FC Zona Karvonen

Karvonen: target heart rate via heart rate reserve

The Karvonen formula (Karvonen, Kentala & Mustala, 1957) sets a target heart rate from your heart rate reserve (HRR) rather than from a flat % of HRmax: HR_target = HR_rest + intensity% · (HR_max − HR_rest). Because it folds in resting HR, the intensity tracks your individual fitness, which makes for a sharper prescription than %HRmax on its own. Take a quick example: HRmax 180, rest 60, intensity 70% → HR_target = 60 + 0.70·120 = 144 bpm. The usual zones by %HRR run as follows: Z1 50-60% (recovery), Z2 60-70% (endurance), Z3 70-80% (tempo), Z4 80-90% (threshold), Z5 90-100% (VO2max).

Applications: exercise prescription and training zones

Physiologists and personal trainers lean on it for exercise prescription, cardiac rehabilitation programs use it too (post-infarction protocols sit at 40-70% HRR), and it carries over into endurance sports. Devices like Garmin, Polar and Suunto let you switch to HRR-based zones, which tend to be more reliable than %HRmax for runners and cyclists whose resting heart rate is low.

FAQ

How do I measure HRmax? The gold standard is a graded exercise test. Shortcuts like 220 − age or Tanaka (208 − 0.7·age) give you a rough figure, but they can be off by 10-15 bpm.

And resting HR? Take it the moment you wake up, still lying down, counting for 60 s. Trained athletes often land at 40-50 bpm, while sedentary adults sit closer to 70-80.

Karvonen vs %HRmax? Karvonen is the more personal of the two. Two people with identical HRmax but different resting rates end up with different prescriptions, and that gap reflects their real fitness more honestly.