Is the rate your heart should beat at during exercise to be sure you are working hard enough to see a benefit
but not working too hard to be unsafe.

yes  it is you shouldnt go too far as to not be safe but you should go far enough to receive results

Explanation:

when you rub, you also apply pressure, that pressure can urge the poop to come out. i think that when your rubbing, you also might be slightly breaking it up and that can further fill the stomach.