The Respiratory System

The primary function of the respiratory system is gas exchange, which consists of movement of oxygen into the body and removal of carbon dioxide. To achieve this goal, respiration can be divided and four major functions. First of all, we have pulmonary ventilation, which means the inflow and outflow of air between the atmosphere and the lung alveoli; second, the diffusion of oxygen and carbon dioxide occurs between the alveoli and the blood; after this, these gases are transported in the blood and body fluids to and from the tissue cells. Finally, all these steps are controlled and regulated by respiratory center and receptors. (GUYTON, A.C.; HALL, J.E. 2006)

During the practice of physical exercise, skeletal muscles are in a state of maximal

It is known that during maximal exercise, even it has a remarkable increase, the real pulmonary ventilation does not achieve the maximal breathing capacity. This is a very important characteristic of our respiratory system because provides a withdrawal period for athletes, giving them extra ventilation that can be claim in special conditions as exercise at high altitudes, exercise under very hot conditions and abnormalities in the respiratory system, for example.

When we talk about respiration, exercise and training, it is essentially understand VO2 Max, the abbreviation for the rate of oxygen usage under maximal aerobic metabolism. Studies have demonstrated that during a moderated exercise VO2 Max increases only about 10 per cent, whereas the VO2 Max of a marathoner is about 45 per cent greater than that of an untrained person. Part of this greater VO2 Max of the marathoner probably is genetically determined, however, it is also likely that many years of training increase the marathoner’s VO2 Max by values considerably

This is expressed in terms of milliliters of oxygen that will diffuse each minute for each millimeter of mercury difference between alveolar partial pressure of oxygen and pulmonary blood oxygen pressure (GUYTON, A.C.; HALL, J.E. 2006). Unlike VO2 Max, the oxygen diffusion capacity increases considerably as the exercise becomes high intensity. During maximal exercise, blood flow through the lungs increases as a consequence of dilatation of pulmonary capillaries, providing a greater perfusion and enlarging the surface area through which oxygen can diffuse into the