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About Garmin Vo2max calculation

  • Just something that makes me wonder about the calculation of the Vo2max in our garmin watches. From what I know garmin uses your current speed with your heartrate to measure your Vo2max. But what if I do a fartlek run and I run an uphil?? It looks like Vo2max drops like *** in such cases because the watch reads your speed (which drops due to the uphills) with your high heartrate (due to the extra effort you add) and thinks that your stamina or whatever drops as well, which in reality is not true. If they had added the barometer in the equation then it would calculate in a smarter way. I mean the 955 has a barometer-Altimeter!..

Just some thoughts. I don't know if it has been mentioned already...

  • Afaik uphill passages are consinderes in this calculation. And it works also fine in my case. I just disabled it for trail running, because wenn there is snow or the trail condition is very challanging this is not considered. The watch can't just know it.

  • From my experience I seriously doubt that Garmin takes elevation into account when calculating Vo2max... The VO2 max estimate relies on metrics like heart rate, pace, and workload, without directly incorporating elevation or its physiological effects into the calculation, which to me is kind of stupid and I've seen that in my exercises and productivity especially when I do fartleks. However, if there is an official statement by Garmin that says otherwise then I would be glad to see this. 

  • I can confirm I have the same experience as Stefan.

    For pure curiosity, I have closely tracked the metrics from my forerunner for years and never observed that a hilly terrain or a fartlek harms the vo2max metric.

    But it is just my personal experience; I can’t guarantee that, and my coach uses field tests for performance management.

  • Ascents/descents are taken into account, as you can see in the graph on their website: www.firstbeatanalytics.com/.../

  • I also have some doubts whether uphills are taken into account for calculating VO2max. Some time ago I moved permanently from the plains to the mountains, and flat taining became impossible, there are always some elevations. Then my VO2max dropped by about 7 according to the watch, but my form did not deteriorate at all, and I even think it improved.

    This was around SW 16.x. Perhaps this has been corrected in the current software versions, because they introduced an estimate of the pace relative to the slope - GAP and my VO2max estimate has almost fully returned to what it was on the plains.

  • Ascents/descents are taken into account, as you can see in the graph on their website: www.firstbeatanalytics.com/.../
    This was around SW 16.x. Perhaps this has been corrected in the current software versions, because they introduced an estimate of the pace relative to the slope - GAP and my VO2max estimate has almost fully returned to what it was on the plains.

    Assuming that Garmin does use GAP (grade-adjusted pace) for VO2 Max calculations to account for changes in elevation, I have my doubts whether that helps as much as it should, bc I don’t trust Garmin GAP at all.

    I’ve found that Garmin GAP is pretty bad (both objectively and compared to GAP calculated by other platforms such Strava and runalyze).

    For example, when I look at GAP for a lap or activity which is either net uphill (ascent > descent), or ascent equal to descent but both are non-zero (e.g. running up a hill and down the same hill), I would expect GAP to always be faster or equal to regular pace. This is what I see on platforms like strava and runalyze. On Garmin, in both of these situations, GAP is often slower than regular pace, which makes zero sense.