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The Truth About Heart Rate and Exercise

Do you really need to track your heart rate when you work out? Experts weigh in.

From the WebMD Archives

If you're even a semi-serious exerciser, you've probably read or heard that it's a good idea to know your resting and maximum heart rates and to track your heart rate during workouts.

Well, yes and no.

Knowing how fast the heart is beating before, during, and after exercise can be helpful for some people, including heart patients and competitive athletes. But experts tell WebMD that much of the conventional wisdom about heart rate and exercise is wrong.

Take this quiz to separate fact from fiction about heart rate and exercise.

1. TRUE OR FALSE: It's vital to monitor your heart rate during exercise.

FALSE. It all depends on who you are and why you're exercising.

If you have heart disease and your doctor has forbidden you to exercise strenuously, monitoring your heart rate during workouts is a good way to avoid pushing your heart into the danger zone. Heart rate monitoring can also make sense for serious runners, cyclists, and other athletes who are eager to optimize their aerobic fitness.

But otherwise, there's no pressing need to know your heart rate.

"The majority of people simply don't need to monitor their heart rate," Gerald Fletcher, MD, professor of medicine at the Mayo Clinic in Jacksonville, Fla., tells WebMD.

Edward F. Coyle, PhD, agrees. He's a professor of kinesiology and health education at the University of Texas at Austin and director of the university's Human Performance Laboratory.

Coyle's work has included studying the muscular efficiency and physiological factors -- including heart rate -- in Lance Armstrong during his acclaimed cycling career. But Coyle says that for most people, it's not essential to track heart rate during exercise.

"If you're exercising for health, the most important thing to do is get off the couch," Coyle says. He says that for most people, the key is to "enjoy their exercise, so they keep doing it."

2. TRUE OR FALSE: Resting heart rate is a good indicator of aerobic fitness.

TRUE. Regular aerobic exercise makes your heart stronger and more efficient, meaning that your heart pumps more blood each time it contracts, needing fewer beats per minute to do its job.

Continued

"For most people, a normal resting heart rate is between 60 and 90 beats a minute," Coyle says. "Athletic training can lower that rate by 10 to 20 beats per minute."

But if you have a lower resting heart rate than someone else, don't assume that you're in better shape than them, or vice versa. Two people can be equally fit and have significantly different resting heart rates.

"Both a couch potato and a highly trained marathoner could have a heart rate of 50 to 60," says Benjamin D. Levine, MD, professor of medicine and cardiology at the University of Texas Southwestern Medical School and director of the Institute for Exercise and Environmental Medicine, both in Dallas.

3. TRUE OR FALSE: Maximum heart rate declines with age.

TRUE. As we all know, exertion makes the heart beat faster, and the greater the exertion, the faster the heart rate. But there's an upper limit on how fast your heart can beat, and that limit is affected by age.

"Maximum heart rate is unrelated to exercise training," Hirofumi Tanaka, PhD, tells WebMD. He's an associate professor of kinesiology and health education at the University of Texas and director of the university's Cardiovascular Aging Research Laboratory.

"Whether you're a couch potato or a highly trained athlete, that rate declines about seven beats per minute for each decade," Tanaka says. Regular exercise can lower your resting heart rate, but it does nothing to slow the age-related decline in maximum heart rate.

4. TRUE OR FALSE: Moderate exercise promotes weight loss more effectively than vigorous exercise.

FALSE. Weight loss is a matter of simple arithmetic: To shed pounds, you must burn more calories than you consume. And when it comes to burning calories, the greater the exertion, the greater the rate at which calories are burned.

Working out at about 60% to 75% of your maximum heart rate (the so-called "fat-burning zone") burns fewer calories than working out at 75% to 85% of your maximum heart rate (the so-called "aerobic" or "cardio" zone).

But caloric burn depends on a workout's duration as well as its intensity -- and it's easier to work out longer when exercising at a lower intensity.

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5. TRUE OR FALSE: There's a simple and reliable formula for calculating your maximum heart rate.

TRUE. There is such a formula -- but there are two big caveats.

For starters, it's not the familiar 220 minus your age in years. That formula, first promulgated in the 1960s, works reasonably well for people under age 40. But it overstates the maximum heart rate for older people.

A more accurate formula is the one published in 2001 by Tanaka in the Journal of the American College of Cardiology: Multiply your age by 0.7 and subtract that figure from 208. For example, a 40-year-old has a maximum heart rate of 180 (208 - 0.7 x 40).

Formulas aside, maximum heart rates vary, even among people of the same age. "The formula is only relevant for groups of people," Levine says. "For individuals, the prediction is off by plus or minus 10 to 20 beats per minute."

It's possible, of course, to determine your maximum heart rate by running or riding a bike to the point of exhaustion. But because it can be risky, exercising that intensely is not recommended for men over 45 or women over 55, as well as for heart disease patients or people with heart disease risk factors, unless they have been exercising regularly or have been cleared to exercise by their doctors.

6. TRUE OR FALSE: Using a heart rate monitor can help boost your fitness level.

TRUE. Electronic heart monitors, typically consisting of a wristwatch-like display and an electrode-studded chest strap, are used by serious runners, cyclists, etc. while training and even during races. By providing accurate, real-time heart rate information, the monitors help athletes pace themselves.

But even if you're not preparing for a marathon or a century ride, using a heart rate monitor can help motivate you to exercise. How? By turning your regimen into a solitaire of sorts: Can your regimen lower your resting heart rate? Can you exercise at the same pace but get your heart to pump more slowly? Can you shorten the time it takes your heart rate to return to normal after a workout?

It's not easy to answer these questions when you take your pulse manually, but quite easy with a heart rate monitor. "No one really needs a heart rate monitor," Fletcher says. "But some people love to play with these things, and that motivates them to exercise."

WebMD Feature Reviewed by Louise Chang, MD on October 23, 2009

Sources

SOURCES:

Gerald Fletcher, MD, professor of medicine, Mayo Clinic, Jacksonville, Fla.

Edward F. Coyle, PhD, professor and director, Human Performance Laboratory, University of Texas at Austin.

Benjamin D. Levine, MD, professor of medicine and cardiology, University of Texas Southwestern Medical School, director, Institute for Exercise and Environmental Medicine, Dallas.

Hirofumi Tanaka, PhD, associate professor, kinesiology and health education, director, Cardiovascular Aging Research Laboratory, University of Texas at Austin.

Scott Crouter, PhD, department of exercise and health science, University of Massachusetts Boston.

Tanaka, H. Journal of the American College of Cardiology, January 2001; vol 37: pp 153-156.

© 2009 WebMD, LLC. All rights reserved.

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