A new  government-sponsored research on middle-aged and elderly American veterans conducted by the exercise testing and research lab in the cardiology department of the Veterans Affairs Medical Center in Washington, D.C. 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.

The study, the largest ever, concluded that as you increase your fitness, you are decreasing in a step-wise fashion the risk of death. That conclusion applies more or less equally to white and black men, regardless of their prior history of cardiovascular disease.

In the study, the 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). The research team tracked fatalities through June 2007, and 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.

According to 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. the point is, it takes relatively little exercise to achieve the benefit we found," . "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."

The results was published in the Feb. 5, 2008 issue of Circulation and were released online Jan. 22.