What is the formula to determine 60% of heart rate reserve?

This option conflates the age-predicted max HR calculation with the HRR percentage and omits the resting heart rate component entirely.

Multiplying maximum heart rate by 60% is the straight percentage-of-max method, not the Karvonen HRR method, and does not account for individual resting heart rate.

This option correctly computes heart rate reserve but omits the final step of adding resting heart rate back, which would yield an inaccurately low and unusable target heart rate value.

Heart rate reserve (HRR) is calculated as maximum heart rate minus resting heart rate, representing the usable range of the heart. To find a target at 60% of HRR, the formula is: (Maximum HR - Resting HR) x 60% + Resting HR. Adding resting heart rate back in the final step anchors the target above the individual's true baseline, producing a more personalized and accurate training zone than simpler percentage-of-max methods.