Oxygen consumption (VO2) may be defined as ones ability to extract oxygen from the atmosphere via the respiratory system sand transport it in the blood to the working tissues (eg. muscles) for the energy production by the oxidation of carbohydrate and fat. The highest rate at which you can uptake oxygen is termed the maximal oxygen consumption (VO2max). Research has shown VO2max to be one of the most important determinants of aerobic or endurance performance.