Journal of Human Kinetics volume 54/2016, 163-171 DOI: 10.1515/hukin-2016-0047 163 Section III – Sports Training Optimization of Game Formats in U-10 Soccer Using Logistic Regression Analysis by Mario Amatria1, Daniel Lapresa2, Javier Arana3, M. Teresa Anguera4, Belén Garzón2 Small-sided games provide young soccer players with better opportunities to develop their skills and progress as individual and team players. There is, however, little evidence on the effectiveness of different game formats in different age groups, and furthermore, these formats can vary between and even within countries. The Royal Spanish Soccer Association replaced the traditional grassroots 7-a-side format (F-7) with the 8-a-side format (F-8) in the 2011- 12 season and the country’s regional federations gradually followed suit. The aim of this observational methodology study was to investigate which of these formats best suited the learning needs of U-10 players transitioning from 5-a- side futsal. We built a multiple logistic regression model to predict the success of offensive moves depending on the game format and the area of the pitch in which the move was initiated. Success was defined as a shot at the goal. We also built two simple logistic regression models to evaluate how the game format influenced the acquisition of technical- tactical skills. It was found that the probability of a shot at the goal was higher in F-7 than in F-8 for moves initiated in the Creation Sector-Own Half (0.08 vs 0.07) and the Creation Sector-Opponent's Half (0.18 vs 0.16). The probability was the same (0.04) in the Safety Sector. Children also had more opportunities to control the ball and pass or take a shot in the F-7 format (0.24 vs 0.20), and these were also more likely to be successful in this format (0.28 vs 0.19). Key words: soccer, adaptation, child, observational methodology, logistic regression. Introduction The potential benefits of sport for children and can also affect their sensation of competence extend beyond the mere practice of sport (Holt et (Clemente et al., 2012). al., 2006). Children who take part in learning- There is broad consensus across soccer based sports activities, i.e. activities tailored to federations in Europe and indeed worldwide that their learning needs, will develop better motor, young soccer players should play small-sided situational, psychological and social skills than games, as these allow for better skill development children who take part in activities largely and understanding of individual and group focused on results (Holt et al., 2012). In addition, tactics. There is, however, variation between results-based sporting activities may even have a countries and even within countries, as the bodies detrimental outcome on the overall learning responsible for organizing regional youth leagues process (Malina, 2001). In soccer, the relationship are frequently free to decide which competition between the number of players and the size of the format to use. This is the case in Spain, for pitch influences a child’s ability to perform example, which has 19 regional federations. A technical-tactical tasks effectively and efficiently, wide range of game formats are used across the 1 - Department of Physical Activity Sciences and Sports. Pontifical University of Salamanca, Spain. 2 - Department of Educational Sciences. University of La Rioja, Spain. 3 - Department of Education. International University of La Rioja (UNIR), Spain. 4 - Department of Behavioural Sciences Methodology, Institute of Brain, Cognition and Behavior. University of Barcelona, Spain. Authors submitted their contribution to the article to the editorial board. Accepted for printing in the Journal of Human Kinetics vol. 54/2016 in December 2016. 164 Optimization of Game Formats in U-10 Soccer Using Logistic Regression Analysis country up to the junior level (12-14 category), McGarry, 2007). which is when the standard 11-a-side format (F- Although many clubs and federations 11) is introduced. At the III Grassroots Soccer now use the F-8 rather than the F-7 format, there Conference organised by the Royal Spanish Soccer is no clear evidence on which format offers the Association (RFEF) in 2005, representatives of the most favorable learning environment for young association discussed the possibility of replacing soccer players. In this study, we performed an the format used at the time for U-12 players, i.e. 7- exploratory study to examine whether the a-side soccer (F-7), with 8-a-side soccer (F-8), recently introduced F-8 format provided better which was considered to be more balanced. The learning and skills development opportunities F-8 format was introduced for all youth soccer among U-10 soccer players who had just moved matches played between teams representing up from F-5. Spain’s 19 regions in the 2011-2012 season, and logically, the different federations throughout Material and Methods Spain followed suit by gradually introducing this The observational design employed was format for regional leagues. As mentioned, the nomothetic (observation of three first-year U-10 situation across Europe varies considerably, with soccer teams), multidimensional (focus on different small-sized game formats used for numerous dimensions that comprised the different age groups. It is therefore important to observation instrument used), and consisted of analyze specific formats in specific age groups to inter-sessional and intra-sessional follow-up (i.e. determine their impact on learning. In the current analysis of successive matches for each of the study, within the framework of an observational three game formats studied) (Anguera et al., methodology design (Anguera, 1979), we applied 2011). Observation was non-participatory, active, a series of logistic regression models to investigate scientific and characterized by total perceptivity. whether F-7 or F-8 was better suited to the Participants learning needs of children aged 8-10 years moving We used an intentional sample drawn up from futsal (F-5). The matches analyzed took from an F-5 competition organised by one of place at the end of the 2011-2012 season between Spain’s regional federations for players in their teams about to move up from F-5 to the newly first year of the U-10 category. Participation in this introduced F-8 format. competition was determined by the number of Considering the multiple dichotomous matches the teams had won in the regional league variables of interest in studies of sport, together (F-5). The three top-ranking teams in the with the potential offered by logistic regression tournament were then invited to play in an F-5, F- analysis applied to observational methodology 7 and F-8 triangular tournament. To ensure inter- (Lapresa et al., 2016), recent years have witnessed sessional consistency, the following parameters a marked increase in the number of observational were kept constant across all matches: a pitch (a methodology studies applying logistic regression university sports hall for the F-5 tournament and analysis to the field of sport and physical activity a standard artificial grass pitch for the F-7 and F-8 (Tenga et al., 2010; Arana et al., 2013; Casal et al., tournaments), match length (50 minutes for F-5 2015). We built a multiple logistic regression and 30 minutes for F-7 and F-8), a referee (the model to predict the success of offensive moves same for all matches), ball size (no. 5 for F-5 and by players aged 8-10 years in three game formats no. 4 for F-7 and F-8), and division of the pitch (F-5, F-7 and F-8) according to the zone of the into equivalent zones using rubber adhesive tape pitch in which the move was initiated. Success and cones placed just outside the perimeter of the was defined as a shot at the goal (Castellano et al., pitch. 2012; Lapresa et al., 2013a). In addition, we built Observation instrument two simple logistic regression models to analyze We used the observation instrument the technical-tactical performance of players designed to study technical-tactical actions in according to how well each of the game formats grassroots soccer. The instrument is based on met their learning needs (Yates and Williams, different versions of the Football Observation 2009; Stratton et al., 2004) and influenced the System (SOF, after its initials in Spanish) (Jonsson chances of a successful outcome (Lames and et al., 2006). It is a combined field-format category Journal of Human Kinetics - volume 54/2016 http://www.johk.pl by Mario Amatria et al. 165 system, with exhaustive, mutually exclusive the data. Agreement between data was analyzed categories nested in a multidimensional field using Cohen's kappa statistic in GSEQ (v.5) format structure (Anguera and Hernández- following the recommendations of Bakeman and Mendo, 2013). The pitch (40 x 20 m for F-5 and 70 Quera (2011). Each of the data sets (team x 40 m for F-7 and F-8) was divided into three observed/match) produced for the three game equally sized horizontal sections and three formats yielded a kappa statistic of over 0.86, equally sized channels running the length of the which according to the criteria of Prieto et al. pitch. The three horizontal sections were defined (2014) guaranteed the agreement between them. as the Safety Sector (defending third), the Within the generalizability theory Creation Sector (midfield third), and the (Cronbach et al., 1972), we used the design Definition Sector (attacking third). The creation Category / Match (C/M) for the three game sector was further divided into two subsections formats. The relative generalizability coefficients comprising zones 40, 50 and 60 on one side of the for each of the game formats (e2 = 0.94 for F-5; e2 = half-way line (Own Half) and zones 41, 51, 61 on 0.97 for F-7; and e2 = 0.95 for F-8) indicated a high the other side (Opponent’s Half) (Table 1).