Diaphragmatic breathing, also called belly breathing, is the act of using the diaphragm while breathing to ensure a full deep breath. The diaphragm is a dome-shaped muscle located beneath the lungs. Using the diaphragm allows air to fill the lungs fully. This is the type of breathing that is used in most relaxation practices, including biofeedback and yoga.
In diaphragmatic breathing, the diaphragm contracts upon inhale. This flattens the dome shape, expands the belly forward, and pushing the lower ribs out to the sides. During the inhale, the upper chest and shoulders should remain still. During the exhale, the diaphragm relaxes and the lower ribs and belly move inward. This helps to expel all of the air from the lungs.
One way to learn to do diaphragmatic breathing correctly is to breathe with one hand on your belly and the other on your upper chest. When you inhale, your belly hand should move outward. When you exhale, it should move inward. The hand on your chest should remain still.
A common problem associated with diaphragmatic breathing is that people tend to inhale and exhale too deeply too quickly. The goal is to fill your lungs slowly so that the breathing rate is dramatically reduced.