Program your clients' cardiovascular training with precision. Use the Karvonen method to calculate individualized heart rate zones and optimize every cardio session.
This method calculates heart rate zones using the heart rate reserve (difference between max HR and resting HR). It is more accurate than the simple percentage method because it accounts for the client's individual fitness level.
Measure upon waking, before getting out of bed
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Heart rate training zones divide the intensity spectrum from rest to maximum effort into five distinct bands. Each zone targets different physiological systems and produces different adaptations — from fat oxidation and mitochondrial development in Zone 2, to lactate tolerance in Zone 4 and peak power output in Zone 5.
| Zone | % HR Reserve | Primary benefit |
|---|---|---|
| Z1 – Recovery | 50–60% | Active recovery, warm-up |
| Z2 – Base aerobic | 60–70% | Fat oxidation, mitochondrial development |
| Z3 – Aerobic | 70–80% | Cardiovascular capacity, VO2max |
| Z4 – Anaerobic threshold | 80–90% | Lactate tolerance, threshold power |
| Z5 – Maximum | 90–100% | Peak power, VO2max |
The classic simple-percentage approach (e.g. "70% of max HR") treats two clients identically if they share the same age — ignoring how fit they actually are. The Karvonen formula corrects this by incorporating the heart rate reserve (max HR minus resting HR), so a well-trained athlete with a low resting HR gets different zones from a sedentary person of the same age.
For coaches, this means every prescription is truly individualized. Collecting a client's resting HR takes under a minute and dramatically improves the precision of every cardio session you program for them.