Oxygen, Hormones, and Performance: A Case Study of Menstrual Cycle Effects on Athletic Physiology

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The menstrual cycle represents a fundamental biological rhythm in a woman’s life. This study aims to analyse the potential influence of the menstrual cycle on female athletic performance, specifically focusing on variations in body composition, muscle oxygen saturation, and post-exertion recovery. The sample consisted of a 21-year-old female athlete (a former elite-level basketball player), who performed a Bulgarian Split Squat test once a week throughout a complete menstrual cycle. In the data analysis, the menstrual cycle was verified using biological and hormonal markers, the coefficient of variation in muscle oxygen saturation was calculated, and visual inspection was employed to assess the observed curves. The results indicated minor variations in muscle mass (ranging from 38.8 kg to 40.4 kg) and fat mass (10.7 kg to 11.9 kg) across different phases of the cycle. Additionally, an increase in force production (4–5 repetitions increasing to 13–14) was observed, likely due to elevated oestrogen levels in the bloodstream. In conclusion, the menstrual cycle should be considered when designing training programmes for female athletes, ensuring an individualised approach that accounts for hormonal fluctuations and their impact on performance.