What are the average levels of cardiac output during the first few minutes of exercise?

Cardiac output during exercise is an important physiological measure that indicates the amount of blood the heart pumps in a minute. During the initial stages of exercise, the body undergoes various physiological changes to meet the increased demand for oxygen and nutrients by the muscles.

In the first few minutes of moderate to vigorous physical activity, cardiac output begins to rise significantly. It typically ranges from about 20 to 30 L/min at rest and can increase to about 20 to 45 L/min depending on the intensity of the exercise. The chosen answer appropriately reflects a realistic estimate of around 45 L/min, which aligns with physiological studies indicating that as exercise commences, an increase in heart rate and stroke volume occurs to maintain adequate blood flow.

As exercise continues to progress, cardiac output may increase further, especially during sustained or high-intensity efforts. However, during the very early stages of exercise (the first few minutes), a level around 45 L/min is representative of the body's initial response to an increase in physical activity, accommodating the rise in muscle metabolism and promoting enhanced oxygen delivery.