A special Pranayamic exercise, namely, Mula Bandha involves forceful contraction of the sphincter muscles of the anus. It also requires the perineum , the general region between the anus and the genital organs, to be strongly pressed by the heel. There are many people who practice Mula-Bandha as a part of Siddhasana exercise. Some even carry it on as separate exercise also.

Since this wonderful Pranayamic exercise concerns itself with the lower ends of the nervous system in the human trunk, it is called Mula-Bandha, which denotes anal contraction.

The techniques of exercising of Mula Bandha involve special techniques to be adopted. There are two `anal sphincters`, one internal and the other external, located at the end of the rectum. Circular muscles form both these `sphincters`, the external sphincter constituting the anus.

It is important to note that though the anal contraction alone goes to execute Mula-Bandha, anal contraction also involves contraction of the whole pelvic region. Hence some regard Mula-Bandha as a practice exercise of pelvic contraction.

This Mula-Bandha exercise is anticipated to work upon the central and sympathetic nervous systems via the terminal nerves present in the anal sphincters.

Special preventions are needed to be taken while undertaking the vigorous exercise of Mulla - Bandha. If one practices this `asana` following the wrong methods , as a side effect one may suffer from serious constipation problems and also digestive irregularities.