It's a beautiful, brisk day and you're feeling fine, so you head to your health club for
a workout. You stretch and warm up, as usual. Feeling better than ever, you get on the elliptical trainer and punch in your numbers: weight, 155; age, 60; and target heart rate, 85% of maximum. At last you get going,
easy at first, then at a nice, steady clip. You're just starting to sweat, but you're not feeling the least bit stressed — and the red warning light goes on.
You've exceeded your maximum heart rate, but you still feel
great. What's wrong? To find out, you need to understand the concept of maximum heart rate and to consider new data that may give you a bit more leeway.
The old formula
When doctors need
to determine a person's maximum heart rate with precision, they order an exercise stress test. The patient exercises on a treadmill or bike while a cardiac monitor records his EKG; when he's going all out, his heart
rate will also be at its maximum. It's the gold standard, and it's the only way to get precise heart rate targets for cardiac patients and for people taking beta blockers or other medications that slow the pulse.
For all its value, though, exercise testing also has limitations. It is expensive and time-consuming, and it does a rather poor job of predicting exercise-induced complications in men without diagnosed
heart disease (see Harvard Men's Health Watch, May 1997 and April 2002). But if you don't have an exercise test, how can you estimate your maximum heart rate?
For more than three decades, doctors
have relied on a formula designed by Dr. William Haskell and Dr. Samuel Fox. After reviewing the results of about 10 earlier exercise studies, they noticed that the maximum heart rate declines in a predictable fashion
as people age. When they constructed a graph comparing maximum heart rate with age, they came up with a simple equation to explain the relationship: maximum heart rate = 220 – age in years.
This formula has been so useful that it's been applied to virtually all healthy men and women without a critical reappraisal — until now.
A case in point
According to the standard
formula, a healthy, 55-year-old man should have a maximum heart rate of 165 (220 – 55 = 165). But when doctors put one vigorous 55-year-old on a treadmill, they observed a maximum heart rate of 178 beats per minute,
which is almost 8% above his "maximum." True, the subject was rather special; President George W. Bush was getting his annual checkup at Bethesda Naval Hospital after his first six months in office.
The president was in top shape: He was able to run on the treadmill for an extraordinary 26 minutes, and doctors found an excellent blood pressure of 118/74 along with fine results for his cholesterol profile (total
cholesterol 170, LDL cholesterol 112, HDL cholesterol 42, triglycerides 80). It's a tribute to his balanced exercise program, which includes jogging, swimming, weight lifting, and using an elliptical trainer. Word has
it that he's even installed a treadmill on Air Force One.
President Bush works out more than most men, and he may have also inherited some health and stamina from his fit and famous father. But if his fitness is as
exceptional as his status, his maximum heart rate is not so unusual, at least according to a new formula.
The new formula
Hirofumi Tanaka, Kevin Monahan, and Douglas Seals have probably
never met President Bush, but the Colorado scientists did review 351 publications that reported the results of exercise tests on 18,712 men and women of all ages. They found that the old formula overestimates the actual
maximum heart rate in young adults but underestimates it in people over 45. Based on their meta-analysis of earlier studies, the researchers devised a new formula, then validated it by testing it on 514 men and women
between 18 and 81. Although the new formula involves a bit more math than the original equation, it appears to be more accurate: maximum heart rate = 208 – (0.7 x age in years).
Even with the new formula, the
president's maximum rate of 178 exceeds the predicted maximum of 169.5 (208 – 38.5), but for ordinary guys, the new formula is likely to be even closer to the mark.
Practicality
The new
formula is of great interest to exercise physiologists, and it may have practical implications for healthy men who choose to use their heart rates to guide their exercise training for optimal aerobic fitness and
athletic performance.
The first step is to be sure aerobic training is suitable for you. For men over 40, or for younger men who are sedentary and out of shape, that means a medical checkup. If you have any symptoms
of heart disease or if your doctor detects cardiovascular abnormalities or major risk factors, you really should have an exercise stress test. But if your doctor finds you healthy, you can proceed without one.
The
next step is to learn how to take your pulse, using the carotid artery in your neck or the radial artery in your wrist. Practice while you are resting comfortably; because your heart rate will be slower at rest, it will
be easier to take your pulse. After you've mastered the technique, begin checking your pulse during exercise. If you don't want to count for 60 or even 30 seconds, you can count the beats during 10 seconds, then
multiply times 6 to find your heart rate.
Once you can count your pulse, you can adjust your pace to keep your heart rate in the target range of 70%–85% maximum. You can use either the old or new equation to estimate
your maximum heart rate; to make it easier, the table on page 4 compares the two and gives you training targets for each.
If you're just getting started, aim for the low end of your target range. And if that seems
tough, exercise even more gently; you'll still get plenty of help for your heart, and you'll be able to build up gradually as you get in shape. And no matter what your heart rate is doing, listen to your body as you
work out. Chest pain or discomfort, undue fatigue or shortness of breath, excessive sweating, and lightheadedness are among the warning symptoms that should tell you to stop exercising and get help.
You can choose
among many aerobic activities; brisk walking, jogging, swimming, stair climbing, aerobic dancing, cross-country skiing, rowing, and singles racquet sports are examples. Best of all is a mixed program; the variety will
keep your muscles vigorous and your mind fresh. And remember to warm up before you exercise and to cool down afterward; walking, stretching, and calisthenics are ideal.
Second opinions
Your heart rate is the most precise way to monitor the intensity of your exercise. The new formula tells young men they don't have to push quite so hard to reach a realistic target, and it reassures older men who are in
top shape that they can be a bit more vigorous. But the new formula won't replace a simpler (if less accurate) way to gauge the intensity of your exercise.
Although it's subjective and may not satisfy serious
athletes, the "talking pace" method is quite useful for most men who want to get into shape: Work hard enough so you'll break into a sweat and breathe a bit faster, but not so hard that you are too winded to
talk with a companion, real or imagined.
If your goal is maximum fitness with minimum risk, you'll need to keep track of your exercise intensity; you'll get the best results for your heart as well as your
athletic performance. But if your goal is health, you can achieve excellent benefits with even less fuss: just walk for 30–45 minutes a day, aiming to cover 2–3 miles. You may never rival President Bush, but you'll
improve your blood pressure and cholesterol, chip away at your body fat, and reduce your risk of heart disease, stroke, diabetes, colon cancer, and possibly prostate cancer (see HMHW, December 2001).
For health, a daily dose of 30 minutes of moderate exercise will produce big gains. But you'll get additional benefits from additional exercise, and you'll also boost your aerobic fitness and athletic performance. After
more than 30 years, scientists have developed a new formula for the maximum heart rate to help guide men who decide to go presidential — at least where fitness is concerned.
