Śivasaṃhitā 3.108

The instruction is precise and physiologically aware: fill the udara (belly) gradually and according to one’s own capacity. The adverb śanaiḥ — ‘slowly’ — is not incidental; it sets the tempo for the entire breathing practice described in this chapter. Force is not imposed but applied with discernment.

The term yathāśaktyā combines yathā (‘according to’, ‘in proportion to’) with śakti (‘force’, ‘power’), forming an instrumental compound meaning ‘according to one’s own power’. This phrasing acknowledges individual variability in practice: there is no single standard, but rather a constant calibration with the practitioner’s actual capacities.

In classical prāṇāyāma, deep abdominal inhalation — pūraka — constitutes the active phase of expansion. Filling the belly before the chest corresponds to diaphragmatic breathing, which maximizes lung volume and stimulates the vagus nerve, promoting calm within the autonomic nervous system.