Works on Haṭhayoga like Gheraṇḍa Saṁhitā describe ‘Ṣaṭkarmas’ or six purifi-catory techniques for cleansing the body. ‘Dhauti’ the first of these is of four kinds: antardhauti, dantadhauti, hṛd-dhauti and mūlaśodhana. Antardhauti, the first of these is again of four varieties, viz., vātasāra, vārisāra, vāhnisāra or agnisāra, and bahiṣkṛta.
Agni or vahni represents the ‘fire’ of the digestive system (often called jāṭharāgni or vaiśvānarāgni), the capacity of digestion and assimilation. The health and strength of the body depends on the proper functioning of the digestive system. Agnisāra-dhauti is prescribed for the removal of functional disorders and even organic defects of this system.
The process consists in ‘pressing the navel knot a hundred times against the spinal cord’ by breathing out and contracting the abdominal muscles. This is said to result in the body acquiring a divine lustre and vital energy.
As in all other Haṭhayogic exercises, this also should be practised under the direct guidance of a guru.