Acute effects of prolonged exercise on serum lipids.

The acute effects of a single prolonged exercise session on the serum concentrations of cholesterol, triglycerides (TG), glycerol, high density lipoprotein (HDL) cholesterol, and the major HDL protein, apolipoprotein A-I(apoA-I), were examined in 12 trained male runners participating in a 42-km footrace. Serum TG levels were unchanged up to 4 h after the race, but at 18, 42, and 66 hr mean reductions of 65%, 39%, and 32% were observed. Free glycerol concentrations were increased fivefold immediately after the race, but did not differ from prerace levels by 4 hr. Total cholesterol concentration did not change immediately after exercise, but unexpected significant reductions of 6%-10% were found at 4-66 hr. Only small and transient increases in HDL cholesterol and apoA-I levels were noted after exercise. These results suggest that prolonged exercise acutely lowers TG and total cholesterol, but has little effect on HDL mass.