Originally Posted by Panza

As an exercise physiologist I can chime in and say that it measures your body's ability to utilize oxygen out of the maximum available O2 in your body. Cross country skiers can have 91% and tour de france winners can see 88%+ VO2 max. It's confusing and complicated to determine. Instead it's much better to use that tells you exactly the same thing? Calculate your FTP instead. You'll be able to use an FTP to measure your performance and pace yourself in races compared to a VO2 max, which will maybe tell you how much of your max potential you are using. Your "max potential" which can also increase through training. So fairly arbitrary.