Originally posted by Stephen E Goldstone@ M.D.
The muscles that control bowel movements, or sphincters, are concentrated in your anus and lower rectum. These muscles can be divided into an external sphincter and internal sphincter. Your external sphincter, the outermost band of muscle, is under your direct control. You can willfully tighten it, and you can relax it. Your internal sphincter is an involuntary muscle, and as such you cannot willfully cause it to relax or contract. Just as your internal sphincter muscle involuntarily relaxes when feces enter your rectum, it involuntarily contracts when a penis or other object attempts to enter from the outside. This sphincter contraction is beyond your ability to control, no matter how relaxed or sexually aroused you are.
...
Like any muscle, your internal sphincter can contract for only so long before it fatigues and must relax [any of you who know you're tight (and probably anyone else who regularly engages in anal) will know exactly what this means]. When it relaxes, your partner can safely insert his penis without causing you pain. How do you make your muscle fatigue? Easy.
-Unroll a latex condom over your partner's penis.
-Lubricate the condom well.
-Apply a generous amount of lubricant to your outer anal area. Inserting fingers into your anus may cause tearing [if done too abruptly to an unrelaxed ass] and is not necessary if you thoroughly coat your partner.
-Gently lower yourself onto your partner's penis to the point where you feel discomfort. This corresponds to the moment when his penis begins to stretch your contracted internal sphincter muscle.
-Stay in this same position, with your partner's penis applying constant and gentle pressure against your internal sphincter muscle. His pressure will cause your muscle to maintain its contraction until it tires and must relax. And no, you won't be suspended over him in a fit of anticipation for hours upon hours. Thankfully, the muscle usually tires within thirty to sixty seconds.
-When you feel your sphincter relax, sit the rest of the way down on his penis. After a couble of up-and-down movements, your muscle will be sufficiently stretched so that you can move to any position you like.
-It is also important that you do not stimulate your penis (manually or orally) while your partner attempts penetration. Stimulation immediately causes your sphincter muscles to contract and only increases the time it takes your sphincter to relax. Of course, once you accomodate your partner, stimulate all you want.
...
I recommend that anal intercourse be initiated with the receptive partner on top, because this position allows him to be in control. When you are on top, you control penetration according to when your muscle contracts and when it relaxes. Injury occurs from persistent insertion through a tight anus. If your partner is on top and he feels your internal sphincter tighten, he will naturally push harder because he wants to be inside. [basically, it's safer if YOU take control during your first "real" time.]
