Definition of Fitness
Overall physical fitness consists of several components.
The most important of these for most adults is cardiovascular (aerobic) endurance, the ability of the body to take in, transport, and use oxygen efficiently to metabolize carbohydrates and fats for energy.
Other components of fitness include muscular strength, flexibility, and body composition (the relative proportion of lean to fat tissue).
Ideally, an exercise program will help to improve all these components, but a distinction must be made between the regular physical exertion necessary to produce cardiovascular fitness-thus helping to reduce the risk of coronary artery disease—and the level of muscle strength and endurance required for athletic competition.
It is well recognized that even moderate exercise can modify heart disease risk. An expenditure of 2,000 calories a week through exercise is generally considered sufficient. This may come from a variety of sources, including such everyday activities as housework, gardening, and walking the dog.
Expending even a modest amount of energy is better than being sedentary. In fact, those who have been sedentary will actually derive more cardiovascular” benefit from a low-level workout than those who are more fit. As their cardiovascular fitness improves, they will need to expend more energy to produce the same effect.
There are two primary modes of exercise
Aerobic and Anaerobic.
The difference between them is important in choosing which types of activities to include in an exercise program to benefit the heart and circulatory systems.