Aerobic capacity is the maximum amount of oxygen that the body can utilize during an exercise session, usually measured during a brief period of high-intensity exercise. It is possible for a person to improve his or her aerobic capacity over time. A person might also experience a decline in this measurement as a result of a variety of factors, including aging, illness and a decline in physical activity. For elite athletes, their aerobic capacity — also known as VO2 max, short for volume of oxygen maximum — is an important aspect of their physical fitness. Aerobic capacity is not the same as lung capacity, which is simply the volume of air that a person's lungs can hold.
Oxygen Used During Exercise
When people exercise, the body needs to be able to utilize oxygen, which cells need in order to function. The lungs and cardiovascular system work in tandem to deliver oxygen to the body. The more people exercise, the more efficient the process becomes, and the more oxygen the body can utilize within a given period of time. As people are able to use more oxygen, they can work at a higher level of intensity, and their endurance also tends to be extended because they can work harder for longer.
Athletes and other people who are interested can undergo testing that will assess the function of their cardiorespiratory system. During this test, the person engages in aerobic exercise while the air that he or she inhales and exhales is monitored and the levels of oxygen and carbon dioxide in the air are measured. When the exhaled gases reach a steady state that does not change, the athlete has reached his or her aerobic capacity: no more oxygen can be used by the body, no matter how much harder the athlete works.
Causes of Decreased Aerobic Fitness
Many things can affect a person's aerobic capacity. Aging is a major factor, with people older than 40 usually experiencing a decline, even if they keep fit. Chronic illness and disease also can cause declines, which might be permanent or temporary, depending on the nature of the illness. Failure to keep up with a physical fitness plan will also contribute to a reduction in a person's VO2 max, because the body needs to be worked regularly to retain a high efficiency level with respect to utilizing oxygen. Even small amounts of physical activity every day can help people get and stay fit.
Improving Aerobic Fitness
Cardiovascular exercise is used to improve aerobic capacity by strengthening the heart muscle and developing the rest of the cardiorespiratory system. Many people who have started exercise plans have noted that, at the start, they tire quickly and breathe hard because their bodies cannot get enough oxygen. As their fitness program continues, however, their aerobic capacity improves, allowing them to exercise more vigorously and for longer periods of time.