What happens to the total blood flow during heavy exercise compared to at rest?

Blood flow is greater when you exercise because the blood vessels in your muscles dilate. Imagine water flowing through a fire hose compared to a garden hose. Adenosine triphosphate, or ATP, is the way your body uses biochemicals to store and use energy. When ATP gets used up in working muscles, the muscles themselves produce metabolic byproducts (for example, adenosine, hydrogen ions and carbon dioxide). As these byproducts leave the muscle cells, they cause small, thin-walled blood vessels (capillaries) within the muscle to expand or dilate, which is called vasodilation. The dilated capillaries allow increased blood flow, which delivers more oxygenated blood to the working muscle.

Yes he thought they should be left to chance why, because he thought that was the best thing to do