Acute effects of exercise on postprandial lipemia: A comparative study in trained and untrained middle-aged women

Abstract

Repeated episodes of exaggerated postprandial lipemia may hasten the progression of atherosclerosis. The purpose of this study was to compare the lipemic response to a high-fat meal in trained and untrained women in the presence and absence of the acute effects of exercise. Nine endurance- trained and thirteen untrained women aged 40.4 ± 3.3 and 43.8 ± 4.3 y (x̄ ± 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/m2) of 22.2 ± 0.9 and 22.9 ± 2.3, respectively, underwent two trials, each over 2 d. Subjects did not exercise during the 2 d leading up to a trial. On day 1 they either walked for 90 min at 60% of maximal oxygen uptake (exercise), or refrained from exercise (control). On day 2 venous blood and expired air samples were obtained in the fasted state and for 6 h after consumption of a high-fat meal (1.70 g fat, 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 plasma 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 its absence. Exercise decreased insulinemia in trained women (543 ± 25 compared with 433 ± 24 pmol · h/L, P < 0.01) but had no effect in untrained women (592 ± 34 compared with 585 ± 47 pmol · h/L). Total oxidation of fat over the 6-h postprandial period was enhanced by exercise, and to a similar degree in each group of women.