An individual's Max VO2 represents the maximum amount of oxygen that can be extracted from the air breathed in, and transported to the working muscles. It is usually measured in millilitres of oxygen per kilogram of body weight per minute (ml.kg.min).

During most forms of exercise, the body is dependent upon oxygen to provide the energy it requires. Oxygen is extracted from the air by the lungs, and it transported via the bloodstream to the working muscles. As the level of exercise increases there is a corresponding increase in the muscular demand for oxygen.

Exercise that relies heavily on oxygen for the provision of energy is called aerobic exercise. These are generally steady endurance type exercises. In every individual there is a point where the intensity of the activity increases to such a point where the oxygen demand of the working muscles cannot be met. It is at this point that muscles have to obtain the extra energy through anaerobic metabolism, using reactions that do not require oxygen.

The main disadvantage of anaerobic metabolism is that it can only sustain high rates of energy production for a short period of time.

What does it mean?

Athletes with a high Max VO2 value are likely to be those most able to sustain high intensity exercise using aerobic metabolism, thus avoiding the high levels of fatigue associated with anaerobic exercise.

What determines an individual's Max VO2?

The constituents of the Oxygen Transport System determine Max VO2:

• Pulmonary ventilation
• Haemoglobin concentration
• Blood volume and cardiac output
• Peripheral blood flow
• Cellular aerobic metabolism

The state of the oxygen transport system in an individual is determined by:

• Heredity
• State of training
• Gender
• Age