The average football match last for 90 minutes, consisting of two 45 minute halves, with a 15 minute break in between them. Due to football matches consisting of various intensities, it is believed that all three energy systems are used: aerobic, ATP-PC and lactic acid. Here is the data that each system contributes to performance in soccer: • ATP-PC= 60% • Lactic Acid= 20% • Aerobic= 20% (Mathews 1974) Centre backs are required to have the following components of fitness: Component of fitness Definition Example
Cardiovascular endurance “body’s ability to continue exertion while getting energy from the aerobic system used to supply the body with energy” (Lemouse 2014) Being able to last the full 90 minutes of a match where prolonged jogging is required Agility “the ability to move and change direction and position of the body quickly and effectively whilst under control” (Quinn 2014) Jockeying an attacking player running at you who starts running with the ball in one direction, then dribbles the other way, so you adapt your body position
Power “the ability to exert a maximal force in as short a time as possible” (Wood 2010) Being able to jump higher than the attacking player at a corner to win a header Balance “the ability to stay upright or stay in control of body movement” (Wood 2010) Being able to stay on your feet and not be knocked over when challenging for a ball against an attacker Muscular strength “the ability to carry out work against a resistance” (Wood 2010) When coming into contact with an attacking player, being able to muscle them off the ball without committing a foul
Patterns that they would need to perform are running, jumping, tackling, heading kicking and dribbling. According to Mohr (2015) there are 150-250 brief intense actions in football match that elite players carry out. However, research by Thadani (2014) states that the central defence position, defenders only carry out 112 high intensity activities in comparison to a central midfielder who carries out 169 high intensity activities. Reilly (1976) completed a study and found out the percentage of activity a player would complete on average in a game.
The results were: 25% walking, 37% jogging, 20% running below maximum speed, 11% sprinting and 11% running backwards. This was completed via time motion analysis. However, an evaluation of this study was that football has developed in the last 40 years, so the percentage of time completing each activity could have varied. Thandi (2014) also found that centre backs have nearly double the amount of recovery time compared to full backs when completing high intensity activities (60 seconds compared to 32 seconds). Thandi (2014) also found big differences between centre backs and fall backs when it came down to the distance covered per game.
Here is a table to show this: Centre Back Full Back Distance covered 10. 32km 11. 22km High intensity distance covered 764m 1130m Sprint distance covered 211m 350m No. of sprints 33 54 No. of high intensity activities 112 157 This shows us that a centre back has to perform less high intensity activities, and covers less distance than a full back, showing that physiological demands like cardiovascular endurance are less of a requirement for centre backs. However, let’s not forget that players still have to be physically fit, as they do have to cover a distance of over 10km a match.
However, one piece of research from Rebelo et al. (2013) shows that central defenders do perform better than full backs in some activities. The study was conducted on players aged 11-16 and focused on vertical jump tests. They came to the conclusion that central defenders did perform better than full backs and midfielders in this test. However, due to the tests being conducted on performers going through different stages of biological maturity, these results can be seen as misleading, as at this stage it was all about how much players had developed, rather than how high they could jump.
On the other hand, Crafton (2013) studied Manchester United FC’s professional defenders in the 2012-2013 season, looking at the amount of aerial duels that they were involved in and how many of those duels that they won. Jonny Evans and Rio Ferdinand, two centre backs, both won on average 57% and 56% of their aerial duel respectively. On the other hand, Patrice Evra and Rafael, two full backs, both won on average 62% and 59% of their aerial duels respectively.
This contradicts Rebelo et al. 2013) study, and shows that elite footballers for Manchester United FC who played at full back had a higher aerial win percentage compared to their centre backs. There are possible reasons to explain this, like leg power, there is no data to back this up. Activities such as sprinting, heading and kicking are relatively short in duration, so will use the ATP-PC system. As a result, a large blood flow will be needed to replenish phosphate and oxygen stores in the muscles, which will help to remove lactate by products. Reilly (1990) found that the aerobic system is extremely important within football.
The study found that players covering over 10km in a match had an average heart rate of 157bpm. This was found to be the equivalent of 75% of a person’s VO2 max. This applies to centre backs due to finding they cover more than 10km per match. Smaros (1980) backs up this point from Reilly (1990) stating that VO2 max correlated with the number of sprints attempted within a game. Apor (1998) found that high intensity exercises were completed for an average of 3 seconds, using the ATP-PC system, and that low intensity exercises lasted for 30-90 seconds, stressing and using the aerobic system.
This means that the high to low activity ratio and energy system ratio between the ATP-PC system and the aerobic system is from 1:10 to 1:20. It is recommended that footballers should eat a well-balanced diet made up of all food groups (Nutrition 2011). In terms of protein intake per day, Lemon (1994) believes that consuming 1. 4kg-1. 7kg of a performer’s body weight is an adequate amount for football players. Consuming this amount will allow for muscle fibres to repair effectively, allowing for adaptations such as hypertrophy to take place.
Due to physical activities often stressing the ATP-PC system the rates of phosphocreatine depletion will be very high. Therefore phosphocreatine supplementation is arguably needed in order to maintain high levels of it for high intensity activities. Harris et al. (1992) found that the use of phosphocreatine supplementation was most beneficial to anaerobic activity, but also did improve aerobic activities too. Increasing phosphocreatine levels by 30% will result in less depletion as a result (Moon et al. 2007). Looking at carbohydrate intake, Balsom et al. 1999) designed two carbohydrate diets for players, one containing 60% carbohydrates and the other 30%. They wanted to manipulate muscle glycogen contractions.
They conducted movement analysis, and found that players performed 33% higher intensity exercise in the game when on the high carbohydrate diet compared to those on the low carbohydrate diet. However, Ruiz et al. (2005) found that when they studied the diets of four male amateur soccer teams, the overall contribution of carbohydrates was 44% lower than what it should have been.
This shows that amateur players disregard carbohydrates when it comes to their diet, and that maybe amateur players are less aware of the effect that their diet has on their performance. Mackenzie (2015) recommends these percentages of food from each group for a professional soccer player: • Carbohydrates 65% • Fats 20% • Protein 15% Men’s Health (2014) state that the best meal to consume with these percentages of food groups is chicken with a jacket potatoe and some green vegetables such as spinach.
They state that this meal should be consumed the night before a match in order for it to be digested properly and for the performer to feel the full benefits. Whilst studying hydration in soccer, Stone et al. (2005) studied three Premier league clubs to analyse electrolyte requirements for players when it came to hydration. They found a vast difference in salt content in players sweat, ranging from 1. 8 grams to 5 grams of salt lost. Sports drinks such as PowerAde only contain 2. 5 grams of salt in a 500ml bottle, so drinking one of these after a game wouldn’t be enough to replenish lost electrolytes.
They concluded that players should add their own salt to their drinks after games to replenish lost electrolytes. Hill et al. (2008) also support this view, saying that in their study, sports drinks did not hydrate players any faster than water. Montiero et al. (2003) published strategies for soccer hydration pre, mid and post matches. One pre match strategy is hyper hydration. Here, players drink 300ml-600ml of fluid with a pre match meal, and have an extra 150ml-300ml of fluid every 15 minutes, until 45 minutes before kick-off.
This reduces body stress during performance, allowing for performance to increase. One way of hydrating players after a match is by making players ingest 150% of salt that they have lost through performance. This is due to players needing to replace more than 50% of what they have lost in performance to recover to full hydration. Williams (2014) points out that dehydration results in impaired performance and can lead to mild headaches or even heatstroke, and that players suffering dehydration should be removed from competition and attained to by a health professional.
