Tactical behavior in soccer small-sided games : inluence of team composition criteria

his study aimed to compare the tactical behavior of young soccer players during small-sided games played with team composition criteria based on procedural tactical knowledge, aerobic power and speed performance. Eighteen male soccer players played 3vs.3 small-sided games with teams balanced according to players’ performance on Sprint Test, Yo-Yo Intermittent Recovery Test and the ield test of the System of Tactical Assessment in Soccer. Data related to the incidence of tactical principles were analyzed through the proportions chi-square test with Bonferroni’s correction. One-way ANOVA was used to compare players’ ofensive and defensive tactical performance. Results showed diferent incidence of ofensive and defensive tactical principles in games with diferent teams’ composition criteria. It has also been shown a higher defensive performance when the teams’ composition criteria was based on players’ procedural tactical knowledge.


INTRODUCTION
he small-sided games (SSG) are a speciic means of training in soccer and allows the development of abilities inherent to soccer performance 1 in a tactical-situational context similar to the formal game 2,3 .he investigation on the tactical behaviors present in diferent SSG conigurations has developed in the last decades and has lead to a better understanding of the efects of altering diferent SSG characteristics on these behaviors (e.g.ield size, number of players, aim of the game) as a consequence of the growing use of some assessment tools, such as the System of Tactical Assessment in Soccer (FUT-SAT) 4 .Consequently, coaches have increased their possibilities of adjusting these SSG conigurations to the objectives of the teaching-learning process and training sessions 5 .
he development of tactical abilities in the SSG are related to a cooperation-opposition context, evidenced by the two confronting teams, similarly to the formal game 6 .It could be suggested that the alteration of players' characteristics during SSG occurs based on a team composition criterion.Team composition criterion can be deined as the variable used to split players into balanced teams in order to play the SSG.Criteria such as players' original position 7 , aerobic power 8 , and technical skills 8 have been described in the literature and used for teams' composition in SSG.Köklü et al. 8 observed that teams balanced for aerobic power presented a higher distance covered in higher intensities and higher mean heart rate, which shows the inluence of teams' composition in players' physiological and physical responses during SSG.Besides aerobic power, speed performance is a factor that inluences players' soccer performance once it requires high velocities to be reached in order to overcome opponents for ball possession 9 .However, speed performance has not been used as a team composition criterion in the literature.
On the other hand, considering the unpredictability, randomness, and complexity inherent to soccer game 10 , players' knowledge structures are relevant determinants of soccer performance 11 .hus, athletes' procedural tactical knowledge (PTK) can be seen as an alternative for teams' composition during SSG.In this sense, it could be suggested that athletes' knowledge on tactical principles is an important means of assessment of tactical knowledge because these principles are crucial to the understanding of games' logic.However, no study investigated the inluence of tactical ability as a team composition criterion on performance of young athletes.his gap limits the utilization of SSG in training process.
he incipience of the investigation on individuals' abilities as teams' composition criteria in SSG is relected in the heterogeneity of protocols among studies.However, clear justiications for the selection of a teams' composition criterion are still scarce, which limits not only the investigation (and interpretation of previous studies' results) but also training practice with soccer SSG.Although Köklü et al. 8 suggested the use of aerobic power as a team composition criterion with the aim of increasing SSG physiological demand, there is no investigation on the use of tactical ability as a team composition criterion -compared to physical abilities, as previously show in the literature.Besides that, literature presents no information on the efect of diferent team composition criteria on players' tactical responses, which limits the use of SSG as a means of training of tactical abilities in soccer.In this context, this study aimed to analyze the inluence of the teams' composition criteria tactical knowledge, aerobic power, and speed performance on the tactical behavior of young soccer players during 3vs.3SSG.

Participants
his study has been approved by the Research Ethics Committee of the Federal University of Minas Gerais registered under the protocol number CAE 51011915.9.0000.5149.Eighteen male soccer athletes from a national team (six defenders, six forwards and six midielders) aged between 16 and 17 took part in the study.All participants had at least ive years of practice.Before the beginning of data collection, athletes and their legal guardians were explained about all the research procedures and gave their informed consent.

Procedures
At irst, athletes' were assessed for procedural tactical knowledge (FUT-SAT), aerobic power (Yo-Yo Intermittent Recovery Test Level 2) and speed performance (20 meters sprint).All tests were carried out during the irst week, separated by 48 hours.
After these tests, the 18 athletes were classiied from 1 st to 6 th among each playing position according to the diferent variables (FUT-SAT, aerobic power and speed performance) used for composing balanced teams (Box 1).hen, they were divided into 6 teams (A, B, C, D, E, and F) of 3 players each.
In order to minimize the inluence of changing opponents' level on the tactical behaviors, teams A, B, and C did not play against teams D, E and F in any protocol.herefore, there has been a total of 6 diferent games in each protocol (AxB, AxC, BxC, DxE, DxF, and ExF).
Box 1. Players distribution into groups according to the teams' composition criteria and players' individual abilities.

Teams
Tactical Knowledge Aerobic Power Speed Performance Defender Midfielder Forward Defender Midfielder Forward Defender Midfielder Forward Note: Playing positions: D= Defender; M= Midfielder; F= forward.Superscript numbers indicate players' classification in the ranking of athletes of the same playing position in each test used to for teams' composition.
Each data collection session began with a 10-minute warm-up activity that consisted of actions with and without the ball (without opposition) and typical soccer movements.Each game comprised two 4-minute bouts of 3vs.3 SSG interspersed with 4-minute passive recovery.Field size was 36x27 meters with goals sized 5x2 meters, as reported in previous studies 12 .All formal game rules were used, including ofside.

Independent Variable: Team Composition Criterion Based on Tactical Knowledge
Players' procedural tactical knowledge was assessed through the System of Tactical Assessment in Soccer (FUT-SAT) 4 .his ield test consists of a 4-minute 3vs.3 game played in a ield area of 36x27 meters with all formal game rules.he test was ilmed for later analysis.For further information about the FUT-SAT protocol see Teoldo et al.³. he percentage of positive tactical principles was calculated ((total number of positive ofensive actions + total number of positive defensive actions) / (total number of ofensive actions + total number of defensive actions)) based on the observation protocol.

Independent Variable: Team Composition Criterion Based on Aerobic Power
he Yo-Yo Intermittent Recovery Test Level 2 -YIRT2 - 13 was used to assess athletes' aerobic power.his test has been shown to be reliable 14,15 and is an important ield tool for aerobic power assessment of soccer players because of its low cost and high speciicity 14,16 .
he test area for each participant consists of a 20x2 (length x width) straight lane with a 5-meters recovery area. he test protocol comprises several 40 meters (20 + 20) runs with progressively increased velocities controlled by sound signals.Between each run participants have a 10-seconds interval to recover. he test ends when participants fail to reach the inish line at the same time of the sound signals twice.

Independent Variable: Team Composition Criterion Based on Speed Performance
he 20 meters sprint was used to assess speed performance.Athletes performed three 20 meters sprints with three minutes of passive recovery between them 9 .he best trial was considered for analysis.Two infrared photoelectrical cells (photocells) (Matsport timing BTS, Seyssinet, France) were positioned 20 meters apart to register the time spent to cover the 20 meters.Before the test, athletes were positioned before the irst pair of photocells with the preferred foot just behind the start line, in a static comfortable position for running.here was no sonorous stimulus for test to begin and athletes could start the test whenever they considered appropriate.hese procedures have been used in previous studies in soccer 9 .

Dependent variable: tactical behavior
he System of Tactical Assessment in Soccer (FUT-SAT) was used to assess the tactical behaviors related to the Fundamental Tactical Principles 4 .he SSG bouts were ilmed and then analyzed to establish the incidence of the fundamental ofensive and defensive tactical principles among players.he percentage of positive ofensive and defensive tactical principles were also calculated through the ratio between the number of positive tactical principles (ofensive or defensive) and the total number of principles (ofensive or defensive).his percentage was considered a measurement for the quality of the tactical actions in the game. he same tactical principles used as teams' composition criterion were also used as dependent variable in the present study.

Data analysis
he incidence of the fundamental tactical principles in the 3vs.3 SSG played using the diferent teams' composition criteria were compared using the proportion chi-square test and Bonferroni's post-hoc for repeated measures.he ω efect size was calculated as reported in the literature 17 and classiied as small (ω < 0,1, or 1% of total variance), medium (0,1 < ω < 0,3, or 9% of total variance) or large (ω > 0.5, or 25% of total variance) 17 .
All statistical analyses (except for ω efect size -software Microsoft Excel for Windows version 2013) were carried out using the statistical package SPSS (SPSS Version 20.0 for Windows, SPSS Inc., Chicago, IL, USA). he signiicance level was set at 5% for all analyses.

Data reliability
Inter and intra-observer agreements were veriied for experts' observations of the tactical principles during the SSG.In this sense, 11% of the SSG bouts 21 (4 bouts out of 36) were reevaluated after 21 days 18 as recommended in the literature. he Cohen Kappa coeicient and its standard error (SE) were calculated for all the fundamental tactical principles -ofensive and defensive.Values above 0,879 (SE = 0,013) and 0,863 (SE = 0,013) for intra and inter-observer agreements, respectively, indicated high agreement 22 .

RESULTS
Data related to tactical behavior (ofensive and defensive tactical principles) are expressed as the total incidence of each principle in each team composition criteria.Data related to the quality of tactical actions are expressed as the percentage of positive principles (ofensive and defensive). he number of tactical actions per player in each bout corresponded to 14965 (±69,2).SSG played by teams' composition based on tactical knowledge presented higher incidence of ofensive (c²=7,966; p= 0,018; medium efect) and defensive (c²= 43,136; p= 0,001; medium efect) coverage compared to SSG played by teams balanced for aerobic power.here was also a higher incidence of delay (c²= 9,626; p= 0,008; medium efect) and concentration (c²= 6,901; p= 0,032; medium efect) when the SSG were played by teams composed by the aerobic power criterion than when teams were composed by the speed performance criterion.Moreover, there was a higher incidence of width and length with ball (c²= 6,323; p= 0,042; medium efect) when teams were composed based on speed performance compared to tactical knowledge.herefore, the inluence of teams' composition criteria on the tactical behaviors during SSG was conirmed by the results of this study.
Finally, in SSG played by teams balanced for the tactical knowledge criterion it was observed a higher defensive tactical performance (F= 14,778; p= 0,001; minimum efect) compared to the other two criteria (F= 12,678; p= 0,002; minimum efect).

DISCUSSION
his study aimed to analyze the inluence of diferent teams' composition criteria on tactical behavior of young soccer players during 3vs.3SSG.It has been observed that the tactical knowledge criterion induced an increase the defensive tactical performance, as well as behavioral diferences related to the incidence of certain fundamental tactical principles. he understanding that players' behavior during the game -formal game as well as small-sided games -is inluenced by the cooperation established among teammates 23 supports the concerning about the diferent teams' composition criteria that can be adopted.In this study, the improvement of tactical performance presented in the situations when teams were balanced for tactical knowledge indicates that the cooperation patterns established among teammates with the same tactical level, as well as the confrontation against opponents with the same level of tactical knowledge leads to the appearance of better decisions.his decision-making, evaluated by the execution of the tactical principles, relects players' understanding of the time and space management logic 24 .In this sense, time and space management relects the interactions among players, once the cooperationopposition characteristics during the game 25 requires behavioral adjustments depending on teammates and opponents' actions.herefore, when athletes cooperate/confront other athletes of similar tactical level, the establishment of the interpersonal relationships is facilitated during the game and, consequently, a better tactical performance is expected -as shown in this study.
Besides that, considering that the tactical behavior results from an intentional action directed towards a goal in a given environment 26 , it presented some speciicities related to the teams' composition criterion adopted.At this point, a higher incidence of ofensive and defensive coverage was observed in SSG oriented by the tactical knowledge criteria compared to the SSG oriented by aerobic power.here was also a higher incidence of defensive coverage when teams were composed based on speed performance compared to aerobic power.hese results suggest that the coverage actions represent the actions of teammates/opponents that aim to support the player with the ball -ofensive -or the player defending the one with the ball -defensive -which are, therefore, strongly inluenced by teammates and opponents' behaviors 24,27 .hus, the higher incidence of coverage actions reported in the SSG played by teams of similar tactical knowledge relects a better generation of options and decisions, which allows players to constantly ofer support to players directly involved with the ball -penetration/delay dyad.
On the other hand, this study showed a higher incidence of concentration and ofensive unity actions in the SSG played by teams balanced for aerobic power and higher incidence of width and length with ball and defensive coverage in the SSG played by teams balanced for speed performance, reinforcing the behavioral speciicities related to each teams' composition criterion.herefore, team composition based on aerobic power increases the number of ofensive (ofensive unity) and defensive (concentration) actions out of game center and behind the line of the ball.his suggests that players wait for opponents mistakes in order to regain ball possession or progress along playing ield, either setting an organized ofense (ofensive action) or orientating players in ofense (defensive action) to a given direction -frequently the sides of the pitch.he higher incidence of mobility actions -even though it was not signiicant -in the SSG played by teams composition based on speed performance compared to aerobic power reinforces this rationale.However, the non-existence of previous studies on the relationships between tactical behavior and speed/ aerobic performances limits the inferences that can be made from these results, which suggest the need of further investigation in this area.
Once SSG are a means of training often adopted by soccer coaches and physical trainers 28 , the concerns about teams' composition criteria must be summated to the concerns about SSG conigurations -ield size, number of players per team, speciic rules, and others.he results of this study suggest that the tactical knowledge as teams' composition criterion should be adopted when a higher tactical performance is sought in a certain training session.On the other hand, the adoption of the speed performance and aerobic power criteria is appropriate to achieve the speciic tactical behaviors width and length with ball and delay/concentration, respectively.However, future studies with athletes of diferent ages and performance levels should be carried out in order to verify whether the behaviors observed in this study are present in other soccer practice contexts.

CONCLUSION
In general, we can conclude that diferent team composition criteria -based on aerobic power, speed performance and tactical ability -alters tactical behaviors of young players, which is evidenced by the diferences in the incidence of diferent tactical principles.herefore, coaches must consider SSG speciicities when prescribing SSG during training sessions, in order to emphasize training of speciic tactical principles only by changing team composition criterion.For example, SSG played by teams balanced for tactical ability present higher incidence of ofensive and defensive coverage compared to SSG played by teams balanced for aerobic power.On the other hand, the latter presents more actions of ofensive unity and concentration compared to SSG played by teams with similar tactical ability.Finally, the use of tactical ability as a team composition criterion increased tactical performance compared the other criteria.his result suggests that coaches can use this criterion with the aim of facilitate defensive tactical actions, especially in the initial phase of tactical learning, because it allows creating contexts of lower tactical demand.Conversely, in order to increase tactical demand, the results of the present study suggest the adoption of physical/physiological aspects -aerobic power and speed performance -as team composition criteria.

Table 1 .
Influence of teams' composition criteria on tactical behavior during SSG.
* Significant difference (p<0,05) a,b,c: different when compared to compositions based on speed performance, aerobic power, and tactical knowledge, respectively.