ABSTRACT
This study tested the hypothesis that effects of the menstrual cycle on resting blood pressure carry over to dynamic exercise. Eleven healthy females were studied during the early (EP; low estrogen, low progesterone) and late follicular (LP; high estrogen, low progesterone) menstrual phases. Stroke volume (SV), heart rate (HR), cardiac output (CO), systolic blood pressure (SBP), diastolic blood pressure (DBP), and total vascular conductance (TVC) were assessed at rest and in response to mild and moderate cycling exercise during EP and LP. During EP, compared to LP, baseline SBP (111+/-1 vs. 103+/-2 mmHg), DBP (71+/-2 vs. 65+/-2 mmHg) and mean arterial pressure (MAP) (84+/-2 vs. 78+/-1 mmHg) were higher and TVC (47.0+/-1.5 vs. 54.9+/-4.2 ml/min/mmHg) was lower (p<0.05). During exercise, absolute values of SBP (Mild: 142+/-4 vs. 127+/-5 mmHg; Moderate: 157+/-4 vs. 144+/-5 mmHg) and MAP (Mild: 100+/-3 vs. 91+/-3 mmHg; Moderate: 110+/-3 vs. 101+/-3 mmHg) were also higher, while TVC was lower (Mild: 90.9+/-5.1 vs. 105.4+/-5.2 ml/min/mmHg; Moderate: 105.4+/-5.3 vs. 123.9+/-8.1 ml/min/mmHg) during EP (p<0.05). However, exercise-induced increases in SBP, MAP and TVC at both work intensities were similar between the two menstrual phases, even though norepinephrine concentrations were higher during LP. Results indicate that blood pressure during dynamic exercise fluctuates during the menstrual cycle. It is higher during EP than LP and appears to be due to additive effects of simultaneous increases in baseline blood pressure and reductions in baseline TVC.