IADMS Madrid 2001   [back to the Category]

Comparison of two body composition assessment methods...   [read the french version]

Author :   Elizabeth Pedersen, MA

Saturday 3 November 2001
11:15 – 11:25 am Room 1

Comparison of two body composition assessment methods and prediction equations for adult female dancers

Elizabeth Pedersen, MA, University of Toronto, Ontario, Canada; Virginia Wilmerding, PhD, Cristine Mermier, MS, Vivian Heyward, PhD, University of New Mexico, Albuquerque, NM, Ann Gibson, PhD, University of Akron, Akron, OH; USA

Dance is an activity that has been associated with disordered eating as dancers strive to maintain an ultra-thin body. People concerned about the health of dancers have been working to find ways to identify dancers at significant health risk due to too little body fat. Hydrostatic weighing and dual-energy x-ray absorptiometry (DXA) are both clinical methods that are often used as a criterion measure for determining body fat; however both methods are time consuming, not portable, and require highly skilled technicians. Therefore, field methods such as skinfolds and bioelectrical impedance analysis (BIA) are being evaluated for validity and reliability using the unique population of dancers. The purpose of this study was to evaluate the predictive accuracy of two published BIA equations derived specifically for dancers by Yannakoulia et al. (2000) using a single frequency, four-terminal impedance plethysmograph on a sample of American dancers.
Methods: Twelve female dancers ranging in age from 22-47 participated. Height and weight measurements were taken according to standard procedures. Body composition was assessed with skinfolds (Lange caliper, Beta Technology Inc., Cambridge, MD), bioelectrical impedance analysis (BIA-101A Spectrum Analyzer, RJL Systems, Detroit, MI), and DXA (Lunar DPX, Lunar Radiation Corp., Madison, WI). All equipment was calibrated, and measurements were taken by the same technician to reduce the possibility of measurement error. Correlation analysis was run (SPSS-PC, v10.0) to evaluate the predictive accuracy of two different equations (Yannakoulia, et al.) for our sample using %BF DXA as the criterion measure. Paired t-tests were used to evaluate differences between the %BF averages. The first equation (EQBIA) used electrical resistance, height and weight as variables; the second equation (EQBIA-TRI) added the skinfold thickness measured at the triceps brachii.
Results: For the dancers in this study, the average height, weight, age and relative body fat (%BF) as estimated by DXA were 163.89 cm, 56.77 kg, 32.31 yr, and 23.94 %BF, respectively. The correlation between %BF from DXA and %BF estimated using each Yannakoulia et al. equation was significant (p < 0.05). However, EQBIA-TRI displayed a somewhat higher correlation with DXA %BF than did EQBIA (r = 0.81 v 0.78, respectively). The average %BF estimated using EQBIA (28.92%) was significantly different from DXA %BF (p = 0.01). There was no significant difference between EQBIA-TRI (25.03%) and DXA %BF (p < 0.05). The mean difference in %BF between the DXA and EQBIA-TRI was smaller (1.086%BF) compared to the difference between DXA and EQBIA (4.9853%BF) for our dancers.
Discussion: It is important to determine the usefulness and practicality of different body composition methods as a means of estimating the %BF of dancers. While the equations created by Yannakoulia et al. both tended to over-estimate the DXA %BF of our dance population, the EQBIA-TRI equation appeared to predict %BF of our dancers with reasonable accuracy. More cross-validation research needs to be done using these equations because health care specialists need to have practical, expedient, and cost-effective ways to accurately assess body composition in the dance studios and clinics so that at risk dancers may be identified as soon as possible.