Heart Rate Reserve (Karvonen) Calculator
Understanding the Heart Rate Reserve (HRR) Method
The Heart Rate Reserve (HRR) method, also known as the Karvonen Formula, is one of the most accurate ways to determine cardiovascular exercise intensity. Unlike the simple percentage of Max Heart Rate method, the HRR method accounts for your resting heart rate (RHR), which is a significant indicator of your current fitness level.
The Karvonen Formula Explained
The formula calculates your Target Heart Rate (THR) using the following steps:
- Max Heart Rate (MHR): 220 – Age.
- Heart Rate Reserve (HRR): Max HR – Resting HR.
- Target Heart Rate: (HRR × % Intensity) + Resting HR.
Example Calculation
Imagine a 40-year-old individual with a resting heart rate of 70 BPM who wants to train at 70% intensity:
- Max HR: 220 – 40 = 180 BPM
- HRR: 180 – 70 = 110 BPM
- Target HR: (110 × 0.70) + 70 = 77 + 70 = 147 BPM
Intensity Training Zones
| Intensity Level | HRR % Range | Benefit |
|---|---|---|
| Light | 40% – 50% | Warm-up, recovery, basic health maintenance. |
| Moderate | 50% – 70% | Fat burning, aerobic endurance, base building. |
| Vigorous | 70% – 85% | Improved aerobic capacity, athletic performance. |
| Anaerobic | 85% – 95% | Increased speed and power, high-intensity intervals. |
Why Is the HRR Method Better?
Traditional calculations often overestimate target zones for beginners and underestimate them for fit individuals. By incorporating your resting heart rate—which typically lowers as you become more cardiovascularly fit—the HRR method provides a personalized training range that evolves with your fitness journey. If your resting heart rate drops due to improved health, your target zones will adjust automatically to maintain the same relative level of effort.