The main objective of the study was to compare the PA levels in extracurricular environment in U-12 soccerplayers using the accelerometer, as well as to analyze the decision making and execution after the application of two teaching models (DI vs. TGfU). According to the initial hypotheses, TGfU shows significantly higher levels of light physical activity than DI. However, no meaningful differences were found in determinant levels (moderate and vigorous PA). According to the tactical principles, keeping possession of the ball presents significantly higher levels of physical activity in the TGfU compared with the DI, less the sedentary PA that is higher in the direct instruction model. Concerning the second hypothesis, for decision-making, the AonB presents improvements in the TGfU, but it is not significant, while the AofB presents improvements related to DI both in decision-making and in execution.
4.1. Physical Activity
The investigation shows significant light PA levels in the TGfU compared to the DI, and the physical activity levels moderate, vigorous, and MVPA were higher in the TGfU than the DI, but they are not significant. The only variable in which the DI is superior to the TGfU, although not significantly, is sedentary physical activity; in the direct instruction, the players are more inactive.
While the levels of physical activity in the training sessions are not significant between pedagogical approaches, analyzing the training sessions according to the tactical principles between the TGfU and DI, the principle of keeping the ball using the TGfU is the most significant for developing MVPA and less sedentary PA. In the other tactical principles, penetrating the defense and attacking the goal, the DI had higher levels of physical activity, but they are not significant.
The results of the present study do not comply with the recommendations proposed by international institutions to overcome 50% of the time in MVPA [
31], since the TGfU and DI players accumulated 37% of the time in MVPA. Despite this, in this study, the percentage of sedentary PA was lower in the TGfU than in the DI.
Comparing MVPA levels based of previous studies, our research presents an improvement in MVPA levels compared to [
32], who measured physical activity among 6–12-year-old children during soccer practice in one hour with 23% of MVPA, and [
33], with a soccer training of 50 min, obtained 33%. On the other hand, [
34] obtained better results of MVPA than our research. These studies present an average between 49% and 54% of MVPA during one hour of training, respectively. These results improve our study, since our research has a sports practice time of 80 min. Finally, we found MVPA levels comparable to our study in [
35] with 36.8% or less than 50% of MVPA in soccer [
36].
Analyzing the levels of physical activity with the application of pedagogical approach, [
21] obtained significant differences in the percentage of MVPA in the comparison of directed instruction approaches with tactical methodologies (47.08% vs. 31.89%) in hockey, using the triaxial accelerometry RT3 and the System for Observing Fitness Instruction Time (SOFIT) [
37]. These results are higher because the players had previous experience in tactical methodologies in contrast to our sample, since the participants were new to training using the TGfU methodology, during which, while assimilating the learning, physical activity is less. After all, they are standing longer. As the sessions progressed, this downtime was reduced. Nevertheless, [
16] used the same instruments as Harvey in sports such as netball, rugby, and soccer, obtaining higher levels than this study in moderate to vigorous physical activity (50%). With other physical activity assessment instruments such as SOFIT, the group with tactical methodology presented better levels of MVPA compared to the traditional group. However, for the comparison of the studies presented, the use of different instruments to measure it should be considered.
In the present study, modified games based on the TGfU were designed in 3 vs. 3 and 4 vs. 4 format, with field measurements similar to those of [
38] (30 × 25 m); the players were able to perform more movements at high intensity than at medium or low intensity compared to the group with DI training, highlighting the sessions in which the tactical principles of keeping the possession of the ball with an MVPA of 43.60% against 38.05%, respectively, were developed. These types of designs through modified games allow greater possibilities of contact with the ball, with a significantly greater increase in MVPA in 3 vs. 3 formats with 11.64 min [
39]. The modified games present improvements at a physical, technical−tactical, and physiological level [
19]. Nevertheless, to obtain some levels of significant MVPAs, we have to consider a progression and evolution of tactical complexity [
20] with participation in small groups (for example, 2 × 2 or 3 × 3) where the actions of the players in contact with the ball are more constant. Our training sessions were designed in reduced 3 × 3 or 3 × 3 games with a joker and varying ball touches allowing players to constantly move increasing levels of physical activity.
The use of various types of accelerometers used in other studies, such as RT3 in [
21] or wGT3X in our study, differs in showing superior results in tactical models compared with traditional ones. We can establish that accelerometers can be more sensitive to outpatient activities, such as walking and running, compared to specific activities, such as shooting, passing, or dribbling, and are potentially the most frequently performed movements in soccer. This is because the accelerometer reads movement from the area of the body where the device is placed instead of its parts [
40]. We can especially consider in the first sessions that the time of placement of the accelerometers in the players was greater due to learning in the correct position so that they could effectively measure the levels of physical activity. As the sessions progressed, the placement of the accelerometer became faster.
Finally, as it is a novel methodology, more practice is needed by players and coaches to increase MVPA levels, since without previous experience, players require more time in tactical awareness for the assimilation of tactical components during the training. Longer tactical awareness time translates to longer sedentary PA time. Despite this, in this study, the percentage of sedentary PA was lower in the TGfU than in DI.
4.2. Game Performance Evaluation Tool (GPET)
The analysis of the tactical evaluation instrument (GPET) between both approaches can highlight in the TGfU in the AonB significant improvements in the execution success with a change percentage of 42.04% with 12.5% of the DI. However, we did find significant differences in the unsuccessful actions of TGfU with the DI in the execution on AonB with a percentage of change between the pre-intervention phase and the subsequent one of −62.6% and 12.4%, respectively.
On the other hand, assessment the AofB, TGfU presents significant differences in the percentage of change in all the variables with the DI, both the success in the execution in decision-making (23.3% and −14.3% respectively) and decrease in unsuccessful of decision-making (−72.2% and 32.72). Besides, there is an improvement in the success of the execution of the uncheck in the TGfU compared with the DI (36.61% and −9.9%) and a reduction of unsuccessful executions of unchecks (−68.3% and 23.0%), respectively. This may be due to many movements the AofB have to make to find free spaces and be able to receive the pass from their partner.
In the decision-making process, we can establish in our study that the attacking player without the ball trained by TGfU performed an improvement in decision making in unmarking, as established by [
14], who obtained similar results, in percentages, to the results in the present study on the effectiveness of decision making (78.1%) and execution (66.7%) with the AofB. Players at these ages increase the number of supports, [
41] looking for the free spaces of a rival brand, to be able to receive the ball from their teammates and progress to attack the goal. Similar results were found in the support and fixing of variables in other studies [
42]. Through TGfU training, players understand the effective way to perform unchecks, increasing the amount of unchecks and having the right decision making.
Players make more passes, reduce driving, and stop being so individualistic [
28], giving greater importance to support, increasing their number and success, being an essential action in the evolution of the player [
41]. Supports and unchecking are the skills that evolve the most as age increases and have greater importance in their evolution [
41]. These actions are especially important because most of the time, the players hardly have contact with the ball [
43].
Through the design of training sessions with the use of modified games in numerical superiority, we can increase decision making and the execution of unchecks in our research. We can affirm better results in decision making and pass execution, promoting the creation of free spaces by the AofB, less pressure to pass brand free companions, and carrying out a better execution, as well as improving support and uncheck movements [
44].
At this time (U-12), the playing roles (defense, middle, and forward) are appreciated [
43], highlighting the greater participation in those players with a higher level of experience, thus performing cooperative actions with their peers and promoting game performance [
14,
28]. By ages, [
45] in U-10, the AonB presents a success in the executions of the 80%, as well as in U-14 (88%) [
41]. For its part, the AonB also obtained similarity in decision making in driving, although no significant differences were found. In this study, this is reflected in the fact that the passes are shown backwards or that the field of play is given a greater amplitude, to keep the ball, change direction, or continue and deepen on the same side.
Measure up to pedagogical approaches, [
44] obtained significant differences in favor of non-linear pedagogies versus management models throughout 14 sessions through games modified in the AonB in the pass and driving variables, unlike the results of the investigation. This may be due to the tactical awareness in which the players through the feedback are aware of the mistakes that the players make, improving decision making and execution to promote meaningful learning. In our research, players had more problems assimilating corrections when the player had the ball in them, and tactical awareness was longer so that players could assimilate the correct aspects.
Studies with other tactical analysis instruments [
46] used TSAP [
47] in U-14 children with a TGfU soccer teaching unit. The results suggest a strong interrelated process between video-based performance analysis and physical practice, with important comments being a tool to improve game performance in a short period. In our case, video-based performance analysis can be very effective to use during tactical awareness to check for errors that have occurred throughout the modified game and improve it later when the activity is repeated. Other instruments such as the FUT-SAT [
48] compare the tactical behavior of soccer between U-12 and U-13, without finding significant differences in the offensive aspect [
49].
Using the Game Performance Evaluation Tool in other sports, such as futsal, [
50] investigated the performance of the game and differences in decision-making and execution of the AonB in the approval and management of soccer skills with TGfU, highlighting an improvement in pass decision making after the intervention in players with no prior experience in the approach, obtaining results similar to those of our research. This may be because these students developed more improved knowledge, leading to more tactically appropriate decisions [
51]. In our case, the players also had no previous experience in the model and the application period of 6 weeks was too short to obtain more extensive results.
Other sports, such as basketball [
52], compare TGfU and DI through the systematic observation of decision making and the real-life execution of the game, proposed by [
53] and adapted from [
54] in U-14 players. There are significant differences in decision making after the training program with a percentage change in the TGfU (42.8%) compared to the DI methodology (0%).
This study has some limitations; the sample, in which thirty players participated, is small. Moreover, the training of the coach and the players were accustomed to direct instruction and needed adaptation to consolidate the TGfU. Future studies should be expanded in the extracurricular field, with a larger sample with annual planning, also compared by gender, as there are more and more girls linked to soccer, and a comparison between the categories of the initiation stages (U-8 and U-10).
As practical implications, the results of this study allow us to highlight the importance of applying models such as TGfU, which encourages a reduction in sedentary activity. As well as an improvement in the tactical knowledge of AonB as AofB.
As teaching research and an innovation prospect, it would be interesting to expand this project in the extracurricular scope, with a larger sample, as well as to carry out annual planning, also comparing sports practice by gender, as there are more and more girls playing soccer. Moreover, a comparison could be made between the categories of formative soccer, highlighting especially the initiation stages (U-8 and U-10), to assimilate the learning and have them consolidated in stages of later formation (U-12, U-14, or U-16).