Heart Rate Reserve (HRR) Calculator
What is Heart Rate Reserve (HRR)?
Heart Rate Reserve (HRR) is the difference between your measured or predicted maximum heart rate and your resting heart rate. It represents the actual "cushion" of heartbeats you have available for physical activity. Unlike simple Max HR calculations, HRR takes into account your baseline cardiovascular fitness (via your resting heart rate), making it a much more personalized metric for training.
The Karvonen Formula
The calculation performed above uses the Karvonen Formula, which is widely considered the gold standard for determining exercise intensity zones. The formula is:
Target Heart Rate = (Heart Rate Reserve × % Intensity) + Resting Heart Rate
Why HRR is Better Than Max HR Alone
Two people might both be 40 years old (Estimated Max HR of 180), but if one has a resting heart rate of 50 and the other 80, their fitness levels are drastically different. HRR adjusts the training zones to reflect these differences, ensuring the athlete with the lower resting heart rate isn't under-training, and the beginner isn't over-exerting.
Typical Training Intensity Zones
| Intensity Level | % of HRR | Benefit |
|---|---|---|
| Very Light | 50% – 60% | Recovery and warming up |
| Light/Fat Burn | 60% – 70% | Basic endurance and weight management |
| Moderate/Aerobic | 70% – 80% | Improving aerobic capacity and cardiovascular health |
| Hard/Anaerobic | 80% – 90% | Increasing speed and lactic acid tolerance |
| Maximum/Elite | 90% – 100% | Maximal performance and sprint speed |
Real-World Example
If you are 30 years old with a resting heart rate of 60 bpm and you want to exercise at 70% intensity:
- Max HR: 220 – 30 = 190 bpm.
- HRR: 190 – 60 = 130 bpm.
- Target Heart Rate: (130 × 0.70) + 60 = 151 bpm.
In this case, 151 beats per minute is your specific target for a 70% aerobic workout.