I was wondering if it is possible to somehow view the results from the load estimator regression. I find that for most rides, it is quite accurate for me. I would like to write a Garmin Connect IQ app where the user can set zones and, I guess, some constant for each zone, and would then be able to view a liveload estimation when riding with HR only.

Do you mean when using the â€śtime in HR zonesâ€ť model? HRSS (Normalised TRIMP) doesnâ€™t do any regression, it just has a formula using LTHR, resting HR and max HR.

For â€śtime in zonesâ€ť if you are using Chrome and are familiar with the dev tools you can easily get the coefficients. Just right click on Intervals.icu, choose â€śInspectâ€ť and go to the network tab. Select â€śXHRâ€ť in the filter row. Then go to the HR page for the activity. Look for a call that says â€śhr-load-modelâ€ť and click that then â€śPreviewâ€ť. There is lots of info there including the coefficients for the model used for that ride:

```
0: -3.1808302359593688
1: 0.010683864176517956
2: 0.01355717328262192
3: 0.021017892393982683
4: 0.013039836988054998
5: 0.06211736960493642
6: 0.06211736960493642
7: 0.10576411307585556
```

Great, thanks! So for each second in each time zone, I get the given increase/decrease in training load units? Meaning, in this case, for a second in zone one, 0.0106?

Thatâ€™s correct. The first row is the constant term.

Great, I got them! Just one question: intuitively, it seems to me that the coefficient for zone 1 is kind of arbitrary (yours is -3, mine is +30)! How can we understand this, can it be an artifact of the regression?

That first row is the constant term (intercept) so mine is -3.18. The 2nd row is for zone 1 i.e. 0.01068 for me.

Ok, this makes sense. Will post here if I complete an IQ implementation

Although: with the intercept being non-zero, this suggests that the regression works only with *completed* rides and wonâ€™t make much sense live, especially during the first minutes.

Maybe I donâ€™t get it (most likely even ^^) but why does a second in zone 4 give less load than a second in zone 3?

I think that happens due to not great input data. I did try fudging the coefficients so higher zones are always bigger than preceding zones but it caused more trouble. If you have a zone you donâ€™t ride much in and the coefficient isnâ€™t great then that error is propagated up.

I need to try find a regression library that will let me constraint the coefficients so the higher zone ones are always bigger than lower ones.