The purpose of this study was to analyze the day-to-day variance of a typical weekly external training workload of two professional soccer teams from different countries. Twenty-nine players from two professional teams from Portugal and the Netherlands participated in this study. The players’ external load was monitored for 7 weeks, by means of portable GPS devices (10 Hz, JOHAN, Noordwijk, Netherlands). Results revealed that match day -1 (MD-1), i.e. the training day before a match, had significantly (p = 0.001) less training volume (4584.50 m) than the other days. MD-5 (training five days before a match), MD-4 (four days before a match) and MD-3 (three days before a match) were the most intense (390.83, 176.90 and 247.32 m of sprinting distance, respectively) and with large volume (7062.66, 6077.30 and 6919.49 m, respectively). Interestingly, significant differences were found between clubs of different countries (p < 0.05) with the Portuguese team showing significantly higher intensity (sprinting distance) and volume (total distance) in all days with exception of MD-1 than the Dutch team. The results of this study possibly allow for the identification of different training workloads and tapering strategies between countries in relation to volume and intensity. It should be noted, however, that both clubs used a significant tapering phase in the last two days before the competition in an attempt to reduce residual fatigue accumulation.

For sports assessment to be comprehensive, it must address all variables of sports development, such as psychological, social-emotional, physical and physiological, technical and tactical. Tactical assessment has been a neglected variable until the 1980s or 1990s. In the last two decades (1995–2015), the evolution of tactical assessment has grown considerably, given its importance in game performance. The aim of this paper is to compile and analyze different tactical measuring tools in team sports, particularly in soccer, through a bibliographical review. Six tools have been selected on five different criteria: (1) Instruments which assess tactics, (2) The studies have an evolution approach related to the tactical principles, (3) With a valid and reliable method, (4) The existence of publications mentioning the tool in the method, v. Applicable in different sports contexts. All six tools are structured around seven headings: introduction, objective(s), tactical principles, materials, procedures, instructions/rules of the game and published studies. In conclusion, the teaching–learning processes more tactical oriented have useful tactical assessment instrument in the literature. The selection of one or another depends some context information, like age and level of expertise of the players.

This study tested the use of two pedagogical principles of Game-based approaches, representation and exaggeration, in the context of game performance of U10 soccer players. Twenty-one players participated in two 3 vs. 3 small-sided games. The first small-sided game was modified by representation. The second small-sided game was modified by enhancing the penetration of the defense tactical problem for invasion games. Decision-making and execution were assessed using the Game Performance Evaluation Tool. No significant differences were observed between games in the number of decision-making units related to keeping possession, nor in those related to penetrating the defense. No significant differences were observed in any execution ability (ball control, passing, dribbling and get free movements). The findings suggested that both games could provide similar degeneracy processes to the players for skill acquisition (specific and contextualized task constraints in which they could develop their game performance and the capability to achieve different outcomes in varying contexts). Probably both games had similar learner-environment dynamics leading players to develop their capabilities for adapting their behaviours to the changing performance situations. More research is necessary, from the ecological dynamics point of view, to determine how we should use small-sided games in Game-based approaches.

6This study examined players' tactical behaviours based on core tactical principles during 7 small-sided and conditioned games (SSCG) with and without floaters on the sidelines. 8 A total of 24,068 tactical actions performed by 168 Under-17 academy soccer players 9 were assessed using the System of Tactical Assessment in Soccer (FUT-SAT; Teoldo, 12 revealed that players showed different tactical behaviours depending on the SSCG 13 format and playing phase. In "Floaters off" SSCG, players more frequently performed 14 the core tactical principles of concentration during the defensive phase and penetration 15 for the offensive phase of play creating more opportunities for 1 vs. 1 situations. In 16 contrast, in the "Floaters sidelines" SSCG, players made more effective use of playing 17 space (width and length) in the opponent's half during the offensive phase; and limited 18 the space for the opponent by compacting the defence in their own half (defensive unity) 19 due to numerical disadvantage during defensive phase. Findings suggest that the use of 20 floaters (on the sidelines) encourage players to keep ball possession during offensive 21 organisation, as well as promote the team's defensive stability by decreasing the spaces 22 between teammates during defensive organisation.23 24

Grouping people according to chronological age is popular in fields such as education and sport. Athletes who are born in the first months of the year usually have cognitive and physical development differences in contrast to those born in the last months of the same year. That is why competitive teams tend to select older players more often than youngsters. Age differences between athletes born in the same year as well as an over-representation of older players are known as the Relative Age Effect. This effect is extensively described in young and elite team sports such as basketball, volleyball or, ice-hockey, as well as in soccer. The purpose of this study is to examine the state-of-the-art of the Relative Age Effect in youth and elite soccer players. This review summarizes recent research articles on the Relative Age Effect related to competitive soccer from 2010 to 2016. The systematic literature search was conducted in four databases: SPORTDiscus, Medline, EBSCO host and Google Scholar. Although causes and final solutions have not been clearly achieved yet, it is necessary to continue investigating this phenomenon in order to provide a starting point for future research.

Specific football drills improve the development of technical/tactical and physical variables in players. Based on this principle, in recent years it has been possible to observe in daily training a growing volume of small-sided and conditioned games. These games are smaller and modified forms of formal games that augment players’ perception of specific tactics. Despite this approach, the assessment of players’ knowledge and tactical execution has not been well documented, due mainly to the difficulty in measuring tactical behavior. For that reason, this study aims to provide a narrative review about the tactical assessment of football training by using representative tasks to measure the tactical expertise of youth football players during small-sided and conditioned games. This study gives an overview of the ecological approach to training and the principles used for representative task design, providing relevant contribution and direction for future research into the assessment of tactical expertise in youth football.

Using self-determination theory as a guiding framework, this study analyzed the impact of the Sport Education Model in self-determination and motivation, psychological basic need thwarting, enjoymentsatisfaction, boredom, and intention to be physically active in Physical Education (PE) of secondary school students in Spain. Two groups were selected for the study: an experimental group (EG; n=43), which received 19 volleyball lessons following the Sport Education Model, and a control group (CG; n=43), which received 19 traditional Physical Education lessons. Pre- and post-intervention measures were taken in both groups. The results showed significant improvements in intrinsic motivation in EG. The results are discussed, and the suitability of the Sport Education Model to improve self-determined behaviors in Physical Education is emphasized.

10The purpose was to analyze the effect of modification strategies based on the pedagogical principles 11 of the Teaching Games for Understanding approach on tactical constraints of four 3v3 soccer small-12 sided games. The Game performance of 21 U-10 players was analyzed in a game similar to the 13 adult game; one based on keeping-the-ball; another on penetrating-the-defense; and one on 14 attacking-the-goal. Results showed that the modification of tactical problems had a significantly 15 different effect on tactical-context adaptation (p < .005) and for developing passing, dribbling, 16 shooting and getting free skills (p < .005). Small-sided games focused on keeping-the-ball and 17 attacking-the-goal revealed a tactical complexity that was significantly different to the rest of the 18 games (p < .005). With regard to the further investigation of the quality representative task design, 19 these findings highlight the importance of knowing the effects that modification has on tactical 20 constraints and the tactical complexity/technical difficulty involved in developing behaviors. 21Keywords: small-sided games, tactical problems, constraints, game performance . 22 23 24 25 Small-sided games (SSGs) are widely used as a methodological strategy in the teaching of