This study examined the acute (single bout of exercise) and chronic (exercise
training) effects of exercise on plasma lipidlevels in relation to concomittant changes
in plasma leptin concentrations. Fourty sedentary adult subjects were categorized
into 4 groups, ten in each :lean normolipidemic control, obese normolipidemic, lean
hyperlipidemic and obese hyperlipidemic groups. Leptin levels were measured by
ELISA method while plasma lipids including total cholestrol (TC), triglycerides (TG),
high density lipoprotein-cholestrol (HDL-C), low density lipoprotein-cholestrol
(LDL-C), and very low density lipoprotein-cho;estrol (VLDL-C) were measured by
conventional colorimetric methods. These measurements were performed before and
after acute and chronic exercise. Exercisetraining was a high intensity aerobic
exercise performed on cycle ergometer at the level of 85% of maximal predicted heart
rate, twice weekly for 12 weeks. Plasma leptin concentrations were significantly
higher in normolipidemic (P<0.001) and hyperlipidemic (P <0.01) obese groups and
hyperlipidemic (P<0.01) non obese group compared to controls. However, there were
no significant correlations between basal serum leptin levels and any of basal serum
lipid profile parameters in all studied groups. No significant changes in lipid
parameters or leptin concentrations after single bout of exercise. In turn, exercise
training induced significant favorable reduction in TC, TG, LDL-C and VLDL-C and
increase of HDL-C in all group similar significant reduction in serum leptin levels
among the studied groups (P<0.0001). However, there were no significant
correlations between the response of leptin to exercise training (expressed as percent
reduction from the baseline ) with the associated responses to exercise in any of the
lipid profile parameters in all groups. In conclusion, high intensity aerobic exercise
training could improve lipid parameters associated with reduction of serum leptin
concentration. However, this exercise-induced leptin reduction may restore leptin
sensitivity that might regulate metabolic adaptation to exercise.