I think maybe once you have a validated number from a lab you can gauge what your device is saying with that extra piece of hard data. Clearly may not work for everyone but I was impressed anyway - with the closeness not my number 
My fenix 6 is giving me a cycling vo2 max of 59 and a running vo2 max of 55. I’d love for it to be true but I don’t think so 
Mine atm says 64 for running (I haven’t done any really hard workouts since I’ve been more focussed on cycling because of some TT’s I wanted to do good at), and 67 for cycling. My INSCYD test put my VO2Max at 72.
My Garmin Connect currently estimates my Vo2max to 71 for cycling and 64 for running. I’ve tested myself in a lab on numerous occassions, and consistently scored around between 68 and 72 on the bike (but I’ve never tested myself on a treadmill). My old Polar Vantage watch estimated a Vo2max of 72. So my take away from these estimates are that they are probably ball park, and seeminly consistent enough to be used to measure progress - but they’re still just an estimate and a secondary KPI - what really matters is your FTP, your power or how fast you can ride/run.
Hello everyone,
I wonder vo2max anticipation and fatigue relation. I am about to finish general build high volume and doing 70/40 seconds or 80/40s %120 on /%40 off.
But my heart rate do not reach its maximum (it comes ftp hr barely) i guess because of fatigue but garmin says your vo2 is increasing.
So what can we say? Is it really increasing or do not count it because of fatigue?
A lower HR can be caused either by increased fitness or increased fatigue. You have to judge your previous training to decide which. I’m inclined to think the latter if you’ve been on a hig volume plan. Take a few easy days to find out?
Thanks for reply. This is the last week of build. So i am about to start rest week. But my question is about vo2max.
Even though my heart rate low because of fatigue, garmin says your vo2 increased. So is it right or wrong?
If I understand the theories behind the calculations it they do a prediction based on HR at a certain intensity and compare it to your HRmax. If you have a lower HR for a given power the algorithm may assume an increase in VO2max. They don’t take a lower HRmax into account.
If you want to know more in detail, take a look at this thread were their method are being discussed. there are also a link to Firstbeat’s whitepaper explaining the theories.
IMO you may have increased your VO2max some, but you need to be fresh to realize it.
As @TomasIvarsson explains, it is most likely wrong and I have a similar experience. When my recovery week is nearing and my HR is supressed slightly from the accumulated fatigue, garmin will show increase in VO2max. After a recovery week it all goes back to normal (unfortunately 
).
Thanks. I guess it is because of fatigue, and after the rest week i will see.
Thanks. That’s the thing i wanted to hear. So it is normal to see that. I am at the end of 7th week of general build and for 2 weeks my heart rate (max) has been too low. (I could hit 166-7 bpm but max is 180 normally). Yesterday i did 3’ anaerobic effort (400w for 3 mins) but could see 164 bpm. So i can say that my rest time has been come.
I also recommended you to monitor your resting HR, preferably in the morning, just after waking up. An increased resting HR is a sure sign of fatigue.
Ross Tucker covered this on a recent podcast - pretty interesting.
I hide this screen for a reason
Well, depends…
If it goes up it’s real…
If it goes down is fake .
Lazy answer. Read some studies. It’s within 3 to 5% of lab tests. I’m assuming you know you need a power meter, a chest strap will provide better HR data and you need to know your max HR (not 220-age). The percentage of people who will actually do a lab test and then keep doing that to see how they’re progressing is very small.
Way to bump a 4 year old thread…
Wait 'till you see what I unearth today!
I’ve not read all the posts here, so this may have already been mentioned.
I was listening to a physician, on a recent podcast, where one of the hosts asked him about VO2 max on the Garmin watch. When testing in the lab is done vs what the Garmin value reads, highly trained athletes were actually 3-5 points higher than what Garmin estimates, and sedentary people were usually 3-5 points less than the Garmin estimate.