Your cardiovascular system includes your heart, blood vessels and blood. The average adult has about 5 L of blood, according to Montana State University, which gets circulated through the body about once per minute. As you exercise, the rate at which blood is pumped throughout your body, and particularly to your muscles, increases. Cardiac output is a measure of how much blood is pumped through your body in one minute.
Heart Rate and Stroke Volume
Your heart rate and stroke volume are both directly related to your cardiac output. The higher both these numbers are, the higher your cardiac output will be. According to Certified Strength and Conditioning Specialist Phil Davies, the average heart rate of an adult at rest is 60 to 80 beats per minute. During exercise, this figure can increase to more than twice the resting rate.
Stroke volume is a measure of blood pumped from your heart with each beat. The average rate during physical exercise is 110 to 130 ml per beat.
Determining Cardiac Output
Figuring out your cardiac output is as simple as multiplying your heart rate by your stroke volume, or HR x SV = CO. Cardiac output is measured in liters per minute. Physically fit individuals will have a higher cardiac output compared to people who are less active. Cardiac output increases more with intense exercise than it does with endurance training, according to Davies. Heart rate may remain the same during both vigorous and moderate activity, but more blood is needed by your muscles during vigorous activity, so your stroke volume is higher.
The cardiac output for the average adult at rest is about 5 L per minute, but this can vary from 4.8 L to 6.4 L, according to MSU. However, this increases significantly during exercise. For untrained people, the average maximum cardiac output is 14 to 20 L per minute. People in extremely good shape, such as professional athletes, can have a maximal cardiac output as high as 40 L per minute.
How Exercise Affects Cardiac Output
As you do aerobic or resistance training, your heart muscle is also worked out. This can strengthen your heart and even promote hypertrophy, or muscle growth. As your heart is strengthened, it is able to pump blood more efficiently, which leads to an increased stroke volume capacity. As your maximum stroke volume increases so does your cardiac output. This is how elite athletes are able to have more than twice the cardiac output of the average individual in some cases.
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