“The ancient texts on hatha yoga begin with ‘Shatkarma’. They say that one must
first purify the whole body - the stomach, intestines, nervous system and other systems before practicing asana and pranayama and more advanced practices leading to deep meditation.”
Swami Satyananda Saraswati, “The True Spirit of Hatha Yoga”, Yoga Magazine, India, September 1982 – http://www.yogamag.net/archives/1982/isep82/sphatha.shtml
The following are explanations how these five asanas (see pic) work in the Laghoo Shankhaprakshalana practice. This sequence can also be practiced as a ‘dry run’. Each asana is repeated eight times –gently and without any strain. The sequence is performed three times.
1. Tadasana stretches the whole digestive tract and stimulates the cardiac sphincter. It stretches stomach and colon.
2. Tiryaka Tadasana - squeezes and stretches the stomach and small intestine activating peristalsis and the pyloric sphincter.
3. Kati Chakrasana - creates a centrifugal force allowing water to move through the ileocaecal valve into the large intestine and ascending colon.
4. Tiryaka Bhujangasana – here the pressure of the abdomen on floor and the twisting movement assists the water through the entire large colon and beyond to activate the sigmoid flexure.
5. Udarakarshanasana - Alternately compresses and massages lower colon and prompts desire to defecate by stimulating the anal sphincter.
For more information on these practices - Asana Pranayama Mudra Bandha by Swami Satyananda Saraswati - http://www.satyananda.net/shop/view/asana-pranayama-mudra-bandha.