Resting energy expenditure is lower in Japanese female athletes with menstrual disorders than in eumenorrheic athletes

Abstract

Menstrual disorders are health problems in female athletes. It has also been reported that amenorrhea can lead to metabolic suppression. However, studies regarding resting energy expenditure (REE) in Japanese female athletes with menstrual disorders are lacking. The purpose of this study was to investigate whether REE was suppressed in female Japanese athletes with menstrual disorders. In total, 22 highly trained intercollegiate athletes participated in this study; and body composition, REE, thyroid and reproductive hormone levels, and nutritional intake levels were measured. Predicted REE (REEp) was calculated using two different equations based on fat-free mass (FFM) and organ-tissue mass measured by dual-energy X-ray absorptiometry (DXA). Individuals with menstrual disorders (MD group) had significantly lower height, body weight, and fat mass than those in the eumenorrheic (EU) group; however, the FFM did not differ between the groups. Both the measured REE (REEm) and REEm adjusted for FFM in the MD group were lower than those in the EU group. The REEm to REEp ratio, which indicates energy deficiency, was also lower in the MD group. In addition, although the MD group had lower triiodothyronine and progesterone levels, they were still within the normal range. Japanese female athletes with menstrual disorders may have lower REE than eumenorrheic athletes, even if thyroid and reproductive hormones are within the normal range.

Reexamining the calculations of exercise energy expenditure in the energy availability equation of free-living athletes

“…In response to periods of low EA, the hypothalamic-pituitary-thyroid axis adapts to reduce energy expenditure ( 26 ). Athletes with menstrual disorders have demonstrated consistently decreased triiodothyronine (T 3 ) levels ( 9 , 27 ), therefore, a low T 3 level is one objective blood marker that could be used to identify female athletes with low EA. In exercising men, it has been reported that leptin and insulin are reduced, independent of whether low EA had originally occurred with or without exercise; however, low EA did not significantly impact ghrelin, T 3 , testosterone, and insulin-like growth factor-1 (IGF-1) levels ( 28 ).…”

“…Since the introduction of EA in 2007 ( 5 ), numerous researchers have assessed EA in athletes with equivocal results, due in part to no clear methodological guidelines for calculating EA, including techniques used to measure each component of the EA equation ( 6 , 7 ). For example, female athletes with similar EI had different menstrual conditions (eumenorrheic or amenorrheic) ( 8 , 9 ), while in males, EI is similar between cross-country athletes and sedentary controls ( 10 ). Conversely, the mean EEE in female and male athletes at risk for low EA was significantly higher than moderate or no-risk athletes ( 11 , 12 ), suggesting that in athletes, high EEE affects EA values.…”