Nutritional and physiological influences on menstrual status of amenorrheic runners
Women with exercise associated amenorrhea display a disturbance in basal and exercise levels of reproductive, anti-reproductive and stress hormones. Co-incident with chronic exercise are other factors, which alone, also affect the menstrual cycle. Therefore, amenorrheic runners (AR), regularly menstruating runners (RMR) and regularly menstruating sedentary controls (RMSC) were compared for plasma progesterone levels, plasma lipid levels, menstrual cycle characteristics, physical characteristics and nutritional adequacy to determine if the difference in menstrual status could be explained, and to determine whether exercise alone could be attributed as the cause of menstrual cycle disturbances.Plasma progesterone levels were significantly lower in the AR group (. 28 + .02 ng/ml) than in the RMR group (.41 + .06 ng/ml) and the RMSC group (.49 + .06 ng/ml) in the follicular phase. Regularly menstruating runners demonstrated lower plasma progesterone levels in the luteal phase (9.76 + 1.05 ng/ml) than RMSC subjects (10.24 + 2.21 ng/ml). Regularly menstruating runners had a significantly shorter luteal phase length relative to their cycle length (.35 + .01) than RMSC subjects (.46 + .01). Mean age, incidence of parity, age of menarche, height, weight, body composition, max V02 and number of miles run per week did not differ between the RMR and AR subjects. Amenorrheic runners took in significantly less fat, red meat, phosphorous and total calories than the RMR subjects. Serum LDL-C was significantly higher in the AR subjects (89.2 + 9.7 mg/dl) than in the RMR subjects in both the luteal (67.8+ 3.4 mg/dl) and follicular (66.8+ 5.6 mg/dl) phases. Serum HDL-C was significantly higher in the RMR subjects in both the luteal (62.9+ 4.1 mg/dl) and follicular (59.2+ 2.9 mg/dl) phase, and in the AR subjects (63.9+ 4.2 mg/dl), than in the RMSC subjects in the luteal (49.2+ 5.9 mg/dl) and follicular (47.2+ 2.4 mg/dl) phase. Serum VLDL-C did not differ between any groups.This investigation demonstrates that hormonal and lipid level alterations with exercise are significantly different in the amenorrheic runner. However, regularly menstruating runners display alterations which may represent and intermediate or potential phase of menstrual cycle disturbances. The nutritional inadequacy or energy imbalance separates amenorrheic runners from regularly menstruating runners. Thus, it appears that exercise alone is not enough to cause the hormonal disturbances that trigger amenorrhea, and, that exercise associated amenorrhea is not unlike other amenorrheas of hypothalamic origin.