Get moving: New exercise guidelines released by the Health and Human Services Department set a minimum sweat allotment for good health. For most adults, that's 2 1/2 hours a week.

How much physical activity you need depends largely on your age and level of fitness.

Moderate exercise adds up for sluggish adults. Rake leaves, take a quick walk around the block or suit up for the neighborhood softball game. Fitter adults could pack in their week's requirement in just 75 minutes of vigorous exercise, such as jogging, hiking uphill, a bike race or speedy laps in the pool.

Children and teens need more – brisk activities for at least an hour a day, the guidelines conclude.

Consider it the exercise version of the food pyramid. The guidelines released last week aim to end years of confusion about how much physical activity is enough, while making clear that there are lots of ways to achieve it.

"The easy message is get active, whatever your way is. Get active your way," HHS Secretary Michael Leavitt said.

It's OK to start slowly.

"For a total couch potato who does zero, zip, nada, getting up and walking 10 minutes a day is a great start," said Rear Adm. Penelope Royall, deputy assistant secretary for disease prevention.

But people need to work toward eventually hitting that weekly minimum, she added. "Some is better than nothing, and more is better."

The guidelines come as scientists are trying to spread the word to a nation of couch potatoes that how active you are may be the most important indicator of good health.

Yet one-fourth of U.S. adults aren't active at all in their leisure time, government research concludes. More than half don't get enough of the kind of physical activity that actually helps health – walking fast enough to raise your heart rate, not just meandering, for instance.

More than 60 million adults in the United States are obese. Worse, the nation is raising its first generation of children who may be less healthy than their parents. About one-third are overweight and 16 percent are obese. And while young children are naturally active given the chance, schools are decreasing the amount of recess and gym time. By high school, a recent study found, fewer than one-third of teens are getting an hour of activity a day.

To put science behind the how-much-is-enough debate, HHS gathered an expert panel to review all the data. The panel found that regular physical activity can cut the risk of heart attacks and stroke by at least 20 percent, reduce chances of early death, and help people avoid high blood pressure, Type 2 diabetes, colon and breast cancer, fractures from age-weakened bones and depression.

The government used that scientific report to set the minimum activity levels.

"The evidence is clear," Leavitt said Tuesday in announcing the guidelines. "The more physically active you are, the more health benefits you gain."

The kind of exercise matters a lot, said Dr. William Kraus, a Duke University cardiologist who co-authored the scientific report.

Runners like Kraus can achieve the same health benefit in a fraction of the time of a walker.

"If you do it more intense, you can do less time," explained Kraus, who praised the guidelines for offering that flexibility. "This brings it back down to earth for a lot of people."

What do you think?

Do you get 2 1/2 hours of physical activity each week?

Let us know. E-mail

fitness@sacbee.com with your opinion and tell us whether you already meet the guidelines.