What is Aerobics?

Exercise can be aerobic or anaerobic. In aerobic activity, the body needs oxygen due to prolonged exertion. Such exercises include running, swimming, soccer, basketball, fencing, and dance. These activities have many benefits including decreasing cholesterol levels and blood pressure, improving muscular endurance, reducing body fat, strengthening heart and lungs, strengthening bone, ligaments and tendons and combating depression. Anaerobic activity usually consists of high intensity short, punctuated bursts of activity, but it can also include isometric exercise. It also occurs when the body's demand for oxygen exceeds the supply.

Aerobic exercise entails the constant consumption of oxygen by the body at a high level. Aerobic exercise effectively works the cardiovascular system, which strengthens the heart and improves endurance when performing activities such as running or swimming.

Anaerobic exercise strengthens and improves the flexibility of muscles. Anaerobic activity typically involves punctuated bursts of activity, such as lifting a weight.

Anaerobic exercise promotes muscular strength. Examples of anaerobic activities include weight training, football, and tennis. While most of these sports involve some aerobic activity during games, the aerobic activity is not constant. Most aerobic activity in these sports is acquired during the sports training.

A combination of aerobic and anaerobic exercise is often the most effective means of maintaining a non competition fitness level. Both competition and non competition athletes use a combination of anaerobic and anaerobic exercise. Boxers and fencers also train on weights; football and volleyball players run, and soccer players perform isometrics. Combination regimens strengthen the heart, muscles, and overall fitness level.

Contraction by a whole muscle

Isometric versus Isotonic
 

Isotonic contractions are those when the tension on a muscle remains constant but the muscle shortens as in lifting a static amount of weight. Isometric muscle contractions occur when the muscle doesn't shorten as, for example when pushing against an immovable object like a wall. Isometric contraction differs from isotonic in that the myofibrils don't slide over each other much as force is developed. Sliding does occur in isotonic contractions and external work is performed.