Training Effect off since 9.20?

Former Member
Former Member
Hi all,
I was wondering if anybody else feels like their aerobic training effect has been higher than normal since firmware 9.20?

I use a HRM-Run monitor paired with a Fenix 5 sapphire. In the past, training effect has roughly aligned with my average heart rate. So if I had a run where my average heart rate was 150 (low Z3 for me), I would expect an aerobic training effect in the low 3’s. Duration of effort would bump the effect up or down slightly.

As an example to compare 8.00 to 9.20, I have two trail runs on similar terrain.
On 6/2, with firmware 8.00, I ran a 33 mile race with an average heart rate of 166. Aerobic training effect was 4.7. This is about what I would expect based on the effort.
On 7/7, with firmware 9.20, I ran a 15 mile run with a much lower average heart rate of 152. Aerobic training effect was a 4.6. This seems too high based on the effort.

My fitness has not changed much over the last month. I have tried restarting the watch a few times, as well as ensured my heart rate zones are correct on the the watch and Garmin Connect app.

Thanks in advance for any help or insight!
  • One issue that I have noticed with recent FW updates is that it can not just screw with the HR zones, but also with your recorded LTHR. Which will impact the TE calculation. You may want to check your LTHR and pace, as well as just HR zones.

    The other possibility is that the calculated TE is in fact about the same for both runs. Your peak effort (and how long you held it for) is the largest factor in the TE calculation - you can run for miles after that peak, and not add much to the TE for that run. If both runs included a large hill where you held a high effort for 10-20 minutes, then you might get a similar TE, despite the earlier run being longer and having a higher HR average. I am not sure whether your comment about running "on similar terrain" would have a dominating peak effort like this?
  • Former Member
    0 Former Member over 7 years ago
    Thinking about it more, it makes a lot of sense that the largest factor in the TE calculation is the peak effort and how long it’s held for. Otherwise, training status might not be reflective of those harder sustained efforts during a long run.
    Thanks for the insight!