The highest rate at which oxygen can be utilized during exercise is yourVO2 max.
It is also called maximal oxygen consumption or maximal oxygen uptake. VO2 max is often used by athletes to measure performance.
VO2 max is measured in 2 ways: an absolute rate in litres of oxygen per minute (l/min) or as a relative rate in mililitres of oxygen per kilogram of bodyweight per minute (ml/kg/min). VO2max is genetically predetermined for the most part, though it may be improved by several percentage points with training.
Accurately measuring this involves a running test or a cycloergometer test in which exercise intensity is progressively increased until exhaustion while measuring the rate and oxygen concentration of the inhaled and exhaled air.
The Fick Equation is used to determine the results:
VO2 max = Q(CaO2-CvO2)
Q is cardiac output,
CaO2 = arterial oxygen content,
CvO2 = venous oxygen content.
This number varies considerably in the population. For example, an average young untrained male will have a higher VO2 max than an average young untrained female. These scores can improve with training and decrease with age. It is not the most convenient method for the average population as it generally requires controlled conditions and specialized equipment.