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sports medicine

Players made to measure

A study shows who runs more and who has more resistance and greater dash in a football team

Science and football is a rare combination to be found in Brazil. The academic world does not usually select the football pitch as an object of study and neither does the world of the players have the habit of paying attention to what researchers talk about the most popular sport on the planet. In a privileged situation within these two fields, both science and football, Turíbio Leite de Barros, the director of the Medical Center of Physical Activity and Sport at the Federal University of São Paulo (Cemafe/Unifesp) and a physiologist with the São Paulo Football Club team for the last fifteen years, has produced a study that sketches out the profile of the football played today in Brazil from the point of view of the physical demands that the players in each team position are submitted to during a game.

The study was presented last March at the International Football & Sports Medicine Conference, which took place in Los Angeles under the sponsorship of the Federation International Football Association (FIFA). In order to carry out the study, the Unifesp researcher filmed and analyzed the movements of around one hundred professional athletes of São Paulo club in official matches carried out over the last six years and also compared the results of physical tests applied to one thousand players who had passed through the team from 1986 until today.

The main conclusion: there is not just one model of athletic performance, which serves to describe the actions on the field of a typical – and hypothetical – football player, but there are various models, with very distinctive characteristics depending upon the position in which the sportsman plays. The growing specification of the demands executed in each function of the modern football game – striker, attacking midfielder (or simply a midfielder), defensive midfielder, defensive winger (who covers one of the flanks, center-back (defender) and goalkeeper – require players with physical qualities distinctly different.

It is very rare for an athlete to combine the principal requirements of a position if they are not naturally his to begin with. “Today’s football requires more and more specialized players and not multi-positional”, says Barros. “Pelé was very versatile, but this is not the current norm, not even among today’s stars.”

Since Brazilians do not have a standard biotype – there are people with the most varied physical attributes, the fruit of an intense mixture of races -, the country is, in the vision of the physiologist, a storehouse of specialists in all of the positions. “The Europeans have more defined biotypes and cannot count upon this facility”, he comments.

Nevertheless, one cannotsay, beforehand, in which position of the football field the best athletes will be found. “Before saying who is the best, one needs to ask the question: best at what?”, ponders Barros. If they were chosen for track and field tests beginning with the movements that they carry out on the field, probably each position would provide participants for very distinctive competitions. “To dispute a 5,000 meter race, the best would be the wingers and the attacking midfielders who cover on average the greatest distances and have good stamina”, says the Unifesp researcher. “However, the strikers are players more tailored to quick and explosive tests, such as a 50-meter sprint.

This is because the players in this position are those who carry out short dashes”. Following this line of reasoning, those to be chosen for a high jump dispute should be the goalkeeper, the center-backs and the defensive midfielders who come out better when the question is vertical impulse.

The study confirms some intuitive impressions of those who follow football such as that the strikers play in a more fixed position than the other players in the team. And the relevance of the study is, fundamentally, to throw light on aspects such as these and to quantify them. If it is common sense that the strikers move themselves over a small area of the field, how many would be able to accurately say a center forward runs than a midfielder? According to this study, the strikers are those who in general cover the least distance on the field, on average 8.3 kilometers during the ninety minutes of a game.

It is a considerable distance but 18% less than the midfield players, the lungs of the team who on average cover 9.9 kilometers during the game. On this question, the wingers, whose function has gained importance and today corresponds to a wide stretch of the field, come out almost as well as their midfield colleagues. On average they cover 9.7 kilometers during a match, as against 9.5 for the defensive mid-fielders and 8.8 for the center back. The average of the whole team, taking into account the performance of the players at all positions (expect, of course, the goalkeeper) gave 9.3 kilometers per ninety minutes of the ball in movement. It is interesting to note that the strikers and the defenders, whose main function is to annul one another, cover smaller distances that the remainder of the team.

If they cannot be long range runners, the strikers have in compensation the vocation of being fast. When the question is sprinting (short runs at maximum velocity), the kings of the dashes, such as the celebrated Ronaldo, are exactly the attacking players. A center forward carries out as many as fifty sprints during a game, more than half of them up to the maximum distance of fifteen meters. The position in which a player is least requested to carry out this type of movement is the center-back, who does, on average, thirty five sprints during a match. In fact, the defenders tend to be the players with the greater muscular potential and those who move more backwards during a game (more than half a kilometer). What are the qualities of the other positions?

The physical tests and the filming of the São Paulo teams show that while running the vertical take-off of the goalkeeper is unbeatable: his jumps in movement are 19% higher than the average jump executed by his colleagues who play in the defensive line. At rest, who can jump highest are the defensive mid-fielders and the center backs. The standard of impulse of these two positions is 16% better than the average of all of the group.

The performance of the wingers is a case in itself. Boththe physical tests and the videos revealed that they are generally players with an accentuated performance in almost all of the questions – at the least, above the average. They are the most agile, with the best breathing capacity (15% above the team’s average) and they cover the largest distance on the filed with the ball at their feet: 230 meters against 148 of the mid-fielders, the second highest placed on this point). Only in vertical jumping are they below the average of the team. It should be no surprise, therefore, that a winger such as Roberto Carlos, should currently be as valuable as the midfield and attack players where one usually finds the stars of the team.

In order to arrive at the results about the movements carried out in a game played by the São Paulo players, Barros had the collaboration of Wellington Valquer, assistant physical preparation coach of the club and who did his masters at Unifesp. Valquer made use of a methodology developed in Australia, a technique named Withers. Armed with a video camera, the assistant chose a player to be analyzed during a match – it could have been an athlete already capped for his country such as França or the midfielder Kaká, or someone less well known – and would position himself at the side of the field, with eyes only for the chosen player. “I forgot about the game and concentrated on not losing a single movement of the player”, tells Valquer.

Once the filming was over, the more mechanical part of the work began. It is necessary to look at all of the tape and write down, one by one, the player’s movements: when the player walks forward and backwards, when he trots (a movement intermediary between walking and running) forwards, backwards and when he has the ball at his feet; what is the distance covered in side movement; how many sprints were done on the field and what distance was covered in each of them. In the end, possessing all of this raw information provided by the tape, the assistant coach would arrive at the total distance covered by the athlete during the match. “It would normally take up to eight hours to see and write down the filming of a player”, says Valquer. “However, since 1999, when we developed software that allowed us to carry this out in real time, everything has become much easier.”

Confronting the most common demands of each position with the performance of the athletes in the physical tests – a battery of examinations that measure resistance, maximum potency, anaerobic threshold (the physiological point at which the muscles begin to use up more oxygen than the body is capable of transporting), the maximum respiratory capacity, vertical and horizontal jumps, and velocity and agility -, the Unifesp researchers could evaluate well if a player has or has not the preparation and the physical characteristics to play in a certain position.

The studies of the physiologist allowed the sketching out of a parallel between the football practiced today in Brazil and the type of game that predominated in the past. A few decades ago, at the time of Pelé and company, a match took place at a much slower pace and rhythm. In Barros’s opinion, the impression that the old generation of player had more room on the field to carry out their moves makes sense. In the end, the players of another era were less fit athletes than those of the late 20th century. “Some studies show that the distance covered by a football player during a game has increased from 20% to 30% over the last thirty years”, says Barros. The practical result of this acceleration in the search for a goal, is that now the stars have less free space (and time) to dominate the ball and to make a brilliant move.

Barros’s work has also made it possible to compare the physical performance of Brazilian and European athletes. Studies carried out in the Old World show that the players from there cover between 10 and 14 kilometers during a match, while the Brazilians oscillate between 7 and 11 (with the average 9.2 in the case of the São Paulo athletes). “However, one cannot forget that there many games occur at low atmosphere temperature while here the climate is warmer, which naturally puts at a lower level the distance covered during a match”, emphasizes Barros. The maximum consumption of oxygen of the Europeans, an important parameter for the cardiorespiratory efficiency of an athlete, is also around 10% higher than that of a Brazilian player. “Some of our players even went hungry during their infancy. This can jeopardize their physical development. This problem practically doesn’t exist in Europe”, completes the physiologist.