Exercise rights--and wrongs
An hour workout or 30 minutes? Walk or run? Does gardening count?
The day after Thanksgiving in 1967, Ralph Paffenbarger laced up his Army boots and went for a jog. The physician barely made it to the end of the block. He was out of shape, and the boots didn't help. So what made Paffenbarger run? His research into heart disease: He was among the first to show that regular and vigorous exercise dramatically cut the danger. "I decided exercise was something I should be doing," says Paffenbarger, now 80 and a professor emeritus at Stanford. His endurance improved, as did his footwear, and he went on to race in 151 marathons. His research became the basis for fitness recommendations from the American College of Sports Medicine.
Paffenbarger took his own advice and ran with it. But confusion has kept many others from doing the same. Though fitness has proved to be a hedge against obesity, heart disease, high blood pressure, stroke, diabetes, cancer, and osteoporosis, people are terribly mixed up about the right kind of exercise to do to get these benefits.
Do we need long workouts to combat heart disease, or will short, intense ones do the trick? For cardiovascular fitness and other health benefits, the surgeon general advises 30 minutes of moderate exercise most days of the week. But not long ago, the recommendation was for 20 minutes of more vigorous exercise, three times a week. A full hour of moderate exercise every day is the prescription from the Institute of Medicine. Then there are notions about puttering in the garden, ballroom dancing, or vacuuming as a replacement for hitting the gym.
"Most consumers are scratching their heads and saying `What should I do?' " says James Rippe, a cardiologist at Tufts University. Their befuddlement could be why, despite all the pleading from doctors, only about 25 percent of Americans get enough exercise, according to the Centers for Disease Control and Prevention.
Avoiding illness. What you should do depends on your health history, your weight, and your goals. Cholesterol skyrocketing? Jog several miles each week and hit the rowing machine. Have more than a few pounds to lose? You may need to put in an hour or more a day. Concerned about bone loss? Pick up those weights.
For the fortunate folks who are at a normal weight, who are in good health and want to maintain it, 30 minutes of moderate activity, five to seven days a week, is enough. Do this and your risk of disease declines, no matter your age, sex, or race. "You'll get substantial benefits, including a 50 percent reduction in heart attack, a lower risk of colon cancer, and probably a lower risk of breast cancer and Type II diabetes," says Steven Blair, research director at Dallas-based Cooper Institute, which studies exercise and health.
The claim is backed up by years of studies showing that people with moderate exercise patterns have lower disease risks. Why? Exercise gets things moving in the body. Better blood flow to the muscles helps move sugar from blood to muscle cells and so lowers diabetes risk by keeping blood sugar levels under control. In the case of cancer, the mechanisms are less clear. Because exercise keeps your digestive system moving, it may reduce the time colon tissue is exposed to carcinogens. That could cut the risk of colorectal cancer, says Lisa Callahan, medical director of the Women's Sports Medicine Center at the Hospital for Special Surgery in New York.
Pushing hard enough. Moderate activity for half an hour, by the way, is somewhere south of huffing and puffing and somewhere north of an easy after-dinner ramble. "Casually strolling around the mall isn't going to produce health benefits," says JoAnn Manson, chief of preventative medicine at Harvard's Brigham & Women's Hospital. Walking should be brisk enough--3 to 4 miles per hour--to raise your heart rate. You can accumulate that exercise, says Blair. So a 10-minute brisk walk after every meal is fine. Physicians also recommend that most people--but particularly women--get two or three days a week of weight training. This has extra benefits, like building bone mass.
Shedding pounds. But wait. Or, weight. About 65 percent of Americans are overweight, and extra pounds raise the risk of disease. That's where the whole hour, as recommended by the Institute of Medicine, comes in. Researchers combed through an international database and found that the people who maintained a healthy weight exercised, on average, the equivalent of a 60-minute brisk walk per day. Bad news: Some people may need to work out even longer than an hour, depending on their diet, muscle mass, and metabolism. "I've run nearly every day for 35 years, and during that time I've gained 30 pounds," says Blair.
Healthier hearts. If you're built like a greyhound but battle high cholesterol, you may need to do something more intense. A study published last month in the New England Journal of Medicine found that walking or jogging the equivalent of 12 miles per week lowered the amount of dangerous LDL (the bad cholesterol) in overweight people. But it took longer and harder workouts--the equivalent of jogging 20 miles per week--to increase the level of HDL (the good cholesterol). Another study, published in the Journal of the American Medical Association in October, suggests that while walking cuts the risk of coronary heart disease, more vigorous activities like running and rowing reduce it even further.
It's a message Randy Devening has taken to heart. After a heart attack, the 60-year-old retired CEO went to the Cooper Institute to learn how to put together a good exercise routine. Back home in Oklahoma City, he now works out as much as 60 to 90 minutes a day, combining cardiovascular exercise, weight lifting, and stretching. "I just feel better," he says.
Dusting doesn't do it. If you can't face 30 or 60 minutes of exercise, do something, because slight workouts do produce slight benefits. Keep in mind, though, that lighter "exercise," like housecleaning, canoeing, or playing golf, helps burn calories and can be a great add-on to your regular routine but is no substitute for that routine. Mild activity, among other things, does nothing to increase bone strength and density, according to a report in last month's Journal of Internal Medicine.
You can do too much as well as too little. Overdoing it can actually suppress the immune system and increase the risk of getting hurt. Warning signs of overtraining include sleeplessness, fatigue, and injuries like stress fractures. Sheila Lynch, a 47-year-old small-business co-owner in Chicago, says she used to push it with aerobics classes, running, and weight lifting in various combinations, five days a week. "I got a lot of knee injuries," she says. Now she hits the gym three times a week, doing both cardio and weight work. And Paffenbarger, having given up marathons a few years ago, still walks daily in the hills near his California home.
Balancing activities
If a brisk walk for half an hour isn't for you, other exercises done for these specific times will give you similar benefits. Thirty minutes of walking* is equal to:
Jumping rope 11 min.
Jogging** 13 min.
Swimming 19 min.
Moderate cycling 24 min.
Tennis (doubles) 27 min.
Mowing the lawn 30 min.
*15-minute-per-mile pace
**10-minute-per-mile pace
This story appears in the December 23, 2002 print edition of U.S. News & World Report.