Physicians' Academy for Cardiovascular Education

Physical activity pays off for MI prevention, even at high air pollution

Effects of Leisure-Time and Transport-Related Physical Activities on the Risk of Incident and Recurrent Myocardial Infarction and Interaction With Traffic-Related Air Pollution: A Cohort Study

Literature - Kubesch NJ, Therming Jørgensen J, Hoffmann B, et al. - J Am Heart Assoc. 2018;7:e009554

Introduction and methods

Physical activity reduces the risk of cardiovascular (CV) disease through several mechanisms, including improvements in inflammatory status, hemostatic factors, insulin sensitivity, and blood lipids [1]. Outdoor air pollution, on the other hand, leads to worsening of inflammatory status and oxidative stress, and is therefore a CV risk factor [2]. Physical activity in areas with air pollution may increase exposure to pollutants due to exercise-induced higher minute ventilation, leading to higher deposition of the inhaled particles in the lungs [3]. However, it is not known whether the benefit of physical activity on CV risk is reduced by exposure to air pollution.

This analysis of the Danish Diet, Cancer, and Health cohort [4], evaluated the effects of physical activity on the risk of incident and recurrent myocardial infarction (MI) in middle-aged men and women, and assessed whether air pollution modifies the association between physical activity and MI.

The Danish Diet, Cancer, and Health cohort included 57,053 individuals with or without a history of MI, aged 50-64 years, between 1993 and 1997. Individuals with a history of cancer and missing data of interest were excluded for this analysis, leaving a study sample of 51,868 participants. Physical activity (sports, cycling, walking, and gardening) was reported in hours per week (h/wk) using a validated questionnaire [5], and NO2 exposure was estimated for the residential addresses of participants using the Danish AirGIS dispersion modeling system [6], and classified into low (<14.3 lg/m3), medium (≥14.3–21.0 lg/m3), and high (≥21.0 lg/m3) exposure.

Main results


Physical activity, even at moderate levels, reduces the risk of incident and recurrent MI, independently of the exposure to NO2. These results suggest that the long-term benefits of physical activity in primary and secondary MI prevention outweigh the risks associated with exposure to air pollution.


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