Physical activity, obesity and blood lipids

Abstract

To present the evidence concerning the influence of physical activity on the dyslipidaemia of obesity and overweight. Review of a personal library of literature on the interactions of physical activity, lipoprotein metabolism and body fatness. Obesity, in particular abdominal obesity, is associated with dyslipidaemia--specifically elevated plasma concentrations of triacylglycerol (TAG) in the fasted state, an exaggerated postprandial rise in plasma TAG, low concentrations of high density lipoprotein cholesterol (HDL) and possibly a preponderance of small dense low density lipoproteins. Regular physical activity contributes to the avoidance of overweight and hence to the development of dyslipidaemia. Although low levels of body fatness contribute to the high levels of HDL cholesterol and the low levels of TAG in trained people there are other important determinants of these characteristics. In particular, exercise (and probably training, that is regular, frequent exercise over months and years) enhances the metabolic capacity for TAG, possibly through mechanisms involving increased activity of lipoprotein lipase. This, in turn, has effects on other lipoprotein species such that the transport of TAG and cholesterol in the circulation is improved. There is evidence for a dose-response relationship, with for example, higher levels of HDL cholesterol in men and women who expend more energy in exercise. For the majority of healthy, sedentary adults frequent, moderate intensity exercise equivalent to a total gross energy expenditure of about 8.5 MJ per week is probably a sufficient to influence lipoprotein lipids.