Uddiyana Bandha is a type of contraction of muscles in Yoga. Bandha literally means binding. In hatha yoga there are bandhas or locks which involve tight contraction of some muscles and body parts. Four such bandhas are described in traditional texts. Uddiyana bandha is very important among them. Uddina means to jump. This bandha gets its name from the fact that in it two things are said to jump upward, namely, thoracic diaphragm and the vital air, prana. The technique and usefulness of this bandha is described in detail in Hatha Yoga Pradipika (III.56-60) and in many other texts. It is said to be the best among all the bandhas (III.60)
Uddiyana Bandha may be practiced along with pranayama (breath control) or independently. In pranayama it may be practiced while holding the breath in or out. As an independent practice it may be done in a sitting or standing position, and only when holding the breath out. The hands are pressed on the knees, the body is bent slightly forward and exhaling deeply the breath is held out. Then without inhaling, the chest is expanded and the wall of the abdomen is pulled back. It is also called Tadagi mudra when practiced in a position when laying down (on the back). It influences beneficially many functions like digestion, excretion, secretion, respiration, reproduction and so on. It helps to increase vitality and vigor.
When practiced with pranayama, it is employed along with other bandhas like mula bandha (anal lock), jalandhara bandha (chin lock) and jivha bandha (tongue lock) and not alone. It helps a great deal to enhance the benefits of pranayama.