Bug: VO2 max updated although it was switched off for the trail run

I think it would be a problem with the 255, since afaik VO2 Max is always calculated on the watch and saved to the activity FIT file.

Lately I've noticed my watch reporting a vo2 max metric at the end of walking activities!  This seems silly since I don't think walking is in any way limited by O2 consumption.

I have this issue on my Garmin 955 last software update available 

5148720 said:

I have the VO2 max update switched off for the trail run and today after the activity, VO2 max has been updated anyway

That looks like a bug. I suggest you contact Garmin Support to report it.

I don't see this problem on the Epix Gen 2, but I am suspicious that even if it is turned off, the data from the run is used by the watch for things like performance condition or even future VO2 Max calculations. I have not been able to ascertain this for sure. It seems that afterI run a steep trail, my running VO2 Max and performance condition takes a big it for the following runs. Not sure and hard to say given all the parameters at play...

6125703 said:

This seems silly since I don't think walking is in any way limited by O2 consumption.

Not silly at all. It is a key feature of Garmin Firstbeat VO2 algorithm. It can generate a VO2 estimate some sub-maximal efforts.

That said, it seems that Garmin believes that running VO2 Max is better than cycling VO2 Max than walking VO2 Max since this is the order the watch will use to pick an "overall" VO2 Max number. (while keeping track of running and cycling, if they are available and updated within the last 30 days).

Etupes25 said:

I have not been able to ascertain this for sure. It seems that afterI run a steep trail, my running VO2 Max and performance condition takes a big it for the following runs.

You could use https://www.runalyze.com which is free and syncs with your Garmin account. If you add the "VO2 Max (file)" column to the activity list, it will show the VO2 Max from FIT file for every activity, to 2 decimal places. Clearly this number is some kind of rolling average (and reflects what's displayed on your watch, except it's not rounded), but even a small change in the value associated with a trail run activity (compared to the previous activity) would confirm your hypothesis. Just too bad there's no way to get the non-averaged VO2 Max for a single activity. At best you can say it was higher or lower than average. (Runalyze will calculate its own non-averaged per-activity VO2 Max estimate from your HR and pace, though.)

Kinda unrelated, but Garmin even updates performance metrics like acute training load if you start a run but end up discarding it.

Same here. It also updates race pace estimates which can be way off after a difficult trail run. Would be handy if that could also be turned off.