Last Updated: 2003-05-15 10:00:30 -0400 (Reuters Health)

WASHINGTON (Reuters) - A quarter of all Americans get virtually no exercise, raising their risk of heart disease, diabetes and cancer, a government report said on Wednesday.

Only 19 percent get a "high" level of physical activity at work or in their free time, the survey by the National Center for Health Statistics found.

The report, based on 32,000 interviews conducted in 2000, found blacks and Hispanics were less likely to exercise than whites, with just 15 percent reporting they get a high level of physical activity.

Education, income and marital status all affect whether someone exercises.

"About one in four adults with an advanced degree engage in a high level of overall physical activity, compared to one in seven of those with less than a high school diploma," the NCHS said in a statement.

"Adults with incomes below the poverty level are three times as likely to be physically inactive as adults in the highest income group."

Married women are more likely to exercise than women who have not married and men are more likely to exercise than women. The southern United States has the highest percentage of couch potatoes.

"Physical activity -- whether it's walking the dog or simply taking the stairs at work -- is essential to good health," Health and Human Services Secretary Tommy Thompson said in a statement.

"This study helps give us an even fuller picture of our physical activity status," Thompson said. "It confirms that we need to pay more attention to getting adequate physical activity and reversing the alarming rise in obesity that we've experienced nationally during the past decade."

Light or moderate activity was defined as exercise lasting at least 10 minutes that caused light sweating or a slight to moderate rise in breathing and heart rate. Vigorous activity causes profuse sweating, heavy breathing and a pounding heart rate.