You should utilize any one of the following asanas while doing basti:
Utkatasana (unyielding pose). This is the asana in which one practises nauli. This is the traditional method recommended by the Gherand Samhita and Hatha Yoga Pradipika. The legs should be separated by about half a metre. They should be bent at the knees and one should lean forwards and place the hands on the thighs just above the knees.
This asana can be utilized for jala (water) and sthala (air) basti, but if you practise jala basti in this pose then the water will have to be deep. If you have the facilities available to obtain this depth of water then you can use this pose.
Kagasana (crow pose). This is the squatting pose. It is very easy for orientals but difficult for occidentals. It is an ideal position for sucking in both air and water. Less than thirty centimetres of water is required.
Paschimottanasana (back stretching pose). A simplified version of the full form of this asana can be utilized for basti. One should sit on the ground for air basti or in water for jala basti. The legs should be stretched out in front of the body. Exhale as deeply as possible by leaning forwards into the final pose of paschimottanasana; that is one must breathe out and try to touch the head to the knees. Do not worry if you cannot touch your head to your knees. The important thing is that you attain the deepest possible exhalation. This is mainly achieved by contracting the abdominal muscles. The purpose of leaning forwards in paschimottanasana is only to achieve even greater expulsion of air from the lungs. This sitting position has two main advantages:
- It can be practised in shallow water (even less than eight centimetres)
- It can be easily and comfortably practised by almost everyone.
Choose whichever asana suits your body and available facilities.