Weight Loss Heart Rate Calculator

Weight Loss Heart Rate Calculator: Optimize Your Fat Burning Zone :root { –primary-color: #004a99; –success-color: #28a745; –background-color: #f8f9fa; –text-color: #333; –secondary-text-color: #666; –border-color: #ddd; –card-background: #ffffff; –shadow: 0 2px 5px rgba(0,0,0,0.1); } body { font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; background-color: var(–background-color); color: var(–text-color); line-height: 1.6; margin: 0; padding: 0; } .container { max-width: 1000px; margin: 20px auto; padding: 20px; background-color: var(–card-background); border-radius: 8px; box-shadow: var(–shadow); } header { text-align: center; margin-bottom: 30px; padding-bottom: 20px; border-bottom: 1px solid var(–border-color); } header h1 { color: var(–primary-color); margin-bottom: 10px; } .calculator-section { margin-bottom: 40px; padding-bottom: 30px; border-bottom: 1px solid var(–border-color); } .calculator-section h2 { color: var(–primary-color); text-align: center; margin-bottom: 25px; 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Weight Loss Heart Rate Calculator

Determine your target heart rate zone for effective fat burning during exercise.

Calculate Your Fat Burning Heart Rate Zone

Enter your age in years.
Optional: If known, otherwise use estimated MHR.
Measure upon waking, before getting out of bed.
50-60% (Light – Warm-up/Recovery) 60-70% (Moderate – Fat Burning Zone) 70-80% (Aerobic – Cardiovascular Improvement) 80-90% (Vigorous – Performance Training) Select your desired exercise intensity.

Your Target Heart Rate for Weight Loss

BPM
Estimated MHR (BPM)
Heart Rate Reserve (HRR) (BPM)
Lower Target Zone (BPM)
Upper Target Zone (BPM)

Heart Rate Zones Overview

Visual representation of different heart rate training zones.

Heart Rate Zone Details

Zone Name Percentage of MHR Intensity Level Primary Benefit Target Heart Rate (BPM)

Detailed breakdown of heart rate training zones for exercise.

What is the Weight Loss Heart Rate Calculator?

The weight loss heart rate calculator is a tool designed to help individuals identify their optimal heart rate range for maximizing fat calorie expenditure during aerobic exercise. It utilizes age and, optionally, resting heart rate to estimate maximum heart rate and then calculates target heart rate zones. The primary focus for weight loss is typically the moderate intensity zone, often referred to as the "fat-burning zone". This weight loss heart rate calculator assists in ensuring your workouts are challenging enough to burn calories effectively without being excessively strenuous, which can lead to burnout or injury.

Who Should Use It?

Anyone looking to lose weight through exercise can benefit from using a weight loss heart rate calculator. This includes:

  • Beginners aiming to establish a safe and effective exercise routine.
  • Intermediate exercisers wanting to optimize their current workouts for better fat loss results.
  • Individuals who want to understand the science behind heart rate training and its impact on calorie burn.
  • People who have been exercising consistently but not seeing desired weight loss outcomes.

Common Misconceptions

  • Myth: Higher heart rate always means more fat burning. While higher intensity burns more calories per minute, the percentage of fat burned relative to total calories might be lower. The moderate zone often offers the best balance for sustained fat loss.
  • Myth: One-size-fits-all formula. The widely used Tanaka formula (208 – 0.7 x age) is an estimation. Individual maximum heart rates can vary significantly. Factors like genetics, fitness level, and medication can affect actual MHR.
  • Myth: You must stay in the fat-burning zone exclusively. A well-rounded fitness plan includes various intensity levels. Higher intensity intervals can boost metabolism and calorie burn even after the workout is complete (EPOC).

Weight Loss Heart Rate Calculator Formula and Mathematical Explanation

The weight loss heart rate calculator typically employs a two-step process: estimating Maximum Heart Rate (MHR) and then calculating target heart rate zones based on that MHR and the desired intensity percentage. A common and widely accepted formula for estimating MHR is the Tanaka formula, which is an update to the older, less accurate formula.

Step-by-Step Derivation

  1. Estimate Maximum Heart Rate (MHR): The most common formula used in modern calculators is:

    MHR = 208 - (0.7 * Age)

    Where 'Age' is your age in years. This formula is generally considered more accurate across a wider age range than previous estimations.
  2. Calculate Heart Rate Reserve (HRR): This is the difference between your MHR and your Resting Heart Rate (RHR). It represents the range of heartbeats available for exercise.

    HRR = MHR - RHR
  3. Determine Target Heart Rate Zone: The target heart rate (THR) for a specific intensity percentage is calculated using the Karvonen formula, which incorporates HRR:

    THR = (HRR * Intensity Percentage) + RHR

    For example, to find the lower end of the moderate fat-burning zone (60% intensity):

    Lower Target Heart Rate = ((MHR - RHR) * 0.60) + RHR

    And for the upper end (70% intensity):

    Upper Target Heart Rate = ((MHR - RHR) * 0.70) + RHR

Variables Explained

Variable Meaning Unit Typical Range / Input
Age Your current age in years. Years 18 – 80+
MHR Maximum Heart Rate – the highest number of times your heart can beat per minute during maximal exertion. Beats Per Minute (BPM) Estimated: 208 – (0.7 * Age)
RHR Resting Heart Rate – your heart rate when completely at rest, typically measured in the morning. Beats Per Minute (BPM) 30 – 100 (Lower is generally better fitness)
HRR Heart Rate Reserve – the difference between MHR and RHR, indicating available heart rate capacity for exercise. Beats Per Minute (BPM) MHR – RHR
Intensity Percentage The target percentage of MHR or HRR to aim for during exercise, defining the training zone. % 0% to 100% (Categorized into zones)
THR Target Heart Rate – the specific heart rate range you should aim for during your workout based on intensity. Beats Per Minute (BPM) Calculated based on HRR and Intensity Percentage

Using this weight loss heart rate calculator allows you to personalize these calculations, making your exercise efforts more efficient and targeted towards your fitness goals. Proper use of a weight loss heart rate calculator can significantly enhance your workout effectiveness and contribute to sustainable weight management.

Practical Examples (Real-World Use Cases)

Example 1: Sarah, Age 40, Seeking Moderate Exercise

Sarah is 40 years old and wants to incorporate moderate-intensity cardio into her routine 3-4 times a week to lose weight. She measures her resting heart rate (RHR) and finds it to be 68 BPM.

Inputs:

  • Age: 40 years
  • Resting Heart Rate (RHR): 68 BPM
  • Desired Intensity: 60-70% (Moderate – Fat Burning Zone)

Calculations:

  • Estimated MHR = 208 – (0.7 * 40) = 208 – 28 = 180 BPM
  • Heart Rate Reserve (HRR) = 180 (MHR) – 68 (RHR) = 112 BPM
  • Lower Target Heart Rate (60%) = (112 * 0.60) + 68 = 67.2 + 68 = 135.2 BPM
  • Upper Target Heart Rate (70%) = (112 * 0.70) + 68 = 78.4 + 68 = 146.4 BPM

Outputs & Interpretation:

  • Estimated MHR: 180 BPM
  • Heart Rate Reserve: 112 BPM
  • Target Fat Burning Zone: 135 – 146 BPM

Sarah should aim to keep her heart rate between 135 and 146 beats per minute during her cardio sessions. This range ensures she is exercising at a moderate intensity that effectively burns calories from fat while being sustainable for longer durations. She can use this information with her cardio workout planner to structure her sessions.

Example 2: David, Age 55, Improving Cardiovascular Health

David is 55 years old and has been advised by his doctor to increase his physical activity to improve cardiovascular health and aid in weight loss. His RHR is 72 BPM.

Inputs:

  • Age: 55 years
  • Resting Heart Rate (RHR): 72 BPM
  • Desired Intensity: 70-80% (Aerobic – Cardiovascular Improvement)

Calculations:

  • Estimated MHR = 208 – (0.7 * 55) = 208 – 38.5 = 169.5 BPM
  • Heart Rate Reserve (HRR) = 169.5 (MHR) – 72 (RHR) = 97.5 BPM
  • Lower Target Heart Rate (70%) = (97.5 * 0.70) + 72 = 68.25 + 72 = 140.25 BPM
  • Upper Target Heart Rate (80%) = (97.5 * 0.80) + 72 = 78 + 72 = 150 BPM

Outputs & Interpretation:

  • Estimated MHR: 170 BPM (rounded)
  • Heart Rate Reserve: 98 BPM (rounded)
  • Target Aerobic Zone: 140 – 150 BPM

David's target heart rate for cardiovascular improvement and weight loss is between 140 and 150 BPM. This slightly higher intensity will challenge his cardiovascular system more effectively, leading to greater calorie expenditure and improved heart health over time. He should monitor his perceived exertion and adjust as needed, possibly using a heart rate monitor guide.

How to Use This Weight Loss Heart Rate Calculator

Using the weight loss heart rate calculator is straightforward and provides valuable insights for your fitness journey. Follow these simple steps:

Step-by-Step Instructions

  1. Enter Your Age: Input your current age in the designated field. This is the primary factor for estimating your Maximum Heart Rate (MHR).
  2. Input Resting Heart Rate (RHR): Measure your RHR accurately. The best time is right after waking up in the morning before getting out of bed. This provides a more personalized calculation. If you don't know it or cannot measure it, the calculator will use a default average, but it will be less precise.
  3. Estimate Maximum Heart Rate (MHR) (Optional): If you know your actual MHR from a stress test or previous specific testing, you can input it. Otherwise, leave this blank, and the calculator will estimate it based on your age using the Tanaka formula.
  4. Select Intensity Level: Choose the desired exercise intensity from the dropdown menu. For weight loss, the "Moderate – Fat Burning Zone" (typically 60-70% of MHR or HRR) is often recommended for sustained fat calorie burn. However, higher intensities also contribute significantly to overall calorie expenditure and metabolic boost.
  5. Click Calculate: Press the 'Calculate' button. The calculator will instantly display your results.

How to Read Results

  • Estimated MHR: Your estimated highest possible heart rate during intense exercise.
  • Heart Rate Reserve (HRR): The range your heart rate can fluctuate within during exercise.
  • Target Heart Rate Zone: This is the crucial output. It shows the lower and upper limits (in BPM) your heart rate should be within during your workout to achieve the selected intensity level.
  • Formula Explanation: A brief description of the formulas used (e.g., Tanaka for MHR, Karvonen for THR) is provided.
  • Zone Details Table: This table offers a broader view of different training zones and their benefits.
  • Chart: The visual chart helps you quickly understand where your target zone fits relative to other intensities.

Decision-Making Guidance

Use the calculated target heart rate zone as a guideline, not a rigid rule. Listen to your body. If you feel excessively breathless or fatigued, ease off. If you feel you could push harder within the zone, do so. For beginners, starting at the lower end of the chosen zone is advisable. As your fitness improves, you can gradually increase intensity or duration. Consistent exercise within your personalized heart rate zones is key to effective weight loss and improved overall health. For more detailed workout structuring, consider our personalized fitness plan service.

Key Factors That Affect Weight Loss Heart Rate Results

While the weight loss heart rate calculator provides a valuable estimate, several factors can influence the accuracy of the results and your actual heart rate response during exercise. Understanding these factors can help you better interpret your numbers and adjust your training accordingly.

  • Individual Physiology: The formulas used are statistical averages. Your unique genetics, body composition, and cardiovascular system may mean your actual MHR and RHR differ significantly from estimates. A true MHR is best determined via a graded exercise stress test.
  • Fitness Level: A highly conditioned athlete will have a lower RHR and may need to work at a higher intensity percentage to reach the same perceived effort or calorie burn as a beginner. The HRR calculation helps account for this to some extent.
  • Medications: Certain medications, particularly beta-blockers or other cardiovascular drugs, can significantly lower your heart rate, making calculated zones inaccurate. Always consult your doctor if you are on medication and using a heart rate monitor for training.
  • Environmental Conditions: Exercising in extreme heat or humidity can elevate your heart rate above the calculated zones for the same level of perceived exertion. Dehydration also impacts heart rate.
  • Stress and Sleep: High levels of stress or insufficient sleep can elevate your resting heart rate, potentially affecting your HRR and target zones. This highlights the importance of accurate RHR measurement when you are well-rested.
  • Type of Exercise: Different activities stress the cardiovascular system differently. A high-impact activity might raise your heart rate more quickly than a low-impact one at the same perceived exertion. The calculator provides a general guideline applicable to most aerobic activities.
  • Hydration Status: Being dehydrated can cause your heart rate to increase as your body works harder to circulate blood. Maintaining good hydration is crucial for both performance and accurate heart rate readings.
  • Caffeine and Stimulants: Consuming caffeine or other stimulants before exercise can temporarily increase your heart rate, potentially pushing you above your target zone.

Regularly reassessing your RHR and perceived exertion can help you fine-tune your training zones over time. For detailed insights into metabolic health, consider exploring our metabolic rate calculator.

Frequently Asked Questions (FAQ)

What is the "fat-burning zone"?
The fat-burning zone typically refers to the moderate intensity exercise range, usually around 60-70% of your Maximum Heart Rate (MHR). In this zone, a higher percentage of the calories you burn come from fat stores compared to higher intensity exercise. However, higher intensities burn more total calories per minute, which can also be very effective for weight loss.
Is it okay if my heart rate goes above the calculated zone?
It's generally okay for your heart rate to occasionally go above the calculated zone, especially during high-intensity intervals or challenging parts of your workout. However, consistently staying above your target zone might indicate overexertion. Listen to your body, and aim to spend the majority of your workout within your target range for the desired benefit.
How accurate is the age-based MHR formula?
Formulas like 208 – (0.7 * Age) are estimations and are generally considered more accurate than older formulas like 220 – Age. However, individual variation is significant. Factors like genetics, fitness level, and medication can affect your true MHR. For precise measurement, a supervised stress test is required.
Why is my resting heart rate different from the calculator's default?
The calculator might use a general average RHR if you don't provide one. A typical resting heart rate for adults can range from 60 to 100 BPM, but well-conditioned athletes often have RHRs below 60 BPM. Measuring your own RHR upon waking provides a much more personalized and accurate baseline for calculations.
Should I always aim for the fat-burning zone for weight loss?
Not necessarily. While the fat-burning zone is efficient for burning fat *during* the exercise session, higher intensity workouts burn more total calories overall and can boost your metabolism for hours *after* exercise (EPOC effect). A balanced approach incorporating both moderate and vigorous intensity exercise is often most effective for sustainable weight loss.
Can I use this calculator if I have a heart condition?
If you have a heart condition, are taking heart medication, or have any health concerns, you must consult your doctor before using this calculator or starting any new exercise program. Your doctor can provide personalized heart rate guidelines safe for your specific condition.
How often should I update my heart rate zones?
As your cardiovascular fitness improves, your resting heart rate may decrease, and your maximum heart rate might slightly change. It's a good practice to re-evaluate your RHR and potentially recalculate your heart rate zones every 6-12 months, or whenever you notice a significant change in your fitness level or resting heart rate.
What's the difference between %MHR and %HRR for calculating target heart rate?
Calculating based on %MHR (Maximum Heart Rate) is simpler (e.g., 70% of MHR). Calculating based on %HRR (Heart Rate Reserve) uses the Karvonen formula: (HRR * Intensity %) + RHR. The HRR method is often considered more accurate because it accounts for your individual resting heart rate, making the target zones more personalized, especially for individuals with very low or very high RHRs. This calculator uses the HRR method for greater personalization.

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Disclaimer: This calculator provides estimates for informational purposes only. Consult with a healthcare professional for personalized advice.

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Please enter your measured RHR for accuracy.'; } else { rhr = rest_heart_rate_input; } hr_reserve = est_mhr – rhr; if (hr_reserve < 0) hr_reserve = 0; // HRR cannot be negative target_zone_lower = (hr_reserve * intensity_lower_percent) + rhr; target_zone_upper = (hr_reserve * intensity_upper_percent) + rhr; // Ensure target zones are within reasonable bounds relative to MHR and RHR if (target_zone_lower est_mhr) target_zone_upper = est_mhr; if (target_zone_lower > est_mhr) target_zone_lower = est_mhr; if (target_zone_upper < rhr) target_zone_upper = rhr; document.getElementById('heart_rate_reserve').textContent = hr_reserve.toFixed(1); document.getElementById('target_zone_lower').textContent = target_zone_lower.toFixed(0); document.getElementById('target_zone_upper').textContent = target_zone_upper.toFixed(0); var mainResultText = target_zone_lower.toFixed(0) + ' – ' + target_zone_upper.toFixed(0); document.getElementById('main-result').textContent = mainResultText; document.getElementById('formula-explanation').textContent = 'Calculated using the Tanaka formula for MHR (208 – 0.7 * Age) and the Karvonen formula for Target Heart Rate: (HRR * Intensity %) + RHR.'; updateChart(est_mhr, rhr, target_zone_lower, target_zone_upper, intensity_lower_percent, intensity_upper_percent); updateTable(est_mhr, rhr, target_zone_lower, target_zone_upper, intensity_lower_percent, intensity_upper_percent); } function resetCalculator() { document.getElementById('age').value = '35'; document.getElementById('max_heart_rate').value = ''; // Leave empty to use estimation document.getElementById('rest_heart_rate').value = '65'; document.getElementById('intensity_level').value = '60-70'; // Clear errors var errorElements = document.querySelectorAll('.error-message'); for (var i = 0; i < errorElements.length; i++) { errorElements[i].textContent = ''; } calculateHeartRate(); // Recalculate with defaults } function copyResults() { var mainResult = document.getElementById('main-result').textContent; var estMhr = document.getElementById('est_mhr').textContent; var hrr = document.getElementById('heart_rate_reserve').textContent; var lowerZone = document.getElementById('target_zone_lower').textContent; var upperZone = document.getElementById('target_zone_upper').textContent; var formula = document.getElementById('formula-explanation').textContent; if (mainResult === '–') { alert('No results to copy yet.'); return; } var textToCopy = "— Weight Loss Heart Rate Calculation —\n\n"; textToCopy += "Target Heart Rate Zone: " + mainResult + " BPM\n"; textToCopy += "Estimated Max Heart Rate (MHR): " + estMhr + " BPM\n"; textToCopy += "Heart Rate Reserve (HRR): " + hrr + " BPM\n"; textToCopy += "Lower Target Zone BPM: " + lowerZone + "\n"; textToCopy += "Upper Target Zone BPM: " + upperZone + "\n\n"; textToCopy += "Key Assumptions/Formulas:\n" + formula + "\n"; // Use prompt for copying, as navigator.clipboard might not work in all contexts var textArea = document.createElement("textarea"); textArea.value = textToCopy; document.body.appendChild(textArea); textArea.select(); try { var successful = document.execCommand('copy'); var msg = successful ? 'Results copied successfully!' : 'Failed to copy results.'; alert(msg); } catch (err) { alert('Oops, unable to copy using execCommand. You can manually copy the text above.'); } document.body.removeChild(textArea); } // — Charting Logic — var myChart; // Declare globally function updateChart(estMhr, rhr, targetLower, targetUpper, intensityLowerPercent, intensityUpperPercent) { var ctx = document.getElementById('heartRateChart').getContext('2d'); // Destroy previous chart instance if it exists if (myChart) { myChart.destroy(); } // Define standard zones for comparison var zones = [ { name: "Very Light", percent: [0.5, 0.6], range: [0,0]}, { name: "Light", percent: [0.6, 0.7], range: [0,0]}, { name: "Moderate (Fat Burn)", percent: [0.7, 0.8], range: [0,0]}, { name: "Hard (Aerobic)", percent: [0.8, 0.9], range: [0,0]}, { name: "Max Effort", percent: [0.9, 1.0], range: [0,0]} ]; // Calculate ranges for standard zones based on estimated MHR for (var i = 0; i 0) { zones[i].range[0] = Math.max(zones[i].range[0], zones[i-1].range[1]); } if (zones[i].range[1] > estMhr) zones[i].range[1] = estMhr; if (zones[i].range[0] > zones[i].range[1]) zones[i].range[0] = zones[i].range[1]; } // Adjust Moderate zone based on user input if it significantly differs var userModerateLower = Math.round(intensityLowerPercent * estMhr); var userModerateUpper = Math.round(intensityUpperPercent * estMhr); // Find the moderate zone index and update its range if user input is different var moderateZoneIndex = zones.findIndex(z => z.name === "Moderate (Fat Burn)"); if(moderateZoneIndex !== -1) { // Only update if user selection is outside the default range or if MHR calculation changed significantly if (userModerateLower > zones[moderateZoneIndex].range[1] || userModerateUpper 5 || Math.abs(userModerateUpper – zones[moderateZoneIndex].range[1]) > 5) { zones[moderateZoneIndex].range = [userModerateLower, userModerateUpper]; } } var datasets = [ { label: 'Estimated MHR', data: [estMhr, estMhr], borderColor: 'rgba(255, 99, 132, 1)', // Red borderWidth: 2, borderDash: [5, 5], fill: false, pointRadius: 0, tension: 0 }, { label: 'Resting HR (RHR)', data: [rhr, rhr], borderColor: 'rgba(54, 162, 235, 1)', // Blue borderWidth: 2, borderDash: [5, 5], fill: false, pointRadius: 0, tension: 0 }, { label: 'Target Zone', data: [targetLower, targetUpper], borderColor: 'rgba(75, 192, 192, 1)', // Green borderWidth: 4, fill: false, pointRadius: 0, tension: 0 } ]; // Add background color blocks for each zone var backgroundColors = [ 'rgba(153, 255, 51, 0.2)', // Very Light 'rgba(255, 206, 86, 0.2)', // Light 'rgba(75, 192, 192, 0.2)', // Moderate (Fat Burn) 'rgba(255, 159, 64, 0.2)', // Hard (Aerobic) 'rgba(255, 99, 132, 0.2)' // Max Effort ]; var zoneBackgrounds = []; var currentY = rhr; // Start from RHR var maxLimit = estMhr; // Ensure rhr is not higher than the start of the first zone calculation if (zones.length > 0 && rhr > zones[0].range[0]) { zones[0].range[0] = rhr; // Adjust start of first zone if needed } zones.forEach((zone, index) => { if (zone.range[1] > rhr && zone.range[0] lowerBound) { // Ensure valid range before adding zoneBackgrounds.push({ y: lowerBound, y2: upperBound, backgroundColor: backgroundColors[index % backgroundColors.length] }); } } }); // Add a dataset for background colors if any zones were added if (zoneBackgrounds.length > 0) { datasets.push({ label: 'Zone Backgrounds', data: zoneBackgrounds, backgroundColor: zoneBackgrounds.map(bg => bg.backgroundColor), borderColor: 'transparent', // Hide border for background blocks borderWidth: 0, fill: true, type: 'bar' // Use bar type for background blocks }); } myChart = new Chart(ctx, { type: 'line', // Default type, but overridden by bar type for backgrounds data: { labels: ['Heart Rate (BPM)'], datasets: datasets }, options: { indexAxis: 'y', // Make it horizontal scales: { y: { beginAtZero: false, max: estMhr * 1.1, // Give some headroom above MHR min: rhr * 0.9, // Give some headroom below RHR ticks: { stepSize: 5, callback: function(value, index, ticks) { return value + ' BPM'; } }, title: { display: true, text: 'Heart Rate (BPM)' } }, x: { // Hide x-axis as it's not meaningful for this chart type display: false } }, plugins: { tooltip: { callbacks: { label: function(context) { var label = context.dataset.label || "; if (label) { label += ': '; } if (context.parsed.y !== null) { label += context.parsed.y + ' BPM'; } return label; } } }, legend: { position: 'bottom', labels: { filter: function(item, chart) { // Hide background blocks from legend return !item.text.includes('Background'); } } } }, responsive: true, maintainAspectRatio: false, // Allow chart to scale height animation: { duration: 500, // Smooth transition onComplete: function() { // Adjust chart area height dynamically if needed, or set aspect ratio } } } }); // Set a fixed height for the canvas container for better responsiveness control var canvasContainer = document.getElementById('heartRateChart'); canvasContainer.style.height = '300px'; } function clearChart() { var ctx = document.getElementById('heartRateChart').getContext('2d'); if (myChart) { myChart.destroy(); } ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height); // Optionally redraw an empty canvas or placeholder } function updateTable(estMhr, rhr, targetLower, targetUpper, intensityLowerPercent, intensityUpperPercent) { var tableBody = document.getElementById('zone-table-body'); tableBody.innerHTML = "; // Clear previous content var zones = [ { name: "Light Recovery", percentMhr: [0.5, 0.6], percentHrr: [0.5, 0.6], benefit: "Warm-up, cool-down, active recovery" }, { name: "Moderate (Fat Burn)", percentMhr: [0.6, 0.7], percentHrr: [0.6, 0.7], benefit: "Primary fat burning, sustainable cardio" }, { name: "Aerobic", percentMhr: [0.7, 0.8], percentHrr: [0.7, 0.8], benefit: "Cardiovascular improvement, endurance" }, { name: "Threshold", percentMhr: [0.8, 0.9], percentHrr: [0.8, 0.9], benefit: "Performance improvement, lactate threshold" }, { name: "Maximum Effort", percentMhr: [0.9, 1.0], percentHrr: [0.9, 1.0], benefit: "Peak performance, anaerobic capacity" } ]; zones.forEach(function(zone) { // Calculate zone ranges using HRR (Karvonen) method for consistency with calculator output var lowerBound = Math.round((zone.percentHrr[0] * (estMhr – rhr)) + rhr); var upperBound = Math.round((zone.percentHrr[1] * (estMhr – rhr)) + rhr); // Adjust bounds to be within RHR and MHR lowerBound = Math.max(lowerBound, rhr); upperBound = Math.min(upperBound, estMhr); // Ensure lower bound isn't higher than upper bound if (lowerBound > upperBound) lowerBound = upperBound; var row = tableBody.insertRow(); row.insertCell(0).textContent = zone.name; row.insertCell(1).textContent = (zone.percentMhr[0] * 100).toFixed(0) + '% – ' + (zone.percentMhr[1] * 100).toFixed(0) + '%'; row.insertCell(2).textContent = lowerBound + ' – ' + upperBound + ' BPM'; row.insertCell(3).textContent = zone.benefit; // Highlight the currently selected zone var currentIntensityLower = parseFloat(document.getElementById('intensity_level').value.split('-')[0]) / 100; var currentIntensityUpper = parseFloat(document.getElementById('intensity_level').value.split('-')[1]) / 100; var currentSelectedZoneLower = Math.round((currentIntensityLower * (estMhr – rhr)) + rhr); var currentSelectedZoneUpper = Math.round((currentIntensityUpper * (estMhr – rhr)) + rhr); currentSelectedZoneLower = Math.max(currentSelectedZoneLower, rhr); currentSelectedZoneUpper = Math.min(currentSelectedZoneUpper, estMhr); if (currentSelectedZoneLower > currentSelectedZoneUpper) currentSelectedZoneLower = currentSelectedZoneUpper; if (lowerBound >= currentSelectedZoneLower && upperBound <= currentSelectedZoneUpper) { row.style.backgroundColor = 'var(–primary-color)'; row.style.color = 'white'; row.cells[0].style.fontWeight = 'bold'; } }); } function clearTable() { var tableBody = document.getElementById('zone-table-body'); tableBody.innerHTML = ''; } // Initial calculation on page load window.onload = function() { calculateHeartRate(); // Add functionality to FAQ accordions var faqQuestions = document.querySelectorAll('.faq-item .question'); faqQuestions.forEach(function(question) { question.addEventListener('click', function() { var answer = this.nextElementSibling; this.classList.toggle('open'); if (answer.style.display === 'block') { answer.style.display = 'none'; } else { answer.style.display = 'block'; } }); }); };

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