Hi all, I am trying to understand how the below values are being calculated.
Just to make an example, I have for today's run the following "time at zones" values:
Z5 0%
Z4 26%
Z3 30%
Z2 32%
Z1 9%
And in this case, in the HR zones I can see 3,3 z ave HR, 4,9 z max HR. How these values are calculated?
Thanks!
To drive home the point, here are the zones that were recorded to the FIT file for a recent run. Again, only Z1 min, Z1 max, Z2 max, Z3 max, Z4 max, and Z5 max are represented in the file. Note that these are indeed integers.
Ofc nothing stops Garmin from taking these numbers and internally using them anyway they want.
They could in fact take these numbers to represent zones such as:
122.5000000... » 136.49999999...
136.5000000... » 151.49999999
But I really don't think they do (unless you consider that it could be that way as an implementation detail, as mentioned above). (But that implementation detail would only be necessary if in fact there were 2 separate values internally at borders - one for Z1 max and one for Z2 min, for example, and I don't think there needs to be.)
I think the simplest answer of looking at it that my zones are actually:
%HRR / BPM
|-- 100% / 195Z5 |
|--- 90% / 181
Z4 |
|--- 80% / 166Z3 | |--- 70% / 152Z2 | |--- 60% / 137Z1 | |--- 50% / 123
If I could see them in the old Connect website HR zones settings page (not available for new devices), I think that's exactly what it would look like.
Note that these zones are a little different than what I said before, since the watch detected a slightly lower max HR (195) for me than was previously set.
To write these zones differently (making the equalities at the borders explicit)
123 ≤ Z1 < 137 ≤ Z2 < 152 ≤ Z3 < 166 ≤ Z4 ≤ 181 ≤ Z5 < 195
Again I am assuming that if a HR value is on a border (like 137), then it belongs to the higher HR zone (in this case, Z2). This at least matches the fractional HR formula that I guessed, and it also matches Garmin's presentation of the zones in BPM where adjacent zones are separated by 1 BPM (e.g. my time in zones chart shows zones like 123-136, 137 - 151, etc.).
In the end it doesn't matter. I think we all agree that the zones are actually continuous, which is especially obvious if you use % zones, as in % max HR or % HRR. In this case, Garmin shows continuous/touching/pseudo-overlapping ranges in the settings such as 50%-60%, 60%-70%, etc, for the reason that I said above. (It wouldn't work with ranges like 50% - 59%, 60% - 69%, for example, because then you'd have something other than 1 BPM of separation between adjacent zones)
But it doesn't matter so much when you look at BPM values, because Connect never shows fractional BPM values. Internally, any BPM that is recorded to the FIT file is an integer if I'm not mistaken, and any average that is taken is rounded for dispaly.
And I mentioned the formula for calculating fractional zone, which was the point of this thread in the first place. At least that formula works for me. Here's the formula in general:
For a given heart rate H (in bpm), the corresponding "fractional zone" X.Y (where X and Y are integers) is given by:
fractional_hr_zone = X + (H - zone_X_min) / (zone_(X+1)_min - zone_X_min), where X is such that zone_X_min ≤ H ≤ zone_(X+1)_min)
Here I have chosen to write the formula so it would work with either the (supposed) internal continuous ranges, or the user-visible ranges which are separated by 1 bpm.
I could be wrong ofc, since all of this is an educated guess. But it's the simplest explanation (to me, anyway).
And maybe the details don't really matter, so long as we understand that a fractional zone of 4.5 (for example) means that you are halfway (50%) between zone 4 min and zone 5 min.
Similarly, 3.3 means you are 30% between zone 3 min and zone 4 min.
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