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Open Access Research article

The effect of leisure-time physical activity on the risk of acute myocardial infarction depending on Body Mass Index: a population-based case-control study

Eleonor Fransson1*, Ulf de Faire12, Anders Ahlbom34, Christina Reuterwall5, Johan Hallqvist46 and Lars Alfredsson14

Author Affiliations

1 Division of Cardiovascular Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm, Sweden

2 Department of Cardiology, Karolinska Hospital, Stockholm, Sweden

3 Division of Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden

4 Centre of Public Health, Stockholm County Council, Karolinska Hospital, Stockholm, Sweden

5 Research and Development Unit, Jämtland County Council, Östersund, Sweden

6 Division of Social Medicine, Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden

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BMC Public Health 2006, 6:296  doi:10.1186/1471-2458-6-296

Published: 7 December 2006



High body mass index (BMI) and lack of physical activity have been recognized as important risk factors for coronary heart disease. The aim of the present study was to evaluate whether leisure-time physical activity compensates for the increased risk of acute myocardial infarction associated with overweight and obesity.


Data from the SHEEP (Stockholm Heart Epidemiology Program) study were used. The SHEEP study is a large Swedish population-based case-control study, comprising 1204 male and 550 female cases, and 1538 male and 777 female controls, conducted in Stockholm County, Sweden, during the period 1992–1994. Odds ratios (OR), together with 95 % confidence intervals (95% CI), were calculated using unconditional logistic regression, as estimates of the relative risks.


Regular leisure-time physical activity was associated with a decreased risk of myocardial infarction among lean, normal-weight and overweight subjects, but not among obese subjects. Obese (BMI ≥ 30) and physically active persons had an almost twofold risk of myocardial infarction, compared with normal-weight and sedentary persons (OR 1.85, 95% CI 1.07–3.18). The results were similar for men and women.


While regular leisure-time physical activity seems to provide protection against myocardial infarction among lean, normal-weight and overweight subjects, this does not appear to be the case in obese subjects.