Mine is pretty close. It was better when I put in the same max HR and weight from the test into my Garmin.

Mine is reading lower than my last test which was a cycling test. I was tested at 70-72 for cycling, Garmin always indicated around 62-64 but after a Zwift TT 3 weeks ago where I set a new FTP (12W higher, 4.63W/kg) it jumped up to 67 or 68. Now it's back to 64 again.

They values are easily influenced when it's a bit warmer (my Garmins don't have the heat or altitude adaption yet), or when it's a bit more windy like it is here now in Autumn, your average HR will be higher for a given pace which will influence the measurement. For running for instance it's indicating 61 right now where it was indicating 64 a few weeks ago without a change in volume or intensity or whatever. But my average HR is a few beats higher due to all the wind and possibly due to it being chillier outside.

^^^^This. Every time we get a warm spell Garmin drops my VO2max 3-5% (also every time I visit Denver/Boulder due to the altitude).

With normal temps (70Fs) the measurement is pretty close for the bike (a touch high), but 7-10% off (low) for the run.

For running I think is uses HR vs. Pace (since pace is fairly proportional to power, esp. gradient adjusted pace).

For cycling it's HR vs. power (assuming you have a power meter...and it estimates power if you don't).

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Always had too optimistic readings on my Garmin (esp. for bike)
Then did a double lab-test in july (both for run & bike), after inserting the correct measured HR's into my devices the Garmins now perfectly align with the lab-results (to my surprise)
HOWEVER for the lab-results, they did not provide the absolute max. achieved Vo2, instead they report the highest 30 (or 60?) sec avg. So I'm comparing to this value!
(the absolute max is much higher and not really useful)

As other members also indicate, the Vo2max on the Garmin is messed up a bit (low) at high temperatures 30C+ (un)fortunately we do not encounter these temps very often

Thanks, appreciate it.

When you (and jaretdj) mentioned inserting the right HR figures, are those the figures from your lab tested HR? Or observed HR based on your training?

For me, i am riding at about 2 watts per 1 beat of HR for 200 to 300 watts (and holding linearly). I guesstimate my max HR on the bike would be 170, but pure conjecture... Doubt i could hold it for one hour though...

Thanks again

Eric

I did my test at Henry Ford Hospital Human Performance clinic. They did my body composition with my weight, I use that weight in my Garmin since I'm normally within 2-3 lbs of it.

The test was done on a treadmill, they monitored my heart function, BP up to a point, and the air I was exhaling as well as speed. I was able to achieve 172 bpm on the test which is really high for me. I use that HR in my Garmin.

I've been able to match it a few times while running but have achieved as high as 177 bpm a few times while sprinting on my bike at the velodrome while being chased.

For reference: I can hold high 150's - low 160's on the bike during my 20 min FTP tests. I can hold high 150's (bpm) for an hour and 93% of my 20 min FTP tests.

HR results on my run tests are very similar to my bike tests.

Garmin estimates my VO2max at 58-60, my lab test as 58.

I have tested 72 in my exercise physiology lab on the treadmill. My garmin gives me a vo2max in the low 60's. The garmin calculation is too performance dependent. I am a strong swimmer which I think plays into a higher vo2max lab test compared to a more economical runner that will beat me on the road with a lower vo2max.

It's been a while but mine was about 8 points higher in the lab.

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