Thus, according to the prescribed method, exhalation and inhalation repeatedly, like the bellows of the blacksmith are moved rapidly with speed.

This verse provides the defining metaphor of bhastrikā. Bhastrā means “bellows” — the instrument the blacksmith (lohakṛt) uses to fan the fire of the forge. The bellows are moved vegena (with speed) and laghu (rapidly/lightly).

The comparison is exact: just as bellows force air toward the fire to intensify it, bhastrikā forces prāṇa toward the internal fire (agni) to fan the transformative energy. The movement is muhur muhuḥ — repeated again and again.

Vidhividhānena — “according to the prescribed method” — reminds the practitioner that speed does not mean carelessness. Even in vigorous practice, the technique must be precise. Beginners should start slowly and gradually increase speed under the supervision of a master.