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Two studies presented at this year's EuroPrevent, an international forum for preventative cardiology, suggested that demanding physical work is associated with an increased risk for coronary heart disease.

A case-control study conducted by Dr. Demosthenes Panagiotakos, Associate Professor of Biostatistics-Epidemiology at Harokopio University, Athens, evaluated the occupation of 1000 patients.

The study was broken into three groups, 250 patients who had a first stroke, 250 patients with a first acute coronary event, and 500 patients with equally matched controls. They were assessed on a 9-unit-scale to determine how physically demanding the patients' occupation were. The research showed the people who had suffered stroke and coronary events were more commonly engaged in physically demanding occupations compared to the control group.

Various potential contributing factors such as age, sex, body mass index, diet, family history, smoking, and more, were taken into consideration. The study confirmed that patients with less physically demanding occupations were associated with a 20 percent lower chance of having acute coronary events or an ischaemic stroke.

Subjects with physically demanding manual jobs should be considered a primary target group for cardiovascular disease preventions because of their high risk, Dr. Panagiotakos commented. While physical exercise is recommended for good health and well being, stress may be the differential factor linking physically demanding jobs with an increased risk of coronary events.  These occupations are often not well paid, which may restrict access to healthcare systems, noted Dr. Panagiotakos.

The second study, which was conducted by investigators in Belgium and Denmark, also found that physically demanding work is a risk factor for coronary heart disease, even when leisure-time activity is taken into account.

More than 14,000 middle aged men free of coronary heart disease were part of the cohort study which ran from 1994-1998. Questionnaires were used to assess the participants' socio-demographic factors, job strain and level of physical activity both at work and during leisure time. Other coronary risk factors were taken into measured through the questionnaires and clinical examinations.

The study monitored the incidence of coronary events over the course of approximately three years and used statistical modeling to assess the association between physical activity and coronary disease. Other risk factors such as age, education, occupational class, job strain, alcohol consumption and more were also adjusted for.

The results showed an overall beneficial effect of leisure time physical activity, but an adverse effect of demanding physical work. Researcher Dr. Els Clay of the Department of Public Health said an "interaction effect" was also evident. Moderate-to-high physical activity during leisure time was associated with a 60 percent reduced risk for coronary events in men with low occupational physical activity.

After adjusting the study for socio-demographic and well established coronary risk factors, Dr. Clay said men with high physical job demands were more than four times likely to have coronary heart disease when they also engaged in physical activity during leisure time.

"From a public health perspective it is very important to know whether people with physically demanding jobs should be advised to engage in leisure time activity."

Dr. Clay noted that additional physical activity during leisure time in those who are already physically exhausted can be an overloading effect on the cardiovascular system.

"However, only few studies until now have specifically addressed this interaction among both types of physical activity, and conflicting findings have been reported. More research using detailed and objective measures of activity is needed."