Body mass index, body fat mass and the occurrence of amenorrhea in ballet dancers

To evaluate the connection between menstrual disorders and body fat mass, we examined a group of 30 ballet dancers and a group of 30 non-athletic girls (controls). Body mass index (BMI) was calculated and percent body fat (FAT%) was measured using the bioelectrical impedance method. A questionnaire was used to obtain age at menarche and duration of menstrual cycles. Ballet dancers had significantly lower values of BMI (18.56 +/- 1.53 vs. 19.96 +/- 2.12 kg/m2) and FAT% (18.85 +/- 4.50 vs. 23.41 +/- 4.34%) compared with controls. According to BMI, 50.0% of ballet dancers and 23.3% of the control group were underweight. Of underweight ballet dancers, 66.7% had lower values of body fat, while most underweight girls from the control group had normal body fat. Normal-weight obesity was registered in 40.9% of the control group and in 6.7% of ballet dancers. Amenorrhea was found in 20.0% and oligomenorrhea in 10.0% of ballet dancers. Ballet dancers more frequently had later appearance of menarche and menstrual cycles of longer duration than did non-athletic girls. A significant negative correlation was found between menstrual cycle duration and FAT% among ballet dancers (r = -0.415). To prevent complications caused by changes of body fat mass, we conclude that body composition assessment in ballet dancers is very important.