Comparison of Two Different Training Methods for Improving Dribbling and Kicking Skills of Young Football Players

### Abstract

The purpose of this study was to examine the effectiveness of two different training methods on the performance improvement of dribbling and kicking technical skills of young football players (8-11 years old). The sample consisted of 90 boys aged 8 to 11 years old. Participants were randomly assigned to three practice groups of 30 participants each group, that is, two experiment groups (experiment group A, experiment group B) and one control group. Practice according to training method A included a 20 min warm-up period, 20 min of practicing technical football skills, 20 min game and a 5min cool-down period. Practice according to training method B included a 20min warm-up period followed by 45 min of technical skills’ training with no time given for a cool-down period. Control group participants followed the physical education program according to school’s curriculum. Three measurements were conducted to evaluate technical skills. Initial measurement took place prior the onset of the program, whereas the second measurement conducted after the eighteen (18) weeks of training followed by the final measurement four (4) weeks after the end of the program to assess maintenance of skills attained. Results showed improvement in dribbling and kicking skills of the two experiment groups, whereas no statistically significant differences were noted in the control group for the specific skills measured. Furthermore, it was noted that benefits of training method B maintained for a longer period of time compared to training method A. Future studies using larger samples, in different age ranges, and sports are needed in order to further verify probable advantage of training method B compared to other methods.

**Keywords:** training methods, comparison, children’s football, dribble, kick.

### Introduction

In European football, two training models dominate the field during the last decades on which all training choices that are available to coaches are based. Training model A (15) follows a specific training implementation procedure in football. That is, a training unit, that includes a warm-up period consisted of exercises with or without the use of a ball, the main part aiming to improve performance of technical football skills with no previous fatigue present as no physical condition program precedes followed by a football game adapted to the objectives of the main part. Last, a cool-down period concludes the training unit and signals the end of practice.

In training model B (16) the procedure followed during a training unit in football includes a warm-up period that is adapted to the objectives of the main part with ball use, followed by the main part where only technical training takes place. This pattern is in effect until the onset of the microcycle involving technique application, as from this point and beyond more football game is used. In this training model no cool-down period exists on the contrary to training model A. According to Lehnertz (14), technical training should constitute the final piece of a training unit as dynamic registrations that are created definitely require a consequent phase of consolidation (13).

In summary, differences that are observed between the two training methods during the six microcycles could be described as follows: Training method A includes a 20 min warm-up period, 20 min performance improvement of technical football skills, 20 min football game and 5 min cool-down period. In training method B, a 20 min warm-up period takes place, followed by 45 min for improving performance of technical football skills. According to training method B, no cool-down period is needed and no particular importance and time is given for such purpose.

Planning, guidance, and application of training according to these two models have led previously to successes as well as to failures. Up to now, it is not possible only through the examination of results (success or failure) to say with certainty which is the most advisable method in football training.

Although it is extremely difficult to locate relative studies concerning the comparison of complete and different training methods emphasizing football technique, many researches use football ability tests to measure pass accuracy, ball control and dribbling (6,20,5). Van Rossum and Wijbenga (21) reconstructed Kuhn’s (12) technique tests for football players and applied them in Dutch children teams. Overall, six technique tests are considered by the researches as reliable and valid for football practice: 1. Kick accuracy, 2. Ground pass with accuracy, 3. High pass with accuracy, 4. Dribble, 5. Controlling ball on air using one leg, and 6. Controlling ball on air using two legs.

French and Thomas (10) research conducted to young basketball players aged 8-10 and 11-12 years (high level athletes, beginners, and no-athletes) to examine the importance of knowledge element on the development of basketball skills showed that high level athletes of both age ranges exhibited a better performance in dribbling and shooting skills. Correlation analysis showed that knowledge relevant to sport was related to choice of answer, whereas kicking and dribbling skills were in relation to the motor elements of control and execution. Furthermore, it was noted that the development of relative to sport knowledge plays an important role in the high performance of 8-12 years old children, with cognitive development occurring faster compared to motor development (10).

Das and Benerjee (7) investigated effectiveness of periodicity according to the duration of a football training program applied to young football players. Participants (10-12 years old children) were examined with the use of motor and technical skills’ tests in the beginning of the training process and after four (4), six (6), and eight (8) weeks of training. Motor skill tests included evaluation of 30m speed, explosive force, 4 times of 40m agility, flexibility, and 8 min continuous running. Technique tests included measurement of successive goal shots, controlling ball on air using legs, distant pass accuracy, throw-in distance, and dribbling in specific time-period. Regarding motor skill tests results showed that four weeks were enough to improve agility and aerobic capacity and six weeks of training were necessary to improve muscle power and speed, whereas no improvement was noticed concerning flexibility in eight weeks time. In technical skills testing, after four weeks of football practice an improvement in shooting towards target, controlling ball on air and distant pass was noticed, whereas in throw-in and dribbling skills improvement was evident after six weeks. All technical skills were significantly improved after eight weeks of training (7). According to the results of (7) study, a six weeks training program could be considered sufficient to produce evident training results.

Venturelli, Trentin and Bucci (22), evaluated three training methods for improving muscle power of young football players after eight weeks of practice. Twenty one high level football players formed three groups (A1, B1, C1) of 7 individuals each group and followed different training programs. Α1 group followed a free weight-lifting program, B1 practiced according to a specific exercise program and C1 group followed a combined training program. Results showed that the combined training program (weight lifting for thorasic muscles along with jump and speed exercises) produced better results compared to the other two training programs. Fontes et al. (2007), evaluated maximum cardiac frequency and anaerobic threshold of 10 professional A Division category Brazilian football players on three measurements taking place during training that included “technique”, “tactics”, “game with terms” and “regular game”. According to the results, technique had a lower intensity compared to other analyzed types of training, whereas no differences were noted during training regarding “tactics”, “game with terms” and “regular game”. Furthermore, “game with terms” seemed to offer higher intensity compared to other training conditions. In conclusion, although decrease of field dimensions increases, in turn, ball contact, intensity seems to lessen due to the reduction of high in energy actions of football players.

Taxildaris (19), using Heidelberger Basketball Test (4) in adolescent age girls (11-14 years old), examined improvement of football skills’ technique level between a control group of female athletes that did not follow any exercise program and two experiment groups following a “general” exercise program and a “specialized” exercise program. Results showed that group of “specialized” practicing exhibited a statistically significant difference compared to group following the “general” exercise program in terms of pass and shooting technical skills measured. Furthermore, although not statistically significant a tendency in favor of the specialized training group was noticed in dribbling and penetration & shooting skill, whereas control group did not present any progress.

As it is shown, motor and technical football tests have been widely applied by many researches, with special attention given to kicking and dribbling abilities as the most important skills that each football player should possess to the highest degree. Dribbling virtuosity of the footballer who has the ability to control the ball with his legs and surpasses his opponents, is the most effective and fascinating technique that is always admired by every athlete and spectator (3). Dribble use allows possession of ball throughout the football court until a player is free of guard in a favorable position to receive the ball and score.

According to (11), dribble as well as ball guidance presumes the covering of ball with the body, eye-contact with the team-mates, peripheral sight, avoidance of the opponents’ attack and surpassing of opponents using manoeuvres. Furthermore, although dribbling style of each football player is unique, one can recognize the short dribble, the dribble of ball between opponent’s legs, dribble of pretending going left and then heading to the opposite (right) direction, ball transport to the left and then dribbling to the right, speed dribble, dribble with turn and “scissors” dribbling (1,2,8,11,18).

Dribble technique requires high concentration and energy and a relaxed body in perfect balance, whereas it also demands continuous control of the game, placement of the opponents in the football court and transition of team-mates. In real game situations in modern football, defenders are always more that the offending players, taking systematically position in front of their goalkeeper’s post. Therefore, in order to penetrate this defensive “wall” and apart from other technical or tactical inventions, dribbling ability of players is a very important skill for the outcome of the game that is added to the overall strategy of the team (2).

The objective goal in football is scoring, thus, scoring ability with legs, head or with the ball stopped is of vital importance for every football team that requires the best possible technique aiming to send the ball to the opponent goal-net. All other skills in football are of little importance in case players do not take advantage of their opportunity to kick the ball and score. Kicking the ball constitutes the final expression of the game since every time a player attempts to score that doesn’t mean he will succeed, however, without performing this skill is very difficult to accomplish anything. A good scoring ability requires the player to be capable to kick the ball in narrow spaces under the pressure of the opponent, plus, team-mates’ contribution is needed to provide the opportunity for attempting to score under the best possible conditions (11).

The development of such important technical skills in football should start from a young age. In case a proper selection of training method during practicing and acquisition of these skills takes place, the young athlete will develop his technique at his full potential as well as his effectiveness to perform successfully during training and official football games. However, reviewing the literature it seems that no researches are conducted examining the effectiveness of training methods A and B on the development of such important skills.

The purpose of this study was to compare the effectiveness of the two training methods according to model A (17, 15) and model B (16) in the performance improvement of basic football skills of young football players (8-11 years old).

### Methodology

#### Sample

Random selection was used to choose children from the 3rd to 6th school classes first by selecting nine (9) out of thirty-three (33) primary schools of Volos city. In each school researchers provided information to children and their legal guardians about the purpose of the study.

The initial sample of children showing interest to participate was 98 children who were also informed that their participation was voluntary. Individuals were also aware that all the information provided was confidential and they were free to withdraw at any point without prejudice. Overall, the legal guardians of two children did not sign the consent form whereas 6 children decided not to participate prior the initiation of the first training session. As a final result, 90 boys, aged 8 to 11 years old, all primary school students constituted the final sample of this study. Participants were separated randomly in three (3) groups (experiment A, experiment B and control) of 30 participants each group (See Table 1). Written informed consent was obtained from all participants and their legal guardians prior participation. All experimental procedures were approved by the Institutional Review Board of Ethics Committee for investigations involving human subjects.

#### Training program

Overall duration of research was 22 weeks. Initial measurements of all participants along with participants’ separation in three groups (experiment group A, experiment group B and control group) were conducted prior the beginning of the training program (at the end of October. See Table 2). Next, the training period lasting 18 weeks followed with the final measurement taking place at the end of the training period (beginning of March). An additional measurement four (4) weeks after the end of the training program was also conducted to assess maintenance of skills attained.

Experiment groups followed different training programs focusing on the development of six technical skills (transition of ball, dribbling, pass, ball control, head and kick) with special attention given to the development and monitoring of dribbling and kicking ability. Experiment group A practiced according to training method A and experiment group B followed the training method B, whereas control group individuals did not participate in any football program and simply followed the physical education program according to their school’s curriculum, that included track and field events, general team sports’ practice (in basketball, volleyball, handball, and football) and dance.

The weekly program of the two experiment groups included two training units of 65 min each one (every Tuesday and Thursday) where technical skills were practiced and one training unit playing a 60 min football game (every Saturday). In each training unit, practice for the experiment group A according to training method A included a warm-up period with or without the ball, the main part of practicing technical football skills, a football game and a cool-down period. Practice according to training method B for the experiment group B included a warm-up period with the ball followed by 45 min of technical skills’ training with no time given for a cool-down period. In particular: Table 2.

Furthermore, training programs A and B for the participants of experiment group A and B respectively were divided in three middle-term cycles of six weeks duration each one, with each middle-term cycle including 6 micro-term cycle training units. In each middle-term cycle emphasis was given to the two out of the six skills practiced, whereas the other four skills were practiced as well but to a less quantity (See Table 3).

In addition, the six micro-cycles within each middle-term cycle were structured in pairs according to the aims pursued to achieve in every two training units. Exercises used in micro-cycles were the same so much in training method A as much as in training method B (See Table 4).

All training units were accomplished by two physical education (PE) teachers who were also qualified football coaches with specialty in football. Prior the beginning of research, the two PE teachers were informed and practiced on the application of each training program followed, that is, training program A applied by the 1st coach and training program B applied by the 2nd coach respectively.

#### Testing procedures

Russell (18) tests regarding dribbling and kicking skills were selected for the purpose of this research, as they are immediate, easy to measure and dynamic with no “static” exercises included such as kicking a still ball or controlling the ball on air. Furthermore, they have been devised and recorded by the English Football Federation and evaluated for a long period of research time by the Social Statistics Department of Southampton University, exhibiting a high level (0.90) of reliability (18). The advantage of Russell’s tests is that they are performed in real game conditions (5).

In each measurement its participant performs two skills during testing. The purpose of the kicking test was to gain the highest number of point by aiming to shoot the ball in to the half of the goal furthest away from the player shooting (18).

In dribbling test each individual was asked to imagine the markers as defenders and to dribble the ball as quickly as possible in front and away from markers, ABCD from the start of the course to the finish (18)

The coding system for the number of successful kicking efforts and dribbling in relation to time of skill execution was as follows (See Table 5).

These tests could also be used in the form of football exercises during training or combined in one more complex activity. In this way, the coach could assess technical skills of his players not only through testing but also through practice.

Technical skills’ evaluation of the participating children was conducted by four (4) physical education teachers who were also football coaches trained by an experienced instructor. Video tape recording to assess reliability of each coach as well as between coaches judging the results was used through the application of tests on 20 children other than those participating in the program. In particular, 20 children performed the two skills in question prior the onset of the program, their performance was videotaped and PE teachers were then asked to watch the video and evaluate each test two times. Intra-class k correlation factor to assess reliability between coaches was equal to 0.71 (k = 0.71) whereas for each coach, k intra-class correlation factor was 0.80 (k = 0.80).

Final measurement was limited in students who followed training programs consistently, three times per week for eighteen (18) weeks without absences. All students in each group loosing three or more training units were automatically excluded from the study.

#### Statistical analysis

Planning application included a 3×3 measurement (initial, final, maintenance) x Group (experiment group A, experiment group B and control group C) with repeated measurements (ANOVA repeated measures) used to locate possible differences existing among the training methods in terms of performance in dribbling and kicking skills. The importance of differences between the means of cells was examined with the application post hoc test of multiple comparisons Scheffe. The importance of difference between the medium averages of performance was examined using Scheffe post hoc test. Level of statistical significance was set at p0.05.

### Results

Cronbach a analysis, the most widely accepted technique of indicating reliability, was used to examine reliability of skills’ measurements in each group (See Table 6).

Pre-test measures showed that all 3 groups started from the same point of reference in term of base line performance prior the beginning of the intervention (dribbling F(2,87)=2.526, p=.086, and kicking F(2,87)=2.769, p=.068 skills).

Observing means of dribbling technical skill for the experiment groups A and B (See Table 7), an increased performance is noticed from the first (October) up to the third measurement (April). In the control group, an ascendant course of mean is observed in the second measurement (March) as well as a mean stabilization at the third measurement.

Performance difference between the three training methods in dribbling skill was checked with the application of two-way ANOVA, from which one was with repeated measurements. Mauchly’s test showed that the three groups exhibited homogeneity in their variance (p >.050).

The interaction between the two factors (skills and training methods) in relation to time was not found to be statistically significant (See Table 8).

Statistically significant differences were observed between the groups (See Table 9) in dribbling performance [F(2.87) =5.159, (p<.001)], that is, the effect of training methods was different concerning the development of dribbling skill in total measurements.

Application of Scheffe post hoc test showed the following statistically significant differences: a) between the second and third measurement (Scheffe value = 1.80 (p<.050) of training method B and control group program (See Table 7), b) on the third measurement between training method B and control group program (Scheffe value = 2.20 (p<.001) and c) on the third measurement between training method Α and control group program (Scheffe value = 1.70 (p<.050).

No statistically significant differences were noticed between training method A and training method B in dribbling performance (See Table 9), with a Scheffe value on the second measurement equal to.60 (p>.050), whereas on the third measurement Scheffe value was .50 (p>.050). Finally, no statistically significant differences were observed between training method A and control group program on the second measurement (Scheffe value= 1.20, p>.050).

Observing means of kicking skill for the experiment group A (Table 7), an increased performance is noticed from the first up to the second measurement followed by a decrease on the third measurement. In the experiment group B an increased performance from the first up to the second measurement is also observed, followed by a stabilization of performance on the third measurement. Control group exhibited a slight increased course of means from the first up to the third measurement.

As in dribbling skill, performance difference between the three training methods in kicking skill was checked with the application of two-way ANOVA, from which one was with repeated measurements, with Mauchly’s test indicating a homogeneity in groups’ variance (p >.050).

The interaction between the two factors (skills and training methods) in relation to time was not statistically significant (See Table 10).

Statistically significant differences were observed between the groups in kicking performance [F(2.87)=14.533, p<.001], that is, the effect of training methods was different regarding the development of kicking skill in total measurements (See Table 9).

Scheffe post hoc test application revealed the following statistically significant differences in kicking skill performance: a) on the second measurement (Scheffe value = 1.20 (p<.050) between training method B and training method A (See Table 9), b) on the third measurement between training method B and training method A (Scheffe value = 1.67, p<.001), c) on the second measurement between training method B and control group program (Scheffe value = 2.00, p<.001) and d) on the third measurement between training method B and control group program (Scheffe value = 2.40, p<.001).

Finally, no statistically significant differences were noticed between training method A and control group program in kicking performance with a Scheffe value on the second measurement equal to 1.20 (p>.050) whereas on the third measurement Scheffe value was .50 (p>.050).

Overall, comparison of means revealed statistically important differences existing as regards to performance improvement of dribbling and kicking football skills in total measurements resulting from the application of different football training methods.

### Discussion

The improved performance of dribbling skill recorded in this study as a result of 18 weeks of training is in agreement with (7) stating that a training program of at least six weeks duration can be considered as fair enough to produce positive training results in technical skills’ development.

Both training methods seemed to produce positive results related to an improved performance in dribbling skill up to a point where no differences were located. As a result, comparison between training method A and training method B revealed no statistically significant differences in final and maintenance measurement, although a superiority tendency of training method B compared to training method A was also noticed.

In particular, no statistically important differences in performance were noted between training method A and control group program apart from maintenance measurement. However, between training method B and control group program such differences do exist not only in maintenance results but in final measurement also, a finding that indicates the greater influence of training method B to improve dribbling.

As for kicking skill, comparison of means showed also a statistically significant improved performance resulting from training method B application. The improved performance in kicking skill recorded only for the participants of training group B is not in agreement with (7) study that in general a training program of at least six weeks duration is enough to produce positive results in technical skills’ development. In this study, findings suggest that after 18 weeks of training this was the case for dribbling but not for kicking skill improvement. Thus, it seems that not only duration of program according to (7) notion is important, but also the “nature” of skill itself. In addition measurements between groups during, point out an influence of the training methods on kicking performance that is different according to group.

Comparison between training method A and training method B illustrated statistically important differences in final and maintenance measurement. More specifically, individuals following training method B improved their kicking skill performance according to final measurement and sustained this performance until maintenance measurements. On the contrary, participants of training group A improved slightly their performance on final measurement whereas on maintenance measurement returned to their initial performance level. As an overall result, individuals practicing according to training method B exhibited a greater improvement of kicking skill performance compared to A group individuals up to a point that this improvement was statistically significant.

Furthermore, results showed that training method A and control group program did not produce performance differences in kicking ability as no differences were noted between the two methods in final and maintenance measurement. On the contrary, such differences were evident between training group B and control group in the same measurements. The fact that training method B significantly improved kicking skill performance compared to training method A and control program, indicates clearly the superiority of training method B in order to improve the specific skill measured.

Overall, results of this study showed that the use of training method B helped young players to improve performance more according to skill and to maintain training results for a longer period of time. Thus, findings suggest that when it comes to young players, football coaches should use more the training method B suggested by (16) compared to any other method (17, 15).

Future studies should examine whether the application of the two training methods produce different results in all fundamental football skills taught, apart from dribbling and kicking, that is, transition of ball, pass, head, and ball control. In this way, it would be ascertained whether training method B is more proper for teaching basic football skills to young players throughout their whole developmental period. Moreover, future studies should use larger samples, in different age ranges and sports (e.g. basketball, volleyball, handball etc) in order to further verify the probable advantage of training method B.

### Applications In Sport

Improvement of fundamental football technical skills influences to a great extent the progress of young footballers in their later athletic course and future (Van Rossum & Kunst, 1993). The findings of this study suggest that when it comes to technical skills’ improvement, football coaches of young players should use more training method B during the initial microcycles of each training session compared to any other method so as to maximize performance and achieve high dexterity levels of crucial football skills such as dribbling and kicking.

### Tables

#### Table 1
Mean age of groups

Group N M SD
Experiment Group A 30 9.47 1.07
Experiment Group B 30 9.73 1.11
Control Group 30 9.60 1.07

#### Table 2
Training unit of groups

Experiment Group A Experiment Group B Control Group
Warm-up Period 15 min with or without ball use 5 min stretching exercises 15 min with ball use with activities adapted to the purposes of the main part 5 min stretching exercises 5-10 min Introductory activities and reporting of lesson’s objectives
Main part 20 min of practicing technical football skills 20 min football game 45 min of technical skills’ training 25-35 min Activities relative to the lesson’s purposes
Cool down period 5 min 5-15 min Game activities, outline of main lesson points, discussion with students

#### Table 3
Middle-term cycle structure

Training Program (18 weeks)

Training Program (18 weeks)
1st Middle-term cycle
(6 weeks)
2ος Middle-term cycle
(6 weeks)
3ος Middle-term cycle
(6 weeks)
DRIBBLING
BALL TRANSITION
Pass, control, head, kick
PASS
BALL CONTROL
Dribble, ball transition, head, kick
KICK
HEAD
Dribble, ball transition, ball control, kick

#### Table 4
Structure of microcycles in pairs in each middle-term cycle

Middle – term cycle
Micro-cycles (Training units) 1st 2nd 3rd 4th 5th 6th
Training Method A Learning of Skills Development of Skills Stabilization of Skills Competition Technique (football game)
Training Method B Learning of Skills Technique Learning Technique Application Additional Technique Training Competition Technique (football game)

#### Table 5
Skills scoring system

Kicking Dribbling
Number of Successful Efforts Points Time in Sec Points
16 10 <14 15
15 8 14-17.9 12
12-14 6 18-19.9 9
9-11 4 20-21.9 6
<9 2 >22 3

#### Table 6
Cronbach’s α reliability analysis of results

Groups N Cronbach’s α Dribbling Cronbach’s α Kicking
Experiment Group A 30 .85 .70
Experiment Group B 30 .83 .40
Control Group 30 .83 .40

#### Table 7
Arithmetic means, standard deviations and Schefe’s post hoc tests of significant differences between groups on the dribbling and kicking test

1. Pre-test 2. Post-test 3. Retention test
Variables Groups N M SD M SD M SD Post hoc test (Scheffe)*
Dribbling a. Experiment group A 30 7.80 2.80 7.70 2.81 6.40 2.46 Dribbling: 2b-2c, 3a-3c, 3b-3c
Kicking 3.27 2.07 3.67 2.11 3.20 1.54
Dribbling b. Experiment group Β 30 9.00 2.36 9.60 2.54 7.80 2.17 Kicking: 2a-2b, 2b-2c
Kicking 2.67 1.21 4.87 1.80 4.87 1.80
Dribbling c. Control Group 30 9.50 2.24 10.00 1.98 7.80 2.44 3a-3b, 3b-3c
Kicking 2.40 .81 2.87 1.36 2.47 .86

* pairs of groups between whom significant differences have been detected

#### Table 8
ANOVA means in dribbling and training methods according to time

Source SS df MS F p
Method (A) .971 3 .324 .486 .693
Method (B) .513 3 .171 .257 .856
Control (C) 2.00 3 .668 1.00 .397
AxB 2.55 4 .638 .958 .436
AxC 6.42 4 1.06 2.41 .058
BxC .716 3 .239 .359 .783
AxBxC .184 2 .092 .138 .871
Error 44.61 67 .666

#### Table 9
Independent Groups ANOVA Comparing Mean dribbling and kicking

Source Ss df Ms F p η2
Between Groups
Dribbling 52.87 2 26.43 5.87 .004 .119
Kicking 36.30 2 18.18 13.45 .000 .236
Within Groups
Dribbling 83.70 87 39.32
Kicking 49.99 87 24.99

#### Table 10
ANOVA means in kicking and training methods according to time

Source SS df MS F p
Method (A) 3.39 4 .849 1.124 .353
Method (B) 1.18 4 .280 .370 .829
Control (C) .681 3 .227 .301 .825
AxB .249 2 .125 .165 .848
AxC 1.18 2 .589 .780 .463
BxC 2.63 5 .526 .696 .628
AxBxC .604 2 .302 .400 .672
Error 47.58 63 .755

### Figures

#### Figure 1
Performance diagram of dribbling skill

![Figure 1](/files/volume-14/438/figure-1.jpg)

#### Figure 2
Performance diagram of kicking skill

![Figure 2](/files/volume-14/438/figure-2.jpg)

### Acknowledgments

I would like to express my gratitude to all young footballers and their parents who made this research possible with their willingness to participate. Also, I would like to thank the Ethics Committee of the University of Thessaly for its guidance throughout the whole research procedure.

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### Corresponding Author

Christos Plainos
Leivaditi 5
University of Thrace /Department of Physical Education and Sport Science
Nea Ionia 38446
Volos, Greece
<chplainos@yahoo.gr>
(697) 773-8230

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