What is the primary determinant of the maximal rate of oxygen consumption?

The primary determinant of the maximal rate of oxygen consumption, also known as VO2 max, is cardiac output. Cardiac output is a measure of the amount of blood the heart pumps per minute, and it is calculated by multiplying stroke volume (the amount of blood pumped by the heart with each beat) by heart rate (the number of beats per minute).

At maximal exercise levels, the body's demand for oxygen increases significantly, and cardiac output must increase to meet this demand. This means that both the stroke volume and heart rate play important roles, but it is the overall cardiac output that is most directly responsible for determining how much oxygen can be delivered to the muscles during intense exercise.

While stroke volume and heart rate are components that contribute to cardiac output, focusing solely on them does not account for the total volume of blood being circulated. Blood pressure, while an important cardiovascular parameter, does not directly determine the maximal rate of oxygen consumption. Instead, it is influenced by both cardiac output and vascular resistance. Therefore, cardiac output is the most comprehensive indicator of the capacity of the cardiovascular system to deliver oxygen to working muscles, which is why it is identified as the primary determinant of maximal oxygen consumption.