Objectives Previous studies have shown conflicting results concerning the association between heavy physical work load and risk of coronary heart disease (CHD). The aim of this study was to investigate the association between long-term exposure to heavy physical work load in middle age and risk of CHD among Swedish men during almost 20 years of follow-up.

Methods The study is based on a cohort of around 40 000 Swedish males, born 1949–51, with census information on occupation in 1985 and 1990 (at ages 34–41). Aspects of physical workload was estimated from job exposure matrices based on questions concerning heavy lifting, strenuous work postures, and physically strenuous work from the Swedish Work Environment Surveys 1989–97. Mean values for each physical exposure variable were assigned to over 300 occupational titles from the censuses conducted in 1985 and 1990. Only those 29 530 subjects who were in the same quintile of exposure both years were included in the analyses. Information on smoking behavior and body mass index (BMI) was collected at compulsory conscription for military training in 1969/70 (at 18–20 years of age), and follow up data on CHD (1457 cases) between the years 1991–2009.

Results An increased relative risk of CHD were found among workers in the quintiles with medium low (HR=1.36 CI95%=1.14–1.62), medium (HR=1.46 CI95%=1.23–1.74), medium-high (HR=1.62 CI95%=1.36–1.91), and high (HR=1.45 CI95%=1.22–1.71) exposure to heavy lifting at work compared with those in the quintile with low exposure to heavy lifting. After adjustment for smoking and BMI the risk estimates were somewhat lower but still significantly increased. Risk estimates of the same magnitude were seen for a number of other aspects of the physical work environment.

Conclusion There was an association between long-term exposure from heavy physical work load and CHD even after adjustement for smoking and BMI.