Is Walking Enough?
Better Step Lively
Nov. 13, 2000 -- Legs striding, arms pumping, I'm hustling down
a long corridor at the Cooper Institute of Aerobics Research in Dallas,
alongside exercise scientist Andrea Dunn, PhD. Her studies have helped make
walking more than just a way to get from here to there; she and her colleagues
have elevated it to a respectable form of exercise.
Today, Dunn has agreed to show me just how brisk a walk must be
to count as a workout. I'm hoping that in the process she'll also help settle a
growing debate in the field of exercise research: How hard and how long do you
need to work out to stay healthy? The answer is still controversial. But new
research is beginning to provide a clearer picture.
Brisk walking gained the status of exercise after a landmark
1989 Cooper Institute study came to a surprising finding: that people who were
only moderately fit were significantly less likely to die of heart disease than
those who never got off the couch. True, people who were super fit had the
lowest death rates. But all their extra work gained them only a modest
advantage -- 10% to 15% -- over the moderately fit group. The study, which
followed some 13,000 men and women for more than eight years, was published in
the Nov. 3, 1989, issue of the Journal of the American Medical
Start of an era
The Cooper study, and others that followed, profoundly changed
the thinking of many researchers. Many sports scientists came to believe that
moderately intense physical activities such as walking, gardening, or cleaning
house -- dubbed "exercise lite" -- could provide most of the health
benefits of more conventional exercise. To lead author Steven Blair, PhD, and
his colleagues, this meant that instead of exhorting people to strive for
levels of exercise that most of them would never achieve, health professionals
could urge their patients to engage in the kinds of exercise they might
actually get out and do.
Even the U.S. surgeon general joined the ranks, issuing
guidelines that encourage Americans to engage in "a minimum of 30 minutes
of physical activity of moderate intensity (e.g., brisk walking) on most, if
not all, days of the week." The era of "exercise lite" had
Walking shoes became the rage. A magazine called Walking
was born. And hoofing it through the neighborhood became the exercise of choice
for many active Americans.
Not just a walk in the park
But a decade after the famous study's release, some researchers
argue that we've been sold a bill of goods. "Exercise lite is to exercise
what lite beer is to beer. It's pretty bland stuff," says Paul Williams,
PhD, an exercise scientist at the Life Sciences Division of the Lawrence
Berkeley Laboratory in California. "Exercise lite has given many Americans
a false sense that a stroll through the neighborhood is all you need to stay
healthy. Instead of pushing people to be more active, it's given them an excuse
to do as little as possible."