Endurance Training & Menstrual Cycle: Effects of Follicular- & Luteal Phase-based Training in Subjects without Oral Contraception

Abstract

PURPOSE: The follicular and the luteal phase of the menstrual cycle (FO and LU) are characterized by a different profile of hormones. This is especially true for the interaction between estradiol (E2), Testosterone and IGF-1, all of them possible anabolic hormones on the level of the muscular cell. They might be important supporting factors for adaptation processes during endurance training. We, therefore, investigated the effects of follicular phase-based versus luteal phase-based endurance training (FT and LT) on endurance capacity. METHODS: 13 healthy eumenorrheic untrained or moderately trained women without oral contraception completed endurance training on a cycle 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, progesterone (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: fT was significantly higher in FO as compared to LU, Prg was higher in LU and tT, E2, DHEA-S and IGF-1 were not significantly different between the two phases. There was a tendency for a VO2max increase after FT (+3.3 ± 5.3 ml/min/kg, p=0.065) and after LT (+2.7 ± 4.8 ml/min/kg, p=0.076) without any difference between FT and LT. The increase of Wattmax was significant after 3 month for both, FT and LT. We found a clear trend (p=0.076) for a higher increase of Wattmax after FT (+34.8 ± 19.2 Watt) as compared to LT (+27.8 ± 16.6 Watt). There wasn't any significant change of muscle diameter after FT and LT. CONCLUSIONS: FT showed a tendency for a greater effect on maximal performance on bicycle ergometer as compared to LT. This is probably due to the specific hormonal milieu during each phase of the cycle. 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 on the molecular level of the skeletal muscle.