Do folks think displayed VO2 max values are reasonably accurate?

In 2016 I used forerunner 630, my estimate VO2max was about 47-48. In 2017-2018 I used fenix 5, and the estimate VO2Max's about 54-56. Yes I felt my stamina had been improved, but not that much :) Then My fenix 5 had problem, so I have used the old FR630 for 2 months, and my VO2max go to 48 again :)

In 2016 I used forerunner 630, my estimate VO2max was about 47-48. In 2017-2018 I used fenix 5, and the estimate VO2Max's about 54-56. Yes I felt my stamina had been improved, but not that much :) Then My fenix 5 had problem, so I have used the old FR630 for 2 months, and my VO2max go to 48 again :)

Wonder which is correct?

My watch says that I'm at 60 but my lab test in the fall had me at 63. Close enough I suppose!

In 2016 I used forerunner 630, my estimate VO2max was about 47-48. In 2017-2018 I used fenix 5, and the estimate VO2Max's about 54-56. Yes I felt my stamina had been improved, but not that much :) Then My fenix 5 had problem, so I have used the old FR630 for 2 months, and my VO2max go to 48 again :)

Which one is right?
Found something interesting in https://www.worldfitnesslevel.org/
In that I was requested to input some data, including Max HR and resting HR. The algorithm said that my expected VO2Max for my age is 46. However, It say I have the fitness of an average under 20 years old, so my actual fitness level is vo2Max 58. Hmm.. I think I am right to take those numbers as a toy :)

In 2016 I used forerunner 630, my estimate VO2max was about 47-48. In 2017-2018 I used fenix 5, and the estimate VO2Max's about 54-56. Yes I felt my stamina had been improved, but not that much :) Then My fenix 5 had problem, so I have used the old FR630 for 2 months, and my VO2max go to 48 again :)

Do you have different heart rate zones set on the two watches? Are you using the same heart rate monitor? Do you have all of your profile information, like weight, updated on each device? Are you doing the same types of workouts?

People need to realize that:

• These are estimations
  
• As anything in life, it's garbage in, garbage out - you need all of your profile and zone data to be correct to give the closest possible result - and then that it's still just a (#1) estimation. But with good data, at least a slightly more reliable one.
  

Interestingly, as I've gotten more fit, and done the lactate threshold test to zero in my heart rate zones better - I've found less consistency depending on type of run, I used to get pretty consistent results on long slow runs as I did shorter higher intensity runs. Now I measure a bit better on the higher intensity runs, but never more than a point difference.

Max HR plays a huge role in the calculation. Right now my vo2max is saying that my half marathon time is roughly 2 minutes faster than I ran last May (at 5000 feet above sea level). I'm not in half marathon shape right now, so that assumes that I've trained for that distance and everything else goes exactly right. In my case my Max HR is probably a little less than what I've set in the watch as I haven't hit that number while running in quite some time. So I bet the watch is getting it "mostly right."

The number itself isn't terribly useful for me, but the trend-line is something I use regularly.

Do you have different heart rate zones set on the two watches? Are you using the same heart rate monitor? Do you have all of your profile information, like weight, updated on each device? Are you doing the same types of workouts?

People need to realize that:

• These are estimations
  
• As anything in life, it's garbage in, garbage out - you need all of your profile and zone data to be correct to give the closest possible result - and then that it's still just a (#1) estimation. But with good data, at least a slightly more reliable one.
  

Interestingly, as I've gotten more fit, and done the lactate threshold test to zero in my heart rate zones better - I've found less consistency depending on type of run, I used to get pretty consistent results on long slow runs as I did shorter higher intensity runs. Now I measure a bit better on the higher intensity runs, but never more than a point difference.

I changed nothing on my profile (weight, maxHR, etc..) just change the watch as my preference activity tracker.

Thankfully at last, I got new fenix 5 (as replacement) since a week ago, used the trueUp so it picked up the last VO2Max 47 recorded from the FR630. I have recorded 3 runs wearing the new F5, and each time I got 1 increment in VO2Max, so now my VO2max is 50. Maybe it will go to hovering at 54-56 again, soon :)


Sorry for my English, it's not my native language..

It depends on a number of factors, the most important of which is your heart rate zones. Plenty of information and discussion around VO2max in the forum. Have a read through some of the threads.

It has nothing really to do with the HR zones set on your watch, those are just to help you along and guide your efforts if you want.

For good results, though, you absolutely want to make sure your HRmax is right for you personally. If you don't know your HRmax, it uses an estimate of "220-age" (I think that's it). This is important information when it comes to understanding your intensity of effort relative to your personal maximum. If your HR is 150 and your HRmax is 170.. this is pretty intense. If on the other hand your HR is 150 and your HRmax is 200,well, it's a different story.

I think it's top 15% of general population, not only runners. My VO2max as assessed by garmin puts me in the top 5%, and I think it's quite accurate, as the race predictor is based on that, and my PBs are quite close to what the race predictor says.

This is correct. The reference table is based on the general population - not just runners and not just Garmin users.