Maximum Oxygen Consumption Maximum oxygen consumption, also referred to as VO 2max is one of the oldest fitness indices established for the measure of human performance. The ability to consume oxygen ultimately determines any human's or animal's ability for maximal work output over periods lasting greater than one minute. The higher the number, the greater the potential work rate. The amount of exercising skeletal muscle and the ability of muscle to utilize supplied oxygen Cardiac Output Cardiac output is defined as the mathematical product of heart rate times stroke volume . Heart rate is nothing more than the number of times the heart contracts per minute.
Stroke volume represents the amount of blood ejected by the heart with each beat.
The ventricles of the heart fill with blood during a period of time called diastole. The ventricles are maximally filled at a time just before the heart contracts called end diastole . The contraction phase is referred to as systole. Consequently, stroke volume equals end diastolic volume - end systolic volume. In an untrained individual heart rate is about 72 beats per minute so stroke volume is about 70 milliliters.