Answer: C - The Karvonen formula calculates heart rate reserve based on resting heart rate and age-predicted max heart rate. This can provide information about acceptable target heart rates within the range from resting to maximal.
Here's how the formula works:
Calculate your maximum heart rate (MHR) by subtracting your age from 220. For example, if you're 30 years old, your MHR would be 220 - 30 = 190.
Measure your resting heart rate (RHR) by taking your pulse for one minute when you first wake up in the morning. You can do this by placing your index and middle fingers on your wrist, just below the thumb, and counting the beats.
Calculate your heart rate reserve (HRR) by subtracting your RHR from your MHR. For example, if your MHR is 190 and your RHR is 60, your HRR would be 190 - 60 = 130.
Determine the lower end of your target heart rate zone by multiplying your HRR by the lower end of your target heart rate percentage (usually 50-60%) and then adding your RHR. For example, if you're aiming for a target heart rate of 50%, you would multiply your HRR (130) by 0.5 and then add your RHR (60) to get 130 x 0.5 + 60 = 125 beats per minute (bpm).
Determine the upper end of your target heart rate zone by multiplying your HRR by the upper end of your target heart rate percentage (usually 70-80%) and then adding your RHR. For example, if you're aiming for a target heart rate of 80%, you would multiply your HRR (130) by 0.8 and then add your RHR (60) to get 130 x 0.8 + 60 = 164 bpm.
Therefore, according to this formula, a 30-year-old person with a resting heart rate of 60 bpm and a maximum heart rate of 190 bpm who wants to exercise at 50% to 80% of their maximum heart rate range should aim to keep their heart rate between 125 bpm and 164 bpm during exercise.
