Relative VO2. I think that is ml/kg/min? I prepared to say WKO is spot on 
But doesn’t WKO5 depend on you doing maximal efforts, but Garmin’s approach does not?
Right now the two are 9 points apart for me, with Garmin being closer to what I’d guess based on previous lab tests. But, I haven’t really gone hard since I started riding again a few months ago.
Come to think of it, I don’t think I’ve set a max HR for my Garmin - where do you do that?
We were shown in ex fizz class how to estimate VO2 to within 10% from power and HR using a really simple approach. It doesn’t seem like it would be hard to improve on that with a bit fancier maths.
Unless Garmin uses elevation, wind and temperature their vo2 max calculations will be useless.
My vo2max for running is super elevated for what I know I’m capable. It claims I have a vo2max of 58 and claims that I’m capable of a 249 marathon. Lolz!
In a lab all variables are controlled and measurements are made over perfect condition…
Anyway. Is another make believe number. As long as it trends up, you are ok…I think
My estimated cycling value goes up or down depending on what workout I do. If the workout has short intervals with short recoveries that don’t allow HR to recover it goes down. If there is a solid 20 minute interval it goes up.
The running value changes depending on if I run inside or outside because my Running style/cadence changes so it thinks my pace is different that what it really is. The watch learns a GPS pace vs. Cadence relationship outside and then assumes it is the same inside.
I think changes in the value may be of some use but you have to factor in what sort of workout you just did. It also only has one HR max. My running HR max is higher than my Cycling HR max, which is Itself higher than my swimming HR max.
Seom Garmin units have started integrating in temperature and altitude as factors in how it rates your performance. Wind shouldn’t matter because it uses power & HR, so that would allow you to gauge effort regardless of wind conditions.
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Why would you need to know any of those things to estimate your VO2max?
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In theory, you need to know maximum heart rate to then determine a lactate threshold heart rate. Evaluating the corresponding power numbers against your LTHR would allow you to determine the power you, in theory, would be able to hold for an hour (FTP) and the combination is how VO2 is calculated. The actual math is substantially more complicated and can be found in some of the previously posted papers, but essentially you’re trying to compare % of your max HR to corresponding power numbers.
Heat, terrain and weather will affect the hr.
Going up a hill will elevate your hr.
Running with head winds will elevate your hr.
Running when it hot and humid will elevate your hr.
Most Garmin models don’t take into consideration if you are on flat or uphill, or if it’s 50 degrees,cloudy and calm vs 81, 98% humidity and 13 mph winds.
This is mostly a running problem.
On the bike we have power and that’s probably moke thinks more accurate.
FWIW Garmin tells me I’m 55 and WKO says 54. Friend tells me his Garmin says 74 and WKO tells me his is 72.4. No idea the validity of the two software programs and neither of us have tested in a lab, yet.
So you meant that you think you’d need to know those things to estimate VO2max accurately, not just to estimate it, period?
For running, the FirstBeat algorithm uses HR vs HR Max, and your pace. So indeed in theory other factors would be needed (if you do a long downhill run, your HR vs pace relationship will be biased, and the algorithm would be pushed towards a higher VO2Max estimate, unless “level pace” is used in the estimate, for example).
In any case - the Garmin estimate I get from running is way high, as in 20%, when compared with a beep test I did some time ago. I only use it as relative measure (“my VO2Max probably improved, since Garmin says it did”), and of course as an ego booster. This said, I can measure the same relative improvement through other means, such as looking at average pace vs average HR on a weekly basis.
Like i said before. It just a pretend number. I take it as a trend over time, fully aware of the limitations and how inaccurate it is.
I am just pointing the fact the it is not a real vo2max, just a rough estimate that might be biased based on your location and the HR you are using.
And remember… Knowing is half the battle.
For probably a lot of the people that the only thing that matters.
Like you… I look for a trend over time. When i started the HIM training, my number went down. Now that running and cycling are coming along, the number has gone up.
I will do a ramp test tomorrow, expecting FTP to go up. And with that my bike number will go down, and my running number will likely go down too.
Yes you have to maintain your WKO model which means the odd effort here and there. If you’re racing or doing hard drop rides you probably won’t have many efforts to make. It isn’t hard to throw down a sprint every so often and the longer intervals often get taken care of for my through group rides outside.
Yup, it’s really not an issue keeping hard short/med/long efforts in the 90-day window of WKO5’s power model.
Right, that’s what I’m seeing as well. Garmin is just going by my age-predicted HR, though, so the fact that it seems about right seems to be just chance.
You can enter an HR Max in your Garmin profile.
Meaning the number gets over-written?
I’ve never had my vo2 measured but my garmin currently has me at 71. I think it might have gotten a slightly spiked HR reading once upon a time (200bpm whereas my ramp test usually tops me off around 185bpm) so I’m going to assume it’s a slightly inflated number. My ftp might be 290-295 at the moment (4.1ish w/kg) at 40 years of age
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I’ve been as high as 65 (earlier this year at low elevation) and now I’m down to 56 after moving back to elevation. But I think switching to a polarized training plan a couple months ago was the primary reason for the drop. I’ve been doing a lot more long low intensity rides and my Fenix thinks I suck now.
I just use it as a guide, not gospel.