Shooting Ball Accuracy with U16 Soccer Players after Preparation Period

The main aim of the research was to identify a level of quantitative changes of the shooting ball accuracy with U16 soccer players under the infl uence of the programmed soccer training of six weeks a summer preparation period. The training programme covered 44 training units. The research was made on a sample of 120 soccer players. For the assessment of shooting ball accuracy the three tests were used: Straight foot accuracy in the vertical target, Elevation foot accuracy in the vertical target and Elevation head accuracy in the vertical target. In the area of comparative statistics, used t-test for big paired samples. Based on the numerical values of the t-test it can be concluded that there are statistically signifi cant diff erences in all three variables to estimate the shooting ball accuracy. In this research the authors were guided by the fact that this kind of training program in preparation period, where dominates the situational model training is very eff ective in terms of raising the shooting ball accuracy with U16 soccer players, because the model that is used in this training period abounds in exercises in which dominates the shooting ball accuracy, in straight and elevation line. The obtained results can be directed towards innovation plans and programs in the preparation period, and the adaptation of the same needs of the respective population.


Introduction
Soccer is the most popular sport in the world, with close to 270 million participants (Akbari, Sahebozamani, Daneshjoo, & Amiri-Khorasani, 2018). Soccer is a sport that is characterized by numerous and varied complex dynamic kinesiology activities that are characterized by a large number of cyclic and acyclic movements (Gardasevic, Bjelica, & Vasiljevic, 2017;Sermaxhaj, Popovic, Bjelica, Gardasevic, & Arifi , 2017). Soccer consists of various types of movements and actions like tackling, jumping, sprinting and kicking (Reilly, Williams, Nevill, & Franks, 2000;Amiri-Khorasani, Osman, & Yusof, 2009). Th e high specifi city of loading, decision making under pressure of opponents (Hulka, & Weisser, 2017) in all four moments of play, possession of the ball, the opponent's possession of it, the transformation aft er winning the ball and the transformation aft er losing the ball depends on the ability of players to perform certain movements of varying intensity, in diff erent directions and the diff erent sections of the fi eld (Gardasevic, Bjelica, & Corluka, 2018a;Gardasevic, Bjelica, & Corluka, 2018b). Th ey must have developed basic and specifi c motor abilities . Level of adaptations and time to reach at degree of adaptation according to training objectives are determining type of training which coaches may choose (Amani, Sadeghi, & Afsharnezhad, 2018). One of the specifi c motor skills, which should be at a high level, is a shooting ball accuracy.
Th e shooting ball accuracy is considered as the very important ability of the soccer player. A good soccer player is the one who is able to perform complex situational-motor actions coordinated in a certain space and in time period as short as possible and with good shooting ball accuracy (Corluka et al., 2018).
Th e main objective of this study was to determine the level of quantitative changes of the shooting ball accuracy with U16 soccer players, under the infl uence of a programmed soccer training which included one preparatory period of forty-two days.

Methods
Th is was a longitudinal study with an aim that in the two time-varying points determine quantitative changes of the shooting ball accuracy in soccer players (15 years±6 months) under the infl uence of programmed training process, which included a summer preparation period for the competition season in a unique cadet league of Montenegro and the cadet league middle region of Montenegro. Th e training program lasted 42 days and was carried out on the auxiliary soccer fi eld of FC Sutjeska-Niksic. Th e training program included 44 trainer units, within which 8 friendly matches were played.
For data processing only the results of those respondents who have undergone a complete program of work and who have joined the initial and fi nal measurement are taken. Th is study included a sample of 120 young cadet soccer players of 4 teams, all from Niksic. Parents of all participants signed a consent form, which was in accordance with the Helsinki Declaration. Before programmed work all respondents had passed medical check-ups to make sure they could access the training process. When selecting the instruments (tests) it was taken into account that they meet the basic metric characteristics, which means the appropriate age and objective material and spatial conditions. For the assessment of the shooting ball accuracy, the following tests were used: 1. Straight foot accuracy in the vertical target; 2. Elevation foot accuracy in the vertical target; 3. Elevation head accuracy in the vertical target.
Straight foot accuracy in the vertical target is performed in an open or closed space of minimum dimensions of 30 x 5 meters. Th e participant stands with a ball 25 meters from the goal. He leads the ball 5 meters with two touches and shoots it on goal from 20 meters away from the goal. Th e participant has 10 knocks on the goal. Points are: hit the central goal (the goal is 1.5 m wide)=3 points; hit the goal from the side (the goals are 1 m wide)=2 points; hit above and beside goal=1 point.
Elevation foot accuracy in the vertical target is performed on the football fi eld. Th e participant stands with a ball 30 meters from the goal. He leads the ball 5 meters with two touches and shoots it on goal from 20 meters away from the goal. Th e participant has 10 knocks on the goal. Points are: hit the goal that the ball does not reach the ground in its path=3 points; hit in the goal frame that the ball does not reach the ground in its path =2 points; hit above and beside goal=1 point; if the ball on its way reaches the ground before entering the goal=1 point.
Elevation head accuracy in the vertical target is performed in an open or closed space of minimum dimensions of 15 x 5 meters. Th e participant stands with a 15 meters from the goal. He leads the ball 5 meters his head with two touches and shoots it on goal his head from 10 meters away from the goal. Th e participant has 10 knocks on the goal. Points are: hit the goal that the ball does not reach the ground in its path=5 points; hit the goal that the ball has one touch the ground in its path=3 points; hit in the goal frame and missed the goal=1 point; hit above and beside goal=1 point; if the ball on its way reaches the ground before entering the goal=1 point.
Considering that these are cadet age players (15-years±6 months), in a sensitive period of psychophysical development, program is tailored specifi cally to their age, taking into account the time spent in the previous training process. Time structure of the training ranged from 60 to 120 minutes, depending on the goals and objectives of the training unit and it was divided into 3 phases: 1. Introductory-preparatory part (25-30% of the duration of training); 2. Th e main part (60-65% of the duration of the training); 3. Th e fi nal part (up to 10% of the duration of training) In the introductory-preparatory part of the training the emphasis was on raising the operating temperature in children. As a tool, various elementary games with a ball were used that enabled work on the elementary basics of technique and tactics, also the various polygons with exercises the shooting ball accuracy were used. A variety of games and exercises to increase joint mobility and strengthen muscles also applied at this stage.
At the fi rst stage of the main part of the training the intensity is slightly increased compared to the warm-up phase and the training program was implemented through a variety of ball games. With a game method, the respondents were taught and practiced soccer skills through a large number of repetitions. At the second stage of the main part of the training the players mostly had a free game on two goals that allowed them creative activities and highlight of individual, imagination, independent thinking and hard work, applying the elements that teach by the method of the game from the fi rst stage of the main part, and thus strengthening the willing quality. At this stage of the training the intensity was the greatest. At the final part of the training the task was lowering the physiological curve to an optimum level, and low-intensity activities were used: stretching and relaxation exercises, competitive game of penalty kicks, free kicks.
Data obtained from the survey were analysed using descriptive and comparative statistics. In the area of descriptive statistics for each variable both in the initial and the fi nal state central and dispersion parameters were processed as well as measures of asymmetry and fl atness. Th e hypothesis of normal distribution of results was tested on the basis of Kolmogorov and Smirnov test. In the area of comparative statistics, to determine diff erences in the variables used to estimate the shooting ball accuracy at the start (initial state) and at the end (fi nal state) of the training program in the preparation period, we used the discriminative parametric procedure Student's t-test for large dependent samples.

Results
In Tables 1 and 2  First the central and dispersive parameters of variables for assessing the shooting ball accuracy in the initial state were analysed (Table 1).
By analysing the central and dispersion parameters of variables for assessing the shooting ball accuracy in the initial state-values of Kolmogorov and Smirnov test shows that the results in the variable EFAVTI-elevation foot accuracy in the vertical target, have statistically signifi cantly deviation from the normal distribution. For the other two variables for asse-ssing the shooting ball accuracy -it can be seen that the range of results is quite large.
Central and dispersive parameters of variables for estimation of the shooting ball accuracy in the fi nal measurement showed the following values (Table 2).  Based on the results gained, it can be noted that there are statistically signifi cant diff erences in all variables for estimation of the shooting ball accuracy, and therefore can be said that there was statistically signifi cant positive partial eff ects of the training program in the preparation period, and the t-test values were signifi cant at the reliability level p<0.01 for all variables for estimation of the shooting ball accuracy.

Discussion
Th e aim of this study was to, based on the training work program of forty-two (42) days, determine the level of transformation of the shooting ball accuracy with U16 soccer players, under the infl uence of a scheduled soccer training that included one preparatory period. Th is study included a sample of 120 young cadet soccer players of 4 teams, all from Niksic, competing in a unique Montenegrin cadet league and in the middle region league of Montenegro. On the basis of the obtained parameters it can be concluded that the statistically signifi cant partial quantitative eff ects (changes) in all the variables for estimation of the shooting ball accuracy obtained as a result of the training program applied in the preparation period. Th e method of work that has been applied in this training program abounds with exercises dominated by movements with ball in various directions, players are oft en found in unexpected situations, so that the positive transformations are not unexpected (Gardasevic, Bjelica, & Vasiljevic, 2016).
Based on the results of t-test for large dependent samples, with the variables for estimation of the shooting ball accuracy the statistically signifi cant diff erences were determined in all pairs of variables between the initial and fi nal states, at the level of statistical signifi cance (signifi cance), p<0.01. It can be concluded that the training program of work in preparation period has led to the positive transformation in all variables that were estimating, by the structure of a hypothetical setting of the models, the shooting ball accuracy. In this research, the authors were guided by the fact that such a training program of work in preparation period is a very effi cient way of working in terms of raising the level of the shooting ball accuracy with By analysing the central and dispersive parameters of variables for estimation of the shooting ball accuracy in the fi nal stage-it may be noted that the values of arithmetic means are in all three variables at a higher level than in the initial state. Th e values of Kolmogorov and Smirnov test shows that the results in the variable SFAVTF-straight foot accuracy in the vertical target, have statistically signifi cantly deviation from the normal distribution. Th ese results show how that the shooting ball accuracy is complicated for U16 soccer players.
To determine the statistical signifi cance of diff erences in arithmetic means (partial quantitative changes) of variables for estimation of the shooting ball accuracy, the t-test was applied to for large dependent samples. Th e values of t-test were on the level of signifi cance (Sig.) from 0.01 (p≤0.01) in all the variables for the evaluation of the shooting ball accuracy. Th e diff erences of arithmetic means of the initial and the fi nal measurement of variables for evaluating the shooting ball accuracy are shown in Table 3. cadet soccer players. Th e authors conclude that the summer period of 42 days, at cadet soccer players, with such training work program, is optimal for lift ing the shooting ball accuracy to the level required for the competition. Th e gained results can be directed towards innovation of plans and programs of work in the preparation period, and adjusting the same to the needs of the talented players, because European top-level soccer clubs are continually looking for the most talented players.