17 Heart Rate Reserve is Used to Calculate

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Heart Rate Reserve (HRR) & Karvonen Calculator

Intensity: 70%

Your Cardiac Profile

Estimated Max HR: –
Heart Rate Reserve (HRR): –
Target Heart Rate: –

Calculated using the Karvonen Formula.

function calculateHRR() { var age = parseFloat(document.getElementById('ageInput').value); var rhr = parseFloat(document.getElementById('restingHRInput').value); var intensity = parseFloat(document.getElementById('intensityInput').value); var resultArea = document.getElementById('hrrResultArea'); if (isNaN(age) || isNaN(rhr) || age <= 0 || rhr <= 0) { alert("Please enter valid positive numbers for Age and Resting Heart Rate."); return; } // Standard Max HR formula var maxHR = 220 – age; // Heart Rate Reserve calculation var hrr = maxHR – rhr; // Target Heart Rate via Karvonen Formula // THR = (HRR * Intensity%) + RHR var targetHR = (hrr * (intensity / 100)) + rhr; document.getElementById('maxHRResult').innerText = Math.round(maxHR) + " BPM"; document.getElementById('hrrResult').innerText = Math.round(hrr) + " BPM"; document.getElementById('targetHRResult').innerText = Math.round(targetHR) + " BPM"; resultArea.style.display = 'block'; }

What is Heart Rate Reserve (HRR) and How is it Used?

Heart Rate Reserve (HRR) is a sophisticated cardiovascular metric used to calculate specific training intensities. Unlike a simple percentage of your Maximum Heart Rate, HRR accounts for your individual fitness level by incorporating your Resting Heart Rate (RHR) into the equation.

The Karvonen Formula

The 17 heart rate reserve is used to calculate the specific Target Heart Rate (THR) zones that professional athletes and cardiologists use to measure effort. The formula is expressed as:

Target Heart Rate = (Heart Rate Reserve × Intensity%) + Resting Heart Rate

Why Use HRR Instead of Max HR?

Using Heart Rate Reserve is more accurate because it reflects the dynamic range of your heart. For example, two 40-year-olds both have an estimated Max HR of 180 BPM. However, if one is an athlete with an RHR of 50 and the other is sedentary with an RHR of 80, their "available" heart rate capacity is drastically different. HRR captures this nuance.

Typical HRR Training Zones

  • Moderate Intensity (Fat Burning): 50% to 60% of HRR.
  • Aerobic Endurance: 60% to 70% of HRR.
  • Anaerobic Threshold: 80% to 90% of HRR.

Example Calculation

If you are 30 years old with a resting heart rate of 60 BPM:

  1. Max HR: 220 – 30 = 190 BPM.
  2. Heart Rate Reserve: 190 – 60 = 130 BPM.
  3. Target (70% Intensity): (130 × 0.70) + 60 = 151 BPM.

In this scenario, your heart rate reserve is used to calculate that 151 BPM is your ideal target for a 70% intensity workout.

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