Your Threshold Heart Rate Zone:
Enter your details above to see your estimated threshold heart rate.
function calculateThresholdHeartRate() {
var age = parseFloat(document.getElementById("age").value);
var restingHeartRate = parseFloat(document.getElementById("restingHeartRate").value);
var maxHeartRate = parseFloat(document.getElementById("maxHeartRate").value);
var resultDiv = document.getElementById("result");
if (isNaN(age) || isNaN(restingHeartRate) || isNaN(maxHeartRate) || age <= 0 || restingHeartRate <= 0 || maxHeartRate = displayUpperBound) {
displayLowerBound = Math.round(maxHeartRate * 0.88); // A fallback if bounds are reversed
displayUpperBound = Math.round(maxHeartRate * 0.92);
if (displayUpperBound > maxHeartRate) displayUpperBound = maxHeartRate;
if (displayLowerBound < restingHeartRate) displayLowerBound = restingHeartRate;
}
resultDiv.innerHTML =
"Estimated Threshold Heart Rate Zone:" +
"
" + displayLowerBound + " – " + displayUpperBound + " BPM";
// Adding a brief explanation about the zone
resultDiv.innerHTML += "
This range indicates the intensity at which your body begins to accumulate lactate faster than it can clear it. Training here improves sustained high-intensity performance.";
}
.calculator-container {
font-family: Arial, sans-serif;
max-width: 600px;
margin: 20px auto;
padding: 20px;
border: 1px solid #ddd;
border-radius: 8px;
box-shadow: 0 2px 5px rgba(0,0,0,0.1);
background-color: #fff;
}
.calculator-container h2 {
text-align: center;
color: #333;
margin-bottom: 20px;
}
.calculator-form p {
font-size: 0.9em;
color: #555;
margin-bottom: 25px;
line-height: 1.5;
}
.form-group {
margin-bottom: 15px;
}
.form-group label {
display: block;
margin-bottom: 5px;
font-weight: bold;
color: #444;
}
.form-group input[type="number"] {
width: calc(100% – 12px);
padding: 8px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box; /* Include padding and border in the element's total width and height */
}
.form-group small {
font-size: 0.8em;
color: #666;
display: block;
margin-top: 5px;
}
button {
background-color: #007bff;
color: white;
padding: 10px 15px;
border: none;
border-radius: 4px;
cursor: pointer;
width: 100%;
font-size: 16px;
transition: background-color 0.3s ease;
}
button:hover {
background-color: #0056b3;
}
.calculator-result {
margin-top: 25px;
padding: 15px;
border-top: 1px solid #eee;
text-align: center;
}
.calculator-result h3 {
color: #333;
margin-bottom: 15px;
}
#result p {
font-size: 1.2em;
color: #007bff;
}
#result p strong {
font-size: 1.5em;
}
#result small {
font-size: 0.85em;
color: #777;
margin-top: 10px;
display: block;
}