Glossary
Heart rate zones
Bands of heart rate that label how hard you are working, usually 5 of them. The same run can land in 2 different zones depending on which method set them.
What it is
Five bands, cut from one number. Most watches divide your maximum heart rate into fifths and call them zones 1 to 5.
Some use your heart-rate reserve instead. That is the gap between resting and maximum, which shifts the easy zones upward by several beats.
| Zone | % of max | What it is meant to be |
|---|---|---|
| 1 | 50-60% | recovery |
| 2 | 60-70% | easy, conversational |
| 3 | 70-80% | steady |
| 4 | 80-90% | threshold |
| 5 | 90-100% | very hard |
What it is not
They are not standard. Percent-of-max and Karvonen zones can differ by 10 bpm at the easy end. Some coaching systems use seven zones, anchored to threshold rather than maximum.
They are also not a judgement. A run that lands in zone 4 was not a mistake if you meant it to be hard.
What moves it
- Which method your watch uses. The largest single factor.
- Your maximum. Wrong by 10 bpm, every band is wrong by 5 to 10.
- Heat. The same pace costs more beats on a hot day.
- Your resting rate, if the zones use reserve.
When to ignore it
Ignore zones during the first ten minutes of a run. Heart rate lags effort by a few minutes, so the number is behind you.
Ignore them when the talk test disagrees. If you can speak in full sentences, the run is easy, whatever band the watch picked.
Sources
- Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate. Ann Med Exp Biol Fenn 35(3):307-315, 1957 primary
- Seiler S, Kjerland GO. Quantifying training intensity distribution in elite endurance athletes. Scand J Med Sci Sports 16(1):49-56, 2006 primary
- American Heart Association, target heart rates chart (reviewed 2024) reference