Agreement between B-Mode Ultrasound and Air Displacement Plethysmography in Preprofessional Ballet Dancers

Body composition assessments are useful for practitioners to monitor overall athlete health and nutritional status, particularly in aesthetic and weight-class sports that emphasize ideal body weight standards. Portable and accurate measurement tools are especially important for these assessments. Ultrasound has the potential to provide portable body composition assessments, but accuracy must be further studied. Purpose This study aimed to assess the agreement between B-mode ultrasound and air displacement plethysmography (ADP) body composition results in preprofessional ballet dancers. Methods Male ( n = 21, M age = 17.2 ± 1.7 yr, M BMI = 20.5 ± 2.0 kg·m −2 ) and female ( n = 27, M age = 16.1 ± 1.4 yr, M BMI = 18.3 ± 1.3 kg·m −2 ) dancers were assessed by ADP and ultrasound to determine body fat percentage (%BF), fat mass (FM), and fat-free mass (FFM). Pearson’s correlations were used to assess agreement, and paired t -tests were used to determine differences between devices ( α = 0.05). Ultrasound validity was assessed using SEE and total error. Bland–Altman plots were used to identify 95% limits of agreement. Results Agreement was high for %BF (females, r = 0.94; males, r = 0.77), FM (females, r = 0.94; males, r = 0.73), and FFM (females, r = 0.95; males, r = 0.99). However, ultrasound overestimated %BF and FM and underestimated FFM ( P < 0.05) compared with ADP in females only. In addition, there were stronger agreement and lower error for FFM compared with both %BF and FM regardless of sex. Conclusion There is strong agreement between ultrasound and ADP in this population. Although ultrasound may be a useful field tool to assess body composition, future research is needed to refine %BF equations in this population to reduce calculation errors.