Short-term effects of exercise on plasma very low density lipoproteins (VLDL) and fatty acids

PURPOSE: In the fasted state the lipid fuels for muscle metabolism are free fatty acids (FFA) released either from intramuscular triglycerides (TG), plasma albumin, or TG in circulating very low density lipoproteins (VLDL). The purposes of this study were to determine the influence of acute exercise of moderate intensity on 1) plasma total concentration of TG and VLDL components, 2) the plasma concentration and distribution of individual albumin-bound long-chain FFA, and 3) lipid peroxidation as measured by thiobarbituric acid reactive substances (TBARS). METHODS: Eight healthy male subjects each participated in one exercise (EX) and one rest (RE) experiment. In EX the subjects exercised for 90 min at 58+/-5% (mean +/- SD) of maximal O2 uptake on a cycle ergometer followed by 4.5 h bedrest. RE followed the same protocol, but without exercise. RESULTS: In EX there was no immediate change in VLDL concentration during the exercise. After exercise there was a decrease in VLDL, VLDL-TG, -cholesterol, -protein and -phospholipids compared with those after RE. There was no change in percentage composition of VLDL as result of exercise. Total plasma FFA concentration increased appreciably during exercise and remained elevated for several hours postexercise. There was no correlation between the change in FFA concentration and VLDL-TG. There was a significant positive correlation between the exercise-related increments in the various long-chain FFA, but the effect varied so that the relative abundance of oleic acid increased and that of stearic and arachidonic acid decreased during exercise. Plasma TBARS concentration increased during the day in both experiments. CONCLUSION: The results indicate that there is a delay in the effect of an exercise bout on plasma VLDL and confirm that exercise affects various FFA in plasma differentially.