kegel exercises, thats what i was thinking of:

http://www.mayoclinic.com/health/keg...rcises/WO00119

they strengthen your pelvic floor muscles (so you have more volountary control over them).

my thought was... that control over pelvic floor muscles might well assist orgasm. it might be that making your legs go ridid is a way of firming your pelvic floor muscles for orgasm and kegal exercises might teach you to isolate them such that you don't need to make your legs go rigid.

apparently people typically start doing kegal exercises on their backs... but once you get the hang of it you can do them on your stomach, standing up, etc etc.

just a thought