Monday, 28 February 2011

A beautiful game, if you've got the energy for it.

It’s been referred to as the beautiful game and the greatest show on earth but what does it take to be on the world stage - a footballer competing at the highest level? Hopefully by analyzing and reviewing studies done on football professionals it will help you better understand how the demands of the game can guide your development and possibly guide any future ambitions you might have. 
The sport of football has always been popular worldwide and has been more so in the last few years after hosting the recent 2010 FIFA World Cup. Football is enjoyed the world over and this is evident by the vast number of players playing from a very young age. It’s a great sport for developing fitness, skills, sportsmanship and teamwork. Besides minor differences to pitch sizes and playing times, the game remains the same.
This blog is aimed at students and scholars wanting to compete at a top level or just wanting to 'up your game' so your aim in training would be to focus on your development (skills and fitness) and train at an intensity that would replicate a match situation.

But what are these energy demands that are required of you to perform at the top level?
The body's energy source in its most basic form is adenosine triphosphate or simply known as ATP (just like the tennis association =D)
The body utilizes 3 energy systems to provide ATP to working muscles. The best way to differentiate between them is to identify the timeframes in which these systems come into play:

ATP-PCr systemè provides energy for powerful movements over a short duration lasting up to 15 seconds. Think Usain Bolt and his 100m sprint and the movements required. Now think how many times during a football game you’re required to break into a sprint. It will be much less than 100m but the supply of energy needed is the same system.
Research has shown that professional footballers sprint 15m every 90 seconds [1].

Glycolytic systemè provides energy for activity lasting up to 2 minutes. Think a 400m sprinter. Now think how many times in a football game your team might lose the ball in attack and you have to track back quickly to defend. But just as you get back your team begins a counter attack and you have to get to the other end of the pitch. The tempo of the game would dictate this but at an elite level this is normally quite high with intermediate bursts of energy.

Oxidative systemè provides energy over a long period of activity of low to moderate intensity. Think a 10km run. Now think how many times in a match you’re covering a great distance across the entire pitch for the duration of the whole match. 

The ATP-PCr and Glycolytic system are known as the anaerobic pathways (without oxygen) and the Oxidative system is known as the aerobic pathway (with oxygen). All 3 energy systems do not work independently of one another. All three make a contribution, however one or two will predominate. [2] Have a look at the following table which indicates what percentage of each system is used during a typical game.

While the average distance covered by an elite football player during a 90-minute match is over 10km, at an average speed of over 7km per hour, these figures do not accurately represent the full demands placed on a player [2]. In addition to running, a player must jump, change direction, tackle, accelerate and decelerate, etc., and each of these individual tasks requires an energy input over and above that required simply to cover a similar distance at a constant speed. 

Scientific investigation has shown that the true demands on an elite male player can be approximated at roughly 70%VO2max. VO2max has been defined as the highest rate of oxygen consumption attainable during maximal or exhaustive exercise [3]. It is generally considered the best indicator of cardiorespiratory endurance and aerobic fitness.
Research has also shown that VO2 max has a high correlation to the number of sprints attempted during a football game which makes aerobic fitness an important component to footballers [4]. These values suggest that the total energy cost of a game for a typical male player weighing about 75 kg would be about 1600 kcal [2]. This is based on evidence of heart rate, sweat loss, increase in body temperature, and depletion of carbohydrate stores within the muscles. 

Carbohydrate is the main fuel for exercise, especially for prolonged or high-intensity exercise when rates of body fluid loss are high due to the sweating needed to dissipate body heat produced. Low carbohydrate stores in the body and just a small degree of dehydration (2% body mass loss, or 1-2 kg) lead to fatigue and impaired performance [5].
So training in football should focus on all three systems, with more attention on the oxidative system (aerobic) and ATP-PCr system (anaerobic).

In future blogs we will look at what the physical demands are on specific playing positions in the game, different training methods to target the energy systems and go into more detail about energy intake. 

1) Reilly, T., & Thomas, V. (1976). "A motion analysis of work rate in different positional roles in pro football match-play." Journal of Human Movement Studies, 2, 87-97
2) Mohr, M. et al (2006) Physical and metabolic demands of training and match play in the elite player. Journal of Sports Science 24(7): 665-74
3) Wilmore JH and Costill DL. (2005) Physiology of Sport and Exercise: 3rd Edition. Champaign, IL: Human Kinetics
4) Smaros, G. (1980). "Energy usage during a football match." In Proceeding 1st International Congress on Sports Medicine Applied to Football, Vol. II (ed L. Vecchiet), D. Guanello, Rome
5) Thomas, B.B. (1994) Carbohydrate, fluid, and electrolyte requirements of the soccer player: A Review. International Journal of Sport Nutrition 4: 221-236

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