What does cardiac output (CO) measure?

Cardiac output (CO) is a crucial physiological measurement that reflects the volume of blood that the heart pumps in one minute. It is calculated by multiplying the heart rate (number of beats per minute) by the stroke volume (the amount of blood pumped by the heart with each beat). Understanding cardiac output is essential as it provides insights into the heart's ability to supply blood to the body, which is necessary for delivering oxygen and nutrients to tissues and organs.

This measurement is fundamental in various clinical and exercise settings, providing important information about cardiovascular health and performance during physical activity. For instance, during exercise, an increase in cardiac output indicates how well the heart is meeting the heightened demands for blood flow.

In contrast, other options like measuring the amount of oxygen consumed refer to VO2 max, which is different from cardiac output. The pressure exerted by blood on vessel walls corresponds to blood pressure, and the efficiency of heart contractions involves different measures, such as ejection fraction but does not directly define cardiac output. The focus of the question is specifically on the volume of blood pumped, making this answer the most accurate representation of what cardiac output measures.