title: Effects of oral contraceptives on glucose flux and substrate oxidation rates during rest and exercise.
abstract: We examined the effects of oral contraceptives (OC) on glucose flux and whole body substrate oxidation rates during rest (90 min) and two exercise intensities [60-min leg ergometer cycling at 45 and 65% peak O(2) uptake (Vo(2 peak))]. Eight healthy, eumenorrheic women were studied during the follicular and luteal phases before OC and the inactive and high-dose phases after 4 mo of a low-dose, triphasic OC. Subjects were studied in the morning 3 h after a standardized (308 kcal) breakfast. There were significant reductions in glucose rates of appearance and disappearance during exercise of both intensities with OC but not rest. There were no phase effects on substrate oxidation during rest or exercise. These results are interpreted to mean that, in women fed several hours before study, 1) OC decreases glucose flux, but not overall carbohydrate and lipid oxidation rates during moderate-intensity exercise; and 2) synthetic ovarian hormone analogs in the doses contained in OC have greater metabolic effects on glucose metabolism during exercise than do endogenous ovarian hormones.
authors.affiliation: Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, 94720-3140, USA.
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Suh
authors.forename: Gretchen A
authors.initials: GA
authors.lastname: Casazza
authors.forename: Michael A
authors.initials: MA
authors.lastname: Horning
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Miller
authors.forename: George A
authors.initials: GA
authors.lastname: Brooks
mesh_terms: D000328:Adult; D001642:Bicycling; D001786:Blood Glucose / Q000032:analysis; D003276:Contraceptives, Oral / Q000494:pharmacology*; D004958:Estradiol / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005260:Female; D005934:Glucagon / Q000097:blood; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000097:blood; D007700:Kinetics; D007773:Lactates / Q000097:blood; D008137:Longitudinal Studies; D010084:Oxidation-Reduction / Q000187:drug effects; D011374:Progesterone / Q000097:blood; D011659:Pulmonary Gas Exchange / Q000187:drug effects; D011897:Random Allocation; D012146:Rest / Q000502:physiology
chemical_list: D001786:Blood Glucose; D003276:Contraceptives, Oral; D007328:Insulin; D007773:Lactates; D011374:Progesterone; D004958:Estradiol; D005934:Glucagon; D005947:Glucose