VO2 max can be determined by considering 3 factors:
- Cardiac output (or the volume of blood pumped by the heart in one minute)
This is calculated from the heart rate (or the number of beats per minute) and the stroke volume (how much blood is pumped at each beat).
- The oxygen carrying capacity of the blood (or the number of haemoglobin in the red blood cells)
- The amount of muscle and its ability to use the oxygen supplied.
In other words, to have a high VO2 max (and be better at sport), you need to have a big and efficient pump to deliver oxygen right blood to the muscles, and mitochondria rich muscles to use that oxygen and turn it into energy for exercise.
Experiments have shown that the muscles can use much more oxygen than the heart can deliver to them. Long-term training can result in a 300% increase in the muscle’s use of oxygen, but only a 15-25% increase in the amount of oxygen intake. In other words, it isn’t how well the oxygen converts oxygen into energy, but how good the circulatory system is to deliver the oxygen that limits how well a person can exercise.
The value of VO2 max (how much oxygen a person can consume) has two forms:
Absolute VO2 max is measured by the number of litres of oxygen per minute of exercise consumed by a person. However, body mass affects VO2 max, because bigger people often have more muscle! So there is another form of VO2 max. This is called Relative VO2 max, and is equivalent to the number of millilitres of oxygen consumed per minute of exercise per kg of bodyweight.
So basically, for a 30 year old male with no training, his VO2 max will be somewhere between 40-45 ml/min/kg. Training could improve this to 45-50 ml/min/kg. In comparison, an Olympic champion 10,000m runner would have a value of about 80ml/min/kg!! It isn’t training alone that has made such a difference – without it their value would be about 65 – 70 ml/min/kg anyway! Training is important, but if you want to be an athlete you need to pick your parents well!
To put this all in perspective, humans pale in comparison to animal athletes. A thoroughbred horse would have a value of about 150ml/min/kg!!