Endurance Training & Menstrual Cycle: Effects of Follicular- & Luteal Phase-based Training in Subjects with Oral Contraception

Abstract

PURPOSE: Monophasic oral contraceptives (OC) contain fixed doses of estrogen (E) and progestogen (P) which are taken for 21 days, followed by 7 days without any hormone intake, leading to more or less constant concentrations of blood estradiol (E2) and progesterone (Prg) during the first 21 days. The regulation of other interacting hormones like IGF-1, testosterone and DHEAs, all of them possible anabolic hormones on the level of the muscular cell during endurance training, is not clear so far in OC users. Therefore, we investigated possible different effects of "quasi follicular (qFO) phase-based" versus "quasi luteal (qLU) phase-based" endurance training (qFT and qLT) on endurance capacity in OC users. METHODS: 14 healthy women using OC completed endurance training on a bicycle ergometer for each leg for 3 menstrual cycles (12 weeks). The subjects trained one leg mainly in FO (FT) and the other in LU (LT). Blood samples were taken on 11th day of the menstrual cycle in FO and on 25th day of menstrual cycle in LU to analyze values of E2, Prg, total testosterone (tT), free testosterone (fT), IGF-1 and DHEA-S. Prior to and after training, incremental bicycle ergometer tests were done for each single leg for the determination of lactate concentrations, heart rates, maximal power (Wattmax)and maximal oxygen uptake (VO2max). M. quadriceps diameter (Mdm) was measured by means of ultrasound. RESULTS: DHEAs was significantly higher in qFO as compared to qLU and E2, tT, Prg, IGF-1 and fT weren't significantly different between qFO and qLU. VO2max increased significantly after qFT by 5.7 ± 2.3 ml/min/kg and after qLT by 5.3 ± 3.5 ml/min/kg without any difference between qFT and qLT. The increase of Wattmax was significant after 3 month of qFT (+32.3 ± 10.1 Watt) and qLT (+35.9 ± 9.9 Watt) without any difference between qFT and qLT. There wasn't any significant change of Mdm after qFT and qLT. CONCLUSIONS: Both, qFT and qLT showed significant effects on Wattmax without any differences between both interventions. This is in contrast to findings in women without use of OC, who showed a tendency for a higher increase of endurance capacity after FT as compared to LT. Further studies including muscle biopsies and detailed analysis of the hormonal profile though the menstrual cycle are needed in order to understand the underlying mechanisms for these effects.