National Runner's Health Study: What Kind of Exercise is Best?

Two exercisers - one a runner, the other a walker - pass each other on their morning loops.  "Good morning," says the walker, thinking to herself, "Injury magnet. " "Morning," replies the runner, thinking to herself, "Wimp. "

Meanwhile, both spend the next block wondering who has the better exercise regimen.

That's what Paul Williams wants to know.  Williams, a biostatistician at the Lawrence Berkeley National Laboratory, is already six years into the National Runners' Health study, an inquiry into the health of 55,000 volunteer runners.  Starting in February, he and his colleagues began to recruit 55,000 walkers for a similar
study, this one called the National Walkers' Health Study.

For both studies, volunteers across the country fill out two-page questionnaires about their health and exercise habits.  Williams follows up with them at intervals ranging from five to 10 years.  He asks some for permission to verify information with their physicians.

"What we're interested in finding out is specifically what types of exercise provide health benefits and which are the most effective ways to achieve those health benefits," says Williams, a 20-mile-a week runner.

Certainly evidence points to exercise as beneficial in lessening risk factors for heart disease, such as lowering blood pressure and improving cholesterol levels.  And some studies have shown a link between exercise and lessened incidence of breast cancer.  But what Williams and his colleagues want to know is what kind of exercise
works best, and at what levels of intensity.

It's a question that has long divided exercisers and researchers alike.

Williams has begun to publish analyses of data from the National Runners' Health Study.  Data published in the Jan. 27 edition of the Archives of Internal Medicine found that exercise at levels high above the recommended guideline can provide "substantial health benefits. "What's more, those benefits didn't level out as exercise
increased.  Instead, they steadily grew in runners who logged up to 50 miles a week.

The study looked at 8,283 male recreational runners who had no history of heart disease.  The more miles they ran each week, the better their coronary heart disease risk factors, such as blood pressure, body weight and levels of cholesterol and triglycerides (fatty acids) in the blood.

But other researchers point out the study is based on responses that were reported by volunteer runners themselves, then checked with their personal physicians - not gathered by one group of investigators.  The volunteers may also be skewed toward very dedicated runners who pile up high mileages and don't represent the
general population.

And the study was accompanied by editorials from other researchers outlining some of the problems associated with running, and reiterating the health benefits of more moderate exercise.

"Excessive mileage may increase the frequency and magnitude of musculoskeletal injuries, chronic fatigue, amenorrhea absence of menstrual periods, depressed immune function, and other overuse problems, or possibly even increase disease incidence," wrote Dr. Kenneth Cooper and Steven N. Blair of the Cooper Institute in Dallas
in an editorial accompanying the latest report from the National Runner's Health Study.

Cooper, a force in the exercise field since he coined the word "aerobics" nearly 30 years ago, says that his own research and review of other studies convinces him that brisk walking (at a pace as fast as 12 or 15 minutes a mile) can give people health benefits comparable to running, without the risks of musculoskeletal injury
and other problems.

" 'More is better' is antiquated," he says.  Cooper, who ran his last marathon in 1969, now divides his workouts between fast walking and jogging.

And so the studies proceed.

Williams said health issues in the walkers' study are mostly the same as in the runners' study, though there are a few differences. For one thing, while runners usually go out once a day at most, walkers often take a couple of constitutionals a day, which may affect health benefits.

There's another big difference between walkers and runners.

Walking tends to be the exercise of choice of women while the majority of runners are male.

Do women know something men don't?

"I have often held that women have a more balanced view.  I would submit that they're the smarter gender on average," said Mark Fenton, editor-at-large of Walking Magazine.

He theorized that men are more susceptible to the desire to appear competitive at work or play.

Fenton said he hopes Williams' study will back up his premise that walkers are taking the road to good health.


Here are some of the pros and cons of walking and running.  But keep in mind that the best exercise probably is the one you'll do consistently over the long haul.

Walking:

Easy and accessible.

Low impact; rarely leads to injury.

Can exercise your heart and provide health benefits; studies show most people are able to elevate their heart rates by walking fast.

However, walking fast enough to exercise the heart requires some concentration, and it can be difficult to achieve a high enough heart rate for a long enough period to increase aerobic fitness.  You can carry weights, climb hills or carry a pack to make your walking workout more challenging.

Burns calories at about the same rate, mile for mile, as running.

Running:

Also fairly accessible.

Easy to elevate heart rate and achieve training effect for aerobic fitness.  May also be more effective at lowering body fat percentage and blood pressure; heightening the level of HDL, or "good" cholesterol.

Calorie burn is about the same, mile for mile, as walking, but running takes less time - a consideration for busy people.  You will burn more calories running for a half-hour than you will walking for a half-hour.

Potential for injury may be greater - including musculoskeletal injuries.  Excessive running may lead to depressed immune system, absence of menstrual periods and other overuse problems. For those who have been sedentary, a program of vigorous exercise such as running may increase the risk of heart attack, especially in older people.  Those who intend to start a running program should check with their doctors and have a physical examination.