Author(s): CARPENTIER, M., RABINEAU, J., DIEDERICH-AMAND, M., DEBOECK, E., CARPENTIER, A., DEFRAYE, F., DA SILVA FIGUEIREDO, M., KOWALSKI, C., CASSIERS, C., FAORO, V., Institution: UNIVERSITÉ LIBRE DE BRUXELLES - ULB, Country: BELGIUM, Abstract-ID: 2759

INTRODUCTION:
Only 4 to 6% [1-2] of studies in Sports Science focus exclusively on females. They are underrepresented in this field because of the supposed effects of fluctuations in sex hormones. However, there is no clear consensus on the actual impact of the menstrual cycle (MC) on sport performance due to the lack of good quality data [3]. The aim of this research is to objectively assess the influence of the MC and hormonal contraception on athletic performance in females, using a reliable methodology that complies with rigorous guidelines [4].
METHODS:
28 females with spontaneous natural cycles (NC; 25±4 years) and 30 females using monophasic oral contraception (Co; 23±3 years), with similar BMI and physical activity levels, were included in this study. All were nulliparous, of normal weight, in good health, and had normal, regular MC. Each participant was tested at three randomized time points: (phase A) on the 2nd day of menstruation; (phase B) at peak estradiol (measured by daily urine test) for NCs or on the 12th day of MC for Co; (phase C) at peak progesterone (measured by daily urine test) for NCs or on the 21st day of MC for Co. At each visit, hormone levels were measured by blood test, then participants performed a maximal incremental exercise test (CPET) on a cycle ergometer up to maximal effort. Gas exchanges and heart rate (HR) were measured continuously. 24 h later, they performed a 30-s maximal anaerobic rectangular test (Wingate test). Lactate concentrations were measured 5 min after both tests. The effect of group, phase, and their interaction was studied using linear mixed-effects models and, when significant, repeated measures correlations were performed with either blood progesterone or estradiol levels in NC.
RESULTS:
In NC, the MC phase did not affect VO2, respiratory exchange ratio, ventilation, O2 pulse, and power during CPET, whether at maximal effort or first ventilatory threshold (VT1). The same was true for lactate levels. However,VCO2max was higher at phase A vs. C (+5.2%, p=0.035), which was correlated with changes in progesterone levels (r=-0.31, p=0.024). VO2/HR slope was lower at phase A vs. C (-8.7%, p=0.001), in line with changes in progesterone levels (r=0.41, p<0.01). Even though the workload at VT1 was similar in both groups, the relative effort expressed as %VO2max in Co was greater than the one in NC (56.6% vs. 51.3%, p=0.003). Phase and group did not impact the results of the Wingate test in terms of maximal power, mean power, fatigability, or lactate level.
CONCLUSION:
Hormonal fluctuations during spontaneous natural MC do not appear to affect maximal aerobic or anaerobic abilities, clarifying the debate caused by the lack of quality data in the literature. However, progesterone seems to have a non negligible effect on both ventilatory and cardiac efficiency, without modifying VO2max. Furthermore, oral contraception may impair aerobic efficiency at moderate intensity.

[1]Costello, 2014
[2]Cowley, 2021
[3]Sherwin, 2026
[4]Schmalenberger, 2021