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Dulcimer

macrumors 6502a
Original poster
Nov 20, 2012
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New watchOS 9 feature: Heart Rate Zones.

You can view the automatically set ones in the iOS Watch app > Workout > Heart Rate Zones.

Late 20s male, not that fit, mine are as follows:

Zone 1: <142
Zone 2: 143-153
Zone 3: 154-165
Zone 4: 166-176
Zone 5: 177+
Max HR: 189

Am I crazy or is this completely off? My Zone 1/2 boundary starts at 75% of my max. What’s Apple’s calculation for this?

Most sources online seem to mostly agree with roughly the following zones and exercise intensity descriptions:

Zone 1: 50-60% very light
Zone 2: 60-70% light
Zone 3: 70-80% moderate
Zone 4: 80-90% hard
Zone 5: 90%+ intense
 
I was curious too and searched a bit the other day. It looks like they are using the Heart Rate Reserve method to calculate the zones. So, in addition to your Max HR you should also take your resting HR into account.
 
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I’ve never thought the %-based calculation made any sort of sense. A fit person’s heart rate will increase less, and less rapidly, than a person who is less fit.

Take someone whose resting heart rate is eg. 50. If they get their heart rate to 140 through physical activity, that activity is already moderate (maybe a tempo run). Whereas someone less fit whose resting heart rate is, say, 80, may get to 140 walking up an incline (I’m not judging, and I’m not trying to offend—I’m basing this on experience).

According to the simplistic %-based calculation, those two individuals hitting 140 BPM (provided they’re the same age and gender) are in the same heart-rate zone, and thus undergoing a similar level of effort.

From the above, it is clearly necessary to take fitness level into account. Resting heart rate is generally considered a good proxy for it (or at least it’s one that the Apple Watch can actually use to make the determination).

With that being said, I’ve never paid attention to heart-rate zones, because I’ve never found any benefit vs. exercising by feel, in exchange for all that micromanagement and the stress of obsessing over numbers. Plus, there’s a dozen or more formulae for calculating max HR, and all of them seem wrong (you routinely find people far exceeding their max HR, for instance).

But I hope the above shed some light on the situation.
 
Last edited:
My zones are

Zone 1: <135
Zone 2: 136-149
Zone 3: 150-163
Zone 4: 164-176
Zone 5: 177 +
 
I was curious too and searched a bit the other day. It looks like they are using the Heart Rate Reserve method to calculate the zones. So, in addition to your Max HR you should also take your resting HR into account.
Yes you’re right. Even says it there on the settings page! Never heard of this calculation before but doing it myself roughly lines up with Apple’s numbers. Thanks for pointing it out.
 
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I’ve never thought the %-based calculation made any sort of sense. A fit person’s heart rate will increase less, and less rapidly, than a person who is less fit.

Take someone whose resting heart rate is eg. 50. If they get their heart rate to 140 through physical activity, that activity is already moderate (maybe a tempo run). Whereas someone less fit whose resting heart rate is, say, 80, may get to 140 walking up an incline (I’m not judging, and I’m not trying to offend—I’m basing this on experience).
The definitely describes me with the incline :p working on it! But alright, that does make sense actually. Thank you for explaining it.
With that being said, I’ve never paid attention to heart-rate zones, because I’ve never found any benefit vs. exercising by feel, in exchange for all that micromanagement and the stress of obsessing over numbers. Plus, there’s a dozen or more formulae for calculating max HR, and all of them seem wrong (you routinely find people far exceeding their max HR, for instance).
Fair point, but it can be nice to have a simple number or visual as a proxy for exercise intensity.
 
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Dunno, seems pretty normal to me. My numbers:

Rest: 42
Max: 184

This is about 100% accurate. The zones themselves:

Zone 1: <126
Zone 2: 127-140
Zone 3: 141-154
Zone 4: 155-168
Zone 5: 168+

Running below 120 BPM is fairly "difficult", as in it's really hard to remain THAT slow. Especially for extended periods. Above 15 km it has to slow down to brisk walk (pace goes above 8 min/km), pretty much, even for me, and I'm pretty darn fit (half marathon every other day).

This is for cardio, of course. Weight training is a completely different story, although I can get my HR above 120 with even just short sets of push-ups and pull-ups for about 15-20 minutes.
 
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