Triathlon Heart Rate Training Zones Calculator

This calculator relies on the Karvonen formula, which factors in your Heart Rate Reserve (HRR) by utilizing both your Maximum Heart Rate (MHR) and Resting Heart Rate (RHR). First, the HRR is found by subtracting RHR from MHR. Then, specific percentages (ranging from 50% to 100%) are applied to the HRR, and the RHR is added back in. The fundamental equations are: HRR = MHR - RHR, and Target Zone = (HRR x Percentage) + RHR. This approach provides a much more personalized and accurate intensity gauge than using maximum heart rate alone.

Imagine an athlete with a Maximum Heart Rate (MHR) of 190 beats per minute (bpm) and a Resting Heart Rate (RHR) of 50 bpm. First, compute the Heart Rate Reserve: 190 - 50 = 140 bpm. Next, to find the 70% aerobic endurance training zone, multiply 140 by 0.70, which equals 98. Finally, add back the resting heart rate of 50: 98 + 50 = 148 bpm. Repeating this process for other intensities maps out your complete multi-sport training spectrum.

Always measure your resting heart rate first thing in the morning over several consecutive days for the highest accuracy. Recalibrate your maximum heart rate periodically, as fitness improvements will shift your physiological thresholds over time. Remember that environmental factors like high heat and humidity can elevate your heart rate independently of effort.