The Study Of The Relationship Of Negative Energy Balance And Endocrine Disorders In Female Athletes

Background: Exercise-associated menstrual disturbance (EAMD) has many forms, including delayed menarche, luteal phase defects, anovulation, oligomenorrhoea and amenorrhoea. EAMD has been observed in many athletes across a wide spectrum of sport activities and recreationally active women. LPD and anovulatory cycles represent the most common menstrual cycle abnormality associated with exercise. Although the exact mechanism underlying these menstrual disturbances remains unclear, many hypotheses has been put forward to elucidate it, including body composition hypothesis and stress hypothesis. But the energy availability hypothesis is the research focus recently, which holds that the impact of energetic stress and its key components are likely involved. Researches also show that female athletes suffer form hormonal disorders, especially amenorrhea athlete.Purpose: Menstrual cycles of these subjects are carefully observed, and the hormones and substrate in the blood and urine are measured, so the prevalence and incidence of EAMD in professional athlete will be known. Through the measurement of various hormones and the analysis of hormonal disorders of different forms of EAMD, we can discuss whether LPD and anovulatory cycles are also in a hypometabolic state to save fuels. Through the measurements of energy intake and energy expenditure, the relationship of energy intake and expenditure can be probed, and the association of EAMD, exercise stress and energy availability can be discussed.Methods: 30 professional female athlete and 8 sedentary female are involved as exercise group and sedentary group respectively。After 2 menstrual cycles observation, all cycles are classified as 4 groups (SedOvul, ExeOvul, ExeLPD, ExeAnov). Food intake and activities are recorded and measured, and the time span is 5 days, occurred in the early follicular phase. Blood sample is drawn in the observed early follicular phase, and is analyzed for blood glucose, TSH, total T4, free T4, total T3, leptin, insulin, hGH, IGF-I, IGFBP-3, cortisol, ACTH, LH, FSH and Ghrelin levels. The first morning urine is collected from the 12th day of the menstrual cycle to the next menses, and the urine sample is analyzed for E1C, PdG, LH and Cr. Energy balance is estimated by subtracting energy expenditure from dietary energy intake, and energy availability is estimated by subtracting exercise energy expenditure from dietary energy intake. Exercise energy expenditure is measured by the SenseWear PRO2 Armband and corrected by the training time plan. The hormone levels, dietary energy intake and energy expenditure are compared in these groups.Results: 1. The prevalence and incidence of LPD and anovulatory cycles in exercise group are significantly higher than that in the sedentary group(P<0.01), and the cycle inconsistency is also significantly higher in the exercise group(P<0.01). 2. The prevalence and incidence of abnormal ovary function in the exercise group is 100% and 97%. 3. In the LPD cycle, the follicular phase is prolonged and luteal phase is shorted(P<0.05), the LH, E2 and progesterone levels are declined(P<0.05), and the ovary function is damaged. 4. The T3, insulin, leptin levels of LPD and anovulatory cycles are decreased(P<0.05), the cortisol level of LPD and anovulatory cycles is increased(P<0.01), the hGH, IGF-I, IFGBP-3 of LPD and anovulatory cycles have no shifts, and the Ghrelin, fasting blood glucose levels of LPD and anovulatory cycles have no changes. 5. The energy intake and energy expenditure of exercise female are significantly higher than those of sedentary female(P<0.01). The energy deficiency of exercise group is more serious than the sedentary group, and the energy availability is lower(P<0.05). 6. The CHO intake of exercise female is lower than the standards recommended by the national sports bureau, and the protein and fat intake is higher than the standards. 7. T3 correlates with energy balance and available energy positively, and insulin correlates with energy balance positively(P<0.05).Conclusions: 1. In the research of reproduction function of female athletes, the LH peak measurement in the urine can be used to ascertain whether the ovulation is happen and the time of ovulation. 2. In the study of reproduction function, menstrual cycle length is not suitable as a correct index for the ovary function of female athlete. 3. EAMD has a high prevalence in exercise female. In this study, the prevalence and incidence of EAMD are 100% and 97%, and there is also a higher inconsistency between cycles. 4. In LPD and anovulatory cycles, LH peak in the mid menstrual phase is decreased or varnished, E2 and progesterone excretion is decreased and ovary function is damaged. 5. In LPD and anovulatory cycles, blood T3, leptin, insulin level are declined and cortisol level is increased, which indicated that exercise female is in a hypometabolic state. 6. In this study, the CHO intake of exercise female is lower than the standards recommended by the national sports bureau, and the protein and fat intake is higher than the standards. 7. In LPD and anovulatory cycles, dietary energy intake is less than the energy expenditure, which indicates the exercise female is in an energy deficiency, energy availability is lower.