In this section we explain the science of standing. Standing affects our circulatory system (especially the Venous System) which is responsible for moving blood throughout the body via our veins. When we stand, we subject increased pressure on the walls of our veins, and if standing in a static position, that intensity increases.
Think of the heart as the central pump in the circulatory system. With each beat, the heart pumps blood through the vessels, which transport oxygen and nutrients to all tissues and arteries of the body. Oxygenated blood leaves the left side of the heart. The arteries carry the blood away from  the heart and the veins return the blood back up the heart. The main venous return pump is in the calf muscle. The foot has many tiny complex veins. Veins in the legs have one-way valves to help blood flow back to the heart against the force of gravity. The blood pushes through the valves toward the heart and the valves close to prevent backward flow. With each step that we take when we walk, the foot and calf muscles contract which forces the blood up through the venous system against gravity back up to the right-hand side of the heart.