FW 13.21: VO2Max isn't changing

First of all congratulations on the vo2max value! Did you just get the 955 a few weeks back. It looks like it is slowly adjusting. The same thing happened to me when I switched from the 945 to the 955. The 945 had a more *bouncy" algorithm, while the 955 adjusts the VO2MAX more slowly, maybe 0.1 per day. Unfortunately Garmin connect only reports integer so it dorsn't look like it's changing, but it actually is. There have been many requests to Garmin to report VO2MAX with decimals, but they have ignored them so far, so if your VO2MAX is between 63.5 and 64.5 it will always show 64. Like other said, the VO2MAX accurate vale is in the fit file of the activity do other software can show it, run analyze is the only one I know for sure. I was able to plot it over time and you can clearly see when I changed watch how much more consistent and slowly adjusting the VO2MAX is in the 955. The watch has a lot of issues (for example I never, in 5 months, had an FTP detection), but I think the VO2MAX is actually good. It is just the way it is reported in the app that is confusing...

Sure, here you go:

The point is that shows my BIKE Vo2, but I don't train with 955 on my bike (outdoor with E530 and now, indoor, activities are uploaded from TrainerRoad to Connect). That would indicate the "backoffice" algorithm works well (I observed this decline of fitness after my sickness).

My RUN Vo2 is on 60 for half a year now, where race predictions skyrocketed (understandably, I'm weak now):

Interesting! So it seems like cycling VO2Max is working ok, but running VO2Max is a little strange. I'm not sure because right now I cannot run, I can only bike due to a foot injury, so I have not had a running VO2Max detected in several months. Three questions: Are you running frequently? Do you use a chest strap? At the end of the run do you see a VO2Max value on the same screen as the recovery time?

MarcinKoprowski said:

I don't get vo2 after the run on my watch, but when i go to Connect Mobile and check Vo2 max it says "updated today" with no change of value

Hi, Where do you see that on Connect App. On the IOS one I've never noticed "updated today" appearing

Use Runalyze , you will see the VO2 max from the .fit file to two decimals and you will see it moves in small increments.  I did submit an idea to Garmin that they show the decimals . For information mine moves daily in the decimals and over the past three month with my increases in activity intensity and duration has increased by 2 whole digits and will likely tick to the next one shortly based in teh move in the decimals.

Here it is, iOS:

Ah ok I see it. Never realised it ...will see how it moves, especially on a day I dont run.

That is how the .fit file data is reflected in Runalyze for most of November . You see in the decimals it moves.

And this is the average of each of the last 12 months.

Runalyze is a really nice application (web based only)

Interestingly the Garmin changes whole digits at around the X.25 mark  so 63.25 would show as 64 as an example

On 13.21 and my VO2Max has continued in free-fall. Was steady for "always" - minor fluctuations - over three years with my 945. When I got the 955 VO2Max started dropping, no bottom in sight. My run loads, weekly distance, workouts, pace etc. are essentially unchanged for the last year. Definitely something different with how the 955 calculates this. Pretty sure there's no way I've lost > 10% of my overall fitness over the last three months.