Now hear this, couch potato: Hard jobs protected against heart disease

Hard work on the job, however, protected only men who weren't obese, according to the study conducted by Joan Dorn, UB assistant professor of social and preventive medicine. The study charted work and leisure-time physical activity in a random sample of white men between the ages of 15-96 years who were living in Buffalo in 1960. The men were part of a larger population-based study of blood pressure. Interviewers had gathered extensive demographic and lifestyle information, including data about physical activity.

Dorn and colleagues tracked down survivors and revisited original data to examine the long-term association between daily physical activity and death from all causes, as well as death from coronary heart disease.

They found that in non-obese men, having a physically demanding job lowered the risk of coronary heart disease by 35 percent, and of dying from all causes by 20 percent.

"In this sample, the majority of men who were active were active mainly at work," Dorn said. "The kinds of activity they were involved in, such as lifting, carrying, shoveling and other kinds of physical exertion, probably protected them because they did it all day, every day, even though they may not have been very active at other times. They probably expended a lot of calories on the job."

Most of today's work force is sedentary, however, and therein lies the problem.

"Our culture has changed," Dorn noted. "Jobs that require hard physical labor hardly exist anymore. We know that being active helps you live a longer, healthier life. So if you aren't active during the day, you can't spend the evening on the couch if you care about your health."