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1Department of Health, Nutrition, and Exercise Sciences, 2School of Nursing, and 3Department of Medical Technology, University of Delaware, Newark, Delaware
Submitted 22 November 2005 ; accepted in final form 9 May 2006
Reproductive hormones such as estradiol and progesterone are known to influence autonomic cardiovascular regulation. The purpose of this study was to determine whether amenorrheic athletes (AA) have impaired autonomic cardiovascular regulation compared with eumenorrheic athletes (EA). Thirty-five athletes were tested: 13 AA (19 ± 1 yr), 13 EA (21 ± 1 yr), and 9 EA (23 ± 1 yr) on oral contraceptives (EA-OC). Multiple indexes of autonomic cardiovascular regulation were assessed: respiratory sinus arrhythmia (RSA), cardiovagal baroreflex sensitivity (BRS) via phase IV and phase II of the Valsalva maneuver, a spontaneous index of BRS, and the heart rate and blood pressure responses to orthostatic stress (20-min 60° head-up tilt). RSA was not different among the groups. There were no group differences in the spontaneous index of BRS (AA = 30 ± 6, EA = 24 ± 3, EA-OC = 29 ± 5 ms/mmHg) or in phase II (AA = 8 ± 2, EA = 7 ± 1, EA-OC = 8 ± 1 ms/mmHg) of the Valsalva. There was a difference in BRS during phase IV (AA = 21 ± 3, EA = 15 ± 1, EA-OC = 26 ± 6 ms/mmHg; ANOVA P = 0.04). Tukey's post hoc test indicated that BRS was greater in the EA-OC group compared with the EA group (P = 0.04). There were no differences in cardiovascular responses to orthostatic stress among the groups. In conclusion, AA do not display signs of impaired autonomic function and orthostatic responses compared with EA or EA-OC during the follicular phase of the menstrual cycle.
cardiovagal; baroreflex sensitivity; cardiovascular; estrogen
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