One mechanism by which prior exercise decreases the plasma triacylglycerol (TG) response to dietary fat may involve enhanced clearance of TG-rich lipoproteins. The purpose of the present study was to examine the influence of moderate intensity exercise on postprandial lipemia and muscle lipoprotein lipase (LPL) activity. Eight physically active, normolipidemic men aged 27.0 years (SD 4.2), body mass index 24.5 kg. m(-2) (SD 1.3), participated in 2 oral fat-tolerance tests with different preceding conditions. The afternoon before one test ( approximately 16 hours), subjects cycled for 90 minutes at 62.3% (SD 1.7%) of maximal oxygen uptake. Before the other test, subjects refrained from exercise. Samples of muscle, venous blood, and expired air were obtained in the fasted state. Subjects then consumed a high-fat meal (1.4 g fat, 1.2 g carbohydrate, 0.2 g protein, 73 kJ energy per kg body mass) before further blood and expired air samples were collected until 6 hours. The 6-hour areas under the TG concentration v time curves for plasma and for the chylomicron-rich fraction were lower (P <.05) after exercise (plasma, 7.91 [SE 1.09] v 5.72 [SE 0.47] mmol. L(-1). h; chylomicron-rich fraction, 1.98 [SE 0.51] v 0.92 [SE 0.16] mmol. L(-1). h). Muscle LPL activity was not significantly influenced by prior exercise, but the 4 subjects who had higher muscle LPL activity after exercise also had the most noticeable decreases in postprandial lipemia. The difference in lipemia between trials was inversely related to the difference in LPL activity (rho = -.79, P <.05). In the fasted state and postprandially, carbohydrate oxidation was lower after exercise (P <.05). Thus moderate exercise attenuates postprandial lipemia, possibly by altering muscle LPL activity.
Copyright 2001 by W.B. Saunders Company