What Happens To The Blood Flow To The Viscera During Exercise?

Your body works as efficiently and effectively as it can to provide your muscles the blood flow they need during exercise. One mechanism in doing so is to redirect blood flow. Through a vasoconstriction and vasodilation response, the body is able to redirect bloodflow to the areas of the body that need it most.

Visceral Blood Flow

Blood flow priorities change between rest and exercise. During rest, your body is able to devote most of the blood flow to the organs in the viscera. This spares the blood flow to the skeletal muscles. In fact, at rest, only about 15 to 20 percent of blood flow is delivered to the skeletal muscles. During exercise, your body becomes less concerned with digestion, urination and reproduction, the actions produced mainly by the organs in the viscera. Therefore, blood is shunted away from the viscera and given to the working skeletal muscles. During exercise, nearly 80 to 85 percent of blood flow becomes delivered to the skeletal muscles.

Aerobic Significance

The change in blood flow from your viscera to your muscles accommodates the need for an increase in metabolism. Aerobic metabolism is the primary source for energy production inside your skeletal muscle cells because it is sustainable for the long term. Aerobic metabolism is the process of energy production that involves oxygen; since blood delivers oxygen, this redistribution is important.

Thermoregulation

During exercise, it is also essential for blood to flow toward the surface of the skin. Heat is a product of the increase in your body's metabolic rate. When blood approaches the surface of the skin, it loses heat through means of both evaporating sweat as well as convection. This aspect of blood flow is especially critical during periods of exercise in hot temperatures.

Mechanism

Your autonomic nervous system is divided into two opposing components: the sympathetic and parasympathetic system. During rest, the parasympathetic nervous system predominates, maintaining the blood flow to the viscera. However, exercise stimulates the control to move toward the sympathetic system, which stimulates an increase in blood flow through heart rate and blood pressure. The sympathetic nervous system also redirects blood flow through vasoconstriction and vasodilation away from the viscera and toward the working muscles.