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Heart zones (Karvonen)
Your 5 personalized training zones with the Karvonen method, which takes into account your resting HR.
Why the Karvonen method
The classic calculation in % of max HR is imprecise: it ignores your resting HR, which varies enormously depending on your training level. A sedentary person at 70 bpm rest and an athlete at 45 bpm rest with the same max HR will have very different training zones.
The Karvonen method (1957) takes into account the HR reserve (= HR max − HR rest), which gives much more personal and precise zones.
Formula: Target HR = Resting HR + (% × Reserve HR)
The 5 zones and their use
Zone 1 — Active recovery (50-60% HR res.)
Very easy, you can hold an entire conversation. Use: warm-up, cool down, recovery after hard session. Very easy effort to maintain for 1 hour+.
Zone 2 — Fundamental Endurance (60-70%)
Heart of training volume in any runner. This is the area where you burn the most fat, develop your capillarization and your mitochondria. 80% of your outputs should be in zone 1-2 (polarized method).
Zone 3 — Tempo / aerobic (70-80%)
Marathon pace for an average runner, semi pace for a beginner. Sustained effort, you speak in short sentences. Useful for long “sustained” outings in marathon prep.
Zone 4 — Anaerobic threshold (80-90%)
10K semi pace for an experienced runner. You hardly speak anymore. Sustainable 20-40 min maximum. Used for tempo runs and long intervals (1000-2000 m).
Zone 5 — VMA / sprint (90-100%)
Maximum intensity. Lasts 30 seconds to 5 minutes depending on the sub-zone. Used for short intervals (30-30, 200-400 m). Very educational but expensive, to be dosed (1-2 sessions/week max).
Karvonen vs % max HR simple
Example: 35 year old athlete, max HR 185, rest HR 50.
- % HR max simple: zone 2 (60-70%) = 111 to 130 bpm.
- Karvonen (reserve HR): zone 2 (60-70% reserve HR) = 50 + 60-70% × (185-50) = 50 + 81 to 95 = 131 to 145 bpm.
A difference of 15-20 bpm. The Karvonen method better reflects the true intensity felt.
How to measure your resting HR
The reference measurement: when you wake up, still lying in bed, before getting up. Count beats for 30 s × 2, or use a heart rate watch in day mode.
Tips:
- Measure several mornings (at least 3) and take the average.
- Not after a night of drinking or a late meal (artificially high resting heart rate).
- Resting HR decreases with training: remeasure every 3-6 months.
The “polarized” model (80/20)
Recent studies (Seiler, Esteve-Lanao) show that a 80% volume distribution in zone 1-2 + 20% in zone 4-5, avoiding zone 3 (often "gray zone" too hard to be easy, too easy to be formative), gives the best results over time. This is the model used by the majority of modern running coaches.
Questions fréquentes
Karvonen, without hesitation. It has been the scientific method of reference since 1957. The simple % HR max zones are a gross simplification that does not take into account your training level.
Yes. Your resting HR drops sharply with training (10-20 bpm for a beginner who becomes a serious amateur). Recalculate your zones every 3-6 months.
At least 80% of the total racing time. Over 5 hours of running/week, that's 4 hours in zone 1-2, and 1 hour in zone 4-5. Zone 3 should be used sparingly (long outing at marathon pace).
Garmin/Polar/Suunto watches default to a simple HR% max or their own proprietary method. You can usually switch to Karvonen mode in advanced settings.