Garmin connect give me my fitness age when viewing my Vo2max. It tells me my fitness age is 20, I am 36.
Given that in the real world your potential peak condition peaks between age 25-28, I cant work out if a fitness age of 20 is much better than a fitness age of 36!
Does it assume that infinitely younger is better? So if next week my fitness age dropped to 18, would this signify an increase in fitness? Or a decrease in fitness given that it would be further away from the peak fitness age of mid-late 20s?