Assessing Body Composition in Paralympians: Accuracy of Different Measurement Methods Compared with Dual-Energy X-Ray Absorptiometry

Background: Paralympic athletes represent a highly heterogeneous athletic population, which poses unique challenges for body composition assessment. This study evaluated the accuracy of Bioelectrical Impedance Analysis (BIA), Air Displacement Plethysmography (ADP), and a set of skinfold equations in estimating relative fat mass (%FM) in Paralympians, using Dual-Energy X-Ray Absorptiometry (DXA) as reference method. Methods: Sixty-six male and sixty-seven female Paralympians underwent body composition assessments on the same day. The %FM estimated using BIA, ADP, and six existing skinfold equations was compared with %FM measured by DXA (%FM_DXA). Accuracy and agreement between the methods were evaluated using two-tailed paired-sample t-tests, concordance correlation coefficients, reduced major axis regression, and Bland-Altman analysis. Linear regression analyses with the %FM_DXA as dependent variable and anthropometric measurements as independent variable were also carried out. Results: BIA, ADP, and skinfold equations exhibited poor agreement with DXA and significantly underestimated %FM_DXA, with systematic biases ranging from -1.8% to -10.7% in both men and women. In both groups, skinfold sums showed strong correlations with %FM_DXA (r > 0.7), with the nine-skinfold model providing the best prediction (adjusted R2 approximately 0.8). Conclusions: The results of this study indicate a lack of transferability of available methods for assessing body composition (skinfold equations, BIA, and ADP) in estimating %FM_DXA in both male and female Paralympians, as these methods proved inaccurate. Future research is needed to further investigate the accuracy of methods for assessing body composition in this population, taking into account the specific impairment and health condition of the athletes.