I found this article after seeing a programme on UK TV about the benefits of squatting for rectal problems including anal fissures. This is meant to help relieve constipation and stop straining by opening things up more when visiting the bathroom.
I have not tried it myself but the suggestion the programme made was to either put you feet on their tip toes or raise them off the floor by using a few books as a platform or a box even. Basically the trick is to try and bring your knees above your waist.
Has anybody else heard of this?
http://www.relfe.com/toilet_seat_constipation.html