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VO2MAX estimate always drops 1-2 points after a long trail run

silentvoyager
over 2 years ago

Whatever Garmin does to estimate VO2MAX for trail running activities, that doesn't seem to work right for me. Every time I do a real trail run on mountainous terrain, in a beginning of a run get a negative 3-5 points in Performance Condition. Then, at the end of the run VO2MAX drops by one, sometimes two points.

Then next day, despite being tired after a long run, when I do a mundane easy recovery run, the VO2MAX goes up to the previous level.

So overall it stays stable, but it is annoying that the trail running VO2MAX seems to underestimate my performance.

I am relatively stronger trail runner than I am a road runner. I am relatively good on uphills compared to a typical road runner with the same VO2MAX. But perhaps the algorithm doesn't fully take the elevation gain into the account, especially on steeper terrain. Or perhaps it doesn't properly take the technical terrain into account. Or perhaps it doesn't take into account an added weight of water and gear carried on long training runs, which can easily be 3-5 lb (1.5-2 kg). I guess the added weight alone is sufficient to drop the performance enough for 1 point of VO2MAX. 

  • 0 over 2 years ago

    VO2Max on trail runs option is relatively new unless you go back a bunch of version where it treated trails like road and really messed up ( I would drop 10 or so every winter with snowshoe running. All the things you say “perhaps it doesn’t …” mess it up. The watch doesn’t know you are carrying extra weight or slowed down due to rocks and roots or the ground is muddy or sandy etc etc etc.  The model falls apart under circumstances the impact your effort to maintain a pace and the watch cannot take into account.  My trail running tends to be on technical stuff ( or snow in the winter) so I just leave VO2Max off for trail running. 

  • 0 over 2 years ago

    I seem to recall that we used to have a separate VO2Max for trailrunning activities? Just checked, there is a setting under trail-run settings to disable VO2Max calculations, but not sure if that is the way to go.

  • 0 over 2 years ago in reply to GJRodenburg

    Yes, I know. I consider disabling it for trail running. The problem is that most of my runs are trail runs. I don't have the same problem on simpler and less hilly suburban trails. But it happens every time on more mountainous trails. 

  • 0 over 2 years ago

    If you pay attention to the changes it seems obvious the algorithm is based on speed and HR. Trail runs by their nature are slower, and usually have more hills (e.g. higher HR). It's not that advanced of a metric, just an indicator.

  • 0 over 2 years ago

    I have also noticed this as well as that my age also drops when my vo2max drops. At least Garmin's got that right :}

  • 0 over 2 years ago in reply to silentvoyager

    Then use the run activity (or copy it and modify data screens and name “east trail” or something) with VO2Max and use a Trail Run activity with it turned off for technical trails. As I and others said, it will be inaccurate on anything other than simple trails.  It’s a model/algorithm trying to estimate a laboratory test done under strict and controlled conditions. 

  • 0 over 2 years ago in reply to lustyd
    lustyd said:
    If you pay attention to the changes it seems obvious the algorithm is based on speed and HR.

    I don't think that is how it works. In many cases both my performance condition and the estimated VO2MAX increased when running uphill - that is when my HR was higher than usual but the pace was slower than usual. I think the algorithm estimates power or something like that. That is what made it possible for Garmin to enable VO2MAX for trail running in the first place.

    But I agree with others that estimating that on a technical terrain must be tricky. 

  • 0 over 2 years ago in reply to razmichael
    razmichael said:
    Then use the run activity (or copy it and modify data screens and name “east trail” or something) with VO2Max and use a Trail Run activity with it turned off for technical trails.

    That's what I consider. I don't have to use the Run activity. I could as well just have two different Trail Run based activities - one with VO2MAX and another without. Or perhaps I could use Ultra Run activity for my longer runs on more technical terrain.

    My other observation is that VO2MAX is actually unaffected by including a lot of walking into trail runs when on steep terrain. But when I try to actually run the steep terrain, that's when VO2MAX gets punished. For example, yesterday I ran the first two miles uphill in 31 minutes, gaining 1300 feet. That is about 12% average grade. But according to my watch my performance was abysmal compared to running on flat terrain. Had I walked that, the VO2MAX would be unaffected. 

  • 0 over 2 years ago

    Same here. Specially when I do runs with a lot of elevation. It clearly doesn’t take into account the elevation. And vo2max needs to be high to climb mountains and do long runs on them