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.
Hartslagreserve
135bpm
185 − 50
Maximale hartslag
185bpm
Rusthartslag
50bpm
| Zone | Bereik | Wat het traint |
|---|---|---|
| Z1 | Herstel 118–131 bpm | Actief herstel en opwarming; bevordert de doorbloeding zonder vermoeidheid toe te voegen. Heel makkelijk, RPE 1–2. Volledig gesprek mogelijk, nauwelijks buiten adem. |
| Z2 | Duurvermogen 131–145 bpm | Aerobe basis, vetverbranding en capillaire dichtheid, de brood-en-boterzone. Comfortabel, RPE 3–4. Volledige zinnen mogelijk. |
| Z3 | Tempo 145–158 bpm | Aerobe capaciteit en spierduurvermogen; 'matig zwaar' constant werk. Inspannend, RPE 5–6. Alleen korte zinnen. |
| Z4 | Drempel 158–172 bpm | Lactaatdrempel, je houdbare wedstrijdtempo-plafond. Zwaar, RPE 7–8. Een paar woorden per keer. |
| Z5 | VO₂max 172–185 bpm | Maximaal aeroob vermogen en VO₂max via korte, harde intervallen. Heel zwaar tot maximaal, RPE 9–10. Praten lukt niet. |
Z1 · Herstel. Actief herstel en opwarming; bevordert de doorbloeding zonder vermoeidheid toe te voegen. Heel makkelijk, RPE 1–2. Volledig gesprek mogelijk, nauwelijks buiten adem.
Z2 · Duurvermogen. Aerobe basis, vetverbranding en capillaire dichtheid, de brood-en-boterzone. Comfortabel, RPE 3–4. Volledige zinnen mogelijk.
Z3 · Tempo. Aerobe capaciteit en spierduurvermogen; 'matig zwaar' constant werk. Inspannend, RPE 5–6. Alleen korte zinnen.
Z4 · Drempel. Lactaatdrempel, je houdbare wedstrijdtempo-plafond. Zwaar, RPE 7–8. Een paar woorden per keer.
Z5 · VO₂max. Maximaal aeroob vermogen en VO₂max via korte, harde intervallen. Heel zwaar tot maximaal, RPE 9–10. Praten lukt niet.
- Karvonen verankert zones aan je hartslagreserve (HRmax − rusthartslag), waardoor het zones beter personaliseert op je fitheid dan alleen %HRmax; een fitte sporter met een lage rusthartslag krijgt navenant lagere doelen.
- Meet je rusthartslag direct na het ontwaken, liggend, vóór cafeïne. Een fout van 5 bpm in de rusthartslag verschuift elke zone.
Een PDF met je resultaten, plus een QR-code om ze altijd opnieuw te openen.
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