Heart Rate Reserve (HRR)
Heart Rate Reserve is the difference between your maximum heart rate and resting heart rate. It represents your available heart rate range for exercise and is the foundation of the Karvonen method for calculating personalized training zones.
Heart Rate Reserve (HRR) quantifies the gap between your heart's maximum capacity and its baseline at rest. A higher HRR indicates greater cardiovascular headroom for training. For example, a runner with a max HR of 190 and a resting HR of 55 has an HRR of 135 bpm — meaning they have 135 beats per minute of usable range for exercise intensity.
The Formula
Heart Rate Reserve
HRR = Max HR − Resting HR
Why HRR Matters
Simple %MaxHR methods treat all runners as identical. But two runners with the same max HR of 190 can have vastly different fitness levels based on their resting heart rate.
Runner A: Max 190, Resting 80. At 70% MaxHR = 133 bpm. But 133 bpm is only 53 beats above rest — a light effort for this runner.
Runner B: Max 190, Resting 50. At 70% HRR = (140 × 0.70) + 50 = 148 bpm. The Karvonen method correctly gives a higher target that reflects this runner's superior fitness.
How to Calculate
Determine your maximum heart rate through a field test or use the estimate 220 − age.
Measure your resting heart rate: take your pulse for 60 seconds immediately upon waking, before getting out of bed. Average 3-5 morning readings.
Subtract resting HR from max HR. The result is your Heart Rate Reserve.
- Measure first thing in the morning, before getting out of bed or drinking coffee.
- Use a chest strap or wrist HR monitor for accuracy. Manual pulse counting works too — count for 60 seconds.
- Average 3-5 consecutive morning readings to account for daily variation.
- Illness, stress, alcohol, and poor sleep can all elevate resting HR. Discard outlier readings.
Training Zones Using HRR
50–60%
Active recovery and warm-ups
60–70%
Easy runs and long runs
70–80%
Marathon-effort sustained runs
80–90%
Lactate threshold training
90–100%
High-intensity intervals
FAQ
Q. What is a normal resting heart rate for runners?
Most adults range from 60-100 bpm. Regular runners typically see 50-60 bpm, while elite endurance athletes can be as low as 35-45 bpm. A lower resting HR generally indicates better cardiovascular fitness.
Q. Does HRR change as I get fitter?
Yes. As fitness improves, resting HR drops while max HR stays roughly the same, so your HRR increases. This means you have a wider effective training range — recalculate your zones every 4-8 weeks.
Q. Can I use HRR if I take heart rate medication?
Beta-blockers and some other medications lower both max and resting HR, which affects HRR calculations. Consult your doctor and consider using Rate of Perceived Exertion (RPE) instead.
Calculate Your Training Zones
Use the Karvonen formula with your Heart Rate Reserve to get personalized, accurate training zones.