Leisure-time physical activity and the risk of primary cardiac arrest

Background: Because the risks of sudden cardiac death and myocardial infarc tion are transiently increased during acute bouts of high-intensity activit y, it is an important question from the public health perspective whether r egular participation in moderate-intensity activity confers overall protect ion from sudden cardiac death. Participants and Methods: We used data from a population-based case-control study to assess the associations of regular high-intensity and moderate-in tensity leisure-time physical activity with primary cardiac arrest. Cases w ere patients with primary cardiac arrest, aged 25 to 74 years, attended by paramedics between 1988 and 1994 in King County, Washington (n = 333). Cont rols were randomly identified from the same community (n = 503), matched fo r age and sex. All case patients and controls were free of prior clinical h eart disease, major comorbidity, and self-reported poor health. Spouses of case patients and controls were interviewed to assess participation in 15 h igh-intensity and 6 moderate-intensity physical activities during the prior year. Results: Compared with subjects who performed none of the activities, the o dds ratio for primary cardiac arrest from matched analyses was 0.34 (95% co nfidence interval, 0.13-0.89) among subjects who performed only gardening a ctivities for more than 60 minutes per week; 0.27 (95% confidence interval, 0.11-0.67) among subjects who walked for exercise for more than 60 minutes per week; and 0.34 (95% confidence interval, 0.16-0.75) among subjects who engaged in any high-intensity activities, after adjustment for age, smokin g, education, diabetes, hypertension, and health status. Conclusions: The results suggest that regular participation in moderate-int ensity activities, such as walking and gardening, are associated with a red uced risk of PCA and support current exercise recommendations.