Sunday, 14 October 2012

Anaerobic Science of Soccer

Cardiovascular fitness is developed by engaging in aerobic activities. These are activities that you can maintain over a sustained period of time and use oxygen. Anaerobic activity works differently. It is activity that requires high levels of energy and is done for only a few seconds or minutes at a high level of intensity. The term anaerobic means “without oxygen.” Participation in anaerobic activities leads to anaerobic fitness, which may be defined as higher levels of muscular strength, muscular endurance, and flexibility.

Anaerobic training involves consecutive intervals of intense activity and rest, or less intense activity. As in the course of a game, field players perform a number of short sprints separated by longer periods of jogging. Therefore, this type of conditioning is particularly relevant to soccer and quite effective in burning calories and lowering body fat. Anaerobic training is used to increase strength and power through intense muscular activity. Your muscles generate energy by converting glucose into lactic acid. But because of the strenuous nature of the activity and the fact that oxygen is not needed, this sort of exercise can only be maintained for short periods of time. Oxygen only comes into play after the exercise, when it is needed for recovery and metabolism of glucose to supply more energy. This is why resting time is crucial to maintain a successful session of anaerobic training.

Science of Anaerobic:
Anaerobic exercises can not last for long periods of time because they do not use oxygen for energy and lactic acid is produced in the muscle cells as a by-product. Lactic acid build up effects muscle action and function. Anaerobic exercises use muscles at a high intensity for a short period of time.

Anaerobic exercises must be coupled with recovery periods. Lactic acid can contribute to muscle fatigue and lactic acid to be converted by the body during a recovery period before another anaerobic exercise can be performed. During the recovery period, the muscles will use oxygen to assist in replenishing the energy that was used during the anaerobic exercise.

Anaerobic exercise requires a person to move at an increased pace or to perform the exercise with greater effort compared to an aerobic exercise. In theory, exercising anaerobically can cause the body to burn more calories than aerobic exercising. However, during anaerobic exercises, oxygen is not delivered in sufficient quantities to allow the cells to continue burning fat. Instead, the muscle cells burn mainly carbohydrates which burn more quickly and do not require oxygen.

Respiration without oxygen

Anaerobic Exercise
There are three energy-producing systems in the human body, one of which is aerobic (using oxygen), and two of which are anaerobic (not using oxygen): ATP-CP and Glycolysis.

For the first few seconds you exercise you're using the ATP-CP system. This relies on stored ATP (adenosine triphosphate, the molecule that produces the energy in all living things, from bacteria on up). Another stored molecule, CP (creatinine phosphate) helps restore your ATP. CP is restored aerobically (with oxygen).

When you exercise beyond the limit of your ATP-CP stores (anything more than a few seconds) the second anaerobic system kicks in: anaerobic glycolysis. This makes ATP from glucose (sugar) stored in your liver and muscles. You get the glucose from eating carbohydrates. (Eating a reasonable amount of carbs after exercising helps increase the glucose stores.) When you exercise beyond the limits of your ATP-CP and glucose systems, your body needs to start producing energy "on the fly" [without O2] using lactic acid instead. That is anaerobic Respiration - without O2.

The ATP stored within muscle is the primary source of energy for muscle
contractions during very short bouts of exercise performed at high intensity. The available supply of this chemical is limited to about 3 s and so if strenuous exercise is to continue the ATP must be reformed. Phosphocreatine (PCr) also stored within the muscle is broken down by creatine kinase, allowing ATP to be regenerated and muscle activity to be continued

This reaction takes place in the absence of oxygen and so is termed anaerobic. As ATP is the substrate that muscle uses directly, its stores are not depleted whereas those of creatine phosphate can be reduced considerably. In certain activities, such as repeated bouts of high-intensity exercise, increasing PCr stores by means of ‘creatine loading’ can benefit performance, notably in the later efforts in the sequence. Its benefit in soccer match-play is less likely, but creatine loading may be of value in certain training contexts by permitting more work to be performed at high intensity.

When the recovery period between high-intensity activities is too short or if
successive sprints are performed, the PCr stores may be reduced to very low levels. The next available source of energy is from the anaerobic breakdown of glycogen stored within the muscle. Glycolysis is the major means of anaerobic energy production but its capacity too is limited to 30–40 s. Anaerobic degradation of glycogen causes lactic acid to increase within muscle which slowly diffuses into the circulation. Hydrogen ions increase, lowering the pH levels within muscle and subsequently in the blood. The level of performance drops, an effect that has been linked with the elevation in muscle lactate. Other explanations of fatigue have included increased concentrations of potassium in the interstitium, reduced neural activation of the muscle fibres, or a failure of the excitation–contraction coupling process. Either a reduced rate of calcium release from the sarcoplasmic reticulum or a decreased rate of calcium re-uptake to the sarcoplasmic reticulum could also be implicated. 

Irrespective of the causes of fatigue during all-out exercise, it is clear that high intensity activity cannot be sustained for long without a respite for recovery before commencing the next bout of heavy exercise. During a match the fatigue experienced can be transient, the player recovering when the pause is sufficiently long. Further pressure on this individual whilst temporarily fatigued will place him/her at a disadvantage. The player will be much better able to cope after following a regimen of anaerobic training.

Anaerobic training has multiple effects, the most important of which are
enhancement of neural activation of muscles, increased activity of creatine
kinase and the enzymes in the glycolytic pathway. Anaerobic training can also
increase the amount of glycogen stored within the active muscles and enhance
their capacity to neutralize the effects of hydrogen ions, thereby delaying or
offsetting fatigue. The aims of anaerobic training can be expressed as:
  • to improve the rate of force development and the peak force achieved during brief, fast movements;
  • to improve speed over short distances;
  • to enhance the provision of anaerobic energy so that an all-out sprint can be sustained for longer without training;
  • to improve the capability of performing repeated sprints by enabling the player to recover quickly from strenuous efforts.
These aims refer to power and acceleration, speed and speed endurance

(production and repetition) respectively. These components of physical

conditioning for soccer must be complemented by other attributes that form

unique requirements of the game. These include agility, reactions, timing of

movements and implementation of games skills accurately and often at speed. There is a wealth of practices for training these characteristics, adapted from training theory rather than based on experimental evidence.

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