VO2 max Garmin readings

I’m aware that Garmin’s V02 max is not perfect and not the same as a lab test, but it was always fairly close when I was trail running and seemed an accurate representation of how I felt with improvements and detraining etc.

Since starting TR (wahoo kickr v6) my cycling v02 has been ping-ponging up and down.

Every v02 max interval on my short power build (6-7 breakthrough ranges) put my v02 max up 1 or 2 points and point to increased fitness. Every threshold and, todays endurance ride at 2.2, drops my v02 max back down 1 or 2 points.

I race DH and enduro, so I feel very capable of the v02 max intervals, often upping intensity by 10% or more. Thresholds absolutely destroy me, especially longer than 4 minutes, but I haven’t failed an interval yet.

Is this just a case of my body is better trained for the short intense intervals and my watch is picking this up? If so, would I be better off focusing on another couple rounds of base etc?

It’s a double whammy of estimated FTP being inflated due to high glycolytic contribution and not sufficiently developed “aerobic” conditioning. Under no conditions one should fail a 10min threshold effort.

So yeah, more base and tailor your training program to your own strengths/weaknesses.


Is there a zero missing here? Surely that is meant to be 40 minutes? Threshold shouldn’t be destroying you although it can be harder for some to recover from depending on your predominate / ratio of muscle fibre type.

Sounds like something is very off even if you have a very low FTP vs VO2max (fractional utilisation.)


Think the Garmin VO2max estimates use your power values to pick an “expected” VO2max from a list. It thinks your power values should lie on a curve, and it uses each workout to pick a curve from a list. Because your short power is better than average, after those intervals, it picks a higher value from the list. Since your threshold power sounds less than avarage, after those intervals, it picks a lower value from the list. That’s why you’re yo-yoing between them.

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Are you dual recording - using TR app to control trainer and in parallel recording on a Garmin watch or Garmin bike computer? What are you using to record heart rate? Are you recording all cycling workouts (power and heart rate) on Garmin?

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I find that my VO2max goes up with VO2max or is maintained with VO2max, Threshold or TTs. But usually goes down with less intense endurance rides and group rides if I don’t put a dig in. Whilst I dual record mos workouts I cheat on the endurance ones and only have TR record them unless its an outside session, which hopefully there’ll be more of now the clocks have changed.

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Everything recorded on trainerroad via kickr v6 and wahoo HR strap. Then imported.

Yeah this is what I figured

No zero missing. Seriously struggled to get through the later thresholds at the end of the build program… “la dama Blanca” etc

Then it’s not your threshold if struggling at 4 mins.

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So even if you’re doing a bunch of Z2 work, for example, it uses the available data to extrapolate your expected, VO2 max?

IIRC, Garmin claims its VO2 max calculation is within +/- 5% of a proper lab test.

My understanding of Garmin VO2 Max is that it needs an accurate Max Heart rate to be within that +/- 5%. I personally use the highest value I’ve observed on the bike in the current season. (174 for me vs. 178 that I saw running over a year ago)

Beyond that, I think it’s estimating based on power output and heart rate as a percentage of max for that power output.

I did a recent VO2 Max block and watched my Garmin VO2 Max trend up by 4-5 points. Take a rest week, go into a threshold block with more endurance, and it backed off by 3 points. Anecdotally, I have a harder time with threshold efforts than VO2 so I think for me I can say there’s some variation and noise based on the type of work I’m doing vs. my strengths even though I’m getting fitter.

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Garmin use their subsidiary Firstbeat to estimate VO2max and according to this article, doesn’t actually use power values. No idea how their algorithm works from heart rate data alone and they are, unsurprisingly, a bit sparse with explaining how they do it. I’ve just had a week off the bike followed by a week of very easy endurance. It’s knocked my blue down in that time to 38 from 42! I assume because I’m not feeding their algorithm the right sort of information.

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Yet it won’t work for me unless I record power :exploding_head: :exploding_head:

Edit: The cycle units do but the watch units don’t :exploding_head: :exploding_head: :exploding_head:

I’m betting that’s mostly marketing jargon. They say this on the Firstbeat page:

This includes a focus on heart rate and running/walking speed. Movement speed and heartbeat data are used to investigate the relationship between internal and external workloads. In other words, how hard your body is working to produce your performance.

Granted that’s running, but I’m still betting they’re using heart rate as the proxy for how hard you’re working, and power as the proxy for performance when you’re on the bike. Pretty sure I’ve read that take elsewhere too.

That article is about running, where they use pace/speed vs HR. Cycling uses power and HR.

This is a better intro article:


I’ve just scanned through it but if it dropped my vo2max by so much then I presume that when I’m properly better as soon as I do an effort of sufficient duration and power it will reassess my Vo2max in conjunction with whatever my heart rate was for the effort. Otherwise it will keep dropping it.

Yes I think that is true. FWIW I get a lot of vo2max increases off shorter tempo / sweet spot intervals.

With at least one long-ish hard effort in 90-day window, WKO5 and Garmin and Intervals are all in agreement on estimated vo2max.

I started taking more notice of Garmin metrics after reading a post of yours on another thread a while ago. I’ve also noticed that it bumps it up after that as well. Possibly because I’ve got a sky high Low Aerobic and a pathetically low High Aerobic & Anaerobic numbers