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.
Reserva de frecuencia cardíaca
135bpm
185 − 50
Frecuencia cardíaca máxima
185bpm
Frecuencia cardíaca en reposo
50bpm
| Zona | Rango | Qué entrena |
|---|---|---|
| Z1 | Recuperación 118–131 bpm | Recuperación activa y calentamiento; favorece el flujo sanguíneo sin añadir fatiga. Muy fácil, RPE 1–2. Conversación completa, casi sin agitarte. |
| Z2 | Resistencia 131–145 bpm | Base aeróbica, oxidación de grasas y densidad capilar; la zona fundamental del día a día. Cómodo, RPE 3–4. Puedes mantener frases completas. |
| Z3 | Tempo 145–158 bpm | Capacidad aeróbica y resistencia muscular; trabajo continuo 'moderadamente duro'. Exigente, RPE 5–6. Solo frases cortas. |
| Z4 | Umbral 158–172 bpm | Umbral de lactato, tu techo sostenible de ritmo de competición. Duro, RPE 7–8. Unas pocas palabras seguidas. |
| Z5 | VO₂max 172–185 bpm | Potencia aeróbica máxima y VO₂max mediante intervalos cortos e intensos. Muy duro a máximo, RPE 9–10. Sin hablar. |
Z1 · Recuperación. Recuperación activa y calentamiento; favorece el flujo sanguíneo sin añadir fatiga. Muy fácil, RPE 1–2. Conversación completa, casi sin agitarte.
Z2 · Resistencia. Base aeróbica, oxidación de grasas y densidad capilar; la zona fundamental del día a día. Cómodo, RPE 3–4. Puedes mantener frases completas.
Z3 · Tempo. Capacidad aeróbica y resistencia muscular; trabajo continuo 'moderadamente duro'. Exigente, RPE 5–6. Solo frases cortas.
Z4 · Umbral. Umbral de lactato, tu techo sostenible de ritmo de competición. Duro, RPE 7–8. Unas pocas palabras seguidas.
Z5 · VO₂max. Potencia aeróbica máxima y VO₂max mediante intervalos cortos e intensos. Muy duro a máximo, RPE 9–10. Sin hablar.
- Karvonen ancla las zonas a tu reserva de frecuencia cardíaca (HRmax − FC en reposo), por lo que personaliza las zonas según tu condición física mejor que el simple %HRmax: un atleta en forma con una FC en reposo baja obtiene objetivos proporcionalmente más bajos.
- Mide la frecuencia cardíaca en reposo a primera hora de la mañana, tumbado, antes de la cafeína. Un error de 5 bpm en la FC en reposo desplaza todas las zonas.
Un PDF con tus resultados personalizados, más un código QR para volver a abrirlos cuando quieras.
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