During heavy exercise, how much cardiac output may increase?
Cardiac output is the amount of blood pumped by the heart into the aorta in one minute. Heart beats 72 times per minute and pumps out about 70 mL blood during each beat.
Cardiac output = Stroke volume × Heartbeat ( 70-72 times per minute) = about 5 litres.
This amount is only a little less than the total volume of blood (about 6.8 litres) present in the whole body. Mild exercise like walking raises the heart output to about 11 litres.
When we perform exercise the rate of breathing and the rate of heart beat also increased. During vigorous exercise our body may need three to four times of cardiac output because at that time muscle need more oxygen. It's obvious if oxygen supply are increased there must be increased in blood supply that leads to increase rate of heart beat. Cardiac output changes with age, size, sex, temperature,etc. It is directly proportional to the size of the organism, amount of blood entering the heart, metabolic rate etc. but it is inversely proportional to age and peripheral resistance.
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