Anaerobic_exercise

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Anaerobic exercise is used by athletes in non-endurance sports to build power and by body builders to build muscle mass. Muscles trained under anaerobic conditions develop differently, leading to greater performance in short duration, high intensity activities, which last up to about 2 minutes.Anaerobic training

Aerobic exercise, on the other hand, includes lower intensity activities performed for longer periods of time. Such activities like walking, running, swimming, and cycling require a great deal of oxygen to generate the energy needed for prolonged exercise.

There are two types of anaerobic energy systems, the ATP-PCr energy system, which uses creatine phosphate as the main energy source, and the lactic acid (or anaerobic glycolysis) system that uses glucose (or glycogen) in the absence of oxygen. Events or activity that lasts up to thirty seconds relies almost exclusively on the former, phosphagen, system. Beyond this first thirty seconds the lactic acid system begins to predominate. This provides an inefficient use of glucose, and produces by-products that are thought to be detrimental to muscle function. Continuing activity beyond two minutes becomes aerobic. The lactic acid system can still provide some of the required energy during aerobic exercise, as the body has the capacity to get rid of the anaerobic by-products. The efficiency of by-product removal by muscles can improve through training.Aerobic training

Lactate threshold (LIP or Lactate Inflection Point)

The lactate threshold (LT) is the exercise intensity at which lactic acid starts to accumulate in the blood stream. This happens when it is produced faster than it can be removed (metabolized). This point is sometimes referred to as the anaerobic threshold (AT), or the onset of blood lactate accumulation (OBLA). When exercising below the LT intensity any lactate produced by the muscles is removed by the body without it building up. The lactate threshold is a useful measure for deciding exercise intensity for training and racing in endurance sports (e.g. distance running, cycling, rowing, swimming and cross country skiing), and can be increased greatly with training.

Fartlek (speed-play) training and interval training take advantage of the body being able to temporarily exceed the lactate threshold, and then recover (reduce blood-lactate) while operating at below the threshold, but still doing physical activity. Fartlek and interval training are similar, the main difference being the relative intensities of the exercise, best illustrated in a real-world example: Fartlek training would involve constantly running, for a period time running just above the lactate threshold, and then running at just below it, while interval training would be running quite high above the threshold, but then slowing to a walk or slow jog during the rest periods. Interval training can take the form of many different types of exercise and should closely replicate the movements found in the sport.(3)

Fartlek would be used by people who are constantly moving, with occasional bouts of speed, such as soccer players, while interval training is more suited to sprinters, who exert maximum effort and then can stop exerting completely. With both styles of training, one can exert more effort before fatiguing and burn more calories than exercising at a constant pace (continuous training), but will emphasize training the anaerobic system rather than the aerobic system. Long duration training below the lactate threshold is recommended to primarily work the aerobic system.

Accurately measuring the lactate threshold involves taking blood samples (normally a pinprick to the finger, earlobe or thumb) during a ramp test where the exercise intensity is progressively increased. Measuring the threshold can also be performed non-invasively using gas-exchange (Respiratory quotient) methods, which requires a metabolic cart to measure air inspired and expired.

Although the lactate threshold is defined as the point when lactic acid starts to accumulate, some testers approximate this by using the point at which lactate reaches a concentration of 4 mM (at rest it is around 1 mM) .

References

See also

• Aerobic exercise

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