Cardiovascular activities, like walking, jogging and biking, can help you develop or maintain the health of your heart, circulatory system and lungs. Not all cardio workouts are equal, however. How effective a workout is at boosting your cardiorespiratory system depends on the intensity of your session. To know whether you're exercising at the right intensity, first calculate your target heart rate and then periodically check your heart rate while you're working out to make sure you stay within this ideal range.

What is Target Heart Rate: Definition and Why You Should Care

Target heart rate is the ideal heart rate for maximizing the fitness benefits of your cardiovascular workouts. When you're exercising within the range of your target heart rate, you're making your body work at an intensity that is best for building the strength of your heart, developing the efficiency of your lungs and building the proficiency of your circulatory system. Bottom line, you get the most out of your training when you work within the target heart rate range.

Your target heart rate range, according to the American Heart Association, is 50 to 85 percent of your maximum heart rate. Exercising at a moderately intensity will often bump your heart rate to 50 to 69 percent of your maximum heart rate and hard, more intense workouts will commonly charge your heart rate to 70 to 90 percent of your maximum heart rate.

Calculating Your Target Heart Rate: An Equation to Estimate

To calculate your estimated target heart rate range, first find your maximum heart rate by subtracting your age from 220. For example, if you're 40 years old, your estimated maximum heart rate is 220 minus 40, or 180 beats per minute.

Next, take your estimated maximum heart rate and multiply that value by both 0.5 and 0.85. Using the same example as above, with a maximum heart rate of 180, you would multiply 180 by 0.5 to get 90 as the low value in your target heart rate range, and multiply 180 by 0.85 to get 153 as the high value in your target heart rate range. Therefore, an individual 40 years old can estimate that they should exercise at an intensity that increases their heartbeat to between 90 and 153 beats per minute.

The Truth About the THR Equation: It's Just an Estimate

Now that you've calculated your target heart rate range, it's important to understand that the value is strictly an estimate. The formula is decades old and researchers have found that the equation will regularly overestimate or underestimate a person's maximum heart rate, and therefore target heart rate. You may notice that you feel as if you're not exercising hard enough when you're working at the lower end of your target heart rate range. You may also find that you feel like you're exercising at an intensity that's higher than what's comfortable. To truly determine your exact maximum heart rate, and thus target heart rate, you would need to undergo a stress test.

Ways to Monitor Your Heart Rate During Exercise: With or Without Equipment

Keeping track of your heart rate during a workout is easy with a heart rate monitor. Today's monitors don't even require a chest strap. You can purchase a bracelet that reads the beat of the radial heart rate at the inside of your wrist and then displays that up-to-the-second value to you like a watch.

If you don't have the funds for a heart rate monitor, you can take your own pulse. Press the tips of your forefinger and middle finger of your right hand onto the blood vessels at the inside of your left wrist. Count how many times your heart beats for 10 seconds and then multiply that value by 6 to determine your heart rate in beats per minute. While this method is relatively simple, it often requires you to slow or even stop your workout while you count and watch a clock.

If you'd rather not slow your workout to check your pulse, an easy way to gauge whether you're within your target heart rate range is to use the "talk test." If you feel like you can easily hold a conversation while you're working out, you're not working at a high enough intensity and need to pick it up. If you feel like you would struggle to get any words out, you're working out at too high of an intensity and need to ease up a bit. Ideally, you feel like you can hold a conversation, but would struggle to talk in long sentences. When this happens, you can be pretty well assured that your heart rate is within the target heart rate range.