VO2 max is the measure of the peak volume of Oxygen (VO2) you can consume and use in a minute. It is measured in ml/kg/min and so you can see that it is also relative to body weight.
As we already know, Oxygen is needed to produce energy. The harder you exercise the more Oxygen you use in order to produce sufficient energy. However, everybody has a maximum level (their VO2 Max), where Oxygen utilisation is at its peak
If exercise intensity increases beyond this point then the anaerobic energy systems must be used to supply the additional energy. However, anaerobic metabolism produces lactic acid which causes fatigue and so cannot be sustained. Anaerobic energy production also results in Oxygen Debt.
Your VO2 Max can be increased through training, as this causes adaptations within the cardiovascular, respiratory and muscular systems which make the processes of gas exchange, Oxygen transport and aerobic metabolism more efficient.
There are a number of ways of testing your VO2 max. The most accurate is in a laboratory, where exhaled Oxygen and Carbon Dioxide levels are measured whilst running on a treadmill. This allows us to see how much of the Oxygen inhaled (we know 21% of the air we inhale is O2) is used for energy production. VO2 can also be estimated using tests such as a bleep test, or Balke test.
Results vary depending on fitness level, sex, age and genetics. The older you are the lower your VO2 Max is estimated to be. An average score for a twenty-something male would be 40 ml/kg/min with an excellent score being 52 ml/kg/min. An average score for a female of the same age would be 30 ml/kg/min and an excellent score would be 41 ml/kg/min. Some prefoessional sports people (involved in endurance activities) have scores in the 80's!
