I can't change the vo2max from connect web

I set the zones to maximum heart rate.
The range of zone 1 (warm-up) 92-110

if I set the anaerobic threshold
zone 1 becomes 105-129

the heart is always the same xD but how should I warm up?!

For me there is a very serious mistake here.
Otherwise, help me understand why these values are different (garmin connect calculates them when I enter the value).

The values are based on the percentages. The LTHR is rather individual. At some persons it may be closer to the Max HR, at others lower, hence the resulting absolute ranges will differ at individual persons. It also depends how well you established your Max HR. If you just use the default formula 220-age, it may be wrong. And if you use the auto-detection, it is very likely even worse. To get it right, you have to do a dedicated Max HR test. Either in the lab, or a self-guided. And repeating it once a year or so, since the Max HR drops with the age.

Better yet, though, is using the LTHR based zones, and using a chest strap, which will assure that the true LTHR is being detected, and the zones adjusted accordingly, and you do need to bother about adjusting it manually. 

trux said:

The LTHR is rather individual. At some persons it may be closer to the Max HR, at others lower, hence the resulting absolute ranges will differ at individual persons

Very interesting.
I noticed this feature when comparing my performance with other friends. On some occasions I have ride for over 1 hour without reaching 100bpm. This may indicate that my heart rate zones (1 and 2) are lower than what Garmin calculated.
I will delve deeper into the topic by entering the zones manually.
Thank you.

Yes personally I set all my zone % manually, and I also use %LTHR as follows: 1-65%, 2-81%, 3-90%, 4-94%, 5-100%, based on Friel's guidelines: https://joefrieltraining.com/a-quick-guide-to-setting-zone/

I recall these values are within 1% of the Garmin default values, so I suspect Garmin also based their default suggestions on Friel. Note that different devices and apps define zones differently (bottom of zone, top of zone, or both top and bottom), so it's common to see 1% differences here and there -- rounding error / limitations.

Regarding VO2max estimation, it's my understanding from the Firstbeat white papers that our zone settings have no effect. Simply speaking, the algorithm builds a trend from your data of HR vs cycling power or running pace. It then extrapolates that trend to our max HR to estimate the power or pace at max HR. It then uses an empirical formula (based on lab tests) to estimate our VO2 at that power or pace. It calls this the VO2max.

In other words, the estimated VO2max is the VO2 you are estimated to consume at the power / pace you are estimated to do at your estimated max HR.

Obviously there is a lot of extrapolation and statistical assumption going on there, so it's absolutely no substitute for a real VO2max lab test. But its consistency can be improved by ensuring we regularly do sufficient activities at higher intensities to provide good data for our trend, and ensuring we set a realistic max HR for the extrapolation (trux explained these above).

There is nothing we can do about the algorithm using empirical relations to "convert" from power or pace to VO2 -- those statistics may not fit a particular individual -- but at least it's the same conversion each time so it's consistent enough to see if VO2max is trending up or down.

I do speculate that the conversion may be more consistent for cycling than running. Cycling uses power directly, however running uses pace as a roundabout way of estimating "run power" -- unfortunately grade and wind have a significant effect, not just pace.

I also don't know if Garmin/Firstbeat have been making changes to the algorithms over time. If so, it's possible that different devices might give slightly different VO2max estimates from the same activity data.

I think testing with multiple devices is very tricky. To be valid I think both devices need to have separate Garmin Connect accounts, and both devices need to record *all* of the same activities so they both have the same trend history -- remember the VO2max estimate is a *trend* over time (weeks), not an instantaneous estimate from just the current activity (otherwise it would jump up and down too much). The *current* VO2max estimate from an activity is only shown by the Performance Condition, which shows the amount that the current VO2max estimate appears to be above or below the VO2max trend. For example VO2max trend 50 and Performance Condition -3 means VO2max estimate based only on current activity is 47.

Hope that helps!

This information is very important to me right now! When I run I almost never reach fcmax because I try to conserve energy for ride in bike (this would explain the underestimated vo2max in running).

However I did anaerobic threshold test (running) for the first time and vo2max went up +2.
At the end of the test I had the performance condition at +5, so the VO2 would be very close to that of cycling with the calculation you suggested.

In the meantime I have noticed that when I run on Zwift I find the wrong heart rate zones on Garmin Connect, I assume that Zwift calculates by age but I have a different HRmax from the calculation of my age and this perhaps has caused some inconsistencies.

Now I'm reading up on the percentages to set for the heart rate zones, I'll take inspiration from that link. Thank you

Yes if much of your activities are at lower intensities (therefore lower heart rates), then the algorithm needs to extrapolate more to reach your max HR. That could increase the uncertainty/variability of the VO2max estimate. The more regularly we have high-intensity activities, it should be easier for the algorithm to build a stable trend and require less extrapolation, which should give more consistent VO2max estimates. (That's a lot of "shoulds" -- I'm assuming the product works as claimed!)

You can put your maxHR into the Zwift settings, unfortunately we can't control how Zwift sets up the HR zones. For me personally this is useless so I ignore Zwift's HR zones entirely.

NicK said:

In the meantime I have noticed that when I run on Zwift I find the wrong heart rate zones on Garmin Connect

Zwift shouldn't be affecting your HR zones in Garmin Connect. Are you sending the activity directly from Zwift into Garmin Connect? Or instead recording the run on a Garmin device?

Kyle J said:

Zwift shouldn't be affecting your HR zones in Garmin Connect. Are you sending the activity directly from Zwift into Garmin Connect? Or instead recording the run on a Garmin device?

HR Zones are always included in each activity FIT file, they do not come from the account settings. They come from the source (device or app settings). 

HR Zones are always included in each activity FIT file, they do not come from the account settings. They come from the source (device or app settings).

Hmm, that hasn't been my experience. I mean the app may include zone info in the FIT file, however in Garmin Connect the activity shows the zones I've set in Garmin Connect. So I've always assumed that GC post-processes the data based on its own zone settings, instead of adopting any the 3rd-party app embedded in the FIT file.

But, I haven't tested that direct Zwift-to-GC connection since end of 2021, so maybe something has changed? (It was before Garmin began supporting Training Status from some 3rd-party apps such as Zwift for example.)

Since I don't do direct Zwift uploads to GC anymore, I don't have anything more recent to check. I could try testing it next time tho. But I would be viciously displeased to discover GC using Zwift's garbage HR zones instead of the custom ones I set in GC. Could be yet another reason to recommend people avoid doing direct uploads from Zwift to GC.

Yes it seems that's not the case with Zwift (which is the subject of Nicolò B's comment). I've seen the HR and power zones in FIT files from Garmin devices, but none in FIT files from Zwift. (Maybe other apps are different.) So Zwift's HR zones shouldn't be popping up in Garmin Connect, so I'm not sure what's happening there in Nicolò B's case.