Best measured in the morning before getting out of bed.
—
Max Heart Rate (BPM)
—
Heart Rate Reserve
Your Metabolic Training Zones
Zone
Intensity
Heart Rate Range
Metabolic Benefit
Understanding Metabolic Heart Rate Training
The Metabolic Heart Rate Calculator uses the Karvonen Formula to determine your optimal training zones based on your age and resting heart rate. Unlike simple calculations that only account for age, this method incorporates your individual fitness level through your resting heart rate (RHR), providing a much more accurate guide for metabolic conditioning.
Why Resting Heart Rate Matters?
Your Resting Heart Rate is a strong indicator of cardiovascular efficiency. A lower RHR typically indicates a stronger heart and better aerobic fitness. By using the Heart Rate Reserve (Max HR – Resting HR) in our calculations, we ensure that the intensity zones are scaled to your specific metabolic capacity.
The 5 Metabolic Zones
Training in specific heart rate zones triggers different metabolic adaptations in the body:
Zone 1 (Recovery): Very light intensity. Promotes blood flow and helps muscles recover without placing stress on the cardiovascular system. Used for warm-ups and cool-downs.
Zone 2 (Aerobic Base / Fat Burning): This is the "metabolic sweet spot" for burning fat. The body relies primarily on fat oxidation for fuel. Training here improves mitochondrial density and endurance.
Zone 3 (Tempo / Aerobic Capacity): A challenging pace where you are building the efficiency of blood circulation. This improves the heart's ability to pump blood and the muscles' ability to utilize oxygen.
Zone 4 (Lactate Threshold): Hard effort. You are training your body to tolerate and clear lactate. This zone improves your ability to sustain high-speed efforts.
Zone 5 (VO2 Max / Anaerobic): Maximum effort. This zone is sustainable for only very short periods. It improves neuromuscular power and top-end speed.
How to Use This Data
To maximize metabolic efficiency, experts often recommend "Polarized Training," where approximately 80% of your training is done in Zones 1 and 2 (building the base), and 20% is done in Zones 4 and 5 (building high-end capacity). Constant training in the "grey zone" (Zone 3) can often lead to fatigue without optimal metabolic adaptation.
Safety Note
Always consult with a physician before starting a new exercise program, especially if you have a history of heart conditions. This calculator provides estimates based on population averages (220 – Age) and should be used as a guideline rather than a medical diagnosis.
function calculateMetabolicHR() {
var age = parseFloat(document.getElementById('ageInput').value);
var rhr = parseFloat(document.getElementById('rhrInput').value);
// Validation
if (isNaN(age) || age 110) {
alert("Please enter a valid age between 10 and 110.");
return;
}
if (isNaN(rhr) || rhr 200) {
alert("Please enter a valid resting heart rate between 30 and 200.");
return;
}
// 1. Calculate Max Heart Rate (Standard Formula)
// Note: Using 220 – Age is standard, though Tanaka (208 – 0.7*age) is also used. We stick to standard for general familiarity.
var maxHR = 220 – age;
// 2. Calculate Heart Rate Reserve (Karvonen Method)
var hrr = maxHR – rhr;
// Display Summary
document.getElementById('maxHRResult').textContent = Math.round(maxHR);
document.getElementById('hrrResult').textContent = Math.round(hrr);
// 3. Calculate Zones
var zones = [
{
name: "Zone 1",
title: "Recovery",
minPct: 0.50,
maxPct: 0.60,
color: "#6c757d",
benefit: "Warm up & Recovery"
},
{
name: "Zone 2",
title: "Fat Burn",
minPct: 0.60,
maxPct: 0.70,
color: "#28a745",
benefit: "Basic Endurance & Fat Burning"
},
{
name: "Zone 3",
title: "Aerobic",
minPct: 0.70,
maxPct: 0.80,
color: "#ffc107",
benefit: "Cardiovascular Fitness"
},
{
name: "Zone 4",
title: "Anaerobic",
minPct: 0.80,
maxPct: 0.90,
color: "#fd7e14",
benefit: "Lactate Tolerance"
},
{
name: "Zone 5",
title: "VO2 Max",
minPct: 0.90,
maxPct: 1.00,
color: "#dc3545",
benefit: "Max Performance & Speed"
}
];
var tableBody = document.getElementById('zonesTableBody');
tableBody.innerHTML = ""; // Clear previous results
for (var i = 0; i < zones.length; i++) {
var zone = zones[i];
// Formula: Target HR = ((MaxHR – RestingHR) * %Intensity) + RestingHR
var minBPM = Math.round((hrr * zone.minPct) + rhr);
var maxBPM = Math.round((hrr * zone.maxPct) + rhr);
var row = document.createElement('tr');
var badgeStyle = "background-color: " + zone.color + ";";
row.innerHTML =
"