H&r Calculator

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Heart Rate (Karvonen) Calculator

Calculation Results

function calculateHR() { var age = parseFloat(document.getElementById('hrAge').value); var resting = parseFloat(document.getElementById('hrResting').value); var intensity = parseFloat(document.getElementById('hrIntensity').value); var resultDiv = document.getElementById('hrResult'); if (isNaN(age) || isNaN(resting) || isNaN(intensity) || age <= 0 || intensity <= 0) { alert("Please enter valid positive numbers for all fields."); return; } // Logic: Max Heart Rate (Haskell/Fox formula) var mhr = 220 – age; // Heart Rate Reserve (HRR) var hrr = mhr – resting; // Karvonen Formula: Target Heart Rate = (HRR * Intensity%) + Resting HR var target = (hrr * (intensity / 100)) + resting; document.getElementById('maxHRDisplay').innerHTML = "Estimated Max Heart Rate: " + Math.round(mhr) + " BPM"; document.getElementById('hrrDisplay').innerHTML = "Heart Rate Reserve (HRR): " + Math.round(hrr) + " BPM"; document.getElementById('targetHRDisplay').innerHTML = "Target Heart Rate: " + Math.round(target) + " BPM"; resultDiv.style.display = "block"; }

Understanding the H&R (Heart Rate) Karvonen Calculator

Effective cardiovascular training requires more than just breaking a sweat; it requires precision. The Heart Rate (H&R) Calculator utilizes the Karvonen Formula, which is widely considered one of the most accurate ways to determine target exercise zones because it accounts for an individual's Resting Heart Rate (RHR).

What is the Karvonen Formula?

Unlike the basic "220 minus age" method, which only considers your age, the Karvonen method looks at your Heart Rate Reserve (HRR). Your HRR is the difference between your maximum heart rate and your resting heart rate. By using this metric, the calculator provides a more personalized target that reflects your current fitness level.

How the Calculation Works

The logic behind this tool follows three specific mathematical steps:

  1. Calculate Maximum Heart Rate (MHR): This is generally estimated as 220 - Age.
  2. Determine Heart Rate Reserve (HRR): This is MHR - Resting Heart Rate.
  3. Apply Intensity: The final target is found using: (HRR × Intensity%) + Resting Heart Rate.

Target Training Zones

Depending on your fitness goals, you should adjust the intensity percentage in the H&R calculator:

  • Recovery Zone (50% – 60%): Ideal for active recovery and beginners.
  • Aerobic/Fat Burning (60% – 70%): Enhances cardiovascular endurance and utilizes fat as a primary fuel source.
  • Anaerobic Zone (80% – 90%): Improves your "lactate threshold," allowing you to work harder for longer.

A Practical Example

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

  • Max HR: 220 – 40 = 180 BPM
  • HR Reserve: 180 – 70 = 110 BPM
  • Target Heart Rate: (110 × 0.75) + 70 = 152.5 BPM

By maintaining a heart rate of approximately 153 BPM, this individual ensures they are hitting the exact physiological stimulus required for their training goal.

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