Physical fitness protects men who work long hours from the heart disease that is associated with putting in overtime, a study found.
Unfit men who worked 41 to 45 hours a week were 59 percent more likely to die of heart disease than men working fewer hours, according to a study published today in the medical journal Heart. Their fit counterparts were 45 percent less likely to die of heart disease and 38 percent less likely to die of other causes than unfit colleagues, the study said.
Epidemiologists have long known that working extended hours increases the risk of cardiovascular disease, high blood pressure and diabetes. The study, led by Andreas Holtermann of the National Research Centre for the Working Environment in Copenhagen, is the first to show that fitness can offer protection from some of these detrimental effects.
“Long hours are not a problem if you are physically fit,” Holtermann said in a telephone interview yesterday. “The bad news is that if you aren’t fit, you much more likely to die if you work longer than 45 hours a week.”
The researchers studied about 5,000 healthy men enrolled in a long-term epidemiological project called the Copenhagen Male Study. The scientists used bicycle ergometers to test participants’ fitness levels and questionnaires to determine their work hours and activity levels.
Even moderate fitness decreased the risk of dying from heart disease compared with men who were unfit and worked long hours. Men who were both unfit and worked more than 45 hours a week fared the worst: they were more than twice as likely to die of heart disease as men working under 40 hours.
The most active men were either engaged in heavy physical work such as digging and shoveling, or were active athletes who ran, played tennis or badminton for at least 3 hours a week, the study said.
Overall fitness is combination of exercise, lifestyle and a person’s genetic makeup, Holtermann said. That gives those at risk an opportunity to improve their health.
“This is something people can easily change themselves,” he said.
Working longer hours taxes the cardiovascular system because it cranks up the nervous system, elevating both heart rate and blood pressure. A high level of fitness reduces recovery time and physiological stress during a specific task.
The study is limited by the fact that the men reported both their activity levels and work hours, making the reports susceptible to errors, and by the fact that it only includes Caucasian men, the researchers said.