You should have used this \/



But blood shunting causes the pump you feel in your legs because you body redirects blood from your gut to the active muscles....drink too much water (eat something large) your body will take some (or I should say a larger than normal portion) of the blood that was once for use in your legs and give it to your digestion system to start breaking down or absorbing what ever you ate/drank.

This is a problem because since less blood is in your legs while doing the same amount of work lactic acid will build up very quickly.