Tracking your heart rate helps you find a challenging exercise intensity while also helping you avoid pushing beyond a safe level.

Target heart rate zones are based on a percentage of the fastest rate that your heart can beat per minute. This is known as the maximum heart rate and can be calculated using the following formula:

maximum beats per minute (bpm) = 206.9 - (age in years x 0.67) *

Once you know your maximum heart rate, you can find your target exercise range. For moderate-intensity exercise, aim for a heart rate that is 50 - 70% of your maximal heart rate. For vigorous exercise, aim for 70 - 85% of your maximal heart rate.

Below is an example equation for a 40-year-old person exercising at moderate intensity.

Maximal heart rate: 206.9 - (40 x 0.67) = 180 bpm

50% of maximal: 180 x 0.50 = 90 bpm

70% of maximal: 180 x 0.70 = 126 bpm

To exercise at a moderate intensity, this person should keep her heart rate between 90 and 126 bpm throughout the workout.

Exercise intensity and target heart rate vary from person to person. Beginners should exercise at the lower end of their target heart rate range and increase intensity slowly as the body becomes more fit. Aim for an intensity that meets your goals for calorie burning, challenges your current fitness state, and is safe and tolerable. The best intensity is challenging enough to strengthen your heart, lungs, muscles, and bones while not being so intense that you risk injury.

*Another popular equation is (220 - age in years), but the American College of Sports Medicine recommends this more accurate equation.

Sources

• Centers for Disease Control and Prevention - Target Heart Rate and Estimated Maximum Heart Rate

Lori Rice, M.S., is a nutritional scientist and author with a passion for healthy cooking, exercise physiology, and food photography.