Why Do Muscles Require More Blood During Exercise?
The muscle system comprises all the muscles you use in your body, including the muscles surrounding your vital organs and heart. The bloodstream is the network that connects the muscles in your body, providing oxygen and nutrients and carrying away waste products. The circulatory system and the muscular system work together when you exercise to provide for the increased demands for energy and strength, which increases the blood flow to your muscles.
The Skeletal Muscle System
Skeletal muscles are the muscles found in your legs and arms and throughout the body. The skeletal system is different from the smooth muscle system in organs like your liver and the cardiac muscle in your heart because the skeletal muscles contract voluntarily. This muscle system converts glucose, glycogen, amino acids and fat into ATP using oxygen, which releases a muscle contraction so that the muscle can be used again. This process is known as aerobic respiration.
Blood Flow to Your Muscles During Exercise
When you exercise, you increase the amount of blood flowing to and from your muscles so that more oxygen is supplied to complete aerobic respiration. The extra blood pumping to these muscles is pulled from other organs that have less energy demands during a workout, like your digestive system, which can sometimes lead to indigestion during training. As the demands of the muscles increase, your bood flow increases until you reach your maximum aerobic capacity.
Once the maximum amount of oxygen is being supplied to your muscles by your bloodstream, the cardiovascular system reaches its VO2 maximum, or maximum volume of oxygen transportation. Your muscles can extend beyond the VO2 max by converting glucose directly into lactic acid, but the buildup of lactic acid in the muscle tissue quickly leads to fatigue and cannot be maintained as long as aerobic exercise. Both aerobic and anaerobic respiration can be increased through exercise.
Understanding Your Cardiovascular System
Maximizing your aerobic and anaerobic respiration are crucial parts of becoming a more effective athlete and achieving higher fitness. The bloodstream serves the most important role during a workout, and increasing the rate of oxygen transport through exercise has a very positive benefit on your overall health. Increased blood flow to the muscles is a natural and healthy effect of exercise, and shows that your body is responding correctly to your increased energy demands.
Max Roman Dilthey is a science, health and culture writer currently pursuing a master's of sustainability science. Based in Massachusetts, he blogs about cycling at MaxTheCyclist.com.