Compute your training heart-rate zones with the Karvonen formula (heart-rate reserve). More accurate than '220 minus age'.
Measure on waking, before getting up
Zone distribution (Karvonen)
- Z1Active recovery124–136 bpm · 50–60%
Very easy. Recovery and warm-up.
- Z2Aerobic endurance136–149 bpm · 60–70%
Fat burning. Conversational pace.
- Z3Aerobic149–162 bpm · 70–80%
Improves cardiovascular capacity.
- Z4Anaerobic threshold162–174 bpm · 80–90%
Intervals, tempo. Sustainability limit.
- Z5Maximum174–187 bpm · 90–100%
All-out effort. Sprints and short intervals.
Heart-rate zones let you train at the right intensity for each goal: aerobic capacity, fat oxidation, threshold, etc.
Why Karvonen is better
Using only % of max HR ignores your fitness level. Karvonen uses heart-rate reserve (HRmax − resting HR), individualising the zones. For max HR, the Tanaka formula (208 − 0.7·age) is more accurate than the classic 220 − age, especially after age 40.
Zone 2: the aerobic base
Zone 2 (60-70% intensity by Karvonen) is conversational pace: you can hold a conversation without losing breath. It improves mitochondrial density, fat oxidation and the aerobic base. Elite athletes do 80% of their volume here. It's boring but unskippable.
Frequently asked questions
Why is Karvonen better than % of HRmax?+
Karvonen uses heart-rate reserve (HRmax − resting HR), which accounts for your fitness level. Two people of the same age but different fitness will have different zones.
How do I measure resting HR?+
Upon waking, before getting out of bed, count your pulse for 60 seconds. Do it 3 days and average. A smartband measures it automatically.