Heart Rate Reserve: Better Zones with the Karvonen Method
What heart rate reserve (HRR) is, the Karvonen formula that turns it into training zones, why it beats plain %HRmax, and how to measure the two inputs.
Heart rate reserve (HRR) is the gap between your maximum and resting heart rates. If your max is 190 and you rest at 50, your reserve is 140 beats. The Karvonen method takes a percentage of that reserve and adds your resting heart rate back on top. That one adjustment makes your zones more personal, especially if you are very fit or just starting out.
What is heart rate reserve?
Your heart rate never drops to zero, so not all of your 190 bpm is usable training range. Heart rate reserve is the part that is:
HRR = maximum heart rate − resting heart rate
A fitter heart pumps more blood per beat, so it beats slower at rest. A fitter person therefore has a larger reserve than an unfit person with the same maximum.
The Karvonen formula
The Karvonen method, published by Finnish physiologist Martti Karvonen in 1957, sets each zone boundary like this:
Target HR = resting HR + (intensity % × heart rate reserve)
Say your max is 190, your resting heart rate is 50, and you want the bottom of Zone 2 at 60% intensity:
- Heart rate reserve = 190 − 50 = 140 bpm
- 60% of 140 = 84 bpm
- Add resting back: 84 + 50 = 134 bpm
A plain "60% of max" would give 114 bpm, 20 beats lower.
Réserve cardiaque
135bpm
185 − 50
Fréquence cardiaque max
185bpm
Fréquence cardiaque de repos
50bpm
| Zone | Plage | Ce que cela développe |
|---|---|---|
| Z1 | Récupération 118–131 bpm | Récupération active et échauffement ; favorise la circulation sanguine sans ajouter de fatigue. Très facile, RPE 1–2. Conversation complète, respiration à peine accélérée. |
| Z2 | Endurance 131–145 bpm | Base aérobie, oxydation des graisses et densité capillaire, la zone fondamentale. Confortable, RPE 3–4. Phrases complètes possibles. |
| Z3 | Tempo 145–158 bpm | Capacité aérobie et endurance musculaire ; travail soutenu « modérément difficile ». À l'effort, RPE 5–6. Phrases courtes seulement. |
| Z4 | Seuil 158–172 bpm | Seuil lactique, le plafond de votre allure de course tenable. Difficile, RPE 7–8. Quelques mots à la fois. |
| Z5 | VO₂max 172–185 bpm | Puissance aérobie maximale et VO₂max via des intervalles courts et intenses. Très difficile à maximal, RPE 9–10. Aucune parole possible. |
Z1 · Récupération. Récupération active et échauffement ; favorise la circulation sanguine sans ajouter de fatigue. Très facile, RPE 1–2. Conversation complète, respiration à peine accélérée.
Z2 · Endurance. Base aérobie, oxydation des graisses et densité capillaire, la zone fondamentale. Confortable, RPE 3–4. Phrases complètes possibles.
Z3 · Tempo. Capacité aérobie et endurance musculaire ; travail soutenu « modérément difficile ». À l'effort, RPE 5–6. Phrases courtes seulement.
Z4 · Seuil. Seuil lactique, le plafond de votre allure de course tenable. Difficile, RPE 7–8. Quelques mots à la fois.
Z5 · VO₂max. Puissance aérobie maximale et VO₂max via des intervalles courts et intenses. Très difficile à maximal, RPE 9–10. Aucune parole possible.
- Karvonen ancre les zones à votre réserve cardiaque (HRmax − FC de repos), elle personnalise donc les zones selon votre forme mieux que le simple %HRmax : un athlète en forme avec une FC de repos basse obtient des cibles d'autant plus basses.
- Mesurez la fréquence cardiaque de repos dès le réveil, allongé, avant la caféine. Une erreur de 5 bpm sur la FC de repos décale toutes les zones.
Un PDF de vos résultats, avec un QR code pour les rouvrir à tout moment.
Why does Karvonen beat plain %HRmax?
Percent-of-maximum zones treat everyone with the same max identically. Karvonen folds in resting heart rate, a rough proxy for fitness:
- It accounts for your conditioning. A trained athlete resting at 45 and a beginner resting at 75 get different zones even with the same max.
- The zones track your fitness. As resting heart rate drops, your reserve grows and the zones update. A fixed %HRmax band never moves.
- It spreads the easy end out. Plain %HRmax puts easy efforts at implausibly low heart rates. Adding resting heart rate back lifts the low zones to numbers you can train at.
For how the different systems carve up the range, compare the heart-rate zone models.
How do I find the two numbers I need?
Resting heart rate (RHR). Measure it first thing in the morning, before you get up, averaged over several days. A chest strap or the overnight reading from a wearable both work. A daytime desk reading runs high.
Maximum heart rate (HRmax). Age formulas (220 − age, or the more accurate Tanaka, 208 − 0.7 × age) can be off by 10+ beats for any individual. A field test gives a far better number. See finding your maximum heart rate for both, or the max heart rate calculator for the estimate.
Karvonen vs. lactate-threshold zones
Karvonen is still anchored to your maximum, which barely responds to training and is hard to measure safely. The most individual anchor is your threshold. Zones set from your lactate-threshold heart rate sit where your physiology changes and rise as you get fitter. Many athletes start with Karvonen and move to LTHR zones after a 30-minute test.
For easy aerobic work, see Zone 2 heart rate, explained.
Sources
- Karvonen, M. J., Kentala, E., & Mustala, O. (1957), the original heart-rate-reserve study
- Tanaka, Monahan & Seals (2001), maximum-heart-rate estimation