Study: It pays to be fit in 20s
Participants who were out of shape had more health risks in 30s, 40s

People who are out of shape in their 20s run a high risk of developing high blood pressure, diabetes and other heart attack risk factors by their 30s and 40s, according to a study in which people were given treadmill tests of their fitness.

The lesson: “People can’t wait until middle age to try and protect themselves,” said lead author Mercedes Carnethon, an assistant professor of preventive medicine at Northwestern University.

The study involved about 4,400 men and women who were given a treadmill test when they were 18 to 30. Most of them were followed for 15 years after that.

Those who did not do well on the treadmill test faced double the risk of developing high blood pressure, diabetes or a condition called metabolic syndrome, compared with highly fit participants. Metabolic syndrome is a cluster of symptoms that includes high blood sugar, poor cholesterol levels, elevated blood pressure and a fat belly.

Some participants underwent a second treadmill test, seven years after the first. Those who became more fit during those intervening years reduced by 50 percent their risk of diabetes and metabolic syndrome.

The study is published in Wednesday’s Journal of the American Medical Association.

The findings “confirm what common sense has always told us: Lack of fitness in youth is not a good thing for later life,” said Dr. Teri Manolio, director of epidemiology at the National Heart, Lung and Blood Institute, which funded the research.

Fitness levels were determined by how long participants could walk on a treadmill without becoming fatigued and short of breath.