Heart Rate Zones: What They Are and How to Set Them

The five zones

Runsense sets your zones as percentages of your lactate-threshold heart rate (LTHR), using Joe Friel's running table. Most five-zone models you will meet use percentages of maximum heart rate. Because your LTHR is lower than your maximum heart rate, the same beats-per-minute figure is a higher percentage of LTHR than of maximum, so these percentages run higher. Here they are, with the beats per minute they give at an LTHR of 170:

• Zone 1, very easy: below 85% of LTHR (under about 145 bpm).
• Zone 2, easy: 85 to 89% of LTHR (145 to 151 bpm).
• Zone 3, moderate: 90 to 94% of LTHR (152 to 160 bpm).
• Zone 4, hard: 95 to 99% of LTHR (161 to 168 bpm).
• Zone 5, maximum effort: 100% of LTHR and above (169 bpm and up). Your LTHR sits at the boundary between zones 4 and 5.

Set zones from your own effort

Anchor your zones on an effort you actually ran. Runsense can prescribe a guided lactate-threshold test and read your LTHR from it. The guide on testing your lactate threshold heart rate covers the do-it-yourself version, and the guide on lactate threshold covers what the threshold is.

A formula is a poor substitute. The best-known one is 220 minus your age, and a 2001 pooled analysis of 351 studies (18,712 people) found 208 minus 0.7 times age fits healthy adults better, and that 220 minus age underestimates maximum heart rate in older adults¹. Even so, neither fits one person well. In a 2013 study of 762 sedentary adults whose maximum was measured, the typical error was 12.4 beats a minute for 220 minus age and 11.4 for the better formula². Runners show the same scatter, in different directions for women and men: in a 2018 study of 180 recreational marathon runners, both formulas overestimated the measured maximum by about 5 beats in women, and 220 minus age underestimated it by about 3 beats in men³.

Fixed percentages of maximum heart rate are also a poor guide to where the easy zone sits. In 50 cyclists tested in a laboratory, a fixed percentage of maximum heart rate and blood lactate thresholds differed widely between individuals, while the first ventilatory threshold and the point of maximal fat oxidation lined up with each other⁴.

Effort can check the number. At a conversational pace you are in zone 2 or below. See the guide on the talk test.

Where most of your running belongs

Keep your easy runs in zones 1 and 2 so that the hard days can be hard, and treat zone 3 as a place you choose to visit and not one you drift into. The guide on polarized training covers how much of your running should be easy and where the evidence on the middle zone is not settled.

Why the number on your watch can mislead

Heart rate lags at the start of a run. Your watch shows a heart rate that has not yet caught up with the effort, so judge the first few minutes by feel.

It also drifts upward over a long run, faster in heat or when you are dehydrated, so the same zone can mean a slower pace on a hot day and late in a long run than on a cool day and early. Use zones as one lens alongside pace and perceived effort, and when the number and how you feel disagree, ask why before obeying the watch. The guides on heart rate, pace and effort and heart rate decoupling go further.