VO2 max only with trail run?

I do not have (yet...) an Instinct 2, however VO2 Max recording and displaying in Garmin watches is prioritized based on the type of activity. Unless the Instinct 2 manual states otherwise, what you see below (taken from one of their support pages) should apply:

The type of activity you complete can determine if you will receive an updated VO2 max estimate. Your overall VO2 max estimate is taken based on the following four activity types, listed in order of preference based on their accuracy. The most accurate VO2 max estimate will display in Garmin Connect and will overwrite less accurate methods for 30 days. Not all Garmin products support all methods of VO2 max estimation.

NOTE: If you complete a qualifying cycling activity with a power meter, a separate Cycling VO2 max will populate. The Cycling VO2 max will update each time you meet the Cycling VO2 max estimate criteria.

1. Running Activity With GPS

This activity type yields the most accurate overall VO2 max estimate and will be given priority over all other activity types.

Example: You record a Run activity with GPS, which generates a VO2 max estimate. This VO2 max estimate will display in Garmin Connect and will only update over the next 30 days if you record additional Run activities with GPS. Other activity types below in this list will only update the overall VO2 max estimate when the most recent Run activity with GPS is older than 30 days. 

2. Walking Activity With GPS

Example: You record a Walk activity with GPS, which generates a VO2 max estimate. The next day, you record a Run activity with GPS, which generates a VO2 max estimate. The overall VO2 max estimate in Garmin Connect will be updated regardless of the age of the Walk activity because Running activity with GPS is #1 in this list.

3. Walking

This applies to walking done during daily routine without recording an activity.

4. Running Activity Without GPS (Using Foot Cadence as a Speed Estimate)

The complete page from I copied and pasted the above is here:

https://support.garmin.com/en-US/?faq=HVMcrDvQ3m2xEFh1aVMbU8

This other page may be helpful too:

https://support.garmin.com/en-US/?faq=lWqSVlq3w76z5WoihLy5f8

supifant said:

Is trail running the only activity with that possibilty? Because I am not running, I am only hiking/walking.

With Instinct 2 you can measure VO₂max at Running, Trail Running, and at Cycling. At walking / hiking you usually do not reach the lactate threshold HR for sufficiently long time that would allow measuring the VO₂max with reasonable accuracy. If you do reach those high values of HR during hiking, record it as Trail Run, and the VO₂max will be measured. You can change the type of the activity later back to hiking, if you wish. I think the VO₂max remains preserved, even if you change the type of the activity (without guarantee - I did not test it with Instinct 2 yet)

So, if I understand you two correctly: Other Garmin-gear does VO2max even on walking without GPS, but the Instinct 2 only does it for 3 activities?

That would be very disappointing, as I liked the Instinct already, but avoided it, as it had no VO2max capabilities. So now, as the 2 is out and it has the capabilities, I bought it, because the rest of the package seemed already attractive to me.

And yes, I am an obese guy hiking rather steep mountains, so for instance, I am doing a little hill directly on my hometurf nearly every single day, which is 180m of elevation. HR then is about 130-155, which is well beyond 70% of my max heartrate (assumed 170, as i am fifty y.o., which should be accurate, because I can't go north of 160 for longer than a few seconds)

So yes, workaround would be to always choose "trail run" - which, as I understand, does not affect anything else.

supifant said:

Other Garmin-gear does VO2max even on walking without GPS

I believe it is only at some older devices that did not really measure the VO₂, with the current FirstBeat algorithms using the HR Variability, but rather did only very raw inaccurate estimates from the pace and HR. Anyway, for getting the VO₂max value, you need to spend at least 10 minutes with the HR over 70% of your max HR. Read some more info for example in the document: VO2 Max Estimator for Outdoor Watches: 

• To generate a Running VO2 Max estimate, you must record a run or walking activity with heart rate for a minimum of 10 minutes above 70% of your max heart rate. On most outdoor watches, running VO2 Max can only be estimated when using the Running or Walking profiles. 

Another workaround, if you are not bothered about the inaccuracy of VO₂max values estimated at indoor activities, or at walk, is using one of many available Connect IQ apps.

Thanks for the answers. So to get a rather precise VO2max, certain circumstances must be met and that is taken into account by only "allowing" certain activities. All else is a trade-off. Yup, I will try with the trail run - as I am not running, but only walking my VO2max will be low - but eventually progress may be visible anyhow (if there is any)

• Hi, Assuming you want to loose weight too (I did the same, same age as you) I could recommend long walks with (in the beginning) very short running intervalls, like walking 500m then run 100m or even only 50m, then walk again 500m etc. and repeat this 3-4 times during a workout. Add a warmup (10 minute brisk walking) and a cool-down. Over time you can lengthen the running Intervalls and shorten the walking ones. Try to stay in your lower HR Zones (1-2) while walking and running (so you must really run slowly)  to train your lower aerobic capacity which will make your system using fat as an energy source. I lost a lot of weight this way, my leg muscles strengthend and over time I was able to run without walking in between with low HR and increasing distance. Have fun !