Key takeaways:

• Occupational physical activity increased heart disease risk in men compared with sedentary occupational activity.
• However, the opposite was true in women.

Strenuous occupational physical activity increased risk for ischemic heart disease in men but not in women, researchers reported.

“This emphasizes the importance of taking sex differences into account in studies of health effects of [occupational physical activity],” Karen Allesøe, PhD, MSc, MPH, of the department of occupational and social medicine at the Center for Clinical Research and Prevention at Copenhagen University Hospital in Denmark, and colleagues wrote in the European Journal of Preventive Cardiology.

In a prospective cohort study, Allesøe and colleagues examined the relationship between occupational physical activity and risk for ischemic heart disease, as well as the impact of sex on the relationship, in 3,105 individuals (1,706 men and 1,399 women; mean age, 43.6 years; average follow-up period for men, 25.5 years; average follow-up period for women, 29 years) from the Danish Monica 1 study. Baseline data were collected between 1982 and 1984.

To determine participants’ occupational physical activity levels, researchers developed the following four categories for a self-reported questionnaire: sedentary; light; moderate, some lifting; and strenuous, heavy lifting.

Compared with sedentary occupational physical activity, the risk for ischemic heart disease in men was higher for participants who reported light (age-adjusted HR = 1.25; 95% CI, 0.96-1.64), moderate (age-adjusted HR = 1.49; 95% CI, 1.08-2.05) and strenuous (age-adjusted HR = 1.45; 95% CI, 0.94-2.22) occupational physical activity.

Meanwhile, for women, the risk for ischemic heart disease was lower in light (age-adjusted HR = 0.72; 95% CI, 0.51-1.02), moderate (age-adjusted HR = 0.83; 95% CI, 0.5-1.38) and strenuous (age-adjusted HR = 0.35; 95% CI, 0.05-2.55) occupational physical activity categories compared with sedentary.

In addition, all levels of occupational physical activity in men were associated with a higher risk for ischemic heart disease compared with sedentary work for women (P for interaction between occupational physical activity and sex = .048), according to the researchers.

“Future studies should investigate the underlying mechanisms for this difference, whether it is differences in exposure and/or physiological differences between the two sexes,” Allesøe and colleagues wrote.