WEDNESDAY, Jan. 23 (HealthDay News) -- Even a moderate amount of exercise can dramatically prolong a man's life, new research on middle-aged and elderly American veterans reveals.

The government-sponsored analysis -- the largest such study ever -- found that a regimen of brisk walking 30 minutes a day at least four to six days a week was enough to halve the risk of premature death from all causes.

"As you increase your ability to exercise -- increase your fitness -- you are decreasing in a step-wise fashion the risk of death," said study author Peter Kokkinos, director of the exercise testing and research lab in the cardiology department of the Veterans Affairs Medical Center in Washington, D.C.

That conclusion applies more or less equally to white and black men, regardless of their prior history of cardiovascular disease. According to Kokkinos, that may be because the veterans in the study all received the same level of care, regardless of income.

This evened the playing field, he said, giving him "great confidence" in the results, which will be published in the Feb. 5 issue of Circulation and were released online Jan. 22.

In the study, Kokkinos and his team reviewed information gathered by the VA from 15,660 black and white male patients treated either in Palo Alto, Calif., or in Washington, D.C.

The men ranged in age from 47 to 71 and had been referred to a VA medical facility for a clinically prescribed treadmill exercise test sometime between 1983 and 2006. All participants were asked to run until fatigued, at which point the researchers recorded the total amount of energy expended and oxygen consumed.

The numbers were then crunched into "metabolic equivalents," or METS. In turn, the researchers graded the fitness of each man according to his MET score, ranging from "low-fit" (below 5 METS) to "very-high fit" (above 10 METS).

By tracking fatalities through June 2007, Kokkinos and his colleagues found that for both black and white men it was their fitness level, rather than their age, blood pressure or body-mass index, that was most strongly linked to their future risk for death.

Every extra point in MET conferred a 14 percent reduction in the risk for death among black men, and a 12 percent reduction among whites. Among all participants, those categorized as "moderately fit" (5 to 7 METS) had about a 20 percent lower risk for death than "low-fit" men. "High-fit" men (7 to 10 METS) had a 50 percent lower risk, while the "very high fit" (10 METS or higher) cut their odds of an early death by 70 percent.

"The point is, it takes relatively little exercise to achieve the benefit we found," noted Kokkinos. "Approximately two to three hours per week of brisk walking per week. That's just 120 to 200 minutes per week. And this can be split up throughout the week, and throughout the day. So it's doable in the real world."

Alice H. Lichtenstein, director of the Cardiovascular Nutrition Lab at Tufts University's USDA Human Nutrition Research Center in Boston, agreed.

"What this finding demonstrates is that levels of physical activity that should be achievable by anyone can have a real benefit with respect to risk reduction," she said.

"What's really important to understand is that you don't need special clothes, special memberships, special equipment," added Lichtenstein, former chairwoman of the American Heart Association's nutrition committee. "It's something everyone can engage in. And although we don't know from this research that this applies to women as well, there's no reason to suspect that it wouldn't."

More information

There's more on physical fitness at the U.S. Centers for Disease Control and Prevention.

SOURCES: Peter Kokkinos, Ph.D., director, exercise testing and research lab, cardiology department, Veterans Affairs Medical Center, Washington D.C.; Alice H. Lichtenstein, D.Sc., director, Cardiovascular Nutrition Lab, Gershoff professor of nutrition, USDA Human Nutrition Research Center, Tufts University, Boston, and former vice chair, nutrition committee, American Heart Association; Jan. 22, 2008, Circulation, online

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