What does glucose do?

Glucose is defined as "sweet". It's a type of sugar you get from different foods you eat daily, and your body uses it for energy. So as it travels through your bloodstream to your cells, it's called 'blood glucose' or 'blood sugar'. And yes, it's an important energy source that is needed by all the cells and organs of our bodies. For example, our muscles and brain. Carbohydrates such as  bread, pasta, fruit, cerealsare common sources of glucose.

Wala! There goes your answer friend :)

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.