ACUTE EFFECTS OF EXERCISE ON POSTPRANDIAL LIPEMIA - A COMPARATIVE-STUDY IN TRAINED AND UNTRAINED MIDDLE-AGED WOMEN

Repeated episodes of exaggerated postprandial lipemia may hasten the p rogression of atherosclerosis. The purpose of this study was to compar e the lipemic response to a high-fat meal in trained and untrained wom en in the presence and absence of the acute effects of exercise. Nine endurance-trained and thirteen untrained women aged 40.4 +/- 3.3 and 4 3.8 +/- 4.3 y ((x) over bar +/- SD), with maximal oxygen uptake of 50. 3 +/- 5.9 and 31.7 +/- 3.6 mL . kg(-1). min(-1), and a body mass index (kg/m(2)) of 22.2 +/- 0.9 and 22.9 +/- 2.3, respectively, underwent t wo trials, each over 2 d. Subjects did not exercise during the 2 d lea ding up to a trial. On day 1 they either walked for 90 min at 60% of m aximal oxygen uptake (exercise), or refrained from exercise (control). On day 2 venous blood and expired air samples were obtained in the fa sted state and for 6 h after consumption of a high-fat meal (1.70 g fa t, 1.65 g carbohydrate, and 0.25 g protein/kg fat-free mass). Exercise decreased lipemia as determined by the mean(+/- SEM) area under the p lasma triacylglycerol concentration versus time curve: trained, 6.96 /- 0.48 compared with 4.87 +/- 0.33 mmol . h/L; untrained, 8.36 +/- 0. 83 compared with 7.01 +/- 0.79 mmol . h/L (control and exercise trials , respectively, both P < 0.05), Lipemia differed significantly between groups in the presence of this acute effect of exercise but not in it s absence. Exercise decreased insulinemia in trained women (543 +/- 25 compared with 433 +/- 24 pmol . h/L, P < 0.01) but had no effect in u ntrained women (592 +/- 34 compared with 585 +/- 47 pmol . hL). Total oxidation of fat over the 6-h postprandial period was enhanced by exer cise, and to a similar degree in each group of women.