External validation of bioelectrical impedance analysis equations for body composition against dual-energy X-ray absorptiometry in Mexican recreational runners

Sports professionals prioritize athlete body composition (BC) due to its relationship to performance. Bioelectrical impedance analysis (BIA) estimates BC using predictive equations, and validating these equations is essential to determine their utility. The aim of this study was to externally validate four bioelectrical impedance equations for predicting body composition in Mexican recreational runners using dual-energy X-ray absorptiometry (DXA) as a reference method. This external validation pilot study followed a comparative, cross-sectional design and included 30 Mexican male recreational runners (aged 38.0 ± 10.7 years). BC was measured using DXA and four BIA equations. A paired t-test was performed to evaluate differences between methods. Equivalent testing, Simple linear regression, and Bland-Altman analysis were carried out to evaluate agreement between methods. Statistical significance was set at p < 0.05. Non-significant differences were found between DXA and predicted values with Macias et al. (2007) and Lukaski and Bolonchuk (1987) equations (p < 0.05). These equations provided equivalence at 5% regions and non-significant bias. In conclusion, Lukaski and Bolonchuk (1987) demonstrate the most accurate equations for the current sample. These equations showed promising results for measuring BC in a cohort of runners; however, caution is advised when applying them to individual tracking.