The Medicine Cabinet: Ask the Harvard Experts: Track Your Heart Rate for Fitness and Heart Health

To track your heart rate with exercise, you will need a smartwatch or fitness tracker. (Dreamstime/TNS)

Q: How does tracking your heart rate provide information about your heart health?

A: Checking your heart rate at rest and with exercise can provide information about your fitness level and may suggest a heart problem if your pulse is too slow, too fast or irregular. Three good times to check your heart rate are soon after you wake up in the morning; during exercise, and in the immediate post-exercise recovery period.

To get a good sense of your resting heart rate, check it every few mornings over the course of several weeks. In general, a lower resting heart rate translates to better fitness and cardiovascular health. A resting heart rate that is too low (less than 50 beats per minute) or also one that is 100 or higher could be a sign of trouble and should prompt a call to your doctor.

You can check your heart rate or pulse using just your fingers. With your index and middle fingers, press lightly on the opposite wrist, just below the fat pad of your thumb. Or press gently on the side of your neck, just below your jawbone. Easier yet, use a smart watch or wrist-worn fitness tracker to display your resting heart rate.

To track your heart rate with exercise, you will need a smartwatch or fitness tracker. These devices automatically calculate your “target” heart rate, or the heart rate you’re supposed to reach during exercise. But target heart rate zones aren’t necessarily accurate for many people. Here’s why: These devices calculate your target heart rate as a percentage of your maximum heart rate, which in turn is an estimate based solely on your age. (One standard formula is 220 minus your age; another is 200 minus half your age.)

The estimated maximum heart rate of a 70-year-old is 150. But that figure might be too low for a 70-year-old who is lean and runs five miles several times a week -- and too high for a 70-year-old who is overweight and whose only exercise is a daily walk around the block.

If you’re working on improving your cardiovascular fitness, one metric you might want to measure is your heart rate recovery. It’s a gauge of how quickly your heart rate drops or recovers after intense exercise. To check it, simply measure your heart rate immediately after exercising, then again two minutes later. The difference between those two values is your heart rate recovery. A value below 20 suggests poor fitness. As with your resting heart rate, multiple measurements over time provide the most reliable information.

If you’re starting or ramping up an exercise routine, your resting heart rate may gradually drop and your heart rate recovery value may slowly rise -- two trends that bode well for your heart and overall health.

Howard LeWine, M.D., is an internist at Brigham and Women’s Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.

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