Older people who do endurance exercise training end up with metabolically younger hearts, according to a study at Washington University School of Medicine in St. Louis. By at least one metabolic measure, women benefit more than men from the training.

Researchers measured heart metabolism in sedentary older people both at rest and during administration of dobutamine, a drug that makes the heart race as if a person were exercising vigorously. At the start of the study, they found that the hearts of the study subjects didn't increase their uptake of glucose in response to the dobutamine.

But after endurance exercise training involving walking, running or cycling exercises three to five days a week for about an hour per session, the participants' hearts doubled their glucose uptake during high-energy demand, just as younger hearts do.

If heart muscle doesn't take in glucose in response to increased energy needs, it goes into an energy-deprived state, which can raise the risk of heart attack. But if it can increase glucose uptake, the heart is better protected against heart attack and ischemia (low oxygen).