Friday Afternoon Poster Presentations: Posters displayed from 1:00–6:00 p.m.: One-hour author presentation times are staggered from 2:00–3:00 p.m., 3:00–4:00 p.m., and 4:00–5:00 p.m.: F-32 Free Communication/Poster – Exercise Testing: FRIDAY, JUNE 2, 2006 2:00 PM – 5:00 PM ROOM: Hall B
PURPOSE: The research literature suggests that menstrual cycle influences changes in energy supply, metabolic, and cardiorespiratory responses. Therefore, the aim of this study was to examine whether variables commonly used in exercise testing are influenced by menstrual cycle phases.
METHODS:Ninteen eumenorrheic women performed two 1 min stage incremental tests on a cycle ergometer during two different phases of menstrual cycle, the follicular phase (FP) and the luteal phase (LP). Our study variables, power output, oxygen uptake (VO2), heart rate (HR), minute ventilation (VE), respiratory exchange ratio (RER), ventilatory equivalents for oxygen and carbon dioxide (VE/VO2 and VE/VCO2) and blood lactate concentration (LA) were evaluated at rest, at exhaustion at different thresholds of aerobic-anaerobic transition and at all stages of the incremental tests. The threshold determination consisted of: 1) an individual anaerobic threshold (IAT) 2) a three phase-model with two lactate thresholds (LTP1 and LTP2 3) a three phase model with two respiratory thresholds (AT and RCP) and 4) the heart rate turn point (HRTP).
RESULTS: Comparing power output, VO2, LA, HR and RER we did not find any significant differences at rest, at maximal load, at any threshold and at any stage of the incremental tests between FP and LP. We observed higher values for VE/VO2 and VE/VCO2 and VE at rest, at several thresholds and several stages of incremental tests in the LP (several of these changes were significantly different).
CONCLUSIONS: Evaluating power output, VO2, HR, LA and RER we were not able to find any changes in menstrual cycle at rest, at exhaustion, at thresholds or in any stage of incremental tests. These data do not support the view of an essential influence of the menstrual cycle on energy supply during exercise. Like others, we observed a higher ventilatory drive in the LP when compared to FP of the menstrual cycle.