shit I never thought of the science behing it ,lol.It's not hard to hold for 30 minutes though.The muscles are what are being used yes, but the nerves are what you are feeling with.This is why alcohol ,or cocaine lengthen the time it takes for you to cum; your nervous system is being stimulated at the same time your fucking .So however you choose to hold your load , its all you ! and let the good love making begin.