Tidal breathing is the inhalation and exhalation method by which mammals breathe. In particular, it refers to the amount of air used when at rest and when breathing functions are automatic. Tidal volume, or the lung's capacity to hold and process air, is measured by doctors trying to study or diagnose respiratory and other health problems.
During tidal breathing in humans, the chest muscles automatically flex along with the lungs. Non-mammals do not use this type of breathing. By contrast, insects have side vents which remain closed until they need to exchange oxygen. Plants absorb oxygen through small holes (stomata) located on stems and leaves, and fish get their oxygen from filtering water through their gills.
To measure tidal breathing, the medical establishment uses several methods. One way is to have the patient wear a special kind of face mask, which will measure the volume of air he breathes out. Measurement can also be taken though fastening bands around the chest and measuring their expansion. Often, measurements are taken when the patient is sleeping or at rest so as to get the most accurate measurement of lung capacity. Measurements from active individuals are also often used during respiratory studies, however.
Measuring tidal breathing has allowed people to set definite standards for healthy respiration. Humans have an average capacity of six liters of oxygen. They do not, however, use their full lung capacity during regular respiration, inhaling only half a liter with each breath on average. Athletes and those born at higher altitudes will tend to have a slightly larger lung capacity. Those who smoke will also have a smaller lung capacity than non-smokers.
Tidal breathing measurements have been used to create treatments for underdeveloped lungs in premature infants, and this medicine has allowed more premature babies to survive. There has also been increased concern with more cases of childhood asthma arising. Studies of tidal breathing have become particularly useful in gauging the effectiveness of asthma medication.
This breathing has also been referred to as "ceiling breathing," because it only uses the top half of the lungs. Singers, yoga practitioners, and others can learn to alter this style of breathing even while at rest through practicing techniques for "floor breathing and "wall breathing." "Floor breathing" utilizes the diaphragm muscle, which brings air all the way to the bottom of the lungs instead of only using the upper lobes. "Wall breathing" focuses on the movements of the rib cage.