title: Low dosage monophasic oral contraceptive use and intermittent exercise performance and metabolism in humans.
abstract: Nine untrained women using low dosage monophasic oral contraceptives (OC) performed an intermittent treadmill test on two different occasions within one pill-cycle to determine the effect of OC on performance and some commonly used metabolic markers. The first test was performed after 5-8 days of resuming the OC agents after menstrual bleeding while the other test was performed after 19-21 days. Performance time on the final exhausting run of six intermittent high intensity 20 s runs was no different between trials [mean days 5-8: 22.3 (SEM 1.2) s vs days 19-21: 22.7 (SEM 1.1) s]. There was no difference in heart rate [peak heart rate days 5-8: 183 (SEM 3) beats.min-1 vs days 19-21: 186 (SEM 2) beats.min-1], oxygen consumption during any run [run 5 of days 5-8: 1,392 (SEM 51) ml.min-1 vs run 5 of days 19-21: 1,494 (SEM 3) ml.min-1] or in any of the metabolic variables measured at any time in venous blood [peak blood lactate concentration days 5-8: 8.4 (SEM 0.3) mmol.l-1 vs days 19-21: 8.1 (SEM 0.5) mmol.l-1; peak blood glycerol concentration days 5-8: 0.39 (SEM 0.02) mmol.l-1 vs days 19-21: 0.38 (SEM 0.02) mmol.l-1; resting free fatty acids concentration days 5-8: 0.25 (SEM 0.05) mmol.l-1 vs days 19-21: 0.29 (SEM 0.07) mmol.l-1; peak blood glucose concentration days 5-8: 6.7 (SEM 0.5) mmol.l-1 vs days 19-21: 6.6 (SEM 0.2) mmol.l-1; peak capillary blood ammonia concentration days 5-8: 139 (SEM 18.3) mumol.l-1 vs days 19-21: 170 (SEM 18.0) mumol.l-1]. These results suggest neither intermittent high intensity exercise performance nor energy metabolism change between days 5-8 and days 19-21 of a low dosage monophasic OC pill during one pill-cycle.
authors.affiliation: Scottish School of Sport Studies, University of Strathclyde, 76 Southbrae Drive, Glasgow G13 1PP, Scotland.
authors.forename: N J
authors.initials: NJ
authors.lastname: Lynch
authors.forename: G
authors.initials: G
authors.lastname: De Vito
authors.forename: M A
authors.initials: MA
authors.lastname: Nimmo
mesh_terms: D000328:Adult; D001786:Blood Glucose; D003276:Contraceptives, Oral / Q000008:administration & dosage*; D004734:Energy Metabolism / Q000187:drug effects*; D045166:Estradiol Congeners / Q000008:administration & dosage; D004997:Ethinyl Estradiol / Q000008:administration & dosage; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects; D005082:Physical Exertion / Q000187:drug effects*
chemical_list: D001786:Blood Glucose; D003276:Contraceptives, Oral; D045166:Estradiol Congeners; D019344:Lactic Acid; D004997:Ethinyl Estradiol