The role of physical activity in the prevention of ischaemic heart disease. A review.

It has been demonstrated that vigorous leisure-time physical activity and hard physical occupational work protect against ischaemic heart disease (IHD), but the protective mechanisms are not clear. According to most research reports programmes of regular physical activity do not lower serum cholesterol concentrations, but they do lower serum triglyceride levels. Dedicated marathon runners have lower serum low density lipoprotein and higher high density lipoprotein levels than controls, but it has not been proved that this lipoprotein pattern is the result of regular, high-intensity exercise. Regular physical exercise lowers the blood pressure to a greater degree in hypertensives than in controls. An exercise programme plus diet had no greater effect on serum total cholesterol levels than did diet alone on subjects with primary hyperlipoproteinaemia types IIa, IIb and IV. However, in types IIb and IV the exercise programme plus diet was more effective than diet alone in lowering serum triglyceride levels. The results of these studies are not valid for deciding whether regular exercise decreases the IHD risk factors studied. Such judgements must be based upon the results of randomized, controlled trials. The only satisfactory trial of this nature to date was done in Helsinki, and its results were inconclusive.