Heart Rate During Exercise Calculator

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Heart Rate During Exercise Calculator

70%

Your Exercise Metrics

Maximum Heart Rate (MHR): —
Target Heart Rate at 70%: —

Recommended Training Zones:

function calculateHeartRate() { var age = parseFloat(document.getElementById("userAge").value); var rhr = parseFloat(document.getElementById("restingHR").value); var intensity = parseFloat(document.getElementById("intensity").value) / 100; if (isNaN(age) || isNaN(rhr) || age <= 0 || rhr <= 0) { alert("Please enter valid positive numbers for age and resting heart rate."); return; } // Formulas: Karvonen Formula // Max HR = 220 – Age // Heart Rate Reserve (HRR) = Max HR – Resting HR // Target HR = (HRR * Intensity) + Resting HR var mhr = 220 – age; var hrr = mhr – rhr; var targetHR = Math.round((hrr * intensity) + rhr); document.getElementById("maxHRResult").innerText = mhr + " BPM"; document.getElementById("targetHRResult").innerText = targetHR + " BPM"; document.getElementById("targetIntensityLabel").innerText = intensity * 100; var zones = [ { name: "Warm Up (50-60%)", low: 0.50, high: 0.60, color: "#9e9e9e" }, { name: "Fat Burn (60-70%)", low: 0.60, high: 0.70, color: "#4caf50" }, { name: "Aerobic (70-80%)", low: 0.70, high: 0.80, color: "#2196f3" }, { name: "Anaerobic (80-90%)", low: 0.80, high: 0.90, color: "#ff9800" }, { name: "Red Line (90-100%)", low: 0.90, high: 1.00, color: "#f44336" } ]; var zonesHtml = ""; for (var i = 0; i < zones.length; i++) { var lowRate = Math.round((hrr * zones[i].low) + rhr); var highRate = Math.round((hrr * zones[i].high) + rhr); zonesHtml += '
' + '' + zones[i].name + '' + '' + lowRate + ' – ' + highRate + ' BPM
'; } document.getElementById("zonesTable").innerHTML = zonesHtml; document.getElementById("hrResults").style.display = "block"; }

Understanding Your Heart Rate During Exercise

Monitoring your heart rate during exercise is one of the most effective ways to gauge the intensity of your workout and ensure you are training safely and effectively. Whether your goal is weight loss, cardiovascular endurance, or peak athletic performance, knowing your specific heart rate zones allows you to tailor your effort to meet those objectives.

How the Calculator Works

This tool uses the Karvonen Formula, which is widely considered more accurate than simple age-based formulas because it accounts for your Resting Heart Rate (RHR). By calculating your Heart Rate Reserve (the difference between your maximum capacity and your heart at rest), the calculator provides a personalized target tailored to your current fitness level.

Exercise Intensity Zones Explained

  • Fat Burn Zone (60-70%): At this intensity, your body uses a higher percentage of calories from fat. It is ideal for weight management and building basic endurance.
  • Aerobic Zone (70-80%): This is the "sweet spot" for improving cardiovascular health. It strengthens your heart and increases your lung capacity.
  • Anaerobic Zone (80-90%): Training here improves your lactate threshold. You will breathe hard and feel the "burn" as your body works harder than it can supply oxygen.
  • Red Line Zone (90-100%): This is maximum effort, usually reserved for interval training (HIIT). It should only be maintained for very short bursts.

Example Calculation

Imagine a 40-year-old individual with a resting heart rate of 70 BPM who wants to perform an aerobic workout at 75% intensity:

  1. Max HR: 220 – 40 = 180 BPM
  2. Heart Rate Reserve: 180 – 70 = 110 BPM
  3. Target Heart Rate: (110 × 0.75) + 70 = 82.5 + 70 = 153 BPM

Important Safety Note

While calculating target heart rates is helpful, always listen to your body. If you feel dizzy, short of breath, or experience chest pain, stop exercising immediately. Consult with a healthcare professional before starting a new vigorous exercise program, especially if you have underlying health conditions or are taking medications that affect heart rate, such as beta-blockers.

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