VO2 max still broken, how to reset?

The VO2 max moves very slowly. Sync with Runalyze Web site and see the movements in the decimals.

It's not a decimal issue. I've had average changes over a month of 4-5 units on Runalyze and it's never changed on my FR955

Let me relay my situation in the hope it may be helpful . If I am repeating what you know I apologise.

I had Runalyze but I didn't realise there is a setting to display the .fit file VO2 Max.  Have you that setting enabled?

My data in that filed and my 955 display track each other, apart form the decimal. Also the 955 display (and the connect graph) changes to a new full digit at about .40  So as an example at around 50.40 the 955 would display 51.

Almost each run the Vo2 max per .fit file date as in Runalyze chnages in the second decimal up or down and in my experience mirrors how my fitness feels.

Thank-you, that is helpful - I didn't know you could display it from the .fit file.

Confirms that Garmin is broken - the VO2 max from the .fit file is stuck at 60, Runalyze can vary 10 units different.

8488635 said:

Confirms that Garmin is broken - the VO2 max from the .fit file is stuck at 60, Runalyze can vary 10 units different.

Keep in mind that Garmin VO2 Max in FIT file and Runalyze VO2 Max aren't directly comparable (even in terms of relative changes).

- Garmin VO2 Max in FIT file is most likely a rolling average (it never changes much from activity to activity)

- Runalyze VO2 Max is apparently per-activity (it can change a lot from activity to activity)

No, as stated by Flowstate  , they are very different calculations. Runalyze uses some other metrics in it. They have a detail of the calculation on their site.

Well I'm not sure what kind of average Garmin is calculating and over what time period. My VO2 max has been (from the .fit files) in the range 60-61 and seems immovable from the day I switched from my Forerunner 35 to 955 in July last year. This has included blocks of de-training for 4-6 weeks because of injury, significant training blocks where fitness has returned. They are so far out of sync in terms of variance and rolling average, something is broken.

To be clear, my layman's understanding is that the principles of Garmin VO2 Max and runalyze VO2 Max are essentially the same: they both compare your pace to your heart rate, assume a linear relationship, and derive an estimated VO2 Max (or VDOT) from that. (I based that on reading the FirstBeat whitepaper and the info on the runalyze site.) Basically if you can run faster for a given HR (relative to your max HR), your VO2 Max will be higher.

Additionally, both Garmin and runalyze may apply some sort of correction factors to the estimate - runalyze uses prior race results and Garmin may look at weekly mileage (or perhaps that's only applied to the race predictor.)

But my main point was that regardless of how VO2 Max is calculated, the Garmin number is fundamentally different because it's apparently a rolling average, while the runalyze number is per-activity. So you'll never see the Garmin number change in the same way as the runalyze number.

8488635 said:

Well I'm not sure what kind of average Garmin is calculating and over what time period. My VO2 max has been (from the .fit files) in the range 60-61 and seems immovable from the day I switched from my Forerunner 35 to 955 in July last year. This has included blocks of de-training for 4-6 weeks because of injury, significant training blocks where fitness has returned. They are so far out of sync in terms of variance and rolling average, something is broken.

That does sound like something is broken for sure. If you detrain I'd expect your VO2 Max to drop 2-5 points.

It looks like I have to do full reset / data delete on the watch. I'm going to try that, though it's a bit annoying obviously!