Set heart rate zones that match your effort
If your easy runs keep reading as moderate, the problem is usually the zones, not the running. Apex Run lets you build them from three different models, then move any boundary by hand — and the change reaches every run you've ever done.
Zones from a stock formula are a guess about a population, and you’re one person. The usual symptom is that every easy run reads as Zone 3, which makes your whole week look harder than it was — and quietly ruins any 80/20 calculation built on top of it.
Where to start: Max HR#
Zones are derived from your maximum heart rate, so that number comes first.
Apex Run reads your date of birth from Apple Health and estimates 220 − age. That’s a reasonable default and a poor personal answer — real maximums vary by 10–20 bpm at the same age. If you’ve ever finished a hard 5K or a hill session and seen a number your watch has never beaten, that’s much closer to your true max than any formula.
Set it in Profile→Settings→Max Heart Rate , switching from the automatic estimate to a manual figure.
Three models to build from#
Under Calculate From Method you get three:
- Max HR % — straight percentages of your maximum. Simple, and what most watches do.
- Karvonen (Heart Rate Reserve) — percentages of the gap between resting and maximum heart rate. Asks for your resting HR, and generally puts easy running in a more believable place, especially if you’re well trained.
- Lactate Threshold (LTHR) — anchored to the heart rate you can hold for roughly an hour. The most accurate of the three if you know the number, and the least useful if you’re guessing it.
Tap Apply to Zones and the boundaries fill in. Nothing is locked after that — every boundary is editable in BPM, so if you know Zone 2 tops out at 148 for you, type 148.
The five zones and what each one is for:
| Zone | What it does |
|---|---|
| Zone 1 | Warms up and aids recovery |
| Zone 2 | Builds basic endurance, burns fat |
| Zone 3 | Improves aerobic fitness and circulation |
| Zone 4 | Raises maximum performance capacity |
| Zone 5 | Develops top-end performance and speed |
Reset to Default Settings puts everything back to the recommended split for your current Max HR, if an experiment goes badly.
What changes when you save#
Your runs show the new zones straight away — the one from this morning and the one from two years ago alike. Nothing to wait for.
Getting the numbers honestly#
- Don’t use a lab-free LTHR guess. If you’re estimating lactate threshold, you’re just doing Max HR % with extra steps. Use Max HR % or Karvonen until you’ve actually done a threshold test.
- Resting HR from your watch, not from a chair. Karvonen wants your true resting rate, which Apple Health already tracks overnight — not a number you took sitting at your desk.
- Sanity-check against feel. Zone 2 should be a pace you could hold while holding a conversation. If yours isn’t, move the boundary until it is; the model works for you, not the reverse.
The metric behind it: Heart rate zones explained
Try it in your browser: Heart Rate Zones Calculator
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Make your easy runs read as easy.
Set your zones once and every run you've ever done shows the right numbers. Custom heart rate zones are free in Apex Run — no subscription.
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