"If you think being physically active at work is helping your heart, think again if you also have workplace stress," said James H. Dwyer, a professor at the Keck School of Medicine at the University of Southern California.
He presented his findings last week at the American Heart Association's Annual Conference on Cardiovascular Disease Epidemiology and Prevention in San Antonio.
Dwyer and lead investigator Cheryl Nordstrom followed 447 California utility company workers for three years in the late 1990s.
The employees -- including managers, meter readers, technicians and administrative assistants -- were between the ages of 40 and 60.
The employees were believed to be under increased stress because they were studied after deregulation resulted in increased competition among utility companies, Dwyer said. The researchers found that those in physically demanding jobs showed the most dramatic thickening of the carotid artery -- related to the buildup of plaque in arteries that can cause disease.
Those with the highest degree of workplace physical activity likewise reported the most job-related stress.
"The big message is that work stress can be a risk factor for early heart disease," Nordstrom said.
The good news, she said, is that leisure time exercise appeared to help protect against heart disease. Workers who exercised at least four times each week away from work showed much less carotid artery thickening than those who did no leisure exercise, she said.
Dwyer said the stress effect is not unique to the utility workers.
"It was not so much the danger of the job as it was the demands of the job, the uncertainties and the difficulties working with other people," he said. "These are the kinds of stresses that develop in any workplace."
In recent years, some studies on the relationship between job stress and heart disease have been in apparent contradiction.
Some studies have found evidence that workers who feel anxious and hostile tend to experience more heart attacks, while other research efforts have failed to find such a link.
Researchers from medical schools at Stanford and Duke universities examined more than 1,000 patients in the early '90s and found that people with high-stress jobs were just as likely as those in low-stress positions to have cholesterol buildup in their coronary arteries.
The study also found that those dealing with work stress were just as likely to have heart attacks or die from heart disease as those who reported little stress on the job.
Dwyer acknowledged that a main difficulty lies in the exact standard of stress, which is hard to measure because it is dependent on individual perception.
"It's going to be difficult to sort out the effects of stress and physical activity and how they interact," Dwyer said.(c) 2001 San Antonio Express-News
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