The classic position for getting started on nauli is by standing up, bending the trunk forward slightly, and supporting the hands on the thighs. A complete breath is exhaled and then the stomach is brought in. The abdominal muscles are then isolated and contracted before being moved in a circle.
It is one of six shatkarma, or purification methods, used in Hatha yoga. Nauli is believed to improve overall health and increase vitality. It also invigorates the manipura and svadisthana chakras.
This is an advanced technique that is difficult to learn and should only be carried out under the instruction of an experienced teacher. Ideally, it is performed in the morning on an empty stomach.