Anaerobic exercise literally means 'exercise without oxygen'. It's a form of exercise intensive enough to generate the body's alternate energy source, glycogen, which is released as energy into the body. Anaerobic exercise is used for stamina and muscle mass gain by professional athletes.
The aerobic (oxygen breaking down glucose) energy sources are used for longer term exercise, but the anaerobic forms, ATP (adenosine triphosphate, a phosphorous based cellular energy source) and glycogen, are actually normally used by the body in these types of exercise. The short term energy bursts are effectively powered by these sources. Anaerobic exercise may involve extremely intensive exercise for up to four minutes.
The main issue with anaerobic training is lactate buildup. Lactate is a byproduct of the anaerobic exercise process, and it's now known that the lactate threshold of tolerance can be built up by training.
Examples of anaerobic exercise
Weight lifting: A good example of anaerobic exercise is weight lifting. This is truly anaerobic, involving a short burst of muscle power. Over that period of time, the body will source energy from glycogen. This type of exercise naturally builds muscle and bone, because of the local-specific effects of anaerobic processes. You literally build specific muscles.
Sprint training: The ferocious stop- start runs, is one of the typical anaerobic classes of exercise. This is a great fitness and stamina exercise, commonly seen in football, basketball, and other 'rapid fire' sports where athletes may have to put on huge bursts of energy.
Push ups: These are perhaps the original local- specific anaerobic exercises, focusing directly on the muscle groups affected. The pushups are a sequence of anaerobic exercises, and they serve the same functions as weights and sprints for those muscles.
Isotonic exercises: These are exercises conducted against resistance, like machines. These are focused anaerobic exercises, again working on specific muscle groups.
Isometric exercises: Isometrics involve muscular contractions against an immovable object like wall. This type of exercise targets specific areas of the body.
Calisthenics: These are exercises like sit ups, pushups and squats are repetitive, high intensity bursts of energy directed at the related musculature. These are repeated expansions and contractions of muscles, usually conducted together in various combinations as part of holistic training programs.
Anaerobic exercise as a fat burner
Opinions vary a lot about the value of anaerobic exercise as an actual fat burner. Some sources claim it's four times better than aerobics, others that it's far less efficient than aerobics. Since most sources usually promote one form of exercise and not the other, 'expertise' can be considered selective.
The facts about anaerobic exercise are:
Note: This type of exercise definitely isn't for everybody. If you have breathing or heart issues, it's not for you. A certain level of basic fitness is required, and even pro athletes are careful not to make mistakes in these areas.
If you're interested in anaerobic exercises, best practice is to get assistance from a trainer who can create a good progressive program.