Fitness Metrics
Heart Rate Zones Explained
The five-zone Karvonen model and how to use it in everyday training.
7 min read·Updated 25 June 2026
HG
HealthGood Editorial Team
Last updated 25 June 2026
Reviewed by HealthGood Editorial Standards Board
Heart rate zones translate intensity into something you can monitor in real time with a chest strap or wrist sensor.
The five zones
- Zone 1 (50–60% of max) — very light, recovery and warm-up.
- Zone 2 (60–70%) — easy aerobic, base building.
- Zone 3 (70–80%) — moderate, tempo work.
- Zone 4 (80–90%) — hard, threshold training.
- Zone 5 (90–100%) — very hard, intervals and VO₂ max work.
What to actually do
Most recreational athletes do best with 80% of training in zones 1–2 and the remaining 20% in zones 3–5 — the so-called polarised model.
Frequently asked questions
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References
- World Health Organization — Body mass index (BMI). https://www.who.int
- NHS — Healthy weight and BMI. https://www.nhs.uk
- Centers for Disease Control and Prevention (CDC) — Healthy Weight, Nutrition, and Physical Activity. https://www.cdc.gov
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure. Am J Clin Nutr (1990).