Autonomic Function in Amenorrheic Athletes

Abstract

Reproductive hormones such as estrogen and progesterone are known to influence autonomic cardiovascular regulation. Suppression of these hormones in young athletic women (i.e., athletic amenorrhea) can have adverse health effects (e.g., infertility, increased fracture risk, and endothelial dysfunction). PURPOSE To determine if amenorrheic athletes (AA) have impaired autonomic cardiovascular regulation compared to eumenorrheic athletes (EA). METHODS Sixteen athletes were recruited: 7 AA (20±1 yrs) and 9 EA (21±1 yrs). Two indices of autonomic cardiovascular regulation were assessed: cardiovagal baroreflex sensitivity (BRS) via phase IV of the Valsalva maneuver (slope of the pressure - R-R interval relationship) and the hemodynamic responses to orthostatic stress (20 minute 60 degree head-up tilt while assessing heart rate (HR) via ECG and blood pressure via the finometer). RESULTS (mean±SE) BRS was not significantly different between AA and EA groups (19±3 vs. 14±2 msec/mmHg, p=0.15). Baseline HR (46±4 vs. 55±2 bpm, p=0.07) and mean arterial pressure (MAP; 72±5 vs. 73±3 mmHg, p=0.86) were not significantly different between groups. There were no group differences in MAP at the end of the 60 degree head-up tilt (86±7 vs. 85±3 mmHg, p=0.94). As expected, both groups had a significant increase in HR during the tilt (p < 0.05), although the change in HR from baseline (delta HR: 14±2 vs. 23±4 bpm, p=0.04) as well as the absolute HR at the end of the tilt (60±5 vs. 78±5 bpm, p=0.02) were greater in the EA group. CONCLUSIONS While baseline BRS and MAP responses to a 60 degree head-up tilt were not different between groups, HR responses were modestly blunted during the tilt in the AA group.