The female menstrual cycle: impact on cardiovascular, ventilatory and neuromuscular responses to whole body exercise

Abstract

BACKGROUNDThe female menstrual cycle (MC) is characterized by varying levels of endogenous sex hormones. Previous investigations have indicated that fluctuating levels of estrogen and progesterone may influence vascular function, ventilatory chemosensitivity, and exercise‐induced fatigue throughout the MC. However, a comprehensive analysis of the role of these sex hormones on determining cardiovascular, ventilatory, and neuromuscular responses during whole body exercise is currently lacking. Therefore, the purpose of this study was to investigate cardiovascular, ventilatory and neuromuscular responses to submaximal cycling exercise of eumenorrheic females throughout the MC.METHODSFemales were studied during three MC phases: early follicular (EF; days 1–4), late follicular (LF; days 8–12), and mid luteal (ML; days 8–10 post LH peak). Prior to exercise, venous blood was collected each visit to characterize endogenous hormone concentrations. Subjects cycled at 50 W, 75 W, 100 W, and 80% Wpeak (129 ± 12 W) for 4 min per stage. Heart rate (HR), mean arterial pressure (MAP), femoral artery blood flow (QL, Doppler ultrasound), minute ventilation (VE), oxygen consumption (VO2), carbon dioxide production (VCO2), and estimated arterial hemoglobin saturation (SpO2) were quantified throughout all cycling trials. Preto post‐exercise changes in potentiated quadriceps twitches (ΔQtw) were used to quantify peripheral locomotor muscle fatigue.RESULTSHR, MAP, and QL were not different at any intensity throughout the MC (P > 0.4). VE, VO2, VCO2 were also not different throughout the MC (P > 0.2). Furthermore, neither hemoglobin content, nor SpO2 and arterial oxygen content changed significantly across the MC (P > 0.1). Consequently, leg O2 delivery during exercise at all intensities were similar during the MC. Finally, exercise‐induced peripheral fatigue was not different throughout the MC (ΔQtw: ~47%; P = 0.2).CONCLUSIONFluctuating endogenous female sex hormones do not significantly influence central or peripheral hemodynamics or the ventilatory response to submaximal whole‐body exercise. Similarly, the exercise‐induced development of peripheral fatigue also remains unaltered across the MC during submaximal cycling exercise of the same duration and intensity. Although depending on the research question, these data suggest that controlling for MC phase may not be necessary when examining cardioventailtory or neuromuscular responses to whole body exercise in females, and should encourage the participation of more females in these types of studies.Support or Funding InformationNational Heart, Lung, and Blood Institute (HL‐116579)