Fixed percentages of maximum heart rate locate "zone 2" poorly: the first threshold fell anywhere from 60% to 90%
Is zone 2 a fixed percentage of max heart rate?
The finding
The lactate threshold occurred at 45–74% of VO₂max and 60–90% of maximum heart rate, depending on the person. Fixed percentages "conform poorly" to the intensity domains.
- Authors
- Iannetta D, Inglis EC, Mattu AT, et al.; Jamnick NA, et al.
- Published
- Medicine & Science in Sports & Exercise 52(2):466–473; Sports Medicine 50(10):1729–1756 · 2020
- Evidence
- Read in the primary source; numbers checked.
- Source
- doi.org/10.1249/MSS.0000000000002147
How it was studied
Iannetta: 100 people (46 women) tested in the lab. Jamnick: a review of how exercise intensity is prescribed.
The numbers
Physiologically, zone 2 means exercise just below the first lactate or ventilatory threshold. Jamnick’s review found that a fixed percentage of VO₂max or maximum heart rate "has little merit" for producing domain-specific responses.
What it does not show
Lab studies. They show that a heart-rate band is a rough proxy, not that it is useless.
What Longstanding does with it
The app counts a workout as zone 2 when its average heart rate falls in 65–75% of your predicted maximum. For many people that band is not their physiological zone 2, so read the count as moderate-intensity minutes. It is shown as a share of the 150-minute guideline, never as a percentile.