As explained in the previous articles, prana leaks out through the openings of the body. During the practice of pranayama the mudras and bandhas are practised in order to close the openings and keep the prana in the body.
One of the important bandhas that are practised is Mula Bandha. As a preparatory practice an easier mudra is learnt first: Ashvini Mudra. Both these seal the anus.
The word ashvini means horse and the anal sphincter action of a horse is used as the imagery to describe how to perform this mudra.
Sit in your comfortable and steady asana. Be attentive to the rhythm of the breath as this mudra is practised in conjunction with the breath. As you breathe in, gently contract the anal sphincter muscles. On the exhalation release the sphincter. This is ashvini mudra.
If you find this difficult to learn, imagine that you require the toilet and you have to hold on, as with diarrhoea. Then you are naturally doing the ashvini mudra.
Once you are comfortable with this mudra, you can practice it with your pranayamas.
Swami Vidyananda, resident monk at Ananda Kutir Ashrama.