Application of different methods for body composition determination among female elite level rhythmic gymnasts in Germany

Problem: Female athletes of rhythmic gymnastics (ARGs) are often associated with underweight and malnutrition. Body composition (BC) determinations can help to make statements about nutritional status and health. However, there is no BC database among ARGs in Germany. Method: BC determinations were performed among German ARGs using calipometry and different bioelectrical impedance analysis (BIA). All devices were compared in terms of percentual fat mass (FM%) using ANOVA. Additional parameters for the BIA devices were tested for differences using t-tests. Bland-Altman plot was created to compare the BIA devices in terms of FM%. Results: Twenty-five ARGs (M=15.2 years, SD±2.11) were measured. FM% was determined by calipometry (M=7.51, SD±1.35), InBody (M=11.87, SD±5.1), and BIVA 101 devices (M=16.2, SD±4.26). ANOVA showed significant differences for FM% (F[2, 48]=64.46, p<0.001; partial η²=0.729). For Bonferroni-corrected post-hoc tests, significant differences (p < 0.001) between the three measurement methods were determined. The t-tests in BC parameters also showed significant differences (p<0.001) between the two BIA devices. Discussion: Compared to calipometry, BIA provides additional BC parameters. Nevertheless, the use of different measurement methods and devices in the comparison of BC parameters is not recommended. Reference values must be adapted to the respective devices. Conclusion: Uniform measurements in larger samples and generation of reference values are necessary to explore the prediction in BC on health status among ARG.