Quote:
Anal sex encompasses a variety of commonly practised sexual activities. Although there is nothing remarkable about them in practical terms, there are taboos surrounding them that may arouse strong feelings of moral indignation and anxiety. It is important to remember that while some people find these activities repugnant, others may find them stimulating, exciting, and a normal part of their sexual intimacy.
Anal sex may include the following activities:
anal intercourse - penetration of the anus with the penis or, possibly, with a dildo or vibrator.
fisting - insertion of the fingers, hand, or even the forearm, into the anus.
rimming - oral contact with the anus for sexual stimulation.
Who does it?
There is a common misconception that anal sex is practised almost exclusively by gay men. This is certainly not the case. An estimated one third of gay couples do not include anal intercourse in their lovemaking with about one third of heterosexual couples doing so from time to time. About 10 per cent of heterosexual couples have anal intercourse as a regular feature of their lovemaking. In absolute numbers, more heterosexual couples have anal sex than homosexual couples.
Fisting
This involves the insertion of the whole hand or forearm into the anus or vagina for sexual stimulation. With adequate relaxation it is physically possible and may be acceptable and enjoyable for some couples. But the diameter of the hand or forearm is so much greater than that of the penis there is an increased risk of anal injury. Good anal relaxation in the receptive partner and care by the insertive partner are essential.
I really did look all over in medical journals; I could only find one that stated that because of the increased ability to relax the sphincter muscles may increase the chances of leakage only because of the relaxed state. Almost all said the anus was resilient enough to bounce back from any stretching. 