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.
Riserva di frequenza cardiaca
135bpm
185 − 50
Frequenza cardiaca massima
185bpm
Frequenza cardiaca a riposo
50bpm
| Zona | Intervallo | Cosa allena |
|---|---|---|
| Z1 | Recupero 118–131 bpm | Recupero attivo e riscaldamento; favorisce il flusso sanguigno senza aggiungere fatica. Molto facile, RPE 1–2. Conversazione completa, respirazione appena accelerata. |
| Z2 | Resistenza 131–145 bpm | Base aerobica, ossidazione dei grassi e densità capillare: la zona fondamentale, pane quotidiano dell'allenamento. Comodo, RPE 3–4. Puoi reggere frasi intere. |
| Z3 | Tempo 145–158 bpm | Capacità aerobica e resistenza muscolare; lavoro costante 'moderatamente duro'. Impegnativo, RPE 5–6. Solo frasi brevi. |
| Z4 | Soglia 158–172 bpm | Soglia del lattato, il tetto sostenibile del tuo ritmo gara. Duro, RPE 7–8. Poche parole alla volta. |
| Z5 | VO₂max 172–185 bpm | Potenza aerobica massimale e VO₂max tramite intervalli brevi e intensi. Da molto duro a massimale, RPE 9–10. Non si parla. |
Z1 · Recupero. Recupero attivo e riscaldamento; favorisce il flusso sanguigno senza aggiungere fatica. Molto facile, RPE 1–2. Conversazione completa, respirazione appena accelerata.
Z2 · Resistenza. Base aerobica, ossidazione dei grassi e densità capillare: la zona fondamentale, pane quotidiano dell'allenamento. Comodo, RPE 3–4. Puoi reggere frasi intere.
Z3 · Tempo. Capacità aerobica e resistenza muscolare; lavoro costante 'moderatamente duro'. Impegnativo, RPE 5–6. Solo frasi brevi.
Z4 · Soglia. Soglia del lattato, il tetto sostenibile del tuo ritmo gara. Duro, RPE 7–8. Poche parole alla volta.
Z5 · VO₂max. Potenza aerobica massimale e VO₂max tramite intervalli brevi e intensi. Da molto duro a massimale, RPE 9–10. Non si parla.
- Karvonen àncora le zone alla tua riserva di frequenza cardiaca (HRmax − FC a riposo), quindi personalizza le zone in base alla tua forma meglio del semplice %HRmax: un atleta allenato con una FC a riposo bassa ottiene obiettivi corrispondentemente più bassi.
- Misura la frequenza cardiaca a riposo appena sveglio al mattino, da sdraiato, prima della caffeina. Un errore di 5 bpm nella FC a riposo sposta ogni zona.
Un PDF con i tuoi risultati, più un codice QR per riaprirli quando vuoi.
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