Purpose: Postexercise hypotension (PEH) has been observed in males and females; however, the impact of menstrual cycle phase upon PEH has not been evaluated. We examined the pattern of PEH in the early follicular (EF), late follicular (LF), and midluteal (ML) phases of the menstrual cycle in eight eumenorrheic women following 30 min of exercise at 80% lactate threshold.
Methods: Supine hemodynamic measurements were assessed at rest and then for 45 min following exercise. Blood pressure was measured with manual sphygmomanometry, calf vascular resistance (CVR) via venous occlusion plethysmography, and central hemodynamics with echocardiography.
Results: Cardiovascular parameters did not differ between menstrual phases at rest (P > 0.05). The pattern of PEH was unaffected by menstrual phase, but mean arterial and diastolic (DBP) pressures dropped to significantly lower levels across the recovery period in the EF phase than in the LF and ML phases (mean DBP EF: 69 ± 4; LF 74 ± 3; ML 72 ± 5; P < 0.05). Postexercise cardiac output, stroke volume, ejection fraction, left ventricular dimensions, and heart rate did not differ across menstrual phases (P > 0.05). These parameters, except for left ventricular dimensions in systole and heart rate, varied with recovery time, increasing to a peak between 5 and 10 min postexercise (P < 0.05). CVR displayed a significant interaction between cycle phase and recovery time as resistance increased to greater values in the ML phase compared with the EF and LF phases following 30 min of postexercise recovery (P < 0.05).
Conclusion: Buffering of PEH appears to be enhanced in the LF and ML phases of the cycle where estrogen concentrations are known to be elevated.
Centre for Sports and Exercise Sciences, Institute of Membranes and Systems Biology, University of Leeds, Leeds, UNITED KINGDOM
Address for correspondence: Dr. Karen Birch, Centre for Sports and Exercise Sciences, Institute of Membranes and Systems Biology, University of Leeds, Leeds, LS2 9JT, UK; E-mail: firstname.lastname@example.org.
Submitted for publication February 2005.
Accepted for publication October 2005.