Pressing the perineum with the heel, contracting the anus, and drawing apāna upward — this is called Mūla Bandha.

Mūla means “root” — the bandha that seals the base of the subtle body.

Technical instructions:

• Pārṣṇi-bhāgena sampīḍya yonim — pressing the perineum (yoni) with the heel. This physically closes the lower channel.
• Ākuñcayet gudam — contracting the anus.
• Apānam ūrdhvam ākṛṣya — drawing apāna upward.

Apāna is the descending prāṇa, responsible for elimination and expulsion. Its natural movement is downward and outward. Mūla Bandha reverses this flow, pushing it upward to unite with prāṇa (the ascending energy) at the navel.

When prāṇa and apāna unite, an intense “fire” is generated that awakens kuṇḍalinī.

In modern practice, mūla bandha is described as contraction of the pelvic floor muscles — useful but not identical to the complete technique described here.