Measuring performance during the menstrual cycle: a model using oral contraceptives

The aim of the study was to use a low-dose oral contraceptive (OC) pill to generate consistent estrogen and progestogen concentrations and investigate the relationship between steroid hormone concentrations during the OC cycle and anaerobic performance.

Five female rowers taking a low-dose OC performed tests of anaerobic power (10-s all-out effort) and capacity (1000-m row) on the Concept IIC rowing ergometer at two time points in each of three OC cycles. These time points corresponded to high estrogen and high progestogen (pill day 16-18; TDH) and low estrogen and low progestogen (pill day 26-28; TDL). Blood samples were collected at rest and postexercise for the quantification of 17beta-estradiol (E2), progesterone (P4), glucose, triglyceride, and lactate concentrations.

Endogenous E2 and P4 concentrations were not significantly different between testing days or OC cycles (P > 0.05). Peak power output was higher (P < 0.05) and 1000-m rowing ergometer time faster (P < 0.05) at TDL. Pre- and postexercise glucose concentrations were increased (P < 0.05) at TDL, whereas rest and postexercise plasma triglyceride concentrations were significantly (P < 0.05) lower during this time.

This study found that alterations in anaerobic performance throughout the OC cycle occurred with improved performances corresponding to low estrogen and progestogen concentrations. The OC provided a consistent hormonal milieu reducing inter- and intra-individual variations in sex steroids and standardized all performance and metabolic variables across each OC cycle tested. Given that OC use has a high prevalence among female athletes and provides a controlled hormonal environment, it serves as a good model in which the acute effects of female sex steroids on exercise performance can be studied.