Half an Hour for Health

By Sally Squires
Tuesday, August 14, 2007

Couch potatoes, start your engines.

For those who can't seem to get the recommended 60 to 90 minutes of daily physical activity, new guidelines from the American College of Sports Medicine (ACSM) and the American Heart Association have just set the bar lower.

How low?

The groups recommend 30 minutes of brisk walking -- or similar moderately intensive physical activity -- five times per week for adults. If you're willing to do a higher-intensity workout -- jogging, for example -- you can get by with 20 minutes three times a week. Those amounts are enough to reap major health benefits, according to the guidelines, which also advise that adults lift weights at least twice a week.

If that advice sounds familiar, you're right. It's almost identical to guidelines issued in 1995 by ACSM and the Centers for Disease Control and Prevention.

Confused? You're not alone. Exercise researchers have debated the subject for more than a decade -- and the new guidelines are intended clarify what seems like conflicting advice.

Here are some questions you might find yourself asking about the latest guidelines:

Wow! I might be able to fit in those 30 minutes of exercise, but what happened to the 60 to 90 minutes of activity? That's still the level of exercise recommended by both the 2005 U.S. Dietary Guidelines and by the Institute of Medicine, but it was set to help people control their weight. There's good evidence from the National Weight Control Registry -- a group of several thousand "successful losers" -- that at least an hour a day of activity is needed for weight loss and weight maintenance. But for other health benefits, the new -- that is to say, the old -- 30-minute standard seems to do the trick.

"That's the bottom line," says Steven N. Blair, a professor of exercise science at the University of South Carolina and co-chair of the committee that drafted the latest guidelines. "This is the amount of activity that provides really substantial health benefits."

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