4th Limb · Bahiraṅga
The Breath Made Deliberate — where the outer practice turns toward the inner.
Root: prāṇa (breath, life-force) + āyāma (extension, expansion) — occasionally read as prāṇa + yama (restraint), but the sūtras lean toward “extension / regulation” over suppression. One-line: the breath, made deliberate.
What is Prāṇāyāma
The fourth limb — the doorway
The fourth limb, and the sūtra defining it opens with tasmin sati — “that being achieved” — explicitly presupposing the steadiness of āsana before it. Prāṇāyāma isn't breath exercise in the abstract; it's what becomes possible once the body has stopped fighting the posture.
YS II.50 breaks it into three movements — inhalation, exhalation, and the pause between — each refined through attention to place, duration, and count, growing progressively sūkṣma, subtle. YS II.51 gestures toward a fourth state beyond in-breath and out-breath entirely: a spontaneous suspension where the ordinary rhythm dissolves.
The stated purpose, in YS II.52–53, is direct: the veil obscuring inner clarity thins, and the mind becomes fit — genuinely capable — of the concentration that Dhāraṇā will ask for next.
In the Ashtanga Tradition
Vinyāsa as a moving prāṇāyāma
Here the Ashtanga Vinyāsa method takes an unusual path. Rather than teaching seated breathing exercises early, it embeds prāṇāyāma directly inside the āsana practice — Ujjāyī breath sustained throughout, one breath tied to one movement in the vinyāsa count, the bandhas containing what the breath generates. Gregor Maehle's reading is that vinyāsa itself functions as a moving prāṇāyāma, not a preparation for one. Pattabhi Jois's Yoga Mala treats formal seated prāṇāyāma as something for later — typically once real steadiness has been established in the postural sequences, not before.
Practising It
The fastest lever
On the mat, the audible Ujjāyī breath is both technique and honest feedback — it lengthens or frays with the state of the mind, which makes it a real-time check on pace and presence, not just an aesthetic. Off the mat, breath is the fastest lever most people have access to: one slow exhale before responding to something, rather than after.