Uses heart-rate reserve — needs your true resting HR.
Formula: ((HRmax − HRrest) × intensity) + HRrest — Karvonen, Ann Med Exp Biol Fenn 1957.
What does the Karvonen method mean?
The Karvonen method, published by Finnish physiologist Martti Karvonen in 1957, calculates heart rate training zones using Heart Rate Reserve (HRR) rather than a simple percentage of maximum heart rate. HRR is the difference between your maximum heart rate (MHR) and your resting heart rate (RHR): HRR = MHR − RHR.
The training zone formula is: Target HR = (HRR × intensity%) + RHR. For example, if your MHR is 180 bpm and your RHR is 60 bpm, your HRR is 120 bpm. For 70% intensity: target HR = (120 × 0.70) + 60 = 144 bpm. The same 70% of MHR alone would give 126 bpm, a significant difference that could mean training in the wrong zone.
The advantage of the Karvonen method is that it accounts for individual cardiovascular fitness. A highly trained athlete with a resting HR of 45 bpm will have very different zone targets from an untrained person with the same MHR but a resting HR of 75 bpm. The athlete's higher HRR translates into higher absolute zone boundaries.
Karvonen zones are typically divided into five zones: Zone 1 (50–60% HRR) for recovery; Zone 2 (60–70%) for aerobic endurance; Zone 3 (70–80%) for aerobic threshold; Zone 4 (80–90%) for anaerobic threshold; Zone 5 (90–100%) for maximal/VO₂max intervals.
Reference ranges (Karvonen zones)
| Zone | HRR % | Purpose |
|---|---|---|
| Zone 1 — Recovery | 50 – 60% | Warm-up, cool-down, active recovery |
| Zone 2 — Aerobic base | 60 – 70% | Fat oxidation, aerobic endurance |
| Zone 3 — Aerobic threshold | 70 – 80% | Aerobic capacity improvement |
| Zone 4 — Lactate threshold | 80 – 90% | Speed endurance, race pace |
| Zone 5 — VO₂max | 90 – 100% | Short intervals, maximal effort |
When should you see a doctor?
If you experience chest pain, palpitations, severe shortness of breath, or dizziness during exercise, stop immediately and seek medical attention. Adults over 40 starting a new high-intensity exercise programme, and anyone with cardiovascular risk factors, should have medical clearance before training in Zones 4–5. Heart rate monitors can help ensure you stay within intended zones rather than inadvertently overworking your cardiovascular system.