Fitness age

DarylD VO2 max should be higher for better performance (better usage of Oxygen) - falling VO2 max is not generally an athletes goal :) . It is surprising that your fitness age is going down at the same time - I would expect the reverse - i.e. VO2 Max - 45 tells me fitness age is 20 top 10% for age and gender if my VO2 goes up I'd expect fitness age to go down but probably not much below 20 as late teens early 20's have highest avaerage fitness. Have a look on Firstbeat.com for in depth explanations of VO2 Max and fitness age.

Apologies. I got mixed up do changed my post. My V02 max has increased from 35 to 41. Now its steady at 41 but my fitness age is going down.

DarylD - ah OK so your VO2 Max is static at 41 but your fitness age has gone down is that what you are saying? - so one day you sow VO2 Max 41 Fitness age 25 say then next day VO2 Max 41 Fitness age 23?

Yes that's correct. It's been 41 for a few weeks but my fitness age has gone down 6 years.

DarylD Mmmm... not sure what fitness age has it gone from and to? on the face of it doesn't seem to make sense

I have seen the same. I am quite convinced that it is simply a matter of rounding.

At a VO2Max around 40, a VO2Max change of 1 is equivalent to a change of several years of fitness age. You have probably seen this happening, when you increased your VO2Max from 35 to 41. Your fitness age dropped by a lot more than 6 years, right?

So if the fitness age calculation uses a non-rounded VO2Max, while you see a rounded VO2Max, then you will see variations in fitness age, even if the apparent VO2Max is unchanged.

If you want to investigate this further, you will need to look at the non-rounded VO2Max and compare it to your fitness age. You can do this if you link your Garmin account to a Runalyze account and enable the field "VO2Max (file)". This field will show the VO2Max value, which the Garmin watch stored in the .fit file, with a precision of 2 decimal points.

I see exact the same, but even stranger, two days, the same vo2max but different fitness age (few years!) (at least its improving ;). How is it possible, how to interpret this? Is it really a rounding matter?