|PHYSIOLOGICAL DEMANDS & MATCH PERFORMANCE ANALYSIS|
The physiological load imposed on Professional soccer players can be calculated through observing and analysing competitive match play. Players move in many different directions and at various speeds, hence this activity is known as intermittent exercise. The overall physical loads in professional football are great and vary with respect to the level of competition, playing position and responsibilities as well as environmental factors.
The total distance run by a player offers approximate information on the amount of energy expended and the overall severity of the exercise. On average, all outfield players are required to run between 9 and 13 kilometres. The goalkeeper runs the least around a maximum of 4-6 Km. Overall, professional midfielders run the most whilst strikers sprint the greatest distance. For example, a top centre-forward has been shown to sprint 900 m (> 21 km/h) and runs 1520m at high intensity (14-21 km/h). Indeed players sprint on average once every 90 seconds. Fig 1 below breaks down the total distance run (11.6 km) of a top level midfielder into the percentage of time spent in different running activities.
Even in professional soccer, players are only in possession of the ball for around 2 minutes of the game duration. Most efforts are off the ball; e.g. support runs, contesting possession etc. On average, players only have a short rest for about 3 seconds every two minutes showing the constant effort required over 90 minutes. We must not forget that top-level players also move in different directions such as backwards and sideways running. Studies have shown that Professionals spend 7% of their time moving backwards (e.g. centre-halves retreating to challenge for a long high pass) and that this type of movement actually requires more energy expenditure.
The area where top level football really stands out is the larger amount of high-intensity running undertaken by players. This may demonstrate a greater capacity to respond to the vital moments in football which often require the execution of explosive physical efforts. For example, analysis shows that an International midfielder had to make 18 one-on-one situations in 25 minutes. However, in top level football, some players are shown to run more in the first-half compared to the second, indicating that even professionals show a certain level of fatigue. For example, studies on English and Danish professional players have shown a marked decrease in distance run between the two halves. Apparently, the fitter the player the lesser the degree of fatigue shown. Midfielders in general have a greater aerobic fitness or VO2 Max and are least likely to demonstrate a reduction in distance run between the two halves.Through measuring heart rate values during games, competitive top level match play requires an average oxygen uptake of 75% of VO2 Max which is comparable to that experienced during marathon running. Similarly, measuring blood lactate values are useful for indicating the severity of exercise. Extremely high levels up to 12 mmol-1 have been observed in top level play and progressively higher lactate concentrations from the fourth to the top division in Swedish professional football demonstrate the greater high-intensity nature of the game especially at the top level. Body temperature offers clues on exercise intensity and energy production. Again, similar observations were made on Swedish professional football and the players from top division had the highest post-match temperatures which can again be linked to a greater overall exercise intensity.
Nutrition is another important factor involved in professional match play. For example, players are shown to lose between 1-3.5 kg of their body weight during games mostly through sweating, depending upon the weather conditions. Thus, correct drinking policies need to be undertaken to prevent reduced performance capacity as well as heat injury. In hot weather conditions for example, players carry out less high-intensity movements. Likewise, general correct eating habits are necessary to maintain performance and are unfortunately even neglected in Professional football ! Elite players have been shown to eat too much fat and not enough carbohydrate. For more on nutrition, click here.
Not only do top level players simply have to run, they are constantly tackling, passing, dribbling, heading and shooting to name but a few. For example, professional central defenders show the greatest frequency of jumps per game (around 20) and these factors when added to the various sprints and distances run demonstrate the high physical loads placed on top-level players. In the 1992 European Championships, the average number of passes per player in a game was 35 whilst the number of interceptions was 15. The average number of headers and tackles was 8 and 11 respectively. In general, match analysis has shown that a player touches the ball on average 60-120 times & for 2 seconds per match. Fig 2 below shows the match counts for a professional defender. For more specific game analysis, visit our match archive.