THE INFLUENCE OF THE INTENSITY OF TREADMILL WALKING UPON CHANGES IN LIPID AND LIPOPROTEIN VARIABLES IN HEALTHY-ADULTS

The purpose of the present study was to compare the acute and delayed effects of low- and moderate-intensity exercise on serum lipoprotein c oncentrations. Twelve healthy volunteers (five men, seven women), aged 28 (2) years [mean (SEM)], maximal oxygen uptake (VO2max) 48 (3) ml . kg(-1). min(-1) walked on a treadmill for 90 min, on two separate occ asions, in a balanced design. On one occasion walking was at a grade w hich elicited 32.1 (0.8)% of VO2max, i.e. low intensity, while on the other it elicited 60.1 (1.6)% of VO2max, i.e. moderate intensity (MI). Serum concentrations of total cholesterol (TC), triacylglycerol (TAG) , high density lipoprotein cholesterol (HDL-C) and the subfraction HDL (2)-C free fatty acids (FFA) and free glycerol were measured in venous blood samples drawn before exercise (after a 12-h fast), during walki ng and after 1 h and 24 h of recovery. Serum TAG concentrations decrea sed as a result of the exercise bout over the period of observation (P < 0.05), but this decrease was not different between the two intensit ies. Changes in serum TC concentrations over time differed between tri als (P < 0.05). Serum free glycerol and FFA concentrations increased d uring exercise bouts, these increases being (P < 0.05) greater with MI . The decrease in serum TAG concentrations during and after a single e pisode of either prolonged low or moderate intensity exercise may be a ssociated with an increased clearance and/or a decreased secretion of TAG-rich lipoproteins.