How the zones are calculated
Your heart rate reserve is the range you actually have to work with: your maximum heart rate minus your resting heart rate. Each boundary is your resting heart rate plus a share of that reserve, at 60, 70, 80 and 90%. The method is named after the Finnish physiologist Martti Karvonen.
For example, with a maximum of 188 and a resting heart rate of 52, the reserve is 136. The top of zone 1 is 52 + 60% of 136, which is 134 beats per minute.
Why are these numbers higher?
Because the percentage is taken of the range above your resting heart rate, not of the whole range from zero. The same 60% that gives 113 beats per minute as a share of a 188 maximum gives 134 here. Neither is wrong. They are different scales, which is why zones from different methods cannot be compared.
Using these zones in Kiiro
Kiiro's automatic zones use the maximum heart rate method. To use these instead, switch heart rate zones to Custom in Kiiro's settings and enter the boundaries from the table. They stay fixed until you change them.
Which method should I use?
| Method | You need | Good when |
|---|---|---|
| Maximum heart rate | Your maximum, or your age | You want a quick start. This is what Kiiro uses by default. |
| Heart rate reserve | Maximum and resting heart rate | Your resting heart rate is unusually low or high, so percentages of maximum fit you badly. |
| Lactate threshold | A 30-minute test run | You train seriously and want zones anchored to what you can actually sustain. |
The methods give different numbers for the same person. Pick one and stay with it; do not compare a zone 2 from one method with a zone 2 from another.
Using your zones
- To use them on your watch, see how Apple Watch sets heart rate zones and how to change them.
- For what zone 2 is and why it matters, see Zone 2.
- Kiiro shows your time in zones for every workout and how your weeks split between low, medium and high intensity. See heart rate zones in Kiiro.
