[Benefits and risks of physical activity from the epidemiological point of view]

The recent epidemiological literature on the health effects of physical activity is reviewed. Habitual physical activity is inversely associated with the risk of lethal and nonlethal myocardial infarction in men, in spite of a transient increase in the risk of sudden death during vigorous activity. Several mechanisms could explain this likely though unproved protective effect of regular exercise on coronary heart disease: lipoprotein pattern, functional cardiac capacity, glucose tolerance, and (presumably) hemostasis and catecholamines are favourably affected by vigorous physical activity, which is also inversely related to obesity and smoking. On the other hand, sports seems to be related in a linear way to musculoskeletal morbidity, especially in men. This negative though poorly documented side effect of physical activity renders preventive recommendations more difficult, but it should be kept in mind alongside the suggested cardiovascular benefits of exercise.