Can The Lungs Keep Up With Oxygen During Exercise?

Moderate to intense physical exercise is associated with an increased demand for oxygen and therefore with deeper and more rapid breathing. As a result, many people believe that by simply increasing the rate and depth of their breathing, either consciously or by doing things to expand their lung capacity, they can become stronger at whatever specific exercise or exercises they are performing. Oxygen intake, however, is virtually never a rate-limiting factor in healthy people in aerobic exercise.

Features

When you engage in a type of exercise that is almost entirely aerobic rather than strength-based -- such as running, cycling or Nordic skiing -- there are three basic factors that limit performance: the amount of oxygen you take in and deliver to your bloodstream via breathing; the amount amount of inspired oxygen you transport to the working muscles; and the working muscles' capacity to make use of whatever oxygen they are provided.

Effects

When your rate of ventilation, or breathing, rises in response to the demands of exercise, this is almost always sufficient to provide the body with as much extra oxygen as it is capable of using. The red blood cells that transport oxygen from the lungs to the muscles become saturated, while the working muscles make full use of this supplied oxygen and augment this fuel as needed by generating energy through anaerobic metabolic processes as well.

Misconceptions

Contrary to widespread belief, exercise does not increase people's lung capacity, a genetically determined and static quality that varies with sex and height. However, even were this possible, it would make no difference in terms of exercise capacity because a healthy person is able to breathe in far more oxygen than her body is able to process. It is the number of red blood cells that transport received oxygen to the muscles that puts a ceiling on aerobic potential, explaining why professional runners and cyclists are known to "dope" with banned substances, such as erythropoietin, that boost the number of red blood cells.

Considerations

Although the lungs of an exercising person can "keep up with" oxygen in terms of making maximal use of what is in the air around him, the reverse is not always true. Sometimes there is not enough oxygen in the ambient air to allow for maximal delivery of oxygen to the body tissues no matter how hard someone breathes. This is exemplified by the decrease in oxygen content of ambient air that occurs at higher altitudes, with the physiological effect first becoming noticeable in most humans at about 5,000 feet above sea level and increasing exponentially with elevation. People train at high altitude because it drives up the number of red blood cells in the body without the need to take illegal drugs, in theory making the athlete capable of better performances at sea level.

Benefits

Although lung capacity does not increase with exercise, it is still beneficial for certain people, such as those with chronic obstructive pulmonary disease, to improve the strength of the accessory muscles of respiration, such as the intercostal muscles of the ribs. Because the tissue inside the lungs themselves is damaged in such patients, making the daily job of breathing less work can make COPD sufferers more comfortable.