The influence of estrogen deficiency in physically active women with functional hypothalamic amenorrhea (ExFHA) on cardiovascular regulation is unknown. Three mechanistic studies compared cardiovascular responses to exercise and orthostatic stress in ExFHA women with responses in physically active (ExOv) and sedentary (SedOv) eumenorrheic ovulatory women. Measures included calf blood flow (BF), brachial artery (BA) endothelial dependent and independent function, shear rate (SR), vascular resistance (VR), blood pressure (BP), heart rate (HR), HR variability (HRV), muscle sympathetic nervous activity (MSNA), and serum renin-angiotensin-aldosterone system (RAAS) components.
Study one examined the effects of a single bout of dynamic exercise on vascular function in ExFHA (n=12), ExOv (n=14), and SedOv (n=15) women. Pre-exercise, calf BF and BA endothelium-dependent flow-mediated vasodilation (FMD%) were lower (p<0.05) in ExFHA versus ovulatory women in association with higher (p<0.05) calf VR and lower (p<0.05) SR, respectively. Endothelium-independent vasodilation, assessed at baseline only, was also lower (p<0.05) in ExFHA. Post-exercise, calf BF was increased and VR decreased (p<0.05) in ExFHA women, similar (p>0.05) to that observed in ovulatory women. FMD% and SR were augmented (p<0.05) post-exercise, but both remained lower (p<0.05) in ExFHA versus ovulatory women (p<0.05).
Study two investigated neurohumoral (MSNA and RAAS) BP regulation during orthostatic stress in ExFHA (n=12) and ExOv (n=17) women. Baseline systolic BP was lower (p<0.05) in ExFHA versus ExOv. Neurohumoral measures did not differ (p>0.05) between the groups at baseline. However, during hypotensive stimuli, MSNA increased to a greater extent (p<0.05), yet angiotensin II and renin were not activated in ExFHA women.
Study three examined autonomic control of HR during orthostatic stress in ExFHA (n=11), ExOv (n=17), and SedOv (n=17) women. Lower HR (p<0.05) at rest and during orthostatic stress in ExFHA was associated with markedly elevated (p<0.05) HRV due to higher (p<0.05) parasympathetic modulation. Sympathetic modulation did not differ (p>0.05) between the groups.
These studies indicate altered cardiovascular regulation in otherwise healthy ExFHA women. The influence of estrogen deficiency per se in these alterations are not clear, but in light of the etiology of amenorrhea, it is likely that complex interactions between estrogen and energy deficiency and exercise training are involved.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OTU.1807/43692 |
| Date | 14 January 2014 |
| Creators | O'Donnell, Emma |
| Contributors | Goodman, Jack, Harvey, Paula J. |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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