Heart Rate Zones Calculation Formula

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Heart Rate Zone Calculator

Your Heart Rate Zones:

Zone 1 (Very Light): bpm

Zone 2 (Light): bpm

Zone 3 (Moderate): bpm

Zone 4 (Hard): bpm

Zone 5 (Maximum): bpm

Understanding Heart Rate Zones

Heart rate zones are ranges of heart rate intensity that correspond to different physiological effects during exercise. They are typically expressed as a percentage of your maximum heart rate (MHR) and are a valuable tool for structuring training, improving cardiovascular fitness, and optimizing performance. The most common method for calculating these zones involves determining your Karvonen formula, which takes into account your resting heart rate.

The Karvonen Formula

The Karvonen formula is a widely used method that provides a more personalized approach to determining heart rate training zones compared to simply using a percentage of your maximum heart rate. It calculates your Heart Rate Reserve (HRR), which is the difference between your maximum heart rate and your resting heart rate. The formula is:

HRR = Maximum Heart Rate – Resting Heart Rate

Then, your target heart rate for a specific zone is calculated as:

Target Heart Rate = (HRR * % Intensity) + Resting Heart Rate

Calculating Maximum Heart Rate (MHR)

A common, though somewhat generalized, formula for estimating Maximum Heart Rate is:

MHR = 220 – Age

It's important to note that this is an estimation, and individual maximum heart rates can vary. For more precise measurements, a supervised exercise stress test may be recommended.

The Five Heart Rate Zones:

  • Zone 1 (Very Light): 50-60% of MHR. This zone is for recovery and cool-downs. It feels very easy and you can talk in full sentences.
  • Zone 2 (Light): 60-70% of MHR. This is your aerobic endurance zone, good for building a base fitness level. You can hold a conversation.
  • Zone 3 (Moderate): 70-80% of MHR. This zone improves aerobic capacity and efficiency. You can speak in shorter sentences.
  • Zone 4 (Hard): 80-90% of MHR. This is your anaerobic threshold zone, improving speed and power. Talking is difficult.
  • Zone 5 (Maximum): 90-100% of MHR. This zone is for very high-intensity intervals and maximum effort. You can only speak a word or two.

Example Calculation:

Let's say you are 30 years old and your resting heart rate is 60 bpm.

  1. Calculate MHR: 220 – 30 = 190 bpm
  2. Calculate HRR: 190 bpm – 60 bpm = 130 bpm
  3. Calculate Zones:
    • Zone 1 (50-60%): (130 * 0.50) + 60 = 125 bpm to (130 * 0.60) + 60 = 138 bpm
    • Zone 2 (60-70%): (130 * 0.60) + 60 = 138 bpm to (130 * 0.70) + 60 = 151 bpm
    • Zone 3 (70-80%): (130 * 0.70) + 60 = 151 bpm to (130 * 0.80) + 60 = 174 bpm
    • Zone 4 (80-90%): (130 * 0.80) + 60 = 174 bpm to (130 * 0.90) + 60 = 177 bpm
    • Zone 5 (90-100%): (130 * 0.90) + 60 = 177 bpm to (130 * 1.00) + 60 = 190 bpm

This calculator uses the Karvonen formula to provide a personalized estimate of your heart rate training zones.

function calculateHeartRateZones() { var age = parseFloat(document.getElementById("age").value); var restingHeartRate = parseFloat(document.getElementById("restingHeartRate").value); var resultDiv = document.getElementById("heartRateZonesResult"); var zone1Span = document.getElementById("zone1"); var zone2Span = document.getElementById("zone2"); var zone3Span = document.getElementById("zone3"); var zone4Span = document.getElementById("zone4"); var zone5Span = document.getElementById("zone5"); if (isNaN(age) || isNaN(restingHeartRate) || age <= 0 || restingHeartRate <= 0) { resultDiv.innerHTML = 'Please enter valid positive numbers for age and resting heart rate.'; return; } // Calculate Maximum Heart Rate (MHR) var maxHeartRate = 220 – age; // Calculate Heart Rate Reserve (HRR) var heartRateReserve = maxHeartRate – restingHeartRate; // Ensure HRR is not negative (in case resting heart rate is very high or age estimation is off) if (heartRateReserve < 0) { heartRateReserve = 0; } // Calculate Heart Rate Zones using Karvonen Formula var zone1Lower = Math.round((heartRateReserve * 0.50) + restingHeartRate); var zone1Upper = Math.round((heartRateReserve * 0.60) + restingHeartRate); var zone2Lower = Math.round((heartRateReserve * 0.60) + restingHeartRate); var zone2Upper = Math.round((heartRateReserve * 0.70) + restingHeartRate); var zone3Lower = Math.round((heartRateReserve * 0.70) + restingHeartRate); var zone3Upper = Math.round((heartRateReserve * 0.80) + restingHeartRate); var zone4Lower = Math.round((heartRateReserve * 0.80) + restingHeartRate); var zone4Upper = Math.round((heartRateReserve * 0.90) + restingHeartRate); var zone5Lower = Math.round((heartRateReserve * 0.90) + restingHeartRate); var zone5Upper = Math.round((heartRateReserve * 1.00) + restingHeartRate); // Ensure upper bounds do not exceed MHR zone1Upper = Math.min(zone1Upper, maxHeartRate); zone2Upper = Math.min(zone2Upper, maxHeartRate); zone3Upper = Math.min(zone3Upper, maxHeartRate); zone4Upper = Math.min(zone4Upper, maxHeartRate); zone5Upper = Math.min(zone5Upper, maxHeartRate); // Ensure lower bounds are not less than resting heart rate or negative zone1Lower = Math.max(zone1Lower, restingHeartRate); zone2Lower = Math.max(zone2Lower, restingHeartRate); zone3Lower = Math.max(zone3Lower, restingHeartRate); zone4Lower = Math.max(zone4Lower, restingHeartRate); zone5Lower = Math.max(zone5Lower, restingHeartRate); zone1Span.textContent = zone1Lower + " – " + zone1Upper; zone2Span.textContent = zone2Lower + " – " + zone2Upper; zone3Span.textContent = zone3Lower + " – " + zone3Upper; zone4Span.textContent = zone4Lower + " – " + zone4Upper; zone5Span.textContent = zone5Lower + " – " + zone5Upper; resultDiv.style.display = "block"; }

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