VO2max dropped since change from 735XT to Fenix 5

You just need to give it some time I suspect. Mine has dropped similarly.

Hi,

it looks like my VO2max dropped from 51/52 to 45 over the last week, since I am wearing the Fenix 5. Does anyone have an idea?
I am wearing a HRM strap and occasionally I see some drops. Could it be, that the Fenix 5 is recording the heart rate from the wrist and is therefore calculating a "wrong" VO2max?

https://connect.garmin.com/modern/activity/1656703946

The f5 has had to start re-calculating your VO2max from scratch, so as the manual says, it'll get more accurate once it's got more activities logged on it.

The f5 has had to start re-calculating your VO2max from scratch, so as the manual says, it'll get more accurate once it's got more activities logged on it.

Makes sense. Thank you... Will wait and see ;)

Same here mate, this always happens when you change watch. I got up to 51 on my 735XT and now I'm back down at 43, be good to see it climbing again soon

Even doing a reset on on watch will effect the VO2Max reading because it wipes out the current number and starts from scratch.

I wish they would have something like True Up for things like this where VO2Max, LTHR, FTP could be carried over from different devices within the Garmin system. For some odd reason my 235 reset itself and I wasn't aware of it. Most of the time I train with my F3 but the battery was low yesterday and I used the 235 and at the end of the run it gave me a new VO2Max of 49 and upon sync changed the number in GC to that overwriting the 53 that was there.

Granted, I don't put much faith in the actual number that my watches generate because I'm nowhere close to the times in the VDOT tables that correspond to what Garmin says. But I do like to keep an eye on whether it is going up or down.

Yeah, it does seem odd in this day and age of the cloud that so many Garmin metrics are local-only, especially as if key metrics were calculated server-side, they could take into account activities from multiple devices.

My only guess is that some of it may be linked to licensing, e.g. their agreement with FirstBeat might only be to have the algorithms stored on licensed devices, so all calculation has to be done locally (otherwise you could just change your FIT file to show your device as a fenix 5 to get "free" FirstBeat Analytics from any device). And once you've got a metric such as VO2max, you can't just sync that onto other devices and let them update it as you would need to know the source data that the metric had been derived from. In the same way that if I know your average pace is 5'/km and then you run a 5'25"km, I can't work out your new average pace without access to other data.

Of course that might not be it at all. It does make for a very disjointed experience though.

You're right that a lot of it is down to the licensing with Firstbeat, but there should be some way to reconcile that with only having one number for a given user.

Besides it's not exactly rocket science...you can get VO2Max estimates (and a lot more like fatigue, marathon readiness, etc...) by uploading your runs in Runalyze for free. Interestingly I'm getting the same VO2Max value on Runalyze than on my FR235 and the F5 ;-)

On my Forerunner 235, if you run steep elevation, the watch thinks you lost fitness because all it registered was slow pace and high heart rate. On one particularly steep day, my VO2max went from 52 to 44. I stopped caring after that because I predominantly run elevation and my body is more tuned for the slower steep stuff, but I wonder if the same problem will happen on the fenix 5.

At 36 years old, I find myself reluctant to intentionally go out and do something short and intense, pushing myself to 180+bpm just to get an artificial number. So every now and then, I will do my own safe version of a VO2max test that seems to provide accurate results. I do a 30K divided into 10K x 3 at increasing heart rate zones. I start the first 10K slow and easy = 130-135bpm, second 10K I'm warming up and legs are feeling good = 140-145bpm and the final 10K the bearings are greased and I'm ready to roll = 150-155bpm allowing my heart to drift up to 170bpm in the final 1-2K. This effort would always yield an adjusted VO2max number that I could trust. I think if you show the first beet algorithm your "range", it will know how to give you a good number despite the low overall intensity.