Get moving: The nation's new exercise guidelines 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 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. More fit adults could pack in their week's requirement in 75 minutes with vigorous exercise, such as jogging, hiking uphill, a bike race or speedy laps in the pool.
Children and teens need more — pretty brisk activities for at least an hour a day, say the government guidelines being released Tuesday.
Consider it the exercise version of the food pyramid. The guidelines, from the Health and Human Services Department, 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 told The Associated Press.
It's OK to start slowly. Someone who's done no exercising will start seeing benefits with as little as 10 minutes of moderately intense exercise a day, which is an incentive to work up to the recommended amounts, said Rear Adm. Penelope Royall, deputy assistant secretary for disease prevention.
"Some is better than nothing, and more is better," she said.
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 a quarter 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 are obese.
Worse, the nation is raising a generation of children who may be less healthy than their parents. About a 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 a 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-weakening bones and depression.
The government used that scientific report to set the minimum activity levels.
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's the right kind of exercise? The guidelines advise:
— You don't have get all the activity at once. A walk for an hour three days a week works as well as, say, a 30-minute exercise class on weekdays or saving most of the activity for a two-hour Saturday bike ride.
— For aerobic activities, go at least 10 minutes at a time to build heart rate enough to count.
— You should be able to talk while doing moderate activities but not catch enough breath to sing. With vigorous activities, you can say only a few words without stopping to catch a breath.
— Children's daily hour should consist of mostly moderate or vigorous aerobic activity, such as skateboarding, bike riding, soccer, simple running.
— Three times a week, children and teens need to include muscle-strengthening activities — sit-ups, tug-of-war — and bone-strengthening activities, such as jumping rope or skipping.
— Adults should do muscle-strengthening activities — push-ups, weight training, carrying heavy loads or heavy gardening — at least two days a week.
— Older adults who are still physically able to follow the guidelines should do so, with an emphasis on activities that maintain or improve balance.
These are minimum goals, the guidelines note. People who do more will see greater benefits.