VO2 max is often cited as a measure of the fitness of endurance athletes. But what is VO2 max, and how do you measure it?
VO2 max is an abbreviation for the maximum rate (Volume) at which your body can consume oxygen (O2) during exercie. It is widely used as an indicator of cardiorespiratory fitness. Top athletes can have values as high as 80 ml / kg.min. Sedentary people are usually in the range 30 to 50.
It is measured in a laboratory using sophisticated and expensive equipment. However it is possible to get a pretty accurate estimate using a Ramp Test on a cycle home trainer that can measure your watts. Most "Smart" turbo trainers do this today. Software such as Zwift makes this process very simple, and dare I say, enjoyable, although pushing yourself to the limit is not always pain free!
The ramp test can also be used to measure your FTP (Functional Threshold Power), the maximum power in watts that you can sustain for 1 hour. This is used widely by cyclists as a measure of their fitness.
The procedure is as follows. After completing the test, fill the results in the form below and it will estimate your VO2, PPO and FTP:
- Start at 100w and increase your power output by 25 watts every 150 seconds (2 and a half minutes).
- Record the last completed interval (x), and how far into the uncompleted interval you managed (y).
- Peak Power Output (PPO) = x + 25 * y/150
- Your VO2 max can then be estimated from this peak power and your body weight using the formula: VO2 max = 0.01141 * PPO + 0.435
- FTP can be estimated as 0.825 * PPO
Note that these formulae are only applicable for this specific ramp test. Different tests use different increases and length of intervals, and will have different parameters. The formulae here come from the paper (1).
Zwift recommends a 1 minute ramp test to evaluate your FTP; starting at 100 watts and increasing by 20 watts every munute until exhaustion. FTP here is estimated by multiplying your average watts for the last minute by 0.75.
(1) John A. Hawley and Timothy D. Noakes (1992) Peak power output predicts maximal oxygen uptake and performance time in trained cyclists. Eur J Appl Physiol 65:79-83