title: Augmented vagal heart rate modulation in active hypoestrogenic pre-menopausal women with functional hypothalamic amenorrhoea.
abstract: Compared with eumenorrhoeic women, exercise-trained women with functional hypothalamic amenorrhoea (ExFHA) exhibit low heart rates (HRs) and absent reflex renin-angiotensin-system activation and augmentation of their muscle sympathetic nerve response to orthostatic stress. To test the hypothesis that their autonomic HR modulation is altered concurrently, three age-matched (pooled mean, 24 ± 1 years; mean ± S.E.M.) groups of women were studied: active with either FHA (ExFHA; n=11) or eumenorrhoeic cycles (ExOv; n=17) and sedentary with eumenorrhoeic cycles (SedOv; n=17). Blood pressure (BP), HR and HR variability (HRV) in the frequency domain were determined during both supine rest and graded lower body negative pressure (LBNP; -10, -20 and -40 mmHg). Very low (VLF), low (LF) and high (HF) frequency power spectra (ms(2)) were determined and, owing to skewness, log10-transformed. LF/HF ratio and total power (VLF + LF + HF) were calculated. At baseline, HR and systolic BP (SBP) were lower (P<0.05) and HF and total power were higher (P<0.05) in ExFHA than in eumenorrhoeic women. In all groups, LBNP decreased (P<0.05) SBP, HF and total power and increased (P<0.05) HR and LF/HF ratio. However, HF and total power remained higher (P<0.05) and HR, SBP and LF/HF ratio remained lower (P<0.05) in ExFHA than in eumenorrhoeic women, in whom measures did not differ (P>0.05). At each stage, HR correlated inversely (P<0.05) with HF. In conclusion, ExFHA women demonstrate augmented vagal yet unchanged sympathetic HR modulation, both at rest and during orthostatic stress. Although the role of oestrogen deficiency is unclear, these findings are in contrast with studies reporting decreased HRV in hypoestrogenic post-menopausal women.
authors.affiliation: Cardiovascular Research Laboratory, Department of Exercise Sciences, University of Toronto, Toronto, Ontario M5S 2W6, Canada.
authors.forename: Emma
authors.initials: E
authors.lastname: O'Donnell
authors.affiliation: Cardiovascular Research Laboratory, Department of Exercise Sciences, University of Toronto, Toronto, Ontario M5S 2W6, Canada Department of Medicine, Division of Cardiology, Mount Sinai Hospital, University of Toronto, Ontario M5G 1X5, Canada.
authors.forename: Jack M
authors.initials: JM
authors.lastname: Goodman
authors.affiliation: Department of Medicine, Division of Cardiology, Toronto General Hospital, University of Toronto, Ontario M5G 2C4, Canada.
authors.forename: Beverly L
authors.initials: BL
authors.lastname: Morris
authors.affiliation: Department of Medicine, Division of Cardiology, Mount Sinai Hospital, University of Toronto, Ontario M5G 1X5, Canada Department of Medicine, Division of Cardiology, Toronto General Hospital, University of Toronto, Ontario M5G 2C4, Canada.
authors.forename: John S
authors.initials: JS
authors.lastname: Floras
authors.affiliation: Department of Medicine, Division of Cardiology, Women's College Hospital, University of Toronto, Ontario M5S 1B3, Canada Paula.harvey@wchospital.ca.
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Harvey
mesh_terms: D000328:Adult; D000568:Amenorrhea / Q000503:physiopathology*; D000704:Analysis of Variance; D001794:Blood Pressure / Q000502:physiology; D003430:Cross-Sectional Studies; D004967:Estrogens / Q000097:blood / Q000172:deficiency; D015444:Exercise / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007031:Hypothalamus / Q000503:physiopathology*; D011187:Posture / Q000502:physiology; D017697:Premenopause / Q000502:physiology*; D012084:Renin-Angiotensin System / Q000502:physiology; D014630:Vagus Nerve / Q000502:physiology; D055815:Young Adult
chemical_list: D004967:Estrogens
keywords: autonomic nervous system; energy deficiency; exercise; heart rate variability; oestrogen