Paper of the Month-(January 2018) from Dr. Edgell's research group

Abidi S, Nili M, Serna S, Kim S, Hazlett C, Edgell H. Influence of sex, menstrual cycle and oral contraceptives on cerebrovascular resistance and cardiorespiratory function during Valsalva or standing. J Appl Physiol (1985). 2017 May 18:jap.00035.2017. doi: 10.1152/japplphysiol.00035.2017. 

From the authors:

This paper investigates the role of sex, menstrual cycle and oral contraceptive use on cardiorespiratory and cerebrovascular function. We measured the responses of men and women to either a Valsalva manuever or 10 minutes of standing. Compared to men, women experienced a greater increase of brain blood flow during the Valsalva maneuver, yet there were no effects of the menstrual cycle or oral contraceptive use. During standing, only men experienced greater cerebrovascular resistance, and only women experienced a reduction in respiratory rate. Oral contraceptive use resulted in lower end-tidal CO2 (implying greater ventilation), with higher stroke volume and cardiac output indices compared to non-users at all time points. Women in the high hormone phase of the menstrual cycle (i.e. days 18-24 when there is high estrogen and high progesterone) displayed a tendency toward lower brain blood flow velocity and a higher stroke volume index compared to the low hormone phase (i.e. days 2-5 when there is very low estrogen and progesterone). These results suggest that the female sex hormones estrogen and progesterone (natural and/or pharmaceutical) can influence hemodynamics, and further suggest that sex differences exist in the cerebrovascular and respiratory response to physiological stressors.

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