Assessment of body composition in ballett dancers: correlation among anthropometric measurements, bio-electrical impedance analysis, and dual-energy X-ray absorptiometry.

Abstract

Ballet dancers tend to restrict caloric intake and/or to use inappropriate compensatory behavior (e.g. self-induced vomiting, use of laxatives) in order to maintain a low body weight. Therefore careful assessment of body composition and determination of minimal body weight for maintenance of a desirable percent fat may reduce unnecessary weight loss and decrease the use of a potentially dangerous weight-control behavior. The purpose of this study was to determine body fat in a homogenous group of 59 adolescent, female ballet dancers (age range 14-17 y). Body composition was assessed using three different techniques: skinfold thickness measurements, bio-electrical impedance analysis (BIA), and dual energy X-ray absorptiometry (DXA). Percent body fat and the sum of skinfold thickness were calculated from measurements of four sites (i.e. triceps, biceps, subscapular, and suprailiac). All eumenorrheic dancers were examined in the early follicular phase of the menstrual cycle whereas amenorrheic dancers (or pre-menarcheal) at random. Significant positive correlations were found between skinfold measurements and assessments of body fat by BIA (r=0.48, p<0.001); and between skinfold measurements and assessments of body fat by DXA (r=0.80, p<0.00001). Assessment of body fat by BIA was significantly correlated with assessment of body fat by DXA (r=0.63, p<0.001). The correlation coefficient of percent body fat by skinfolds with DXA (r=0.8, p<0.00001) was significantly higher than the correlation coefficient of body fat by BIA with body fat DXA (p<0.01). In addition the agreement between measurements of body fat by DXA and skinfolds was higher than measurements of body fat by DXA and BIA. This study demonstrates that a simple, inexpensive, field-based method such as skinfold measurements can be successfully used to determine body fat in a homogeneous group of female ballet dancers. This may help to determine a minimal body weight of female dancers based on their percent body fat and as a result may reduce excessive weight loss and prevent the use of a risky weight-reducing behavior.