.001). Balance (Z=-3.12; p=0.002) and Defensive Unity (Z=-3.03; p=0.002).

Discussion

The results indicated that as the age group increased, the players had a greater participation on the game through the performance of more tactical actions. In addition, data showed that U15 and U17 players presented no statistical differences in the efficiency of tactical behaviours, although these two groups exhibited many differences to other groups. In terms of tactical performance indices, the biggest differences were found between 17 and 20 years of age, probably because it is in this period that the transfer of players to first teams occurs⁽³⁾. In the literature, this stage of development has been considered as a critical period in the process of development for the player’s future career⁽³⁷⁾. At a competitive level, the transition to the first team is associated with the expectation of a higher level of performance, alongside with a reduced tolerance for failure. Consequently, players must seek to achieve the best performance to give further sequence to their sports career, integrating the professional team or being negotiated with other clubs⁽³⁰⁾.

Sport researchers have also highlighted that the distinction between performance and behaviours’ efficiency is important for scientists and practitioners, since many of the typical interventions employed by coaches have differential effects on these two issues^{(4, 24, 27)}. Although players may have learnt a particular tactical behaviour, they may not always perform according to their potential because of the effect of various extraneous or performance variables such as the opponent or technical and physical characteristics⁽³⁸⁾. In this study, this has occurred with the younger groups (U11 to U15), where the performance indices of the players did not show many statistical differences. Furthermore, it was possible to verify that the effectiveness of the actions was the most significant factor affecting the tactical performance indices of U17 and U20 players. This inference is possible because, in addition to the efficiency of tactical behaviours, the calculation of tactical performance indices takes into account the effectiveness of the tactical actions. Thus, data displayed in Table 3 indicated only four statistical differences and similar absolute values in the efficiency of tactical behaviours of these two groups, but Table 4 showed more differences, suggesting that effectiveness of the actions was decisive to the better performance of U-20 group, i.e. besides having executed tactical actions with success, they also got better action outcomes.

Whilst the performance indices have fluctuated substantially (lowest value = 20.65; highest value = 67.51) among the age groups evaluated in this study, sport specialists have assumed that learning can be deemed to have taken place if the improvement in performance is relatively permanent during sports developmental stages^{(8, 38)}. In this study, it was verified that there were improvements in the tactical performance indices values with increasing age. Thus, it was confirmed that there were less inter-individual variances and better performances in the oldest groups, probably reflecting the learning progress of the players, and also the most restricted selection concerning several constraints imposed by training and competitive demands.

The results of this study provide important information concerning the tactical behaviours performed by players of different stages of development in Soccer. They may associate with other research findings that have reported the importance of tactical constraints for the player and team’s development in team sports^{(4, 13, 16, 20, 36, 39, 41, 42)}. It has also been reported in literature that the teaching of tactics focused on the general rather than the specific issues has been at least one potential reason for the lack of strong investigation findings that prove the relationship between tactical teaching and performance⁽²⁴⁾. According to these authors (p.190), “The emphasis has been placed on generalizing skills, knowledge, or decision-making of games from one setting to another or from one sport to another, rather than from practice conditions to games.”. In this sense, it is expected that the present study, together with other research findings, can provide a step forward in these matters, since the evaluation of players has been made concerning core tactical principles. The assessment based on these principles allows obtaining knowledge about difficulties and potentials of athletes in specific tactical behaviours, and to set specific training sessions for players according to the characteristics described in this paper, in order to provide them opportunities to try new or different combinations of behaviours that will eventually enable them to reach their goals of further sport development⁽⁴³⁾.

Regarding the efficiency of tactical behaviours, it was observed that the players of U15 and U17 groups presented no statistical difference between them, but they were the groups that had more statistical differences to other groups. Furthermore, it was verified that the tactical performance indices from U17 and U20 groups presented more statistical differences and that these distinctions happened due the effectiveness of the actions obtained by U20 players.

Future research should extend the current findings by examining other groups or competitive levels, in an attempt to verify whether the tactical behaviours are similar or different when performed by other players. Beyond that, it may be interesting to investigate if efficiency of tactical behaviours and tactical performance indices vary according to the players’ positions or if there are relative age effects within each group.

Acknowledgment

Supported by the Programme AlBan, the European Union Programme of High Level Scholarships for Latin America, scholarship nº E07D400279BR”.

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CORRESPONDENCE

Israel Teoldo da Costa

Centro de Estudos em Cognição e Ação (CECA)

Escola de Educação Física, Fisioterapia e Terapia Ocupacional da UFMG

Av. Presidente Antônio Carlos, 6627– Pampulha

Belo Horizonte – MG

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