Target Heart Rate (Karvonen)

This formula estimates the exercise heart rate needed to train at a chosen effort level using heart rate reserve, which is the gap between your maximum and resting heart rates. It works better than using a simple percentage of maximum heart rate because it accounts for individual differences in resting fitness level, so two people with the same max heart rate but different resting rates can train at different target zones. The intensity factor I is usually written as a decimal, so 60% intensity is 0.60.

Use this when prescribing or tracking cardio intensity in running, cycling, rowing, rehabilitation, or sports conditioning. It is especially useful when you want a more personalized training zone than age-based heart-rate formulas provide.

• Using I as 75 instead of 0.75
• Subtracting resting heart rate after multiplying instead of adding it back
• Using an inaccurate max heart rate estimate without checking that it matches the athlete