Running and walking are both popular ways to get a great cardio workout. But is a brisk walk really as good an exercise as a sweaty, heart-pounding run?

Research reported by the American Heart Association finds that walking is just as good as running when it comes to lowering your risk for heart disease.

Researchers analyzed the health of some 48,000 runners and walkers mainly in 40s and 50s. They found that, mile for mile, brisk walking lowers the risk for diabetes, high cholesterol and high blood pressure as much as running does.

The difference? You'll have to spend more time walking than you do running to get the same health benefits simply because it takes longer to walk than to run the same distance. For instance, a 15-minute jog burns about the same number of calories as a half-hour brisk walk.

Keep in mind that the chance of being injured is greater in runners because running puts more stress on the body -- on the joints in particular.

But if you're still thinking of stepping up the pace to running, first check with your doctor, especially if you have arthritis or other health conditions, like heart disease.

And keep in mind that you don't have to stick to either walking or running. You can stay motivated by mixing it up. What's more, adding short sprints to your walking routine will give you a bigger calorie-burning boost for your efforts.