SENSITIVITY OF THE SPEED EVALUATION TESTS OF CARRYING THE BALL IN YOUTH SOCCER PLAYERS

This research is aimed at examining sensitivity of the speed evaluation tests while carrying the ball. The research included 76 male examinees, aged 17 years (+/6 months), who were divided into two qualitatively different subgroups. For determining the speed while carrying the ball, the tests of M type of carrying the ball between cones and slalom ball carrying with a pass were performed. The obtained results proved that the examinees from the group of more successful soccer players (Group 1) scored better on the applied tests when compared to the results of the group consisting of the soccer players from lower ranked clubs and who are not national team members (Group 2). High values of the result homogeneity in the two groups (for the Groups 1 and 2 it was 75% and 68.75% respectively) lead to the conclusion that this ability is essential characteristics of young soccer players. The coefficient of discrimination of 0.269 for the results of M type test and 0.197 for the results of the test of carrying the ball with a pass indicate that the results of the two tests provide possibility to qualitatively distinguish youth players. Therefore, it can be concluded that as a technical element, carrying the ball significantly affects the quality of players’ performance.


INTRODUCTION
Technical abilities of soccer players play essential role in the process of identification and selection of players, in training process planning, tactical formation establishing, determination of training and competition aims etc. (Abbott, Button, Pepping, & Collins, 2005;Bompa, 2000).Consequently, they rank among the essential soccer skills which, if not improved, can limit manifestations of morphological, motor and functional potentials of soccer players (Aleksić, & Janković, 2006).Although the period adolescence is favourable for adoption of new knowledge and skills, it is also extremely unstable, because, affected by growth, it can result in damage to coordination or losing of some already acquired skills.Therefore, improvement of technique is a primary task during the entire training process with young players.Almost all leading schools of soccer in their training programs focus on development of speed and technique as major abilities for the players selection process both for a specific role in a team and for establishment of the level of playing.Ajax academy of soccer, as one of the most recognized schools of soccer, in its training process applies the TIPS principle (technique, intelligence, personality, speed), in which besides personality character and intelligence of playing, development of technique and speed is prioritized (Bangsbo, 2003).
Carrying the ball is an element of soccer technique that is applied when a player cannot find a satisfying solution to play the ball, when he is taking it out of the penalty area, when he wants to conceal his intention prior to playing the ball, when he starts a swerve, when he overruns the opponent once the swerve is over (Radosav, Molnar, & Smajić, 2003).During the game, active time of a player with the ball is only a few minutes.The major part of this period is reserved for carrying the ball which can be rectilinear or curvilinear.By analysing technical activity of players during the game it was observe that better teams spend less time carrying the ball which can be explained by better tactical formation of play, more efficient movement of players without the ball and better overview of play (Hoff, Wisloff, Engen, Kemi, & Helgerud, 2002).During the 165 game, a player carrying the ball covers the distance between 119-286 meters or 1.2-2.4% of the overall covered distance (Di Salvo, Baron, Tschan, Calderon Montero, & Pigozzi, 2007).During one game a player passes with the ball at his feet 0,5-3% of the overall covered distance while ball possession per a player is from 0.3 to 3.1 minute (Jukić et al., 2007).By analysing soccer games it was observed that playing position and tactical tasks determine the frequency of manifestation of certain tactical elements.Soccer players who have ability to carry the ball fast impose as the middle field or side players.The greatest number of ball carrying is realized by defensive linkmen (11.78) who, by touching the ball more try to find the most efficient solution in the game while the least number of ball carrying is realized by the central defence players (Janković, & Leontijević, 2009).While the aforesaid studies are related to senior teams, there are only few studies with this type of match analyses for youth players.During the match the teams run over approximately the same distance with similar medium running speed while more significant differences are noticed in quantity and quality of the use of technical elements.The research led to the conclusion that winning teams realize significantly more kicks which corroborates the importance of technical elements and its position in play (Grant, Williams, & Reilly, 1999;Zubillaga, & Gorospe, 2007).
As the anticipated research is of empirical-research character, the research problem is clearly defined and formulated so as to determine the level of significance of technical abilities in the context of their influence on the quality of soccer teams' play.
The key issue and the entire problem orientation of this research, is related to examination of the sensitivity of the speed evaluation tests of carrying the ball (carrying the ball between the cones or with a pass).It is expected that the research results contribute to solving the problem as for the importance and influence of technical abilities on quality of play of the youth soccer players, as well as to the increase of efficiency of the training programs in the part that refers to the development of technique in players.Additionally, the obtained results should give an answer about those technical skills that make the greatest qualitative difference between soccer players of differently ranked teams.
The subject of this research are technical abilities of the young soccer players.The assessment of technical abilities from the field of specific soccer speed will give an answer to the question whether the speed evaluation tests of carrying the ball were discriminative in the context of qualitative differentiation of young soccer players.
The paper is aimed at establishing the level of technical abilities of the young soccer players of different level of successfulness.In other words, the aim of the paper is to establish technical abilities in context of distinguishing successful and less successful soccer players and to examine sensitiveness of specific tests of carrying the ball in soccer.

METHOD Participants
The research included 76 participants, divided into two groups, Group 1 of 44 male respondents and Group 2 of 32 male respondents, aged 17 years (+/-6 months) who had been included in soccer training process for at least three years.The first subsample (Group 1) consisted of the players from more successful teams while the second subsample (Group 2) consisted of the players from less successful teams.The criterion of successfulness was established based on the teams' ranking in the ongoing championship, number of the national team players who play in the U-21 or U-19 teams, tradition of youth schools and success of the senior teams of these clubs.

Sample of variables
The sample of variables consisted of the variables regarding motor abilities of soccer players, realized by application of the two different tests for evaluation of specific soccer speed of carrying the ball.For establishment of the speed of carrying the ball the tests of carrying the ball between cones (M type of carrying the ball) and slalom ball carrying with a pass were performed.The reliability of these tests was confirmed by their usage in several relevant papers from the field of soccer which are acknowledged on global level (Rosch et al., 2000.;Malina et al., 2005).
In order to examine the influence of specific soccer tests on the speed variables, the following dependant variables were defined: -M type of carrying the ball between cones (vdlp), (expressed in seconds), -Slalom ball carrying with a pass (vdlpd) (expressed in seconds).
The independent variables were: -The dimensions of the set obstacle courses for the speed evaluation tests of carrying the ball.

Measurement protocol
All the tests were performed on the soccer fields with synthetic surface and the examinees performed all the tests in soccer boots.All the tests were performed by a standard size soccer ball (size 5).For this research, we have used the photo cells of the latest generation (Smart speed system, Australia) used to establish time necessary for performance of the tests of carrying the ball.
The test of slalom ball carrying with a pass was performed when a subject carried the ball as fast as possible between 4 cones, and after that he shot in the direction of bench so as to rebound the ball in order to continue carrying it in the direction of target.The starting line was at the same time the finish line.All cones were set in a line, so that the first cone was placed on the start line and the next three at the distance of 2.25m each.The 1.2-meter wide bench was placed at 9 meters form the start line.
The test of M type of carrying the ball was performed in a 9 × 9 -meter square, so that four cones were placed in the square angles, and the fifth cone was put at 4.5m between the first and the last cone.Such placed cones were in the form of the letter "M", which was at the same time the path of the ball carrying.The aim of both tests was to perform it as fast as possible.
Prior to the testing, all the examinees performed a 15-minute warm up in order to avoid possible muscle pull or other injuries that could occur while performing the movement task.After the 15-minute warm up, the players performed the tests aimed at familiarization with the tests, for 10 minutes, at medium performance speed.Besides the respondents the testing included two measurers who controlled test performance and recorded the achieved results.During the main testing each participant performed the movement task three times.

Data processing
Evaluations of the examinees' speed of carrying the ball have parametric features and therefore were analysed by parametric procedures.Result processing was done by a multivariate analysis (MANOVA) and discriminant analysis together with descriptive parameters, mean value, standard deviation (Sd), minimum and maximum of all the values, coefficient of variation (Cv), conficence interval, measures of skewness and kurtosis.The applied univariance procedures included ANOVA, t-test and Roy's test.All statistical test were processed by using the SPSS 17.0 program (SPSS INC Chicago, IL)

RESULTS
Central and dispersive parameters, asymmetry measures and kurtosis in evaluation of participants' carrying the ball represent the groups and indicate a possibility of application of parametric procedures.When observing the Group 1 testing results, it can be seen that minimal (min) and maximal (маx) values results of carrying the ball evaluation indicate that the values are within the expected range (Table 1).Values of the coefficient of variation (KV) indicate to homogeneity of results of the Group 1, for both applied tests (vdlp = 2.96 and vdlpd = 8.34).The results further showed that the distribution of the results is negatively asymmetrical which means that the curve of the distribution of the results is towards higher values, i.e., that there are more worse results with regard to the normal distribution in the test of carrying the ball with a pass (vdlpd -.60).On the other side, in the test of M type of carrying the ball (vdlp) the distribution of the results is positively asymmetrical which means that the distribution curve of the results is towards lower values, i.e. that there are more better results with regard to the normal distribution (.07).Negative kurtosis value (ku) indicate that the curve is flattened in the two speed evaluation tests of carrying the ball (vdlp = -.50;vdlpd = -.22).Distribution of values mostly varied within normal distribution (p) in the test of M type of carrying the ball (vdlp = .89)and in the test of slalom ball carrying with a pass (vdlpd = .80).  2).Values of the coefficient of variation (KV) indicate to homogeneity of results of the Group 2. In the tests of M type of carrying the ball (vdlp) (4.92) and slalom ball carrying with a pass (vdlpd) (9.94).lowered values of skewness (sk) indicate that distribution is positively asymmetrical, which means that the results distribution curve is towards lower values, i.e., that there are more better results compared to normal distribution in the test of carrying the ball with a pass (vdlpd) (-.05).The skewness values (Sk) indicate that distribution is not asymmetrical in the M type of carrying the ball (vdlp) (.02).Negative values of kurtosis (Ku) indicate that the curve is flattened in the two speed evaluation tests of carrying the ball (vdlp = -.82;vdlpd = -.79).Distribution of values mostly varied within normal distribution (p) in the two speed evaluation tests of carrying the ball (vdlp = .98;vdlpd = .99).
Based on the multivariate analysis of the obtained results it can be concluded that there is a statistically significant difference between the two groups of respondents (p=.000).By discriminative analysis for the synthetized results of the two speed evaluation tests of carrying the ball, it was concluded that there is a significant difference and clearly defined limit between the groups of respondents compared to the results of the speed evaluation tests for M type of carrying the ball (vdlp) and carrying the ball with a pass (p= .000).
The coefficient of discrimination indicates that the greatest contribution to discrimination between the two groups, when compared to the results of the speed evaluation tests of carrying the ball in M type of carrying the ball .269(vdlp) while the coefficient was the same for the test of carrying the ball with a pass .197(vdlpd).

Table 3. Features of the groups of respondents according to the results of the speed evaluation tests of carrying
the ball (* -significantly higher, 1 number from the number of modalities of the groups it is higher) Group 1 Group 2 c.disc.M type of carrying the ball lower higher* 1 57.725Ball carrying with a pass lower higher* 1 42.275 Based on the analysis of the results of the speed evaluation tests of carrying the ball by the respondents it can be said that: -the results of the Group 1 of the M type of carrying the ball (vdlp) and the test of carrying the ball with a pass (vdlpd) indicate that this group has features of lower values of the achieved results which means that this group results are characterized by better scores, -the results of the Group 2 of the M type of carrying the ball (vdlp) and the test of carrying the ball with a pass (vdlpd) indicate that this group has features of higher (higher * 1 ) values of the achieved results which means that this group results are characterized by worse scores.
The results showed also that the defined features of the Group 1 are possessed by 33 out of 44 respondents who belonged to this group, which indicated to homogeneity of 75.0%, while homogeneity of the Group 2 was 68.8%.Thus, it can be said that Group 1 was more homogeneous than Group 2.
The results of the M type of carrying the ballvdlp and of the carrying the ball with a pass-vdlpd were presented on the abscise (horizontal axis) and ordinate (vertical axis) respectively (Graph 1).It can be observed that compared to the "M type of carrying the ball" (vdlp), the Group 1 has lowest value of the speed evaluation of carrying the ball i.e. the best result at the test, and the highest value is by the Group 2 i.e., the worst result at the test.Compared to the test of carrying the ball with passing (vdlpd), Group 1 has lowest value of the assessment of the speed of carrying the ball i.e., the best result while the highest value at this test is achieved by the Group 2 and consequently the worst result.As the results of the speed evaluation tests of carrying the ball are expressed in seconds it means that numerically highest result is the worst one while the numerically lowest is the best one.
The procedure of the analysis of the group profiles was done based on the results of the repeated measures of M type of carrying the ball (vdlp1, vdlp2, vdlp3) and carrying the ball with a passvdlpd (vdlpd1, vdlpd2, vdlpd3) between the groups of respondents.By multivariance analysis of variance it was established that there are significant differences between the two groups of respondents, p = .000(Table 4).The analysis of parallelness established that the profile of the two groups of the respondents are not parallel (pп = .005)while the analysis of the equal results established that there is difference between some results of the two groups of respondents, p = .019;.000(Table 4).

DISCUSSION
Carrying the ball is technical ability that takes important place in the structure of the game of soccer.
The application of this technical element depends on the playing position, tactical tasks and the level of technical abilities of the soccer players.Different results were achieved when it comes to the assessment of the time during which a player carries the ball.The analyses show that the player, during the game, while carrying the ball, covers the distance between 119-286 meters or 1.2-2.4% of the overall covered distance (Di Salvо et al., 2007).Jukić and Milanović (2007) in their research concluded that in the course of one match a player covers with the ball at his feet 0.5-3% of the overall covered distance and that the possession of the ball per player is from 0.3 to 3.1 minutes.The greatest number of the ball car-rying are realized by defensive linkmen (11.78) who through greater number of ball touching try to find the most efficient solution in the game (Janković, & Leontijević, 2008).
Taking into account the importance of this technical element, the speed of carrying the ball was evaluated by two tests: the "M type of carrying the ball and the test of carrying the ball with a pass".By the analysis of the achieved results it was established that there is a difference between the respondents from the groups with regard to the results of the speed evaluation of carrying the ball in the tests of M type of carrying the ball (p = .000)as well as in the test of carrying the ball with a pass " (p = .000).
Based on the analysis of the results of the tests for assessment of the speed of the ball carrying in the respondents it can be said that Group 1 realized statistically significantly better results at the test of ball carrying with a pass and at the test of M type of carrying the ball.Contrary to Group 1 the respondents from the Group 2 scored statistically significantly worse results in both speed evaluation tests of ball carrying.Based on the results of this research it can be said that both applied tests are sensitive compared to the set criterion and therefore they clearly distinguish players according to the qualitative level of their successfulness in the game of soccer.Also, carrying the ball in combination with the ball control is an element of soccer technique which significantly affects the efficiency of individual performance in technical and tactical requests of the game.If we consider the data showing that carrying the ball is extremely rarely deployed in competitive activities (Janković, & Leontijević, 2008;2009), it can be concluded for the moment that carrying is not essentially important element of soccer technique.However, through the tasks of ball carrying set in this research a soccer player shows also specific abilities such as sense of the ball, ball kicks and ball receiving (test -vdlpd), agility.Thus, it can be assumed that based on the results of this research, the Group 1 examinees are more successful in the competitive activities, thanks to, among other things, quality and efficiency manifested in the testing abilities (carrying the ball -vdlp, vdlpd).
High values of homogeneity of the results in these two groups of respondents (Group 1 homogeneity 1 -75%, and Group 2 2 -68.75%) lead to the conclusion that this ability is essential quality of young soccer players.The discrimination coefficient of 0.269 for the results of M type of carrying the ball and 0.197 for the results of carrying the ball with a pass indicate that the results of these two tests can lead to qualitative distinction of young soccer players.Therefore, the applied tests in this research can be recommended as a means for identifying promising soccer players for whom it can be anticipated that they will reach high level of competitive efficiency later on in their development.Similar results were obtained by other researchers involved in these types of research (Williams, & Reilly, 2000).Some of the conducted investigations proved that carrying the ball, i.e., some tests of carrying the ball proved the highest level of distinction between young elite and amateur soccer players.(Reilly, Bangsbo, & Franks, 2000a; Reilly, Williams, Nevill, & Franks, 2000b).Additionally, some studies show that the ball carrying is the most selective technical ability of soccer players (Vaeyens et al. 2006).
Based on the results of this research, together with the conclusions from the studies that directly or indirectly dealt with prediction and selection of young soccer players, it is particularly important to underline the importance of carrying and controlling the ball in the overall technical preparation of the youngest soccer trainees.It is through the contents of activities, dominated by this activity of players with the ball, that soccer players develop integrally soccer-specific abilities which positively transfer to later application of competitive forms of soccer technique manifestation.All that has been said in the above text is especially accentuated when it comes to the fact that initial selection is lowered to the age of 5 years.

CONCLUSION
In line with the obtained results it can be concluded that carrying the ball as technical element, has significant influence on the quality of soccer players' performance.Although the tendency of modern soccer play is to quickly release the ball, more precise passes and fast change of movement direction, fast carrying the ball cannot be underestimated.The players who show small variation of the running speed with or without the ball have greater advantage in resolving the situations "one on one", efficient invasion of the space with the ball as well as the resolution of the situations "under pressure" by the opponents.Such features are characteristic for exceptionally talented soccer players and primarily of the technically trained individuals.Therefore, the results of the research confirmed the presumption that success in soccer is directly linked to the level of technical abilities, in this case directly to the technique of the ball carrying.Development and improvement of this technical element is one of the main aims of the training of young soccer players which is supported by the results of this research.(Алексић, & Јанковић, 2006).Како је период адолесценције погодан за усвајање нових знања и вјештина, тако је, у исто вријеме, и изузетно нестабилан, јер под утицајем раста и развоја неријетко долази до нарушавања координације и губљења неких до тада стечених вјештина.Из тога разлога је усавршавање технике примаран задатак током цијелог тенажног процеса младих играча.Готово све водеће фуд-балске школе главни акценат у својим тренажним програмима стављају на развој брзине и технике као главних способности на којима се базира процес селекције играча, како за улогу у тиму, тако и за одређивање нивоа играња.Ајаксова школа фудбала, као једна од најпризнатијих свјетских школа, у процесу обучавања се руководи "TIPS" (technique, intelligence, personality, speed) принципом, гдје се поред карактера личности и интелигенције играња посебна пажња посвећује развоју технике и брзине (Bangsbo, 2003).

Graph 1 .
Ellipses (trust interval) of the groups of respondents in tests M type of carrying the ball (vdlp) and carrying the ball with a pass (vdlpd)

Table 2 .
Central and dispersive parameters and measures of asymmetry and kurtosis of the assessment of carrying the ball of the Group 2 respondents M type of carrying the ball between cones; vdlpd -slalom ball carrying with a pass; М -mean value; SD -standard deviation; Еr -standard error; Мin -minimal value; Маx -maximal value; КV -Coefficient of variation; IP -relation interval; Sk -skewness; КU -kurtosis) Minimal (min) and maximal (маx) values results of the speed evaluation tests of carrying the ball of the respondents from the Group 2 indicate that the values are within the expected range (Table

Table 4 .
Significance of difference between the profiles of the groups of respondents with regard to the results of repeated measurements in the tests vdlp and vdlpd