SHORT-TERM EFFECTS OF EXERCISE ON PLASMA-LIPIDS AND LIPOPROTEINS IN HUMANS

Lipids and lipoproteins play a major role in the cascade of events lea ding up to the manifestations of atherosclerosis as it relates to coro nary heart disease (CHD). Exercise-induced changes in the blood lipid profile appear to be therapeutic, an observation favouring the integra tion of exercise in CHD prevention and treatment programmes. The speci fic stimuli needed to produce such therapeutic effects are yet to be e lucidated; both the repeated, transitory effects of single, isolated e xercise sessions and exercise training effects an likely to be involve d. The focus of this article is on the acute or short term changes of a single session of exercise on plasma lipids and lipoproteins. The sh ort term, exercise-induced changes in plasma lipids and lipoproteins a re reviewed in the context of the role various lipid classifications p lay in coronary artery disease, the many potentially confounding varia bles that are ever-present, and the relative effects of gender, exerci se modality, and exercise intensity. It is concluded that a single bou t of exercise has the potential to induce short term, transient increa ses in the high density lipoproteins HDL and HDL(2) and decreases in t riglycerides in men. For women, more research is needed to determine c learly the exercise induced short term changes in plasma lipids and li poproteins. It appears that duration and intensity of exercise are dir ectly related to the degree of changes observed: bouts of prolonged, i ntense exercise of sufficient energy expenditure appear to induce decr eases in triglycerides and increases in HDL, primarily through HDL(2), of greater magnitude and duration. Exercise induced changes in the pl asma lipid profile appear to have returned to pre-exercise levels by 4 8 hours postexercise. Recognising that the underlying physiological me chanisms for changes in lipids and lipoproteins remain inconclusive, t he roles of the lipid-regulatory enzymes lipoprotein lipase, lecithin : cholesterol acyltransferase, and hepatic triglyceride lipase are dis cussed. It is clear that well controlled studies are needed to examine the effects of exercise on short term changes in the blood lipid prof ile in women.