The human body is a complex network of systems that work in concert to accomplish different tasks, like eating and exercising. The European Union Public Health Information System notes the musculoskeletal, cardiorespiratory, circulatory, neurological and endocrine systems are all involved in physical activity. The systems of the human body communicate electrically and chemically to reallocate the exact resources needed for exercise.
You use your musculoskeletal system extensively during exercise. Muscle fibers contract to shorten muscles in such a way that pivots bones around joints, resulting in the swinging arms and running legs of exercise. When you exercise, your muscles need more oxygen-rich blood and glucose. Your body must shift resources away from some body systems to meet this demand.
Your nervous system plays an important role in exercise, predicting the level of activity and then routing resources to those body systems used during exercise. Your central nervous system increases your heart rate early on in exercise. Your nervous system also signals your muscles to take up more oxygen from the bloodstream, known as oxygen uptake.
Your cardiovascular system includes your blood vessels and your heart, which pumps blood to the rest of your body through those blood vessels. Cardiac output is the amount of blood your heart pumps. According an article published in Clinics in Sports Medicine, the typical person at rest has a cardiac output of five to six liters per minute. Your cardiac output must satisfy the metabolic needs of the body during exercise by providing the body with the oxygen-rich blood it needs to perform the physical activity. Your heart rises to the challenge by increasing the force at which it pushes blood through your blood vessels. Stroke volume, or the amount of blood pumped by one portion of the heart, increases by 30 to 40 percent when you go from a resting state to peak exercise.
Your body must manage blood flow to meet the demand of active muscles while still supplying other vital organs the blood they need to function. During exercise, blood flow to your brain remains relatively constant while blood flow to your kidneys and spleen is cut in half. Blood flow to the muscles of your heart increases by four times during exercise and your body increases blood flow to your skeletal muscles by about ten times during physical activity. Scientists call this increase in blood flow to the cardiovascular and skeletal muscles exercise hyperemia. You experience vasodilatation and decreased vascular resistance when you exercise, which means your blood vessels expand to allow blood to flow more efficiently. Your systolic pressure, or the top number on a blood pressure reading, rises while your diastolic pressure falls.
Increased muscle activity calls on the lungs to produce more oxygen to muscle cells and to remove excess carbon dioxide from the body. There is a linear relationship between cardiac output and oxygen uptake – the more blood your heart pumps, the more oxygen your muscles take from the bloodstream. Exercise causes your respiratory rate to increase four to five times over your resting rate. Tidal volume, or the amount of air you inhale and exhale in a single breath, increases five to seven times.
Your endocrine stimulates certain responses around the body through the use of hormones which act like chemical messengers. Insulin, a hormone, stimulates muscles into taking up glucose from the bloodstream, which the muscles use for energy. Your endocrine system releases other hormones during exercise, such as thyroxine which speeds up metabolism and epinephrine. Epinephrine is beneficial to your cardiovascular system, according to Western Michigan University.
Your entire body gets involved when you exercise, even if that physical activity involves only one or two body parts. Understanding the body systems used during exercise helps you optimize your workouts.
European Union Public Health Information System; Physical Activity; December 2009
Clinics in Sports Medicine: Physiological Effects of Exercise on the
Cardiopulmonary System; Mark A. Booher, MD, Bryan W. Smith, MD, PhD
Western Michigan University; The Endocrine System; Dr. Cheatham; 2011