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Journal of Sports Sciences Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/rjsp20

The influence of pitch dimensions on performance during small-sided and conditioned soccer games ab

b

c

Luís Vilar , Ricardo Duarte , Pedro Silva , Jia Yi Chow

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& Keith Davids

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Faculty of Physical Education and Sports, Lusófona University of Humanities and Technologies, Lisbon, Portugal b

CIPER, Faculdade de Motricidade Humana, Universidade de Lisboa, Lisboa, Portugal

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Faculty of Sports, University of Porto, Porto, Portugal

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Nanyang Technological University, Singapore

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Physical Education and Sports Science, National Institute of Education, Singapore

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Centre for Sports Engineering Research, Sheffield Hallam University, Sheffield, UK

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FiDiPro Programme, University of Jyväskylä, Jyväskylän, Finland Published online: 10 Jun 2014.

To cite this article: Luís Vilar, Ricardo Duarte, Pedro Silva, Jia Yi Chow & Keith Davids (2014) The influence of pitch dimensions on performance during small-sided and conditioned soccer games, Journal of Sports Sciences, 32:19, 1751-1759, DOI: 10.1080/02640414.2014.918640 To link to this article: http://dx.doi.org/10.1080/02640414.2014.918640

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Journal of Sports Sciences, 2014 Vol. 32, No. 19, 1751–1759, http://dx.doi.org/10.1080/02640414.2014.918640

The influence of pitch dimensions on performance during small-sided and conditioned soccer games

LUÍS VILAR1,2, RICARDO DUARTE2, PEDRO SILVA3, JIA YI CHOW4,5 & KEITH DAVIDS6,7 Faculty of Physical Education and Sports, Lusófona University of Humanities and Technologies, Lisbon, Portugal, 2CIPER, Faculdade de Motricidade Humana, Universidade de Lisboa, Lisboa, Portugal, 3Faculty of Sports, University of Porto, Porto, Portugal, 4Nanyang Technological University, Singapore, 5Physical Education and Sports Science, National Institute of Education, Singapore, 6Centre for Sports Engineering Research, Sheffield Hallam University, Sheffield, UK and 7FiDiPro Programme, University of Jyväskylä, Jyväskylän, Finland

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1

(Accepted 23 April 2014)

Abstract This study examined the influence of pitch dimensions in small-sided soccer games in shaping opportunities for performers to maintain ball possession, pass to teammates and shoot at goal. Fifteen amateur standard male participants (M = 21.87, σ = 1.96 years) played 5 v 5 small-sided soccer games in three varying pitch conditions (28 m × 14 m, 40 m × 20 m and 52 m × 26 m). Thirty sequences of play in each condition were selected for digitisation using TACTO software, allowing the capture of bi-dimensional displacement coordinate data of all players and the ball. The values of interpersonal distance between all attackers and immediate defenders and the relative distances of defenders to intercept a shot and a pass were computed as dependent variables. Results showed existence of fewer opportunities to maintain ball possession on smaller pitches, compared to medium and larger pitches. Conversely, the different dimensions set to the pitch did not influence opportunities for players to shoot at goal, or to perform passes to other teammates. By examining the specific spatial– temporal relationships of players and key-task constraints, the data from this study explain how effects of manipulating pitch dimensions of small-sided games might enhance opportunities for acquiring specific movement and decision-making skills. Keywords: ecological dynamics, performance, soccer, small-sided games, practice task design, skill acquisition

Introduction There is growing interest amongst researchers and practitioners in using small-sided and conditioned games (SSCGs) as a method to facilitate learning of soccer skills in individuals of all ages and skill levels (for an overview, see Davids, Araújo, Correia, & Vilar, 2013; Ford, Yates, & Williams, 2010). SSCGs are commonly considered as modified games played on reduced pitch dimensions (small-sided), often using adapted rules and involving a smaller number of players than traditional games (representing manipulations of playing conditions) (Dellal et al., 2008; Gabbett, Jenkins, & Abernethy, 2009; Hill-Haas, Dawson, Impellizzeri, & Coutts, 2011). Compared to more traditional training methods (e.g., typically manifest by extensive repetition of practice drills in static contextual conditions), SSCGs are perceived to be soccerspecific, allowing an optimisation of training time since physical performance, technical skills and

tactical awareness are developed concurrently (HillHaas et al., 2011). However, advantages of playing SSCGs are dependent on game design and the coach's role is paramount since appropriate manipulations of relevant task constraints can lead to enhancement of learning opportunities (e.g., pitch dimensions and number of players) (Davids et al., 2013). Previous research has tended to examine the extent of physiological responses and technical demands imposed upon players. For example, Kelly and Drust (2009) examined 5-a-side soccer games played in areas of 30 m × 20 m, 40 m × 30 m and 50 m × 40 m and concluded that participants’ heart rates were not significantly different between conditions and reported a greater frequency of tackles and shots performed on smaller pitches. The assumed effectiveness of SSCGs is currently predicated on the greater frequency of actions on smaller pitches. However, there is a lack of understanding on

Correspondence: Luís Vilar, Faculty of Physical Education and Sports, Lusófona University of Humanities and Technologies, Lisbon, Portugal. E-mail: [email protected] © 2014 Taylor & Francis

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whether varying task constraints can have a diverse impact on learning of specific skills and enhancement of tactical awareness and decision-making in different SSCG formats. From motor learning literature, the constraints-led approach has been proposed as a reliable framework to explain the potential benefits of SSCGs in learning soccer skills (Chow, Davids, Button, Renshaw, & Araújo, 2006). A key underlying principle of this approach suggests that practitioners can direct learners towards opportunities for action by influencing the dynamics of player–task interactions through manipulating relevant performance constraints (Passos, Araújo, Davids, & Shuttleworth, 2008). This approach emphasises the need for understanding the spatial–temporal relations emerging during play from exploratory and adaptive behaviours of players to task demands and goals (Passos, Araújo, Davids, Gouveia, et al., 2008). For example, research has shown how opportunities to shoot at goal in futsal may be shaped by informational constraints, such as the location of the ball, the goal and nearest defenders (Vilar, Araujo, Davids, Correia, & Esteves, 2013). These findings highlight the need for research to enhance our understanding of how to create effective environments to maximise opportunities for learning and practice these important onthe-ball actions in team sports. Other work investigating players’ performance and decision-making yielded valuable information on the nature of spatial–temporal relations emerging from the locations of players (both teammates and opponents), the goal and the ball (Esteves, Oliveira, & Araújo, 2011; Travassos, Araújo, Duarte, & McGarry, 2012; Vilar, Araújo, Davids, & Button, 2012), with relevance to the impact of pitch dimensions on competitive performance. In soccer, the nearest defender of the ball carrier were shown to use information from their current value of their interpersonal distance (ID) to decide when to change speed and disarm the opponent and gain ball possession (Duarte, Araujo, Gazimba, et al., 2010). Similarly, Vilar, Araújo, Travassos, and Davids (2014) showed that when the ID value between a ball carrier and defender decreased, attacking teammates tend to approach the location of the ball carrier and afford a passing opportunity, in order to maintain ball possession. These findings signal the need to determine the emergence of different opportunities for action as pitch dimensions are altered during practice. For example, it would be interesting to understand how pitch dimensions can be manipulated to influence the ID values between attackers and defenders and induce fewer opportunities for maintaining ball possession. Interestingly, Travassos, Araújo, Davids, et al. (2012) showed that more successful passes emerged

when defenders were further away from the passing trajectory of the ball when attempting interceptions. This information can provide some insights on understanding the creation and dissolution of opportunities for passing, particularly when scaled to the value of the distance the ball has to travel to arrive at the defender's closest point to its trajectory (i.e., possible interception point). Recent investigation of how shots emerge in futsal examined the required defender's movement velocity to intercept the ball by calculating the ratio of an opponent's distance to the interception point of ball trajectory and the time the ball takes to arrive at that same interception point (Vilar et al., 2013). Results showed that attackers seek to move closer to the goal and misalign the positioning of an immediate opponent away from an imaginary shooting line between the ball and the goal. This process of dyadic system destabilisation would increase the required velocity for opponents to move in order to intercept a shot on goal. However, more research is needed to identify the informational constraints that support the successful performance of on the ball actions like shooting at goal when faced with an immediate defender. It is relevant also to examine how manipulation of key task constraints (e.g., area of play) during SSCGs may change the information fields during practice, allowing players to detect opportunities to perform adaptively. This study sought to examine the influence of pitch dimensions in SSCGs in shaping opportunities for performers to maintain ball possession, pass to teammates and shoot at goal. By considering specific spatial–temporal informational variables relating to the locations of the goal, the ball, the defenders and the attackers, we sought to examine how opportunities for action unfolded for different attackers during practice games. Based on theoretical principles of ecological dynamics, it was expected that larger pitch dimensions would benefit attackers seeking to maintain ball possession and score goals. In addition, defenders were expected to have fewer opportunities to intercept the ball on pitches of larger dimensions, since they might be further away from attackers. Ultimately, this paper is expected to provide researchers with some key principles to support the use of SSCGs during training in team sports.

Methods Participants Fifteen male undergraduate students (M = 21.87, σ = 1.96 years) with relevant soccer playing experience at an intermediate performance level (M = 9.87, σ = 4.36 years) were recruited from a course of Physical Education and Sports to

Small-sided soccer games participate in this study. No prior information regarding the aims of the study was given to any participant. All participants gave formal written consent. This study was conducted within the guidelines of the American Psychological Association and the protocol was approved by the participating university ethics committee.

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Data collection Participants were randomly grouped into three teams of five players and played 5 v 5 small-sided soccer games in three pitches of varying dimensions. Data collection was performed on three different days, each one assigned to a different pitch dimension. On each day, participants in each team played twice against the other two teams, not performing in more than 2 matches without a recovery period of 5 min (work/rest ratio was 2:1). The areas of play were set according to the official FIFA rules of futsal (an indoor 5 v 5 soccer game, played in a 40 m × 20 m area). Manipulations were made from the baseline area (40 m × 20 m) to one-third larger (52 m × 26 m) and one-third smaller (28 m × 14 m) dimensions, keeping constant the length per width ratio (2:1) of the pitches. These values represented an individual playing area of 39.2, 80 and 135.2 m2 for small, medium and large pitches, respectively (Casamichana & Castellano, 2010; Fradua et al., 2013). All three sessions took place on an artificial turf soccer pitch with smaller soccer goalposts (6 m × 2 m) under all pitch conditions. Performance during a total of eighteen matches (six matches in each condition) was recorded with a digital video camera Samsung HMX-F90 (Samsung Group, Seoul, South Korea) located in the superior plane, and positioned 45° from one of the goal lines. Its frequency was 25 Hz and resolution was 1280 × 720 pixels. The thirty longest offensive patterns of play in which only one team had ball possession were selected in each pitch condition, yielding a total of ninety playing sequences. More precisely, digital video footage files were trimmed to begin at 8 s prior to loss of ball possession (i.e., a shot being intercepted or the ball leaving the field of play). This value was identified in pilot work undertaken and found to be the maximum common length of all playing sequences. Data analysis The bi-dimensional (2D) virtual movement displacement coordinates of all players and the ball were captured through a digitising procedure using the TACTO software package (Fernandes, Folgado, Duarte, & Malta, 2010). This procedure consisted of following the middle point between the feet of

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each player (working point) with a mouse cursor in each video clip, considering that this point represented an estimate of the projection of the player's centre of mass on the pitch (Duarte, Araújo, Fernandes et al., 2010). A bi-dimensional direct linear transformation (2D-DLT) method was used to convert pixel coordinates into actual pitch coordinates (metres) (Duarte et al., 2012). Data were filtered using a Butterworth low-pass filter, with a cut-off frequency of 6 Hz (Winter, 2005). The attackers’ role was defined in each frame by computing the values of distances of all outfield attackers to the ball. This procedure allowed us to define for each moment, the closest attacker to the ball as A1, the 2nd nearest attacker to the ball as A2, the 3rd nearest attacker to the ball as A3, and the furthest outfield attacker to the ball as A4. The value of interpersonal distance between each attacker and the nearest defender was also computed in each time frame (see Figure 1). Lower IDs captured minimal opportunities for ball carriers to maintain ball possession since defenders were very close to the location of the ball. We acquire the values of the shooting interception points by computing of the shortest distance of all outfield defenders to an imaginary line between each attacker and the centre of the goal (see Figure 1). Moreover, we followed the recommendations of Watson et al. (2011) and computed each defender's distances to the interception points, considering half of the opponents’ shoulder-to-shoulder width (0.40 m estimation) and the radius of the futsal ball used in this experiment (0.10 m). Thus, when the values of the opponents’ distances to the interception points were higher than 0.50 m, we subtracted 0.50 m; when the distances of the opponents to the interception points were equal to, or lower than 0.50 m, we considered it equal to 0 m. We also calculated the distance of the attacker to the interception point. Values of the dependent variable relative distance to intercept a shot (Figure 1) were computed according to the following formula: Relative distance to intercept a shot = Shortest defenders’ distance to the shooting interception point/Attacker's distance to the shooting interception point The values of the passing interception points were calculated by recording the shortest distance of all outfield defenders to an imaginary line between A1 and each of the other attackers. Similar procedures previously used were conducted to compute the values of the variable relative distance to intercept a pass (RDipass) (Figure 1):

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Figure 1. Illustration of the variables examined in this investigation: interpersonal distance (ID) between the ball carrier and the immediate defender; relative distance to intercept a shot calculated by the ratio of the distances of the defender to the shooting interception point (D-Sip) and the ball to the shooting interception point (B-Sip); relative distance to intercept a pass calculated by the ratio of the distances of the defender to the passing interception point (D-Pip) and the ball to the passing interception point (B-Pip).

Relative distance to intercept a pass = Shortest defenders’ distance to the passing interception point/Ball carrier's distance to the passing interception point Low values of relative distance to intercept a shot and a pass captured minimal shooting and passing opportunities, respectively, since defenders were very close to the ball path while the ball was far from their interception point. Conversely, high values of relative distance to intercept a shot and a pass suggest the existence of shooting and passing opportunities. The values of each of the three dependent variables (ID, relative distance to intercept a shot and a pass) during each frame of the 8 s time window of the analysed playing sequences were averaged in intervals of 2 s, registering four repeated measures blocks of trials (1, 3, 5 and 7 s). All data were computed with MATLAB® R2009a software (The MathWorks Inc., Natick, MA, USA).

for relative distance to intercept a pass there were only three levels of attackers (passes to A2, A3 and A4). The sphericity assumption for the repeated measures variable (i.e., the within-participants factor) and the interaction effects were checked using Mauchly's test of sphericity. If violations were found, the Greenhouse–Geisser correction was applied (see Schutz & Gessaroli, 1987). Since the groups were composed of equal sample dimensions, the homogeneity of variances requisition was assumed for the between-participants factor (see Field, 2005, p. 324). Effect sizes were reported as partial eta-squared (η2) and significant results were followed up with Bonferroni's pairwise comparisons. The level of significance was set at P < .05. All statistical analyses were computed using SPSS® 20.0 software (IBM SPSS Inc., Chicago, IL, USA).

Results Data presented in this section are organised sequentially by dependent variables.

Statistical procedures All dependent variables were analysed using a three-way mixed-design ANOVA with two between-participants factors being Pitch dimensions (small, medium and large) and Attacker (A1, A2, A3 and A4), and a within-participants factor being Time (1, 3, 5, and 7 s). One should consider that

Interpersonal distance Statistical analyses revealed a significant main effect for pitch dimensions, F(2,348) = 69.54, P < .001, η2 = .29. Post-hoc tests showed that the mean values of ID were significantly lower in small pitches

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η2 = .04, suggesting that, regardless of the pitch dimensions and attackers, there were significant differences in the mean values of ID at the times examined. Post-hoc tests on time showed that its mean values were significantly higher in 1 s (M = 4.92, sx = .11) than in 5 s (M = 4.41, sx = .09, P < .01) and in 7 s (M = 4.21, sx = .09, P < .001). In addition, the mean values of ID were significantly higher in 3 s (M = 4.75, sx = .10) than in 5 s (P < .05) and in 7 s (P < .001). No significant interaction effects were observed for pitch dimensions X time, F(4.79, 833.89) = .69, P > .05, η2 = .01, pitch dimensions X attacker, F(6,348) = .89, P > .05, η2 = .02, and also for attacker X time, F(7.19,833.89) = 1.75, P > .05, η2 = .01. Finally, no significant interaction effects were found for pitch dimensions X attacker X time, F(14.38,833.89) = .40, P > .05, η2 = .01 on ID.

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Figure 2. The influence of pitch dimensions (A), attackers (B) and time (C) on values of interpersonal distance between outfield attackers and their immediate outfield defenders. *P < .05, **P < .01 and ***P < .001. Mean values are expressed in metres and error bars represent standard deviations.

(M = 3.54, sx = .11) compared to medium (M = 4.79, sx = .11, P < .001) and large pitches (M = 5.40, sx = .11, P < .001). In addition, the mean values of ID were also significantly lower in medium pitches compared to large pitches (P < .01) (Figure 2). Statistical analyses revealed a significant main effect for attacker, F(3,348) = 10.32, P < .001, η2 = .08, suggesting that, regardless of the area of play and time, there were significant differences in the mean values of ID between the attackers examined. Post-hoc tests showed that its mean values were significantly higher in A4 (M = 5.20, sx = .13) than in A1 (M = 4.34, sx = .13, P < .001), A2 (M = 4.34, sx = .13, P < .001) and in A3 (M = 4.42, sx = .13, P < .001). Statistical analyses also revealed a significant main effect for time, F(2.40, 833.89) = 14.80, P < .001,

Relative distance to intercept a shot No main effects were found for pitch dimensions, F(2,348) = .26, P > .05, η2 = .01, nor time, F(2.47,860.98) = 1.31, P > .05, η2 = .01. However, analyses revealed a significant main effect for attacker, F(3,348) = 23.05, P < .001, η2 = .17, suggesting that, regardless of pitch dimension and time, there were significant differences in the mean values of relative distance to intercept a shot between the attackers. Post-hoc tests showed that its mean values were significantly higher in A4 (M = 337.80, sx = 28.63), than in A1 (M = 27.73, sx = 28.62, P < .001), in A2 (M = 70.85, sx = 28.62, P < .001) and in A3 (M = 127.42, sx = 28.62, P < .001). No significant interaction effects were found for pitch dimensions X time, F(4.95,860.98) = 1.11, P > .05, η2 = .01, pitch dimensions X attacker, F(6,348) = .46, P > .05, η2 = .01, and for attacker X time, F(7.42,860.98) = 0.67, P > .05, η2 = .01. Finally, no significant interaction effects were found for pitch dimensions X attacker X time, F(14.84,860.98) = 1.28, P > .05, η2 = .02, on relative distance to intercept a shot (Figure 3). Relative distance to intercept a pass No main effects were found for pitch dimensions, F(2,261) = .83, P > .05, η2 = .01, and for time, F(2.35,613.94) = 2.82, P > .05, η2 = .0,1 on relative distance to intercept a pass. However, the analyses revealed a significant main effect for attacker, F(2,348) = 69.54, P < .001, suggesting that, regardless of the pitch dimensions and time, there were significant differences in the mean values of relative distance to intercept a pass between the examined attackers. Post-hoc tests showed that its mean values were significantly higher in A2 (M = 139.40,

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Figure 3. The influence of the factors pitch dimensions (A), attackers (B) and time (C) on the relative distance to intercept a shot (%). *P < .05, **P < .01 and ***P < .001. Mean values are expressed in percentage and error bars represent standard deviations.

Figure 4. The influence of the factors pitch dimensions (A), attackers (B) and time (C) on the relative distance to intercept a pass (%). *P < .05, **P < .01 and ***P < .001. Mean values are expressed in percentage and error bars represent standard deviations.

sx = 14.60), than in A3 (M = 75.61, sx = 14.60, P < .01) and in A4 (M = 36.95, sx = 14.60, P < .001). No significant interaction effects were observed for pitch dimensions X time, F(4.70,613.94) = 1.63, P > .05, η2 = .01, pitch dimensions X attacker, F(4,261) = .74, P > .05, η2 = .01, and neither for attacker X time, F(4.70,613.94) = 0.36, P > .05, η2 = .01. Finally, no significant interaction effects were found for pitch dimensions X attacker X time, F(9.41, 613.94) = 1.46, P > .05, η2 = .02, on relative distance to intercept a pass (Figure 4).

to the goal during long sequences of play of 5-a-side small-sided soccer games. Based on theoretical principles of ecological dynamics, it was expected that larger pitch dimensions would benefit attackers seeking to maintain ball possession and score goals. In addition, defenders were expected to have fewer opportunities to intercept the ball under larger pitch dimensions because of the increased potential for greater IDs from attackers. By considering the specific spatial–temporal relations emerging from the locations of the goal, the ball, the movement of defenders and attackers in long sequences of play, results from this study showed that a decrease in the pitch dimensions afforded greater opportunities to maintain ball possession, while no differences were observed for opportunities to shoot at goal and pass to teammates. In addition, the attacker positioned furthest

Discussion The purpose of this paper was to study whether pitch dimensions shaped the opportunities for maintaining ball possession, passing to teammates and shooting

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Small-sided soccer games away from the ball seemed to have greater opportunities to shoot at goal, and fewer opportunities to maintain ball possession and receive a pass from a teammate. Results showed that as the pitch dimensions decreased, the values of ID between attackers and defenders also decreased during long sequences of play. This task manipulation was expected to decrease opportunities for attackers to keep the ball as observed previously (Duarte, Araujo, Gazimba, et al., 2010; Passos, Araújo, Davids, Gouveia, et al., 2008). In addition, lower ID values might result in smaller values of time-to-contact between attackers and defenders. Previous research suggests that these changes in values for time-to-contact constrain the distance of the pass performed (Correia, Araujo, Craig, & Passos, 2011). According to Travassos, Araújo, Davids, et al. (2012), interception of the ball by a defender is also more likely to occur under low values of IDs. Therefore, a decrease in the pitch dimensions might enhance the difficulty of the ability of ball carriers for keeping ball possession, constraining them to attempt to dribble past immediate opponents. Results also showed that the values of distances of the three attackers closer to the ball than their immediate defenders were lower than the values of the ID of the furthest attacker to the ball and his defender. These data are in agreement with the findings of Vilar et al. (2014), suggesting that the furthest defenders away from the ball attempted to move backwards in the field and block the ball carrier in case he/she successfully dribbled past his/her nearest defender. As an offensive pattern of play unfolded towards a shot at goal, the values of the ID between attackers and defenders tended to decrease. This result is in line with previous research suggesting that, as attackers approach the goal, the value of attacker-defender ID also decreases (Vilar et al., 2014). Smaller pitches are expected to reduce the time needed for attackers to score goals since they are closer to the opponent's goal. Analysis concerning the opportunities to shoot at goal showed no influence of the manipulation of the pitch dimensions. Theoretical underpinnings from Ecological Dynamics provide the rationale to understand how emerging information is critical in supporting action and is suitable for explaining performance in a game context, rather than just describing observed behaviours (Vilar et al., 2012). Analysis of the effects of different practice designs on specific spatial–temporal relations emerging between performers, such as values of ID and relative distance to intercept a shot and a pass, might be of relevance to practitioners seeking to understand how SSCGs might shape decision-making skills of players (Davids et al., 2013). For example, Kelly and

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Drust (2009) reported a higher number of shots performed in 5-a-side soccer games on smaller pitches compared to larger playing areas. Because the authors did not report the number of goals attained in both conditions, one could not infer whether a higher number of opportunities to shoot successfully emerged or, actually, whether players were misjudging their ability to score goals based on lower distance to the opponents’ goal. Possibly, there is an interaction of the dimensions of the pitch and skill level of players, which can account for differences between effective opportunities to shoot and the percentage of shooting actions. Results also showed that the furthest attacker from the location of the ball had greater opportunities to shoot without the ball being intercepted than the other three outfield attackers. This may be a deliberate strategy by the defending team to try to get players behind the ball to establish a barrier between the shooter and the goal and hoping that this will prevent the goal being scored. One strategy would be for defenders to shift laterally to form a “shield” around the goal and this is in line with the findings of Travassos, Araújo, Vilar, and McGarry (2011) who also showed similar patterns of behaviours by defenders. Finally, no main effect of pitch dimensions was observed on the relative distance to intercept a pass. This result is supported by findings from previous research suggesting no differences in the number of passes and targeted passes under small, medium and large dimensioned pitches in 5-a-side and 6-a-side small sided soccer games (e.g. Kelly & Drust, 2009; Tessitore, Meeusen, Piacentini, Demarie, & Capranica, 2006). However, the current research only considered 2D coordinates, failing to acknowledge the existence of an opportunity to pass through aerial displacements of the ball. This might be a limitation of the present study due to technological restrictions. Interesting implications for practitioners can be established from the results of the present research. Specifically, coaches should consider adaptations of pitch dimensions during SSCGs according to the performers’ level of skill. For example, players in the earlier stages of learning soccer (i.e., with low proficiency to perform and make decisions pertaining to soccer) should practice on bigger pitches since this increases their distances to the defenders and, consequently, might also increase the time available for them to act and decide (Correia et al., 2011). Conclusion This paper highlighted the impact of a specific task constraint, such as the pitch dimensions of smallsided soccer games on influencing the available opportunities for on the ball actions such as

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maintaining ball possession, shooting at goal and passing to teammates during long sequences of play. Here, it was shown how analysis conducted with an ecological dynamics perspective may provide a strong theoretical approach to underpin the effectiveness of SSCGs in enhancing game play performances and learning for all ages as well as levels. The manipulation of specific tasks constraints may amplify information supporting players’ behaviours, inviting them to identify and use specific affordances (i.e., opportunities of action) for successful performance. SSCGs can be used as a powerful exploratory platform supported by a constraints-led approach for teaching and training soccer since it may provide representative learning design (Pinder, Davids, Renshaw, & Araújo, 2011), allowing players to acquire and enhance their perceptual system in relation to their motor system (Jacobs & Michaels, 2007). Here, a new method of analysis has been provided which allows scientific community to understand how SSCGs can be designed to enhance the acquisition of the particular individual on the ball skills central to learning and performance in soccer. By systematically manipulating a key performance constraint and examining its consequences on the specific spatial–temporal relations emerging from the interactions of a ball carrier, a defender and a specific target (such as the goal or another attacker), we are able to understand how players’ performances may be constrained through the practice task, without prescribing any explicit given solution (Davids, Chow, & Shuttleworth, 2005). Acknowledgements The authors wish to thank David Costa, Ivo Café, João Teixeira and Tomás Amaral for helping collecting the data and digitising the selected trials. References Casamichana, D., & Castellano, J. (2010). Time motion, heart rate, perceptual and motor behavior demands in small side soccer games: Effects of pitch size. Journal of Sports Sciences, 28, 1615–1623. Chow, J., Davids, K., Button, C., Renshaw, I., & Araújo, D. (2006). Nonlinear pedagogy: A constraints-led framework to understanding emergence of game play and skills. Nonlinear Dynamics, Psychology, and Life Sciences, 10, 71–103. Correia, V., Araujo, D., Craig, C., & Passos, P. (2011). Prospective information for pass decisional behavior in rugby union. Human Movement Science, 30(5), 984–997. Davids, K., Araújo, D., Correia, V., & Vilar, L. (2013). How small-sided and conditioned games enhance acquisition of movement and decision-making skills. Exercise and Sport Sciences Reviews, 41(3), 154–161. Davids, K., Chow, J., & Shuttleworth, R. (2005). A constraintsled framework for nonlinear pedagogy in physical education. Journal of Physical Education New Zealand, 38, 17–29.

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