Exercise could be the heart's fountai...( Absence may make the heart grow fond...)

Absence may make the heart grow fonder, but endurance exercise seems to make it younger. According to a study conducted at Washington University School of Medicine in St. Louis, older people who did endurance exercise training for about a year ended up with metabolically much younger hearts. The researchers also showed that by one metabolic measure, women benefited more than men from the training.

"We know that the heart deteriorates as people get older, and that's largely because they don't stay as active as they used to," says first author Pablo F. Soto, M.D., instructor in medicine in the Cardiovascular Division. "Past research has suggested that exercise can reverse some effects of aging, and we wanted to see what effect it would have specifically on the heart."

The 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 in response to the increased energy demands produced by dobutamine, the hearts of the study subjects didn't increase their uptake of energy in the form of glucose (blood sugar).

But after endurance exercise training which involved 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.

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

Based on heart glucose metabolism, both the men and women in the study had the same rejuvenating benefit from their exercise programs. But the heart uses both glucose and fatty acids for energy. And wh
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