Ergometer cycling or treadmill running are golden standards for determining VO2-max. Various protocols are be used i.e. increasing load and time intervals until exhaustion with measure of oxygen consumption during the test. Submaximal testing protocols may be used if the test person may be at risk. VO2-max refers to the maximum amount of oxygen you can utilize during exercise. It’s commonly used to test the aerobic endurance or cardiovascular fitness of athletes before and at the end of a training cycle. VO2-max is measured in milliliters of oxygen consumed in one minute, per kilogram of body weight (mL/kg/min). Human activity and work may be measured by the consumption of oxygen in metabolic units determined in kcal/kg/hr. In rest the metabolic activity corresponds to 3.5 units whereas running at high speed may correspond to levels above 50.