Understanding Heart Rate Zones for Training
Heart rate training zones are a popular method for structuring exercise intensity. By monitoring your heart rate, you can ensure you're training at the right level for your goals, whether it's improving cardiovascular health, building endurance, or enhancing performance. These zones are typically based on a percentage of your maximum heart rate (MHR).
The five common heart rate training zones are:
- Zone 1 (Very Light): 50-60% of MHR. Recovery, very easy effort.
- Zone 2 (Light): 60-70% of MHR. Aerobic base, comfortable pace.
- Zone 3 (Moderate): 70-80% of MHR. Aerobic capacity, sustainable but challenging. This is the zone we will calculate.
- Zone 4 (Hard): 80-90% of MHR. Lactate threshold, race pace.
- Zone 5 (Maximum): 90-100% of MHR. Anaerobic, very short bursts of intense effort.
This calculator focuses on Zone 3, often referred to as the "moderate" or "aerobic" zone. Training in Zone 3 improves your aerobic fitness and endurance. It's a sustainable intensity that allows you to maintain a conversation but with some effort.
How to Estimate Your Maximum Heart Rate (MHR)
A common, though simplified, formula to estimate your MHR is 220 minus your age. For example, for a 30-year-old, the estimated MHR would be 220 – 30 = 190 beats per minute (bpm). More accurate methods exist, such as a graded exercise test performed under medical supervision.
function calculateZone3() {
var age = parseFloat(document.getElementById("age").value);
var restingHeartRate = parseFloat(document.getElementById("restingHeartRate").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
if (isNaN(age) || age <= 0) {
resultDiv.innerHTML = 'Please enter a valid age.';
return;
}
if (isNaN(restingHeartRate) || restingHeartRate = 220) {
resultDiv.innerHTML = 'Please enter a valid resting heart rate (e.g., 50-90 bpm).';
return;
}
// Estimate Maximum Heart Rate (MHR) using the 220-age formula
var maxHeartRate = 220 – age;
// Calculate Heart Rate Reserve (HRR)
var heartRateReserve = maxHeartRate – restingHeartRate;
// Calculate Zone 3 lower and upper bounds
// Zone 3 is 70-80% of MHR. Some methods use HRR for zones.
// For simplicity and common usage, we'll stick to % of MHR for Zone 3.
// A more advanced calculation might involve Karvonen formula for other zones.
var zone3LowerBound = 0.70 * maxHeartRate;
var zone3UpperBound = 0.80 * maxHeartRate;
// Ensure bounds are not lower than resting heart rate or above MHR
zone3LowerBound = Math.max(zone3LowerBound, restingHeartRate);
zone3UpperBound = Math.min(zone3UpperBound, maxHeartRate);
// Check for edge cases where calculated bounds might be invalid
if (zone3LowerBound >= zone3UpperBound) {
resultDiv.innerHTML = 'Calculation resulted in an invalid range. Please check your inputs.';
return;
}
var outputHTML = '
';
outputHTML += 'Your Zone 3 (Moderate Intensity) is approximately:';
outputHTML += '
';
outputHTML += '(70% to 80% of your Estimated Maximum Heart Rate)';
resultDiv.innerHTML = outputHTML;
}