Differing associations for sport versus occupational physical activity and cardiovascular risk

Objectives: We investigate the independent and interacting long-term associations of occupational physical activity (OPA) and sport physical activity (SpPA) with the incidence of coronary heart disease (CHD) and cardiovascular diseases (CVD; CHD plus ischaemic stroke) in North Italian male workers. Methods: 3574 employed men aged 25-64 years, free of CVD at baseline, recruited in three population-based and one factory-based cohorts, were included in the analysis. The Baecke Questionnaire was used to assess OPA and SpPA in 'minutes per week' of moderate or vigorous PA. We estimated the associations between different domains of PA and the endpoints, adjusting for major CVD risk factors, using Cox models. Results: During a median follow-up of 14 years, 135 and 174 first CHD and CVD events, fatal and non-fatal, occurred. Compared with the intermediate OPA tertile, the HRs for CHD among low and high OPA workers were 1.66 (95% CI 1.06 to 2.59) and 1.18 (0.72 to 1.94), respectively (P value=0.07). Decreasing trends in CHD and CVD rates across increasing levels of SpPA were also found, with an HR for CVD of 0.68 (0.46 to 0.98) for intermediate/recommended SpPA compared with poor SpPA. We also found a statistically significant SpPA-OPA interaction, and the protective effect of SpPA was only found among sedentary workers, for both endpoints. Conversely, high OPA workers with intermediate/recommended SpPA levels had increased CHD and CVD rates compared with the poor SpPA category. Conclusions: Our results provide further evidence on the health paradox of OPA, with higher CVD rates among workers with intense PA at work. Moreover, the protective effect on CVDs of SpPA is prominent in sedentary workers, but it attenuates and even reverses in moderate and strenuous OPA workers.