Author(s): ODONNELL, E., GOODMAN, J.A., FLORAS, J.S., HARVEY, P.J., Institution: LOUGHBOROUGH UNIVERSITY , Country: UNITED KINGDOM, Abstract-ID: 2507

INTRODUCTION:
Estrogen favorably modulates cardiovascular function, including cardiac autonomic regulation. Accordingly, postmenopausal estrogen deficiency is associated with autonomic imbalance. In contrast, the autonomic consequences of premenopausal hypoestrogenism, such as that observed in exercise-trained women with functional hypothalamic amenorrhea (ExFHA), are less well defined. Clarifying autonomic regulation in this population is important given the central role of autonomic balance in cardiovascular health and post-exercise recovery.
METHODS:
Three age-matched groups (pooled mean, 24±1 years; mean±SEM) were studied: estrogen replete eumenorrheic ovulatory aerobically trained (ExOv; n=10) and untrained (SedOv; n=12) women, and estrogen deficient aerobically trained women with ExFHA (n=9). Heart rate (HR), blood pressure (BP) and HR variability (HRV), an indirect index of cardiac autonomic function, were recorded before and one-hour after 45-minutes of moderate-intensity exercise (60% VO2peak). HRV was assessed in the frequency domain using Fast Fourier Transform to derive high (HF; 0.15Hz-0.4Hz), low (LF; 0.04-0.15Hz), very low (VLF; 0.01-0.04Hz) and Total HRV (VLF+LF+HF). Serum measures of estradiol, progesterone, and triiodothyronine were also determined.
RESULTS:
Exercise trained groups did not differ in cardiorespiratory fitness, weight or BMI (p>0.05). Estrogen and progesterone did not differ between all groups (p>0.05). Pre-exercise, HF was higher (p<0.05), and HR, systolic BP (SBP), diastolic BP (DBP), and triiodothyronine lower (p<0.05) in the ExFHA group compared with both eumenorrheic groups. HRV, BP and HR did not differ between eumenorrheic groups (p>0.05). Post-exercise, all indices of HRV, DBP, mean arterial pressure (MAP), pulse pressure (PP) were decreased (p<0.05), and HR increased (p<0.05) within all groups. However, total power and HF power remained higher in ExFHA (p<0.05) compared with eumenorrheic groups.
CONCLUSION:
Compared with trained and untrained eumenorrheic women, ExFHA have lower heart rate in association with augmented cardiac parasympathetic modulation at rest, both before and one-hour after exercise. In contrast, post-exercise autonomic recovery did not differ between groups, suggesting that estrogen deficiency may not impair cardiac autonomic reactivation in aerobically trained women with FHA.