Heart Rate Running Pace Calculator

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Heart Rate Running Pace Calculator

To maintain a heart rate of BPM, your estimated pace should be:
–:–

Note: This is an estimation based on the linear relationship between heart rate reserve and aerobic intensity.

How the Heart Rate Pace Calculator Works

This calculator helps runners determine their target pace for specific intensity zones by analyzing the relationship between heart rate and running speed. Unlike basic calculators, this tool considers your Resting Heart Rate (RHR) to calculate Heart Rate Reserve (HRR), which is a more accurate indicator of physiological effort.

The Importance of Heart Rate Training

Running at the right intensity is crucial for building aerobic capacity without overtraining. By using a target heart rate, you ensure that your "easy" runs stay easy (Zone 2) and your "tempo" runs hit the correct metabolic threshold. If you find your heart rate is consistently higher than your target at your usual pace, it's a sign to slow down and allow your cardiovascular system to adapt.

How to Use This Calculator

  • Resting Heart Rate: Measure this immediately after waking up for the most accurate result.
  • Current Pace & HR: Use data from a recent steady-state run. For example, if you ran 6:00 min/km and your average heart rate was 150 BPM, enter those values.
  • Target Heart Rate: Enter the heart rate associated with your goal zone (e.g., 130-140 BPM for recovery or Zone 2).

Example Calculation

Imagine you have a resting heart rate of 60 BPM. On a recent run at a 6:00 min/km pace, your heart rate was 160 BPM. If you want to drop your effort to a Zone 2 target of 140 BPM, the calculator determines the proportional change in heart rate reserve intensity and adjusts your pace accordingly—likely suggesting a slower pace of approximately 7:12 min/km.

Factors That Affect Your Pace

Keep in mind that external factors can influence the relationship between pace and heart rate:

  • Temperature: High heat and humidity increase heart rate for the same pace (cardiac drift).
  • Elevation: Running uphill requires more effort, spiking heart rate regardless of pace.
  • Fatigue: Lack of sleep or overtraining can lead to an elevated heart rate.
  • Caffeine: Stimulants can artificially inflate your heart rate readings.
function calculatePace() { var restingHR = parseFloat(document.getElementById("restingHR").value); var paceMin = parseFloat(document.getElementById("paceMin").value); var paceSec = parseFloat(document.getElementById("paceSec").value); var currentHR = parseFloat(document.getElementById("currentHR").value); var targetHR = parseFloat(document.getElementById("targetHR").value); // Validation if (isNaN(restingHR) || isNaN(paceMin) || isNaN(paceSec) || isNaN(currentHR) || isNaN(targetHR)) { alert("Please enter valid numbers in all fields."); return; } if (currentHR <= restingHR || targetHR <= restingHR) { alert("Heart rate values must be higher than your resting heart rate."); return; } // Convert pace to total seconds per unit (km or mile) var totalSecondsCurrent = (paceMin * 60) + paceSec; // Heart Rate Reserve (HRR) Calculation // We assume a linear relationship between HRR % and Velocity (Speed) // Speed = 1 / Pace // Speed_Target / Speed_Current = (TargetHR – RestingHR) / (CurrentHR – RestingHR) var hrrCurrent = currentHR – restingHR; var hrrTarget = targetHR – restingHR; // Calculate ratio of intensity var intensityRatio = hrrTarget / hrrCurrent; // Since Pace is inverse of speed: Pace_Target = Pace_Current / IntensityRatio var totalSecondsTarget = totalSecondsCurrent / intensityRatio; // Convert back to Min:Sec var resMin = Math.floor(totalSecondsTarget / 60); var resSec = Math.round(totalSecondsTarget % 60); // Formatting seconds if (resSec 59 || resMin < 2) { document.getElementById("resPace").innerHTML = "Out of Range"; } else { document.getElementById("resPace").innerHTML = resMin + ":" + resSec + " per unit"; } document.getElementById("resTargetHR").innerText = targetHR; document.getElementById("hr-result").style.display = "block"; }

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