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The Karvonen method calculates target heart rate using heart rate reserve (HRR), defined as the difference between max HR and resting HR. This accounts for individual fitness levels, making zones more accurate than flat percentage approaches.
THR = ((HRmax - HRrest) × %Intensity) + HRrestZone 1 (50-60% HRR): recovery and warm-up. Zone 2 (60-70%): aerobic base building. Zone 3 (70-80%): tempo and threshold work. Zone 4 (80-90%): VO2max intervals. Zone 5 (90-100%): anaerobic capacity and sprint efforts.
When lab-tested HRmax is unavailable, the Tanaka formula provides a more accurate estimate than the classic 220-age method, particularly for trained athletes over 40.
HRmax = 208 - (0.7 × age)Updated: July 2026
Age 35, resting HR 55 bpm, estimated max HR 184. Calculating Zone 2 for long run base building.
→ Zone 2: 132–145 bpm
Age 45, resting HR 62 bpm, looking for Zone 4 targets for track repeats.
→ Zone 4: 154–165 bpm
The 220-age formula has a standard deviation of ±10-12 bpm. Use a field test (e.g., 3-minute uphill all-out effort) or the Tanaka formula (208 - 0.7×age) for better accuracy.
Resting HR decreases as fitness improves. Re-measure resting HR monthly (seated, first thing in the morning, 3-day average) and recalculate zones accordingly.
Polarized training (80% easy zones 1-2, 20% hard zones 4-5) produces better adaptations than chronic moderate intensity. Avoid the 'gray zone' trap.
Determine your personalized heart rate training zones using the Karvonen method. This formula accounts for both maximum heart rate and resting heart rate, producing more accurate intensity targets than simple percentage-of-max methods.