Chapter III Methodology 31
Chapter III METHODOLOGY In this chapter, the procedure adopted for the selection of subjects and variables, criterion measures, reliability of the data, administration of the tests and the statistical technique for the analysis of the data are described. 3.1 Selection of Subjects A total of 240 adolescent boys were selected for the present study. Each of the early and late adolescent groups, age 13-15 and 16-17 years respectively consisted of 120 elite boy soccer players who represented the eighth upper premier league teams of Iran in the academic year 2011-12. 3.2. Selection of Variables All of the participants were initially checked for health in a clinic and got the consent form (appendix-1), and then were participated in the anthropometric, motor fitness and soccer skill tests, as following. 3.2.1. Anthropometric measurements The selected anthropometric tests in the total included 14 items, 12 items as the body size which include the body height, body weight, lengths of leg and arm, girths of upper arm, forearm, thigh and calf, diameters of bi-acromial, bi-crystal, elbow and knee (table 3.1), and moreover, two items as the body composition (i.e. fat mass% and lean body mass%) (Table 3.2) (Matkovic, 2003) with the age and training age to years, were recorded as the raw data in an especial questionnaire (appendix-2). The procedures for the measurement of these variables were adopted from the books of Clarke (1967) and Johnson & Nelson (1987). 32
Table 3.1: Anthropometric variables (Body sizes) No Variables Instruments Measurement unit 1 Body height Measuring tape Centimeter 2 Body weight Digital scale Kilogram 3 Leg length Measuring tape Centimeter 4 Arm length Measuring tape Centimeter 5 Upper arm girth Measuring tape Centimeter 6 Forearm girth Measuring tape Centimeter 7 Thigh girth Measuring tape Centimeter 8 Calf girth Measuring tape Centimeter 9 Bi-acromial diameter Length caliper Centimeter 10 Bi-crystal diameter Length caliper Centimeter 11 Elbow diameter Length caliper Centimeter 12 Knee diameter Length caliper Centimeter 3.2.1.1 Procedures of the anthropometric variables Measuring of the body height: For the measuring of body height, only essential equipment and materials are a flat surface against which the subject stands, a measuring tape or marked surface, and an object to place on the subject s head that forms a right angle to the wall or a backboard. If a wall is used, it should not have quarter round or wainscoting so that the subject can stand against it with heels, buttocks, upper back, and back of the head making from contact. The subject should be measured without shoes. Standing with the back against a support helps the subject to stretch to full height. The chin is tucked in slightly and the head is held erect. The object used to form a right angle to the backboard is pressed firmly on the subject s head (see figure 3.1.1). 33
Figure 3.1.1: Body height 34
Measuring of the body weight: The participant to be weighted should wear a minimum of clothing, such as only gym shorts. While more accurate results are obtained when subjects are weighed in the nude, this often is not practical or desirable. The subject should be weighed at the same time of day and to the same degree of accuracy, usually the nearest half pound or tenth of a kilogram (see the figure 3.1.2). Figure 3.1.2: Body weight 35
Measuring of the leg length: It was measured from the end of the spinal column to the floor. Also it was taken from greater trochanter to floor (see the figure 3.1.3). Figure 3.1.3: Leg length 36
Measuring of the arm length: 3.1.4). It was measured from the acromion process to the tip of the third finger (see the figure Figure 3.1.4: Arm length 37
Measuring of the upper arm girth: Greatest upper arm girth is measured when arm is maximally flexed and upper arm muscles are fully contracted (see the figure 3.1.5). Figure 3.1.5: Upper arm girth 38
Measuring of the forearm girth: Greatest forearm girth is measured when arm is maximally flexed and forearm muscles are fully contracted (see the figure 3.1.6). Figure 3.1.6: Forearm girth 39
Measuring of the thigh girth: The point of maximal right thigh circumference is measured when the subject stands on the leg (see the figure 3.1.7). Figure 3.1.7: Thigh girth 40
Measuring of the calf girth: The point of maximal right calf circumference is measured when the subject stands on the leg (see the figure 3.1.8). Figure 3.1.8: Calf girth 41
Measuring of the bi-acromial diameter: The most lateral margins of the acromial processes is measured with shoulder relaxed and elbow close to the body. It is measured from behind the subject (see the figure 3.1.9). Plate 3.1.9: Bi-acromial diameter 42
Measuring of the bi-crystal (Bi-iliac) diameter: Greatest width of the pelvic girdle is measured at the lateral margins of the iliac crests, taken from in front of the subject (see the figure 3.1.10). Figure 3.1.10: Bi-crystal diameter 43
Measuring of the elbow diameter: With arm flexed to 90 degrees, the widest margin between the lateral and medial epicondyles of the humerus is measured (see the figure 3.1.11). Figure 3.1.11: Elbow diameter 44
Measuring of the knee diameter: With knee flexed to 90 degrees, the widest margin between the lateral and medial epicondyles of the femur is measured (see the figure 3.1.12). Figure 3.1.12: Knee diameter 45
3.2.2 Body composition variables In this study, fat body mass (%) and lean body mass (%) were measured by body composition technique, through the seven component of skin folds triceps, chest, abdomen, mid-auxiliary, supra-iliac, sub-scapular & thigh (Jackson &Pollock, 1985) (table 3.2). Table 3.2: Anthropometric variables (Body composition) No Variables Instruments Measurement unit 1 Mid-auxiliary skin fold Lange skin fold caliper Millimeter 2 Triceps skin fold Lange skin fold caliper Millimeter 3 Supra-iliac skin fold Lange skin fold caliper Millimeter 4 Sub-scapular skin fold Lange skin fold caliper Millimeter 5 Abdomen skin fold Lange skin fold caliper Millimeter 6 Chest skin fold Lange skin fold caliper Millimeter 7 Thigh skin fold Lange skin fold caliper Millimeter 3.2.2.1 Procedure of the body composition Testing one s body fat is an important part of a quality body building program. Having knowledge of one s body fat can be used in determining ones progress and in calculations vital to a bodybuilder s diet (i.e., daily caloric intake). However, there are few guides available that provide clear and accurate instruction. The easiest and most practical method of measuring one s body fat utilizes body fat calipers to measure subcutaneous fat (fat directly beneath the skin) combined with good technique and simple math formulas. 3.2.2.2 Skin Fold Measurement Sites: Many experts recommend seven measurement sites (skin folds) as three point measurements are not as accurate, and nine point tests yield results highly comparable to seven point tests (Plowman & Smith, 2003). This is also what is used for those competing in current and future hyper plasia challenges. Note, when taking these measurements, the individual should 46
be in a relaxed position. The seven sites of the right parts of body are as follows (see the figure 3.2.1) (Fleck, 1981; Plowman & Smith, 2003): Figure 3.2.1: Exact sites for taking subcutaneous skin folds 47
1. Triceps grasp a vertical fold of skin, on the posterior side of your arm (your triceps) at the midline. The measurement should simply be at the halfway mark between your right shoulder and elbow (see the figure 3.2.2). Figure 3.2.2: Triceps skin fold 48
2. Abdominal Take another vertical skin fold one inch to the right of the umbilical cord (belly button) (see the figure 3.2.3). Figure 3.2.3: Abdominal skin fold 49
3. Chest take a diagonal fold, with the long axis of the caliper directed towards the nipple of the chest. It should be measured mid-way between the anterior auxiliary fold (underarm) and nipple (see the figure 3.2.4). Figure 3.2.4: Chest skin fold 50
4. Thigh take a vertical measurement at about the midline of the thigh; approximately half way the distance from the patella (knee cap) to the hip (see the figure 3.2.5). Figure 3.2.5: Thigh skin fold 51
5. Suprailiac (iliac crest) take an oblique measurement slightly above the hip bone, along the natural diagonal curve of the structure, where the oblique muscle is (see the figure 3.2.6). Figure 3.2.6: Suprailiac skin fold 52
3.2.7). 6. Midaxillary grasp a vertical fold of skin, directly under the arm pit (see the figure Figure 3.2.7: Midaxillary skin fold 53
7. Subscapular take an oblique measurement right below the inferior (bottom) edge of the scapula (the shoulder blade) (see the figure 3.2.8). Adapted from Plowman & Smith (2003) Figure 3.2.8: Subscapular Skin fold 54
Skin Fold Measurements Bringing it all together (calculating) once you have your skin fold numbers; you can plug in your measurements into the following equations. 1985). First, calculate your body density (Db) with the following equation (Jackson & Pollock, For men, use the following equation: Db = 1.112 - (.00043499) (sum of 7 skin folds) + (.00000055) (sum of seven skin folds squared) - (.00028826) (age) For feboys, use the following equation: Db = 1.097 (.00046971) (sum of 7 skin folds) + (.00000056) (sum of seven skin folds squared) (.00012828) (age) Once you have the body density, plug this into the following formula for your body fat percentage (Siri, 1961): Body fat %= [(4.95/Db) 4.5] x 100 Examples suppose a 25 year old boy, has 7 measurements, all 5 mm in girth. He would simply plug this into the Db equation as such: Db = 1.112 - (.00043499) (35) + (.00000055) (352) - (.00028826) (25) Db=1.090242601225 He would then plug in his body density into the body fat percentage equation as such: Body fat %= [(4.95/1.090242601225) 4.5] x 100 Body fat %= 4.03 % Finally, to calculate total lean body mass and fat mass, simply take your body fat percentage, divide by 100 (in this case, that would add up to.0403), and multiply it by your body weight to find out how much total body fat you have. Then, subtract your total body fat, by your 55
body weight, to find how much lean body mass you have. Thus, if this man weighed 200 pounds, he would have approximately 191.95 pounds of lean body mass, and 8.05 pounds of fat. Next, their postures were inspected by a specialist in the field of corrective exercise in physical education to determine their probable body faulty postures. After that, they were administered motor fitness tests viz. aerobic fitness, flexibility, power, speed, agility and endurance (Clarke, 1967) (table 3.3). The motor fitness and performance tests were conducted more than 48 hours following a competition or hard physical training to minimize the influence of fatigue on test performance. 3.2.3 Motor fitness variables Motor fitness is a limited phase of general motor ability, with emphasis placed on the underlying elements of vigorous physical activity, but does not include the primary elements of coordination and skills. It is also a more designation than physical fitness. The basic physical fitness elements are muscular strength, muscular endurance, and circulatory endurance; muscular power, agility, speed, and flexibility are added to compose motor fitness. In this study, except the muscular strength, remaining elements were defined as the selected motor fitness that with their special tests (1 mile-run/walk, Burpee, 50-yard dash, AAHPERD shuttle-run, AAHPERD sit & reach and Vertical jump) are presented in table 3.3. 56
Table 3.3: Motor fitness variables No Variables Kind of test Instruments Measurement unit 1 Aerobic fitness 1 mile (run/walk) Stop watch and track court 2 Flexibility AAHPERD Sit and Reach A specific Marked box 3 Speed 50-yard dash Stopwatch and track court 4 Power Vertical jump Chalk powder & marked table Minute & second Centimeter To the nearest tenth of second Centimeter 5 Agility AAHPERD shuttle run Measuring tape; stopwatch; & 2 blocks of wood 5 5 10 cm. To the nearest tenth of second 6 Muscular endurance Burpee test A mat on the floor Number of correct repetitions 3.2.3.1 Procedures of motor fitness tests 1-mile run/walk test: Objective: to measure cardiorespiratory fitness. Sex and age: age 5 through adult, satisfactory for both boys and girls. Validity: the validity of distance runs of 1-mile and over has been demonstrated in a number of studies, such as that by Disch, Frankiewicz, and Jackson, through factor analysis. Equipment: a stopwatch and a track or some type of open area of known dimensions. Directions: as many as dozen people can run at a time. The subject is told that walking is permitted, but the objective is to cover the distance in the shortest possible time. Each runner is assigned a spotter. A tester gives the command, ready? Go the subject uses a standing start. The spotter is positioned near the finish line in order to clearly hear the timer, who calls aloud the time in seconds as the runners cross the finish line. The spotter must watch his or her runner and remember the announced time. Spotters must be impressed with the importance of paying close attention and not talking to other students until they give their runner s time to the recorder. Scoring: the score is the time in minutes and seconds needed to complete the run. 57
AAHPERD sit and reach test: Objective: to evaluate the flexibility (extensibility) of the low back and posterior thighs. Age level: ages 5 to 17 (and adulthood). Sex: satisfactory for both boys and girls. Validity and reliability: the technical manual that this test was chosen because it has been noted in clinical settings that persons with low-back problems often have a restricted range of motion in the hamstring muscles and low back. The validity of the test is thus supported by logic. Reliability coefficients have range from 0.84 to 0.98. Established reliability for the samples was 0.89. Equipment: a specially constructed box with a measurement scale with 23 cm at the level of the feet. Directions: students remove their shoes and sit down at the testing box with their knees fully extended and feet shoulder-width apart, placed against the end board. The arms are extended forward and the hands are placed on top of each other or equally with the fingers of both hands (see figure 2.3.1). The student reaches forward, palms down, along the measuring board four times and holds the maximum reach on the fourth trial. The maximum reach must be held for 1 sec. Scoring: the score is the farthest point reached on the fourth trial, to the nearest centimeter. The most distant point must be touched with both hands. If the hands reach unevenly, a new trial is given. The tester should place one hand on the subject s knees are fully extended. Figure 3.3.1: AAHPERD sit & reach test 58
50-yard dash test: Objective: to measure speed. Age and sex: 6 through 17 years and satisfactory for both boys and girls. Reliability: established reliability for the samples was 0.87. Validity: face validity is accepted. Equipment: two stopwatches or watch with a split-second timer; a suitable running area to allow the 50-yard run plus extension for stopping. Directions: it is advised that two subjects run at the same time. Both start from the standing position. The commands are you ready? and go are given. At the command to go, the starter drops his or her arm so that the timer at the finish line can start the timing. The subjects run as fast as possible across the finish line. Scoring: the elapsed time from the starting signal, until the runner crosses the finish line is measured to the nearest tenth of a second. Vertical jump test: Objective: to measure the power of the legs in jumping vertically upward. Age level and sex: age 9 through adulthood, and satisfactory for both boys and girls. Reliability: an r as high as 0.93 has been reported, and established reliability for the samples was 0.90. Validity: a validity of 0.78 has been reported with the criterion of a sum of four track and field event scores. Equipment and materials: a yardstick; several pieces of chalk; and a smooth wall at least 12 ft high. Directions: the performer stands with one side toward a wall, heels together, and holds a 1-inch piece of chalk in the hand nearest the wall. Keeping the heels on the floor, the student reaches upward as high as possible and makes a mark on the wall. The performer then jumps as high as possible and makes another market the height of the jump (see figure 3.3.2). Three to five trials are allowed. Scoring: the number of inches (or centimeters) between the reach and the jump marks in the best trial, measured to the nearest half inch is the score. Additional pointers: 59
1. A double jump or a crow hop is not permitted on takeoff. 2. The chalk should be extended no farther than necessary beyond the fingertips to make the standing and jumping marks. 3. The reliability and validity of the test can be slightly improved if the performer practices the jump until it is correctly executed before being tested. 4. Body weight may be included in the score, which is then in terms of foot-pounds. Figure 3.3.2: Vertical jump test AAHPERD shuttle-run test: Objective: to measure the agility of the performer in running and changing direction. Age level and sex: age 9 through college age, and satisfactory for both boys and girls. Reliability: not reported in AAHPERD test booklet but for the sample s established reliability was 0.84. 60
Objectively and validity: for both, not reported in AAHPERD test booklet Equipment and materials: marking tape; a stopwatch; and two blocks of wood 2 2 4 inches. Directions: the performer stands behind the starting line and on the signal go runs to the blocks, picks up one, retunes to the starting line, and places the block behind the line; the student then repeats the process with the second block (see figure 3.3.3). Two trials are given, with rest allowed between them. Scoring: the score for each performer is the length of time required (to the nearest tenth of a second) to complete the course in the better of the two trials. Figure 3.3.3: AAHPERD shuttle-run test 61
Burpee test: Objective: to measure the general muscular endurance of the body. Age level and sex: age 10 through college age for both boys and girls. Reliability: r= 0.97 was found for this test when subjects were tested on separate days. Validity: face validity is accepted for this test. Equipment and materials: a mat on the floor. Directions: from a standing position, the student bends at the knees and waist and places the hands on the floor in front of the feet, thrusts the leg backward to a front leaning rest position, retunes to the squat position as in the first count, and stands erect. From the signal go, the exercise is repeated at a constant rate of movement for as long as possible (see the figure 3.3.4). Scoring: the score is the number of correct repetitions. The score is recorded to the nearest whole number. Figure 3.3.4: Burpee test 62
3.2.4 Soccer performance variables Soccer performance in this study was made through the specific skill tests of soccer 50% and coaches view points about performance ability 50%, together as total performance points. Soccer specific skill tests are presented in table 3.4. Six tests of technical skills in soccer were administered (Federac, a o Portoguesa de Futebal, 1986). The tests are recommended by the Soccer Portuguese federation and were used by researchers (e.g. Seabra et al., 2001; Coelho e Silva et al., 2004; Malina et al., 2005). 3.2.4.1 Procedures of the soccer skill tests The tests were administered outdoors on a playing field. The players warmed-up in the usual manner before a practice session (stretching and jogging), and also rested between tests. The tests were administered in a station format and not in any specific order. Ball control with the body (skill 1): within a 9 9 m square, the player had to keep the ball in the air without using the arms or hands. The score recorded the number of hits of the ball before it fell on to the floor. Counting was stopped when the ball hit the floor, or when the participant moved out of the square, or he touched the ball with the arms or hands. One trial was administered, although the participant could start the trial again if he failed to contact the ball three times in the initial attempt. Ball control with the head (skill 2): within a 9 9 m square, the player had to keep the ball in the air using only the head. The score recorded the number of hits of the ball before it fell on to the floor. Counting was stopped when the ball hit the floor, or when the participant moved out of the square, or he touched the ball with any part of the body except the head. One trial was administered, although the participant was allowed to start the trial again if he failed to contact the ball three times in the initial attempt. Dribbling with a pass (speed and accuracy; skill 3): Four cones were placed in a line, 2.25 m apart, within the 9 9 m square, and a fifth mark, a flat surface such as a bench 1.2 m wide, was placed on the end line. The participant was instructed to dribble the ball around the first four marks in slalom fashion, make a pass to the fifth mark and receive/ control the ball, and dribble around the four marks back to the starting line. The objective was to complete the drill in the fastest time possible without knocking down the cones and without stepping out of the square, controlling the ball only with the feet. If a cone (mark) was knocked over, the participant had to 63
place it upright and continue the test. Two stopwatches were activated by the timers at the starting signal and were stopped when the participant crossed the starting line. The average of the two values was used in the analysis. Dribbling speed (skill 4): A cone was placed on each corner of the 9 9 m square (four cones). A fifth cone was place midway (4.5 m) on the line of the square where the test began Thus, the near end had three cones (one on each corner and the third midway) and the far end had two cones (one at each corner). Beginning at one corner, the athlete had to conduct the ball with the feet (dribble) around the three cones (corner directly opposite the starting cone, the cone placed midway, and the cone diagonally opposite the starting cone) in slalom fashion, and then dribble the ball into the fifth cone (i.e. not with a pass). The objective was to complete the drill in the fastest time possible by controlling the ball only with the feet without knocking down the cones. If a cone was knocked down, the participant had to place it upright and continue the test. The overall slalom distance was thus about 40 m. Two stopwatches were activated by the timers at the starting signal and were stopped when the ball was dribbled into the fifth cone. The average of the two values was used in the analysis. Passing accuracy (skill 5): Five targets were placed 2.5 m apart at the end line of the 9 9 m square. The athlete was standing outside of the square at the opposite line of the target. Two attempts at each target were allowed for a total of 10 attempts. The objective was to hit the targets with the kicked ball in succession from one to five; two attempts were permitted for each target. The score was the number of successful target hits; the maximum score was 10 points. Shooting accuracy (skill 6): A 2 3 m goal was set up at the end line of a 9 9 m square. The target was divided by ropes into six sections. One rope was placed horizontally between the posts at a height of 1.5 m. Two ropes were dropped from the crossbar, 0.5 m from each post. Five points were allocated for the upper right and left sections, and two points for the upper middle section. Three points were allocated for the lower right and left sections, and one point for the lower middle section. While standing outside the square at the opposite line of the goal, the player had five attempts at kicking the ball into the goal. The maximum score was 25 points. 64
Table 3.4: Soccer skill tests No Variables Kind of test Instruments Measurement unit 1 2 Ball control with the body Ball control with the head 3 Dribbling with a pass Ball control, body Ball control, head Speed and accuracy 4 Dribbling speed Speed 5 Passing accuracy Accuracy of passing 6 Shooting accuracy Shooting points Soccer court and a ball Soccer court and a ball stop watch, 4 cons, a soccer ball and a bench Stop watch, 5 cons and a soccer ball 5 targets and 5 soccer ball Soccer gate, rope and a soccer ball Number of hits at the ball Number of hits the ball To the nearest tenth of seconds To the nearest tenth of seconds Number of correct performance Points Each variable in objective tests of soccer were given 10 points. The aggregate score of the objective tests were 60 and then they were converted to a scale of 50. 3.2.4.2 Procedure of performance Ability viewpoints The subjects were rated subjectively by a panel of three expert coaches who were associated with the subjects throughout the training year. The subjects were rated by the coaches in the following areas: 1) Overall playing ability 2) Adaptability of the player to the game situations 3) Execution of various skills and techniques by the player during the matches 4) Tactical efficiency 5) Fitness Level 6) Game sense and intelligence of the player 65
7) Indispensability of the player in the team 8) Training age 9) Consistency of the performance Each aspect/area was rated for 10 points making the aggregate subjective score 90. The total of points scored by a subject was first converted to a scale of 50 and then was added to the total of points scored in the six selected skill tests of soccer. The total of score obtained by the subjects for all the 15 items of performance were to become the score (data) for performance ability points of the subjects (independent variable). 3.3 Reliability of Data Establishing the instrument reliability, tester competency and reliability of tests ensured the reliability of the data. 3.3.1 Instrument s Reliability Every instruments which used in this study were included digital stop watches which used for recording of the times; leader or metal tapes which used for measuring of the distances or limb s length and height; Length and Lange skin fold calipers which used for measuring of the sub-skin folds and diameters; digital scale which used for weighing of the body mass, and also soccer court and gate; cons and balls which used for soccer performance tests; track court which used for 1-mile run/walk test; marked box which used for measuring of the hamstring and low back muscles flexibility were selected of the standard instruments that suggested by Practical measurements for evaluation in physical education, by Johnson and Nelson (1987) and Malina, 2005. 66
3.4 Tester Competency The investigator had undergone collecting the data for two months with the help of scientific administrators in coaching and judging to qualify him to conduct the tests and collect data of the subjects in the anthropometric, motor fitness and soccer specific skill variables that were undertaken for this study. The investigator had several collecting session during the research. 3.5 Reliability of the Tests To determine the reliability of the field tests conduction, 20 subjects were selected at random and the research scholar conducted all the tests twice under identical conditions. The correlation coefficient was computed for two measures of each variable. Reliability coefficients obtained are presented in the table 3.5.1 for the anthropometric variables, the table 3.5.2 for the body composition components, the table 3.5.3 for the motor fitness tests and the table 3.5.4 for the soccer specific skill tests. Table 3.5.1: Reliability coefficients of test re-test scores for the anthropometric variables (body size) No Variables Coefficient correlation 1 Body height 0.95 2 Body weight 0.94 3 Leg length 0.96 4 Arm length 0.97 5 Upper arm girth 0.98 6 Forearm girth 0.98 7 Thigh girth 0.98 8 Calf girth 0.99 9 Bi-acromial diameter 0.98 10 Bi-crystal diameter 0.99 11 Elbow diameter 0.99 12 Knee diameter 0.99 67
Table 3.5.2: Reliability coefficients of test re-test scores for the body composition components no Variables Coefficient correlation 1 Triceps skin fold 0.97 2 Chest skin fold 0.98 3 Abdomen skin fold 0.96 4 Sub scapular skin fold 0.97 5 Mid auxiliary skin fold 0.98 6 Supra iliac skin fold 0.97 7 Thigh skin fold 0.96 8 Fat mass % - lean body mass % 0.85 Table 3.5.3: Reliability coefficients of test re-test scores for the motor fitness tests no Variables Coefficient correlation 1 50 yard dash 0.87 2 AAHPERD shuttle run 0.87 3 Vertical jump 0.90 4 AAHPERD sit & rich 0.89 5 1-Mile run/walk 0.75 6 Burpee 0.70 68
Table 3.5.4: Reliability coefficients of test re-test scores for the soccer skill tests and soccer performance no Variables Coefficient correlation 1 Ball control with the body 0.74 2 Ball control with the head 0.72 3 Dribbling with a pass 0.81 4 Dribbling speed 0.82 5 Passing accuracy 0.67 6 Shooting accuracy 0.65 7 Performance viewpoints 0.68 8 Total performance points 0.65 3.6 Statistical analysis: SPSS (version 18.0), (for the latest PASW Statistics, http://www.spss.com/statistics), was used for the statistical analysis. Descriptive statistics for each variables were calculated for the total sample (n = 240). Values are presented as mean values ± SD., Min., and Max., by two age groups (secondary and high school), each group consisted of 120 subjects, and by position forwards/strikers (n = 45), midfielders (n = 89), defenders (n = 73) and goalkeepers (n = 33). Pearson Correlation Coefficient was used to assess the relationship between anthropometric, motor fitness parameters and soccer performance variables. The ANOVA was used to find out differences among positions by variables. Differences between two age groups among the variables were evaluated by the independent samples t-test. Regression analysis was used to estimate the relative contribution of anthropometric and motor fitness variables to each of the six soccer specific skill tests. 69