Abstract des Autors

We have previously demonstrated that females oxidize more lipid and less protein and carbo-hydrate during endurance exercise [21]. Several studies in male rats have demonstrated similar metabolic changes after 4 d of 17-beta-estradiol (E2) administration. Our purpose was to study the effects of E2 administration upon substrate metabolism during 90min of cycle ergometry at 60% VO2peak in 11 healthy, young males. E2 was administered in a single-blind, cross-over, randomized fashion for 11 d (100 microg/d x 3.5d --> 200 microg/d x 3.5 d --> 300 microg/d x 4.0 d). Respiratory exchange ratio (RER), VO2, Ve, HR, lactate, and glucose were measured every 30 min during exercise and E2, testosterone TEST, glycerol and triglycerides were measured prior to exercise T=0 min. Muscle biopsies were taken from the vastus lateralis be-fore and after exercise for glycogen determination. Estradiol treatment resulted in lower plasma TEST (20.8-->7.8 nmol/L, P<0.0001) and higher plasma E2 (168.1 327.3 pmol/L, P<0.002). There were no effects of E2 treatment upon any of the other measured variables including muscle glycogen: (E2-PRE=529.3 -->POST=237.9; PL-PRE=582.2 --> POST=262.4 mmol/kg [dm]). We concluded that short-term E2 treatment increased plasma E2 to female follicular lev-els in males but had no effect upon lipid or carbohydrate metabolism. Verf.-Referat