People who have physically demanding jobs may have an increased risk of suffering heart problems, such as a heart attack or heart disease, two new studies suggest.

The first study was carried out by Greek scientists and it focused on 250 people who had suffered a first stroke, 250 people who had suffered a first acute coronary event, such as a heart attack, and 500 controls who had not suffered any heart problems.

The participants' jobs were graded on a scale of one to nine, with one representing physically demanding work and nine representing sedentary/mental work.

The scientists found that those with the most physically demanding jobs were much more likely to suffer a stroke or coronary event. The results stood even when other factors were taken into account, such as age, body mass index, smoking, high blood pressure and a family history of heart disease.

As people moved down the physical job scale, their risk of suffering a heart-related event reduced.

According to lead scientist, Dr Demosthenes Panagiotakos of Harokopio University in Athens, people with physically demanding jobs should be targeted in relation to prevention of heart disease because of this increased risk.

He noted that while a physically demanding job can be considered exercise, it does not appear to produce the health-related benefits of exercise. This, he believes, may be down to stress. Furthermore, very physically demanding work is often not well paid and this may restrict some workers' access to good healthcare.

The second study looked at over 14,000 middle-aged men who did not have coronary disease at the beginning of a study that began in the 1990s. Risk factors for heart problems were assessed and the men filled out questionnaires about their work and physical activity levels among other things. Each man was followed up for an average of just over three years.

This study by Belgian and Danish scientists found that physical activity associated with leisure time benefitted the men, however physically demanding work had an adverse effect on their health.

"While moderate-to-high physical activity during leisure time was associated with a 60% reduced risk of coronary events in men with low occupational physical activity, this protective effect was not observed in those workers who were also exposed to high physical work demands," explained Dr Els Clays of the University of Ghent in Belgium.

The study found that overall, men with very physically demanding jobs were at least four times as likely to have coronary artery disease when they also took part in leisure time physical activity.

"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.

"The results of this study suggest that additional physical activity during leisure time in those who are already physically exhausted from their daily occupation does not induce a 'training' effect, but rather an overloading effect on the cardiovascular system," Dr Clays explained.

However, he emphasised that only a few studies have specifically focused on 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."

Details of both studies were presented at the EuroPRevent 2013 Congress in Italy, which was organised by the European Society of Cardiology.

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