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Curtin University
School of Physiotherapy

Fitness Testing Assignment: Soccer

Fitness Testing Assignment: Soccer - by Derek Chan

Contents

Introduction

Soccer is one of most popular sports in the world. The game consists of two equal periods of 45 minutes, with a fifteen-minute break between. There are eleven players from each team on the field. The players may be divided into four groups: goalkeepers, defenders, midfielders, and forwards. During the game, players are required to perform activities like jogging, running (forward and backward), kicking, turning, heading and throwing. Fitness is very important for everyone on the field. Therefore, training is important to improve the fitness of the players to prevent them from fatiguing easily, and to improve the skills and tactics of the game.

During the preseason period, players normally do fitness testing in order to determine each player�s physiological condition. From the results of the testing, the coaches can identify the strengths and weaknesses of the players and train them accordingly. Appropriate testing should be specific and reliable enough to reflect the actual status of the fitness of the soccer players. In this context, the features of the soccer game and related physiological testing will be discussed.

Energy System Requirements of Soccer Players

During exercise, muscles use energy that is provided from either aerobic or anaerobic processes. The anaerobic energy is released from the breakdown of adenosine triphosphate (ATP), which is stored within the muscle or produced either by splitting creatine phosphate (CP) or by degrading carbohydrate (CHO) to pyruvate which leads to the formation of lactate. A minor anaerobic energy contribution can also occur by the degradation of adenosine diphosphate (ADP) to adenosine monphosphate (AMP). The aerobic energy is produced in special compartments (mitochondria) in the muscle cell by using oxygen, which is taken up from the blood. The substrates for these reaction are formed through glycolysis (utilisation of CHO), catabolism of fat and, to a lesser extent, protein. The rate of production during exercise and, thus, utilization of substrate is controlled by the intensity of activity. In most cases, the anaerobic processes are so rapid, and the aerobic system has such a capacity that the muscles are able to maintain ATP at a high level during exercise.

The CHO from glycolysis is primarily glycogen stored within the exercising muscles, but glucose taken up from the blood can also be used. The substrates for fat oxidation are triglycerides (TG) stored within the muscles and fat carried in the blood, primarily free fatty acids (FFA) released from adipose tissue and to a lesser extent TG.

In football, players perform many different types of exercise, and the intensity can alter any time from standing to maximal running. From a Danish study , the total distance covered during a match average 10.80 km. This value is very close to the values found for Swedish soccer players but further from the mean values of 8.7km and 13.5 km reported earlier for English players (Bangsbo et al, 1991). The mean distance covered during the first half is 5% greater than the second half of a match. From the same study, the mean distance covered by midfielders was 11.4km, which is significantly further than the distance covered by the defenders (10.1km) and the forwards (10.5km).

On average, Bangsbo et al (1991) observed that the players were standing still for 17.1% of the total playing times. Low intensity running accounted for 35.1%, and this was composed of 1.7% jogging, 17.1% low speed running and 1.3% backward running. High intensity running accounted for 8.1% of the total time, consisting of 5.3% moderate speed running, 2.1% high speed running and 0.7% sprint running.

Thus besides having a well-developed ability to exercise with a high power output the players should also be able to work for a long time. This separates football from sports in which continuous exercise is performed with either a very high or moderate intensity during the entire event.

Aerobic Energy Production

From a review by Bangsbo (1994), heart rate was measured to represent the aerobic demand during the football matches. Mean heart rate of Czechoslovakian football players was 165 beat per minute (bpm). Mean value of 175 bpm was found in a Danish football player and 85% of maximal heart rate (171bpm) was found in Russian player for 57% of the playing time. English league players were also found to have a mean heart rate of 157bpm. Bangsbo (1994) also found that the mean heart rate of six Danish players was 164bpm in the first half of the game and about 10 bpm lower during the second game. Since the oxygen uptake is difficult to measure during football matches, transformation of the mean heart rate to the oxygen uptake could be done by calculating the individual relationship between heart rate and oxygen uptake. One of the players showed that the mean oxygen uptake during the game was 46.2 ml/kg/min (Bangsbo, 1994). However, the transformed data should be interpreted with care as the heart rate measured during football game can be influenced by the emotional and thermal stress as well.

Ekblom (1986) found the maximum oxygen uptake of Swedish players to be about 61ml/kg/min. Similar results have been found in Danish national soccer players (Bangsbo et al, 1991) with a mean maximal oxygen uptake of 60.6 ml/kg/min (although the value of a midfielder was higher it was not statistical significant). Players in a South Australian national soccer league had a VO2max of 57.6 ml/kg/min compared to the 56.7ml/kg/min of a State league team . A recent study by Wisloff et al (1998) reported 63.7ml/kg/min as the mean maximal oxygen uptake of the Norwegian soccer team. The physiological profile for the Australian National Team was found to be 56.9ml/kg/min while the Australian Olympic Team was 59.3ml/kg/min.

Anaerobic Energy Production

CP and ATP utilization in football

The creatine kinase reaction that rebuilds ATP by CP breakdown is activated at the onset of exercise. It is probably so rapid that, together with glycolysis, it can maintain ATP concentration of a high level at the beginning of very intense exercise. However, the CP stores are limited and can last only for a few seconds during maximal running, if CP was the only energy source. After intense exercise, CP is resynthesized rapidly by utilisation of ATP produced from aerobic sources.

In football, the CP concentration alternates continuously as a result of the intermittent nature of the game. Although the net utilization of CP is quantitatively small during a football match, CP has a very important function as an energy buffer, making energy available for the muscles during rapid elevations in the exercise intensity. For elite male players, the total duration of high intensity exercise during a football match was about seven minutes (Bangsbo et al, 1991). This included about 19 sprints with mean duration of two seconds. Degradation of CP, and to a lesser extent stored ATP, provides a considerable amount of energy during the sprinting efforts.

Lactate production in football

The concentration of lactate in the blood is often used as an indication of the anaerobic lactacid energy production in football. Blood samples for lactate analysis have been obtained at half-time and after matches, and in some studies also during match-play. Ekblom (1986) found that the blood lactate concentration for the First Division players of Swedish soccer team were 9.5 and 7.2 mmol-1 after the first and second half, respectively, while the corresponding value for Fourth Division players were 4.0 and 3.9 mmol.l-1, respectively. The Second and Third Division players had values in between. Gerisch et al (1988) found blood lactate concentrations of about 4-6 mmol.l-1 at half-time and immediately after German amateur matches, and similar values were observed in the middle of both halves in a German University friendly match.

Variation in blood lactate concentrations can be large and peak values higher than 10mmol.l-1 have frequently been observed. In addition, determinations of blood lactate from the same player several times during a match have shown large differences (Ekblom 1986, Bangsbo et al, 1991). These findings are likely to be a result of differences in the activities before sampling, since it has been demonstrated that blood lactate measurements were related to the incidence of high intensity activities prior to blood sampling (Bangsbo et al, 1991).

Strength Requirements of Soccer Players

Strength in the lower limb is of obvious concern in soccer: the quadriceps, hamstrings and triceps surae must generate high forces for jumping, kicking, turning and changing pace. The ability to sustain forceful contractions is also important in maintaining balance and control. Isometric strength is possibly important in maintaining a player�s balance on a slippery pitch and also in contributing to ball control. For a goalkeeper almost all the body�s muscle groups are important for executing his skills. For outfield players, the lower part of the trunk, the hip flexors and the plantarflexors and dorsiflexiors are used most. Upper body strength employed in throw-ins and the strength of neck flexors could be important in forcefully heading the ball. At least a moderate level of upper body strength should prove helpful in preventing being knocked off the ball.

Some studies have indicated a relationship between dynamic muscle performance in laboratory and field contexts. Cabri and co-workers (1988) reported a significant relationship between isokinetic leg strength and kick performance indicated by the distance the ball travelled. The relationship was significant for both eccentric and concentric contractions of hip and knee joints in flexion and extension.

Principles of Testing

To develop an individual physical profile

The aim of developing a physical profile is to identity a player�s physical strengths and weaknesses. This can be achieved through the administration of a series of football-specific tests. The information gained from these tests can then be used to set up short- and long-term goals. In the event of a long-term injury, chronic sickness, or planned rest period, a player�s predetermined physical profile will also provide data that can be used for comparison purposes.

To evaluate objectively the effect of a specific training program

The aim of a training program is to improve performance. In order to quantify changes in performance that has occurred as a result of training, baseline data is needed. Baseline data is collected before the start of a training program using a test (pre-test) which must be specific to the type of training that is to be performed. The same test is then repeated (post-test) usually after 6 or more weeks of training. Thereafter, the subsequent progress of players should be periodically monitored through repeated tests.

To monitor progress during rehabilitation.

During a rehabilitation program it is important to monitor how well an injured player is responding to treatment and to know when the player is ready to return to competitive football. Players who return prematurely to competitive football can have a high risk of recurring injury.

To monitor the health status of a player.

The general health status of a player can be monitored by checking heart rate and other physiological responses to a standardized exercise workrate. Early signs of overtraining may be detected by regularly monitoring a player�s physical performance capacity. Heart rate response to the standardized exercise can also be used to evaluate how well players adapt to a new, unaccustomed surroundings.

Selecting a Test

Once the reason for testing has been clearly defined, an appropriately test must be selected. Factors to be considered when selecting a test are discussed below.

Specificity for football

Information gained from a test will be of no benefit to the coach or player unless the recorded measurement can be applied to football.

Reliability

Test-retest reliability refers to how reproducible a test result is from trial to trial, or day to day. Factors which affect reliability can be classified into biological or experimental . The former refers to the relative consistency with which a subject can perform, while the latter concern variations in the way the test is administered. For repeated testing, it is necessary to determine whether there is any difference in two test results, for a given player, can be attributed to a change in the physical status of the player or whether the difference is within the expected measurement variation for the test. Test-retest reliability is usually reported in the form of a correlation coefficient; the closer this coefficient is to 1 the more reliable the test is.

Feasibility

When selecting a test, considerations must be made for such factors as the playing status of the team and availability of facilities and appropriate equipment, as well as for the amount of time required to carry out the test and analyze the test results. For example, with a team which trains twice a week it is not feasible to use the time consuming tests. Time can also be a problem for the coach of a national team where the squads of players are only together for short periods of time. Furthermore, selected squads of players are usually assembled to prepare for a game, therefore exhaustive exercise tests are not recommended in this instance.

Conditions

Testing conditions e.g. running surface, preparation of test areas, and calibration of measuring equipment, must be standardized each time a test is performed. While test conditions can usually be accurately reproduced for test performed in a research or clinical setting, problems can arise with field tests, e.g. if performed on a football pitches the type or condition of the surface can change throughout the year. Extreme variations in environmental conditions should be avoided.

Procedures

The standardization of testing procedures refers to the way in which the test is administered. For example, when a battery of tests are performed on the same day, the order in which each player performed the tests should be standardized. Where possible, the exhaustive tests should be performed last.

Practice should be given if possible to get the player familiarized with the test and this will reduce the learning effect and attain a more accurate test result.

Pre-test condition of players

Players should be well rested before the tests. Usually, at least 24 hours should be allowed after a competitive match. When players have just recovered from an injury or an acute illness this should always be noted. With female players, it is advisable to note any players experiencing detrimental side effects caused by menstruation.

An often-overlooked consideration when testing is clothing and footwear. Suitable clothing should be worn which will not interfere with performance, and in running or jumping tests, the same type of shoes should be worn for repeated tests.

Instructions and test administration

It is essential that players clearly understand how each test should be performed. When using a test which is not possible to test all the players in the team at the same time, other activities should be planned so that players are not waiting for long period of time, however, such activities should not be strenuous enough to affect the result.

Motivation

Players are required to exert the maximal effort in performance tests. Such tests can be greatly affected by the motivation of the players. It is therefore very important that players are well motivated and mentally prepared.

When to administer a test

It is difficult to define exactly when or how often to carry out a test. Some general guidelines are listed in Balsom (1994):

  • When the objective of testing is to evaluate the effect of a training program, sufficient time should be allowed for the desired adaptation to take place, a period of six weeks between tests is usually the minimum time advisable.
  • It is useful to test players just before they are released at the end of each season and again when the training resumes.
  • Data for physical profiles should be collected toward the end of the preseason period when players reach their peak performance level.

Aerobic Testing Procedures

Aerobic fitness is dependent on and limited by the body�s ability to deliver oxygen to the working muscles. The heart, lungs, blood, circulatory system, and working muscles are factors in determining one�s aerobic fitness. Aerobic fitness is important as the soccer players have to cover the total distance around 10km, and 35.1% of the total player time in a game consists of low intensity running.

Estimation of Aerobic Capacity

VO2max can be determined from either maximal or submaximal exercise testing. At maximal exercise level, VO2max is measured directly from expired gases or estimated from exercise intensity. In the laboratory, VO2max can be estimated from treadmill and cycle ergometer performance and heart rate response to the exercise. Field tests can also be conducted to determine the aerobic capacity in football players Grant et al (1995) compared different field test results (Cooper's 12 minute run test, Multistage shuttle run test) with a maximal treadmill test. Results showed high correlations, with coefficients for the Cooper test and Multistage shuttle run test of 0.92 and 0.86 respectively. As football requires frequent change of direction during running, the Multistage shuttle run test may be a more specific test.

Multistage Shuttle Run Test Procedures

Players are required to run back and forth on a 20-meter course, starting at a speed of 8.5kmh-1. The running speed is increased by 0.5kmh-1 every minute. The running speed is regulated by a sound signal emitting from a prerecorded tape. Players try to complete as many stages of the shuttle run as possible, and the test is terminated when the testing player is unable to maintain the prescribed pace. The player will be given a warning signal the first time they are behind the sound signal and the test will be stop at the third warning. The maximal speed corresponding to the last completed stage is used to estimate each player�s VO2max according to the following equation:

VO2max = 31.025 + (3.238 &mult; velocity in last stage) - (3.248 &mult; age) + (0.1536 &mult; age &mult; velocity in last stage)

Normative Data

Male and female normative data in Multistage shuttle run test has been shown by Australian Institute of Sports (AIS, 1998) recently as below:

Squad Multistage Fitness Test Score
Level/shuttle Level/shuttle
as a decimal value		 Predicted O2max
(ml.kg-1min-1)
Males
AIS Youth, May 1996
(n=16)		 Mean 13;05 13.4 58.6
SD 1.2 4.0
Range 10;07-15;01 10.7-15.1 49.0-64.3
Nat U-17, Oct 1996
(n=37)		 Mean 12;12 13.0 56.9
SD 1.1 3.6
Range 10;05-14;13 10.5-15.0 48.3-64.0
Olympic, May 1994
(n=22)		 Mean 13;08 13.6 59.3
SD 0.98 3.4
Range 11;03-15;05 11.3-15.4 51.1-65.4
Females
National, Nov 1996
(n=19)		 Mean 10;09 10.8 49.4
SD 1.2 4.1
Range 9;01-13;11 9.1-13.9 43.6-60.0
Junior, Oct 1995
(n=31)		 Mean 10;01 10.1 47.3
SD 1.1 3.8
Range 8;02-12;02 8.2-12.2 40.5-54.2
Youth, Dec 1995
(n=15)		 Mean 9;06 9.6 45.2
SD 1.4 4.8
Range 6;07-11;07 6.7-11.6 35.4-52.2

Anaerobic Testing Procedures

Soccer players are frequently required to produce high power output and sometimes to maintain it with only a brief recovery. The total time for high intensity running is about seven minutes of the whole game (Bangsbo et al, 1991). The average sprint distance is about 15 meters and occurs once every 90 seconds.

Estimation of Anaerobic Function

Bouchard (1991) classified anaerobic test into short, intermediate and long term anaerobic performance capacity. Short term anaerobic performance capacity is defined as the total output during maximal exercise lasting about 10 seconds, while it last about 30 seconds and 90 seconds respectively for intermediate term and long term anaerobic performance capacity. Wingate test have been described and used in some preseason testing of English football team , American Olympic soccer team , and Hong Kong football team . However, this test is done on a cycle ergonmeter that it seems not specific enough to football. Running may be a more appropriate form of test in football. The Cunningham and Faulkner Test (developed in 1969) has been used in Australia as the a test to determine anaerobic function (Green, 1992). Cunningham and Faulkner test is a maximal run test on a treadmill. The speed of the test will be set at 12.9 km/hour at 20% gradient from horizontal. The time to exhaustion will be measured.

Cunningham and Faulkner Test Procedures

Following a five minutes warm-up at 10.5km/hour and zero incline, stretching is then done to the lower limb muscles including the quadriceps, hamstrings and calf muscles. The treadmill speed and incline will be reset to 12.9 km/hour at 20% incline. Each subject is required to run to exhaustion, which means he is unable to maintain the speed. The elapsed time on the test is measured from the moment at which the subject begin running unsupported to the moment at which the hands of subjects are placed on the supported rail. Time is recorded to the nearest 0.5 second. Strong encouragement is provided throughout the test.

Normative Data

This data are from the South Australia National Soccer League and the State League (Green, 1992)

National League State League
66.2± 10.7 seconds 54.4 ± 8.8 seconds

Sprinting Ability

Sprinting is also one important component of playing in a football match. Bangsbo (1991) showed that the 19 sprints (on average) accounted for 0.7% of the total time of a game. The performance of sprinting is important and it is one of the tests included in the test battery of performance in the Australian Soccer Team.

Testing Procedures

Two sets of timing gates will be used and placed at the distance required (5m, 12m, 20m). A five-minute warm-up should be done followed by stretching of the lower and upper limbs. Several maximal runs over a short distance are allowed in order to familiarize the players with the test. Players then stand 50 cm behind the starting line and some crouch is allowed. The player starts sprinting when ready and strong verbal encouragement is given over the whole course of sprinting. Three trials are performed and the best time reported.

Normative data (AIS, 1998)

Squad Sprint Times (seconds)
5m 10 m 20 m
Males
AIS Youth, December 1977
(n=16)		 Mean 1.11 1.85 3.13
SD 0.06 0.06 0.09
Range 1.05-1.29 1.77-2.01 2.95-3.29
Females
NSWIS State, January 1998
(n=19)		 Mean 1.07 1.85 3.24
SD 0.05 0.07 0.11
Range 1.00-1.14 1.75-1.96 3.10-3.46

Strength Testing Procedures

Muscle strength is also important in soccer as discussed above. It is also included in the test battery of some national and elite soccer teams.

Estimation of Muscle Strength

Various tests of muscle strength and power have been employed for assessment of soccer players. These have ranged from performance tests and measurement of isometric strength to contemporary dynamic measures using computer-linked isokinetic equipment. Different soccer teams have used isokinetic equipment to measure the strength of the lower limb. However, it is difficult to compare these studies as the testing speed chosen is often different.

Limitation

There is a possible limitation in assessing muscle strength and power for soccer with isokinetic equipment. As the kicking action is an accelerating movement rather than a motion with the same speed throughout the range, so isokinetic testing may not be truly reflect the condition in soccer. Further research is needed to understand and develop a more specific test for soccer.

Testing Procedure

Warm-up and stretching exercises are done before the testing. Subject is then instructed to sit correctly and comfortably in the testing seat. The axis of knee and the seat position are adjusted and recorded accordingly. The testing knee is also put in the testing adapter and is strapped to make sure stable and comfortable for testing. After that, the limb weight and the gravity correction will be adjusted before the testing proceed. The testing angle will be adjusted and locked, which is also recorded into the computer system of the equipment. After the positional adjustment has been done, the mode of exercise setting and the speed will be chosen. Before the testing, five repetitions of testing movement will be performed in order to get familiarization of the test. Verbal encouragement will be given during the testing trials. Peak torque will be recorded from the each trial.

Normative Data

The data below is from an American soccer team (Mangine et al, 1990), which tested the isokinetic knee extension and flexion strength at 60/sec and 450/sec on a Biodex dynamometer.

Right leg at 60/s Left leg at 60/s Right leg at 450/s Left leg at 450/s
Extensor torque/BW 126.3±22.0 118.4±.0 72.7±11.0 71.0±13.0
Flexion torque/BW 68.3±12.0 65.0±11.6 47.7±9.0 48.3±8.0
Flexor/extensor ratio 56.0±17.0 56.6±17.0 67.1±18.0 70.1±18.0

Conclusion

Soccer is a game, which include various activities like running, sprinting, heading and kicking. Physiologically, good aerobic, anaerobic function, CP-ATP system, strength and agility is essential to maintain the optimal performance during the game. Therefore, fitness testing will be carried out in order to assess each player�s fitness condition during pre- and post-season. Many fitness tests are available and developed to date, but appropriate tests should be chosen to identify the changes of players specifically. Multistage shuttle run test, Cunningham and Faulkner test, sprint test and isokinetic test for strength are chosen for evaluation of soccer in this context. Limitations are still found in some of the tests and further research is needed so as to design the right physiological testing for soccer players.

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Exercise Physiology Educational Resources 1999