Now nauli: with the shoulders bent forward, rotating the abdomen rapidly from left to right — this is nauli, praised by the siddhas.

This verse introduces nauli, one of the most distinctive techniques of haṭha yoga. The practitioner isolates the rectus abdominis muscles and rotates them in an undulating motion, first to one side (savya - left) and then to the other (apasavya - right).

Amandāvartavegena indicates that the rotation should be rapid and vigorous, not slow. The shoulders lean forward (natāṃsa) while the hands press on the thighs, creating the posture that allows isolating and manipulating the abdominal muscles.

This technique is siddhaiḥ praśasyate — “praised by the siddhas,” the perfected masters. Nauli is considered one of the most powerful practices for stimulating the digestive fire and purifying the abdominal organs. Its mastery requires considerable practice and is a sign of advanced control over the body.