How much exercise is enough?

DURHAM, N.C. — To dramatically cut the risk of life threatening illness like heart disease, diabetes or cancer, the best results are not measured in sweat, but in miles.

Duke Cardiologist Dr. Bill Kraus was part of a federal panel of experts reviewing all available research on the health benefits of physical activity. Kraus said “not being physically active is of substantial detriment to people’s health.”

While the new Food Pyramid recommends at least 30 minutes a day for most days of the week for adults and an hour each day for children, Kraus says the best research doesn't point to any one type of exercise – as long as it's equivalent to 9 to 10 miles per week.

“It doesn't matter how you do it and in fact probably the preferable way for most people is just walking,” Kraus said.

Lora Grinstead, 79, is doing more walking at Duke's Center for Living. Her husband, Elbert, with heart failure, is spending more time on a stationary bike.

Grinstead said she and her husband stay active in ways are sometimes difficult to break down in miles.

“Well I do housework and in summertime, if the garden produces – I do canning – and we go to the lake and we swim,” she said.

More detailed federal guidelines, including final recommendations, will be released later this year, but Kraus said the research doesn't lead to any conclusions about how intensely you should exercise or the daily dosage of exercise.