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High aerobic load = 0

I have been using the same equipment to track my rides since years. Garmin 530 head unit, Vector 3 dual sided power meter pedals and even my HR belt is Garmin. Everything worked fine, but some weeks ago the high aerobic load component of my rides fell suddenly to zero, and does not increase at all, despite the fact that I have not changed my riding or training habits. Low aerobic and anaerobic components increase and move over time, but high aerobic is stuck at zero and I constantly get a "high aerobic shortage" notification. I have not touched any settings, not tampered with power or HR zones. 

What can / should I do?

  • Hi, the algorithm looks for activities that meet certain ranges to be considered as high aerobic. As your fitness improves you need to work harder to achieve the same effect. If you haven't changed your habits, then your VO2max may have improved enough that the same habits are no longer intense enough to be in the range for high aerobic.

    Check your VO2max trend. (Also make sure your maxHR value is reasonable as it's required for a reasonable VO2max trend.) Be sure to do high-intensity activities regularly so that the device keeps your VO2max reasonably up-to-date and to accumulate high aerobic load in your Training Status.

    Also make sure your zones are up-to-date so you're working at the desired intensities as your fitness improves. Personally I find zones based on % lactate threshold to be better since they update as my fitness changes (if lactate threshold detection is enabled). (Zones based on % max HR are static and do not update as fitness changes, so don't target the desired intensities.)

    Also the system is "winner take all" (unfortunately), which means that aerobic load is allocated 100% to either high or low, but not both. So if you do your high aerobic activities as part of a much longer lower-aerobic activity, odds are high that it will be classified as low aerobic. You can try to work around it by breaking up activities into separate recordings, though it can be a bit inconvenient. Otherwise have to accept that the Training Status is often distorted to showing most activities as "low aerobic".

    Hope that helps!

  • same here.
    it's broken since about mid july 2023 despite i do rides as usual, alternating low, medium and high intensity efforts. High aerobic score was used to improve even by some points, now is stuck to 0 all time. Don't know if related to latest update or what else but it's pretty annoying and i don't think it's related to athlete's efforts but on broken algorythm