body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
max-width: 800px;
margin: 0 auto;
padding: 20px;
}
.ehr-calculator-wrapper {
background-color: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 8px;
padding: 30px;
margin-bottom: 40px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.ehr-header {
text-align: center;
margin-bottom: 25px;
}
.ehr-header h2 {
margin: 0;
color: #d32f2f;
font-size: 24px;
}
.ehr-input-group {
margin-bottom: 20px;
}
.ehr-input-group label {
display: block;
font-weight: 600;
margin-bottom: 8px;
color: #495057;
}
.ehr-input-group input {
width: 100%;
padding: 12px;
border: 1px solid #ced4da;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.ehr-input-group input:focus {
border-color: #d32f2f;
outline: none;
box-shadow: 0 0 0 3px rgba(211, 47, 47, 0.1);
}
.ehr-btn {
width: 100%;
background-color: #d32f2f;
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background-color 0.2s;
}
.ehr-btn:hover {
background-color: #b71c1c;
}
#ehr-results {
margin-top: 30px;
display: none;
border-top: 2px solid #dee2e6;
padding-top: 20px;
}
.ehr-summary-box {
background-color: #fff;
border-left: 5px solid #d32f2f;
padding: 15px;
margin-bottom: 20px;
box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}
.ehr-stat-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
font-size: 16px;
}
.ehr-stat-value {
font-weight: bold;
color: #d32f2f;
}
.ehr-zone-table {
width: 100%;
border-collapse: collapse;
margin-top: 20px;
background: white;
}
.ehr-zone-table th, .ehr-zone-table td {
padding: 12px;
text-align: left;
border-bottom: 1px solid #dee2e6;
}
.ehr-zone-table th {
background-color: #f1f3f5;
color: #495057;
}
.ehr-zone-5 { color: #d32f2f; font-weight: bold; }
.ehr-zone-4 { color: #f57c00; font-weight: bold; }
.ehr-zone-3 { color: #fbc02d; font-weight: bold; }
.ehr-zone-2 { color: #388e3c; font-weight: bold; }
.ehr-zone-1 { color: #1976d2; font-weight: bold; }
.ehr-content {
line-height: 1.8;
color: #212529;
}
.ehr-content h2 {
color: #212529;
margin-top: 40px;
}
.ehr-content h3 {
color: #495057;
}
.ehr-disclaimer {
font-size: 0.85em;
color: #6c757d;
background: #f8f9fa;
padding: 15px;
border-radius: 4px;
margin-top: 40px;
border: 1px solid #dee2e6;
}
Understanding Your Elevated Heart Rate
Monitoring your heart rate is one of the most effective ways to gauge the intensity of your physical activity and ensure safety. An "elevated" heart rate is necessary during exercise to strengthen the heart muscle and improve circulation, but understanding the boundaries between a healthy workout zone and a dangerous pulse is critical.
Why Use the Karvonen Formula?
This calculator utilizes the Karvonen Formula, which is widely considered more accurate for individuals than the simple "220 minus age" method. The Karvonen method takes your Resting Heart Rate (RHR) into account.
Because people with higher fitness levels generally have lower resting heart rates, ignoring RHR can lead to target zones that are too low for fit individuals or too high for beginners. The formula used is:
Target HR = ((Max HR − Resting HR) × %Intensity) + Resting HR
What is an Elevated Heart Rate?
In a medical context, a resting heart rate consistently above 100 beats per minute (bpm) is known as tachycardia. However, in the context of fitness, we intentionally elevate the heart rate to achieve specific physiological adaptations:
1. Moderate Elevation (50-70%)
Often referred to as the "Fat Burn" zone. At this level, your heart rate is elevated enough to burn calories and improve basic endurance, but you should still be able to carry on a conversation. This is the safest zone for extended durations.
2. Vigorous Elevation (70-85%)
This is the "Cardio" or aerobic zone. Training here improves your cardiovascular system's ability to transport oxygen. You will breathe heavily and sweat, and talking will become difficult.
3. Peak Elevation (85-100%)
This is the anaerobic zone, utilized for short bursts of high-intensity interval training (HIIT). It helps improve speed and power but produces lactic acid quickly. Spending too much time in this zone without medical clearance can be dangerous.
When is a Heart Rate Too High?
Your calculated Maximum Heart Rate (MHR) represents the theoretical upper limit your heart can handle during extreme exertion. It is generally not recommended to exceed your MHR. If you experience chest pain, severe shortness of breath, dizziness, or palpitations while your heart rate is elevated, stop exercising immediately and seek medical attention.
Medical Disclaimer: This calculator is for educational and fitness planning purposes only. It does not constitute medical advice. If you have a history of heart conditions, high blood pressure, or are taking medication (like beta-blockers) that affects heart rate, consult a physician before starting a new exercise regimen.
function calculateHeartRateZones() {
// 1. Get Input Values
var ageInput = document.getElementById('ehr_age');
var rhrInput = document.getElementById('ehr_rhr');
var resultDiv = document.getElementById('ehr-results');
var age = parseFloat(ageInput.value);
var rhr = parseFloat(rhrInput.value);
// 2. Validation
if (isNaN(age) || age 120) {
alert("Please enter a valid age between 1 and 120.");
return;
}
if (isNaN(rhr) || rhr 200) {
alert("Please enter a valid resting heart rate between 30 and 200 bpm.");
return;
}
// 3. Core Calculations
// Standard Formula for Max Heart Rate: 220 – Age
var maxHR = 220 – age;
// Heart Rate Reserve (HRR) = Max HR – Resting HR
var hrr = maxHR – rhr;
// Check for negative reserve (if RHR > MaxHR, which implies invalid input for this logic)
if (hrr <= 0) {
alert("Your Resting Heart Rate is higher than your estimated Maximum Heart Rate. Please check your inputs.");
return;
}
// 4. Calculate Zones (Karvonen Formula)
// Formula: (HRR * intensity) + RHR
function calcZone(percentage) {
return Math.round((hrr * percentage) + rhr);
}
var z1_min = calcZone(0.50);
var z1_max = calcZone(0.60);
var z2_min = calcZone(0.60);
var z2_max = calcZone(0.70);
var z3_min = calcZone(0.70);
var z3_max = calcZone(0.80);
var z4_min = calcZone(0.80);
var z4_max = calcZone(0.90);
var z5_min = calcZone(0.90);
var z5_max = calcZone(1.00); // Should equal MaxHR
// 5. Update UI
document.getElementById('res-mhr').innerHTML = maxHR + " bpm";
document.getElementById('res-hrr').innerHTML = hrr + " bpm";
document.getElementById('row-z1').innerHTML = z1_min + " – " + z1_max;
document.getElementById('row-z2').innerHTML = z2_min + " – " + z2_max;
document.getElementById('row-z3').innerHTML = z3_min + " – " + z3_max;
document.getElementById('row-z4').innerHTML = z4_min + " – " + z4_max;
document.getElementById('row-z5').innerHTML = z5_min + " – " + z5_max;
// Show results
resultDiv.style.display = "block";
// Scroll to results
resultDiv.scrollIntoView({behavior: "smooth"});
}