Pranayama -- The Yogic Science of the Breath

Prana means life-force, and in the first place it means breath: the movement in and out that never stops while we live. Ayama means extension or restraint. Pranayama, then, is the extension and regulation of the breath -- and through the breath, of the life-force it carries. In the yoga traditions it is the bridge between the outer practices that work on the body and the inner practices that work on the mind.

Patanjali's Yoga Sutras make it the fourth of the eight limbs of yoga, after the ethical restraints and observances (yama and niyama) and posture (asana). Its definition is precise: once a steady, comfortable seat has been achieved, pranayama is the interruption of the flow of in-breath and out-breath.

Patanjali says little about technique. He describes the breath as having three phases -- outward, inward and held -- regulated by place, time and number, becoming long and subtle; and he names the result: the covering over the inner light wears away, and the mind becomes fit for concentration. The Bhagavad Gita, earlier still, speaks of yogis who offer the in-breath into the out-breath and the out-breath into the in-breath, restraining both, as a form of inner sacrifice.

The detailed methods come from the later hatha yoga texts, above all the Hatha Yoga Pradipika of Svatmarama (fifteenth century). Its second chapter teaches that the breath and the mind move together -- when the breath wavers the mind wavers, when the breath is still the mind is still -- and describes eight kumbhakas, techniques of breath retention, after the nadis, the channels of the subtle body, have been purified.

The classical texts are emphatic about caution. The Hatha Yoga Pradipika compares the breath to a lion, elephant or tiger that must be tamed slowly, warning that wrong practice can cause harm. The traditional advice still holds: learn from an experienced teacher; practise on an empty stomach in a quiet, airy place; begin with slow, comfortable breathing and simple alternate-nostril breathing before attempting long retentions or forceful techniques; never strain. People who are pregnant or who have high blood pressure, heart or lung conditions, or recent surgery should take medical advice, and should generally avoid breath retention and the forceful practices.

Modern research has begun to study what practitioners long reported. Studies of slow breathing, at around six breaths a minute, have reported effects on heart-rate variability and on measures of stress, though the evidence is still developing and pranayama is no substitute for medical care. The yogic claim is more modest and more ambitious at once: that by making the breath slow, even and quiet, the mind follows.