What your heart rate zones are
Heart-rate zones are calculated on heart-rate reserve, which is maximum minus resting. With the Tanaka formula, maximum heart rate = 208 − 0.7 × age: at 35 that is 184 beats. With a resting rate of 60, reserve is 124, and zone 2 runs from 60 to 70% of that reserve added back to resting — between 134 and 146 beats. Working off maximum alone, without subtracting resting, leaves the low zones too high.
The formula
Maximum heart rate (Tanaka) = 208 − 0.7 × age · Heart-rate reserve = Maximum − Resting · Zone bound (Karvonen) = Resting + Reserve × percentage. The five zones use 50-60%, 60-70%, 70-80%, 80-90% and 90-100% of reserve.
What each variable means
- Age
- It only feeds the maximum estimate. If you have a maximum measured in a test or a race, that number beats any age formula.
- Resting heart rate
- Beats per minute on waking, before getting up. Measured after coffee or a flight of stairs it reads high and lifts every zone with it.
Precomputed values
| Age | Maximum | Zone 2 | Zone 3 | Zone 4 | Zone 5 |
|---|---|---|---|---|---|
| 20 | 194 | 140-154 | 154-167 | 167-181 | 181-194 |
| 30 | 187 | 136-149 | 149-162 | 162-174 | 174-187 |
| 40 | 180 | 132-144 | 144-156 | 156-168 | 168-180 |
| 50 | 173 | 128-139 | 139-150 | 150-162 | 162-173 |
| 60 | 166 | 124-134 | 134-145 | 145-155 | 155-166 |
The table pins resting at 60 so the effect of age alone is visible. In practice resting rate is what separates two people of the same age: at 48 instead of 60, a 40-year-old's zone 2 moves from 132-144 to 127-140. Which is why a chart printed on a gym wall fits almost nobody.
Run it on your numbers
How to read the result
Zone 2 is the most used and the easiest to ruin: it is the pace at which you can hold a full conversation, and most people run it above that. If your watch shows zone 3 on every easy run, the usual culprit is a badly measured resting rate rather than the training.
Assumptions and limits
- Tanaka estimates maximum with a standard deviation of about 7 beats: two people of the same age can differ by 15 and both be normal.
- Karvonen assumes the resting rate is measured properly. A 10-beat error there moves every zone.
- Cardiac medication, beta blockers above all, invalidates any age-based estimate.
- Heat, dehydration and short sleep raise heart rate at the same effort. A day where zone 2 sits higher than usual describes the day, not the fitness.
