Zero Anaerobic Effect After Hard Run

Former Member
Former Member
How does Garmin calculate Anaerobic effect exactly? I have been using my Fenix 5 for a good few months now, so it?s dialling in to my training nicely now. It?s got to the point that I am starting to really rely on the data it provides me. I have also started to use the HRM run too and that is starting to give me more good data. Yesterday, however, I did a hard run in atrocious weather where I was in my maximum HR zone for a good 3 Miles. When I finished my run I got an Anaerobic effort of zero.

Does anybody know what this may be the case. As I said my HR was in max for a good 20 mins.
i did lose GPS for a short period which gave me bad data but I wouldn?t have thought Anaerobic data would require GPS data to calculate.
  • Send a screenshot of the time in zones, too.
  • Looks to me like there was no interval component to your workout, hence the zero. This is from the Connect website, in case you missed it:

    Anaerobic Training Effect measures heart rate and speed (or power) to determine the workout benefit upon the ability to perform at very high intensity. Repeated high-intensity intervals of 10 to 120 seconds have an especially beneficial impact on your anaerobic capability and therefore result in a higher anaerobic training effect.

    Aerobic Training Effect uses your heart rate to measure the accumulated intensity of exercise on your aerobic fitness and indicates if the workout had a maintaining or improving effect on your fitness level. Steady workouts at moderate effort or workouts involving longer intervals (> 180 sec) have a positive impact on your aerobic metabolism and therefore produce an aerobic training effect.
  • Former Member
    0 Former Member over 7 years ago
    Ah ok. Thanks. Maybe with the update to v6 the algorithms for Anaerobic exercise have changed. Every run I have done prior have had some Anaerobic effect even if it?s low. I have never had a zero Anaerobic effect. I did a 10k race a couple of weeks ago which certainly had no interval aspects and that reported an Anaerobic effect of 2.4

  • With that distribution of time in zones, I'd suggest your zones are too conservative. Maybe the TE algorithm thinks the same thing?
  • Former Member
    0 Former Member over 7 years ago
    It could well be. As I said I have moved from wrist based to Strap based HRM which is now calculating FLT amongst other things and adjusting my zones. It could be that I need to dial in with the HRM before I start getting meaningful numbers for Anaerobic. I was just concerned that with the bad weather and bad gps that there was a fault somewhere.
  • Hi - I just answered a fairly similar question for someone in the FR935 sub-forum.

    You might take a look there.

    https://forums.garmin.com/forum/into-sports/running/forerunner-935-aa/1262046-anaerobic-training-effect-broken-on-6-00?p=1262329#post1262329

    There does seem to be some genuine confusion around regarding what Anaerobic TE is actually measuring, so if you folks have any questions not answered by the other post - just let me know, and I'll try to help if I can.
  • HermanB thanks a lot: very clear explanation
  • Here's a table that shows how some common runs 'should' translate into combined Aerobic and Anaerobic Training Effect scores.

    https://www.firstbeat.com/en/anaerobic-training-effectworkout-explanations/

    Worth noting that the example that RB16k gave maps very nicely onto the anticipated 10k race row. So, it would be perfectly normal to have a low Anaerobic Training Effect score from that run - it is a little weird to have a 0.0.

    I did just notice that he mentioned that his GPS was out for part of the run. It is possible that COULD be a problem.

    While Firstbeat can - and often does - calculate an Anaerobic Training Effect score using only heartbeat data, during running activities with GPS enabled it is my understanding that the GPS data is utilized to help enhance the detection of sprint/interval segments. This is to help identify more precisely when these activities start - which doesn't show up instantly in the heartbeat data.

    What this means in practical terms when you are out for a run and your GPS data is really bad, I have no idea... I'd be surprised if the result was 0.0 - but it might be a unique case.
  • Herman B,
    Do you have an explanation of the Fitness Level anywhere? Does Firstbeat do the algorithms for the lower level garmins as well? It seems my Fenix 5s needs consistent gps (outside workouts) to measure Fitness Level? But a Vivosmart 3 can measure Vo2 max WITHOUT gps?

    What gives?

    My beef is that my watch has rated me 79 years OR OLDER since the beginning. I guess because I don't workout outside enough. I'm a gym rat. It can't get my VO2 Max.