Intraindividual Comparison of the Anabolic Steroid Hormone Profile Between Hormonal Contraceptive Use and the Phases of a Natural Menstrual Cycle in a Recreational Athlete: A Single‐Case Observational Study

Endogenous androgens, including testosterone and the androgen precursor androstenedione, are known to influence muscular adaptation. However, variations in these hormones throughout the natural menstrual cycle (MC) and during oral hormonal contraception (HC) remain underexplored in the athletic population with cycle‐based training approaches. This study investigates variations in steroid hormone profiles under HC and during a natural MC in one recreational athlete. An observational study was conducted on a 25‐year‐old female recreational athlete (167 cm, 60 kg, 6 h training/exercise activity per week). Testosterone and androstenedione concentrations were measured in her urine and plasma every two to 3 days during 3 weeks of HC use (hormonal vaginal ring) and the 1‐week HC break and 11 months later during one natural MC. Hormone analysis was conducted using gas chromatography coupled with mass spectrometry for urine steroids and liquid chromatography coupled with mass spectrometry for plasma steroids. Throughout the MC, urinary total androgen and plasma androstenedione levels peaked around ovulation, followed by a decline in the luteal phase, suggesting phase‐dependent variation in androgen precursor availability. Meanwhile, plasma testosterone remained unchanged throughout the cycle. HC use resulted in lower androgen concentrations with no notable fluctuations in plasma or urine. The suppression of naturally secreted androgens and their respective fluctuations throughout MC induced by HC may have implications for training adaptations and athletic performance. Furthermore, it is essential for female athletes and their coaches to consider the use of HC in order to optimize training strategies.