The Karvonen method is used to determine the Target Heart Rate (THR) for a given activity. This method is considered to be more accurate than other methods for measuring THR because it takes the Resting Heart Rate (RHR) into consideration. The basic formula is: Maximum Heart Rate - Resting Heart Rate = Heart Rate Reserve (HRR). The HRR is then used to find out THR for a given intensity of workout. Ideally for an aerobic activity to have any benefit the THR should be between 60% to 90% of the Maximum Heart Rate (MHR). The MHR is calculated by subtracting an individual’s age from 220. The Karvonen Method is useful in charting the progress of an individual during the course of an aerobic training program.