Estrogen supplementation reduces whole body leucine and carbohydrate oxidation and increases lipid oxidation in men during endurance exercise.

摘要: Healthy active men exhibit higher rates of carbohydrate (CHO) and leucine oxidation lower lipid compared with their female counterparts both at rest during moderate intensity endurance exercise. We postulated that this reduced dependence on amino acids as a fuel source in women was due to the sex hormone estrogen. In randomized, double-blind, placebo-controlled, cross-over design, we investigated effect supplementing 12 recreationally estrogen whole body substrate kinetics Subjects cycled for 90 min an 65% maximum O(2) consumption after 8 d either supplementation (2 mg 17beta-estradiol/d) or placebo (polycose). After 2-wk washout period, they repeated test alternate treatment. On day, primed continuous infusion l-[(13)C]leucine, consumption, CO(2) production, steady-state breath (13)CO(2), plasma alpha-[(13)C]ketoisocaproate enrichments were measured 60, 75, exercise postabsorptive state. Exercise increased energy expenditure more than 5-fold, CHO 6-fold, 4-fold, 2.2-fold (all P < 0.0001), whereas it decreased ratio by 50-70% (P = 0.003) values rest. Estrogen respiratory exchange 0.03). significantly 5-16% 0.04) 16% 0.01), 22-44% 0.024) conclude influences selection men, characterized reliance lipids source.