Appoggio from the Italian verb appoggiare, meaning 'to lean on', 'to be in contact with' or 'to support' is a learned breathing technique that involves slowing down the ascent of the diaphragm for better breath management, resulting in the elongation of the breath cycle during singing. It involves a concerted action on diaphragmatic movement by the muscles of the thorax (chest) and the abdominal wall (the transverse abdominis, the internal oblique, the external oblique, and the rectus abdominis, although to a lesser extent), and involves gaining better control over the breathing mechanism through training the muscles, and enables the singer to pace the breath more efficiently.

It's important to note that appoggio, while requiring a great deal more control than is needed during normal activities and requiring some additional coordination and training, is an extension of the natural breath process, not a substitute for it. It is considered to be the main route for breath management within the international classical singing community.

During normal speaking, the rib cage collapses upon exhalation. Appoggio attempts to avoid this collapse by retaining the elevated inspiratory posture of the rib cage and the sternum the long flat bone located in the centre of the thorax (chest), which connects to the rib bones via cartilage, forming the rib cage with them. The technique slows down the rising of the diaphragm, which aids in breath management. Learning to gain control over the muscles of the side abdominal wall offers true breath support.

If applied appropriately, simulating the posture of breath retention can minimize subglottic pressure. At inspiration, subglottic pressure is at its lowest level and lung volume is at its highest.
In singing, (as well as in the Italian language itself), the term 'appoggio' has both a passive component and an active connotation, and may vary with different technical approaches. For some singers, breath flow pressure becomes a selfsustaining system whereby the singer feels the breath pressure in the body as an influence of stability. The diaphragm remains relaxed and is acted upon rather than being active. something to 'lean on', to use as a support.

Inhalation should be accompanied by a sense of expansion or 'fullness' in the epigastric area, as well as a sense of expansion of the lower ribs. This rib expansion is caused by the contraction of the external intercostal muscles, and should be felt during any substantial inhales. In addition to expansion at the base of the ribs, it can be felt at the front and sides of the torso, between the tenth rib and the crest of the iliac (upper surface of the hipbone) and in the back at the eleventh and twelfth ribs. The wider the rib opening and the longer this expansion can be maintained, the greater the downward hydrostatic pressure and the greater the pull against the elevation of the diaphragm. Lateral abdominal expansion will eventually equal or even exceed the expansion of the front part of the abdomen when the appoggio system is developed and applied. Consequently, this rib expansion is the effect that is typically most noticeable to the singer.

At the height of inhalation, when the singer is breathing deeply and the lower torso is expanded laterally, dorsally and frontally, he or she will likely also feel a sense of 'suspension', in which it feels as though the voice is sitting or resting on something, or a feeling of 'buoyancy'. When he or she begins to sing, this same feeling should be maintained for as long as is comfortable, with the sternum still elevated, the epigastric area still comfortably 'full' and the lower ribs expanded. (It is this position that prevents the diaphragm from rising upward too quickly.) The abdominal muscles should be relaxed, and the singer will find the necessary exhalation will occur without the singer having to be overly concerned about the action of the muscles in the abdominal area. As he or she arrives at about the last third of the exhaling breath, the epigastric area will naturally move slightly inward, but he or she should attempt to keep the lower ribs in as outward a position as possible, without thrusting the muscles outward or downward. This is a learned response that will help retard the ascent of the diaphragm or avoid its early rise.

This lower rib expansion and the epigastric 'fullness' which, in turn, create the feeling of inspiration suspension, is "appoggio".