The Bandhas have traditionally been classified as mudras but their action is subtly different. The sanskrit word ‘Bandha’ means to tighten, seal or lock and this describes the physical action of the body and the effect on the subtle pranic body.
The locks (bandha) are ‘special body manoeuvres which confine the life force in the trunk and thereby stimulate it.’ Georg Feuerstein, The Yoga Tradition, (Hohm Press, 2001), page 395. This means that they can be used to lock the prana in certain areas and redirect their flow into sushumna nadi (ultimately for spiritual awakening).
Physically, the bandhas provide considerable stability during posture and meditation work.
The main bandhas are as follows:
Uddiyana bandha – upward going lock – performed by drawing back the abdomen
Jalandhara bandha – Jaladhara’s lock – done by contracting the throat.
Mula Bandha – root lock – done by contracting the anal sphincter muscle
Maha bandha – great lock – performed by pressing the left ankle against the perineum while placing the right foot on top of the other foot and contracting the anal sphincter muscle. It is also described as a combination of the thre bandhas described above.
There is only a little information about the bandhas in the easily available classical texts. As with much Yoga, it was meant to be taught by a guru and so the written instruction were deliberately obscure. However I have been able to find the following quotes which talk about Bandha generally:
Goraksha Paddhati 1.57 ‘The Yogin who knows maha mudra, nabho mudra, uddiyana bandha, jalandhara bandha and mula bandha partakes of liberation.’
Qouted from: Georg Feuerstein, The Yoga Tradition, (Hohm Press, 2001)
Yogataravali (Sutra 5, Sri Adi Shankaracharya) ‘Jalandhara bandha, Uddiyana Bandha and moola bandha are situated respectively, in the throat, abdomen and perineum. If their duration can be increased then where is the fear of death?’
Qouted from: Swami Satyananda Saraswati, Asana, Pranayama, Mudra, Bandha (Bihar School of Yoga, 1999 – revised)
Georg Feuerstein, The Yoga Tradition, (Hohm Press, 2001)
Gertrud Hirschi, Mudras – Yoga in your hands (Weiser Books, 2000)
Swami Satyananda Saraswati, Asana, Pranayama, Mudra, Bandha (Bihar School of Yoga, 1999 – revised)
Hatha Pradipika of Swatmarama Edited by Dr M.L Gharote and Parimal Devnath, 2001, The Lonavla Yoga Institute