[Health benefits and risks in sports: the other side of the coin].

Regular exercise has varied health effects, ranging from well-documented benefits to suggested risks. Probably the most important benefit is the reduction of the risk of coronary death by approximately one half among male exercisers, who also have a slightly elevated life-expectancy. This cardioprotective effect of physical exercise is not offset by the immediate increase in risk of sudden death during strenuous exercise. Sports-related complaints and injuries of the locomotor system must however also be born in mind. Different sports have different injury rates, but often a dose-effect relationship can be seen within one type of activity. The long-term effects of exercise on bones and joints are of uncertain dignity, since they may range from desirable prevention of osteoporosis to sports-induced premature osteoarthritis. The potentially important health effects of exercise at old age are largely unknown. From a prevention perspective, one to two weekly hours of vigorous exercise or an additional energy expenditure of at least 1000 kcal per week (also with moderate-intensity exercise such as walking) can safely be recommended. At present, only one third to one half of the adult Swiss population are physically that active.