This study investigated changes in brain blood flow, blood pressure, and cardiovascular variables in response to the Valsalva maneuver and a supine-sit-stand posture change in men and women during different phases of the menstrual cycle. The results showed that during the Valsalva maneuver, women had higher cerebrovascular Valsalva ratios compared to men, but no differences between menstrual cycle phases. During the posture change, all groups experienced increases in heart rate from supine to standing, but women in the follicular phase had lower cardiac output and cerebral perfusion pressure when standing compared to the luteal phase. This suggests reductions in stroke volume may contribute to greater orthostatic intolerance in the follicular phase for