Get 2 1/2 hours of exercise per week, U.S. says

Adults should aim to get in 2 1/2 hours of exercise a week and children should run and play for at least an hour a day, according to new exercise guidelines issued by the U.S. government on Tuesday.

The guidelines, meant to be akin to the "Food Pyramid" nutritional advice, are based on studies that show clear health benefits from regular, moderate exercise.

"More than 59 percent of adults don't get enough physical activity and a quarter of adults aren't active at all in their leisure time," Health and Human Services Secretary Michael Leavitt said in a telephone interview.

"I think these are the first comprehensive federal guidelines on physical activity."