How Suunto Calculates Your Max Heart Rate (HRmax)
Suunto defaults to 220 − age and then draws unusually narrow zones on top of it, which is why the same run lands in a different zone than on a Polar.
Suunto does not measure your maximum heart rate. It uses 220 − age by default and tells you plainly to change it if you know your real number. The more interesting difference is what it builds on top: Suunto's intensity zones are far narrower than any other brand's, so the same run can report a different zone on a Suunto than on a Polar.
The zones are the story
Suunto's default zones, as percentages of HRmax:
- Zone 1: below 71%
- Zone 2: 72 to 76%
- Zone 3: 77 to 81%
- Zone 4: 82 to 86%
- Zone 5: 87 to 100%
Zones 2, 3 and 4 are five points wide. Polar's equivalents are ten points wide, running 60 to 70, 70 to 80 and 80 to 90%.
Take an HRmax of 190. Suunto's zone 3 is 146 to 154 bpm, a band of nine beats. Polar's zone 3 is 133 to 152, a band of nineteen. A steady run at 150 bpm sits at the top of Suunto zone 3 and near the top of Polar zone 3, but a run at 140 is Suunto zone 1 and Polar zone 3. The same effort, two very different labels.
Maksimal puls
185bpm
| Zone | Interval | Hvad det træner |
|---|---|---|
| Z1 | Restitution 93–111 bpm | Aktiv restitution og opvarmning; fremmer blodgennemstrømningen uden at tilføje træthed. Meget let, RPE 1–2. Fuld samtale, knap nok forpustet. |
| Z2 | Udholdenhed 111–130 bpm | Aerob base, fedtforbrænding og kapillærtæthed, den helt grundlæggende zone. Behageligt, RPE 3–4. Kan tale i hele sætninger. |
| Z3 | Tempo 130–148 bpm | Aerob kapacitet og muskeludholdenhed; 'moderat hårdt' jævnt arbejde. Arbejdende, RPE 5–6. Kun korte sætninger. |
| Z4 | Tærskel 148–167 bpm | Laktattærskel, dit loft for konkurrencefart, du kan holde. Hårdt, RPE 7–8. Få ord ad gangen. |
| Z5 | VO₂max 167–185 bpm | Maksimal aerob effekt og VO₂max via korte, hårde intervaller. Meget hårdt til maksimalt, RPE 9–10. Ingen tale. |
Z1 · Restitution. Aktiv restitution og opvarmning; fremmer blodgennemstrømningen uden at tilføje træthed. Meget let, RPE 1–2. Fuld samtale, knap nok forpustet.
Z2 · Udholdenhed. Aerob base, fedtforbrænding og kapillærtæthed, den helt grundlæggende zone. Behageligt, RPE 3–4. Kan tale i hele sætninger.
Z3 · Tempo. Aerob kapacitet og muskeludholdenhed; 'moderat hårdt' jævnt arbejde. Arbejdende, RPE 5–6. Kun korte sætninger.
Z4 · Tærskel. Laktattærskel, dit loft for konkurrencefart, du kan holde. Hårdt, RPE 7–8. Få ord ad gangen.
Z5 · VO₂max. Maksimal aerob effekt og VO₂max via korte, hårde intervaller. Meget hårdt til maksimalt, RPE 9–10. Ingen tale.
- Zonerne er simple procentdele af den maksimale puls (Z1 50–60 % op til Z5 90–100 %). De er nemme at indstille, men forudsætter, at din HRmax er korrekt.
- Pulsen halter 1–3 minutter efter belastningen og driver opad i varme eller ved dehydrering ('cardiac drift'), så vurder korte, hårde forsøg på fornemmelsen.
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Neither is wrong. Narrow bands give you finer resolution and punish sloppy pacing. Wide bands are more forgiving and easier to hit. What matters is knowing which system you are reading, because "I did a zone 2 run" means nothing across brands.
Why the default estimate still hurts
Narrow zones make an inaccurate HRmax worse, not better. If your estimate is eight beats high, every boundary moves up by six or seven beats, and a band only nine beats wide can move almost entirely past where you are actually training.
Suunto's own material is candid about this. It notes that age formulas scatter too much to pin down an individual and that the only way to know your maximum is to test it.
How to set it manually
Suunto keeps HRmax in your personal settings, in the Suunto app and on the watch, and uses it for every sport unless you override the zones per activity.
Test first. Build to hard over 10 to 15 minutes, finish with an all-out 60 to 90 second effort, uphill if you can, take the highest reading off a chest strap, repeat within two weeks and keep the higher number. Not for anyone with cardiac risk or new to hard training. The full protocol is in finding your maximum heart rate.
Then enter it, and check your zone boundaries afterwards rather than assuming they updated the way you expected.
The better anchor
Percentage-of-maximum has a structural problem that no formula fixes: it says nothing about your fitness. Two runners with the same maximum and wildly different training get identical zones.
Threshold heart rate does not have that problem, because it moves as you get fitter. If you have tested yours, LTHR zones will place your boundaries better than any percentage of a maximum, and LTHR vs %HRmax zones covers the difference. If you know your resting heart rate but not your threshold, Karvonen is the middle option.
FAQ
What formula does Suunto use for max heart rate? 220 − age by default. Suunto recommends replacing it with a tested value.
What are Suunto's heart rate zones? Five zones as percentages of HRmax: below 71%, 72 to 76%, 77 to 81%, 82 to 86% and 87 to 100%.
Why are my Suunto zones different from my Garmin or Polar zones? Because the bands are narrower. Suunto's middle zones are five percentage points wide where most brands use ten, so the same heart rate maps to a different zone number.
Can I change my max heart rate on a Suunto? Yes, in your personal settings in the Suunto app or on the watch, and you can override zone boundaries per activity.
Does Suunto detect my max heart rate automatically? No. It uses what you give it, so an untouched profile is running on an age formula indefinitely.
Other brands
- Garmin uses Tanaka and raises HRmax from recorded peaks.
- COROS recommends Gellish and offers three zone models.
- Polar uses 220 − age with clean 10-point bands.
- Apple Watch publishes no formula at all.
Sources
- Suunto on intensity zones
- Suunto on resting and max heart rate
- Suunto on calculating max heart rate
- Suunto Run intensity zones
Cover photo by D100a, CC BY-SA 3.0, via Wikimedia Commons.
