Current Energy Availability Is Not Associated With The Menstrual Status Among Japanese Female Athletes

Abstract

PURPOSE: Energy availability (EA) is defined as dietary total energy intake (TEI) minus exercise energy expenditure (EEE) normalized to fat-free mass (FFM). It is well known that chronic reduction in EA, below 30 kcal/kg FFM/day, is associated with impairments of a variety of body function such as menstrual disorder, endocrine dysfunction and decreased bone mineral density (BMD). Little is known regarding EA and the physiological parameters of Japanese female athletes classified according to menstrual status. Therefore, this study aimed to determine the current EA status, hormonal status and BMD in Japanese female athletes. METHODS: Eighteen female collegiate athletes were classified into two groups; the eumenorrheic group (EU, 22±1 years, n = 7) and the menstrual disorder group (MD, 20±1 years, n = 11). The ovulation status was checked before the experimental period using an ovulation test kit, and the date were collected during the early follicular phase in EU group. TEI was assessed using 7-days dietary records, EEE was measured via HR-VO2 methods, and hormonal status was measured from a fasting blood sample. Body composition and BMD were measured by dual energy X-ray absorptiometry. The eating attitude test (EAT-26) was used to assess susceptibility to eating disorders. RESULTS: EA was not significantly different between EU and MD groups (32.2±9.6 kcal/kg FFM/day vs 32.6±8.1 kcal/kg FFM/day). Further, no significant differences were observed in terms of body composition, BMD, and EAT-26 score between the two groups. However, triiodothyronine (T3; 84±14 ng/dL vs 114±21 ng/dL, p<0.01) and progesterone (P4; 0.2±0.1 ng/mL vs 0.4±0.1 ng/mL, p<0.05) were significantly lower in MD group than those in EU group. CONCLUSIONS: The results of the present study suggested that the menstrual status is not associated with current EA, but may be related to chronic energy deficiency among Japanese female athletes.