Aerobic activity is defined by Wikipedia as “a physical exercise that intends to improve the oxygen system and refers to the use of oxygen in the body or the metabolic or energy process”. The ability to absorb oxygen is what everything is about. The body of a well-conditioned person absorbs oxygen much more efficiently than the body of an inactive person.
A medium sized adult’s lungs carry around 300 million tiny microscopic bags called alveoli. The walls of these bags have only one cell thickness, each of which is covered with a grid of blood vessels. When the lungs are filled with air, oxygen flows through the walls of the bag into the blood vessels and enters the bloodstream. These 300 million microscopic alveoli have a total surface area of about 150 square meters (the size of a tennis court) through which oxygen is absorbed.
The problem is that no one can use all of his 300 million alveoli when he breathes. Everyone has a certain part of his lungs that can never force out the air that is in them. The part of the lungs that always retains its air is called “residual volume”, and its purpose is to contain the lungs. The part of the lungs that is useful for breathing is called "vital ability." In an unconditioned body, a much smaller proportion of the lungs is vital capacity, and the residual volume is much larger than it should be. As the body becomes conditioned by regular aerobic activity, the vital capacity of the lungs increases significantly. In a well-conditioned body, the vital capacity of the lungs will be about 75%.
The body needs aerobic exercises to prepare it for the maximum stress it will face. When a person is at rest, his body consumes very little energy and requires a reliable supply of oxygen. But when a person manifests himself, his body may require 20 times more oxygen needed by him when the body is at rest. If the lungs are not able to deliver the oxygen supply the body needs, the heart can cause serious damage or a complete failure, because it works by itself, trying to compensate for the insufficient lung capacity.
The lungs do not have their own muscles. They depend on the surrounding muscles to inflate them when the diaphragm is lowered and the chest expands. As a person independently communicates with regular aerobic exercises, these muscles become toned and acquire more tissue to make them stronger. Regular aerobic activity also helps breathing muscles work much faster. This is an experimental fact. An untrained person will usually be able to breathe about 10 times his life capacity in one minute. After six weeks of significant aerobic activity, the same person will be able to exhale 20% of their vital capacity in the lungs in two minutes.
