This is author's accepted manuscript.Final version available from Human Kinetics via the DOI in this record.PURPOSE: To examine the intermethods agreement of dual-energy X-ray absorptiometry (DXA) and foot-to-foot bioelectrical impedance analysis (BIA) to assess the percentage of body fat (%BF) in young male athletes using air-displacement plethysmography (ADP) as the reference method. METHODS: Standard measurement protocols were carried out in 104 athletes (40 swimmers, 37 footballers, and 27 cyclists, aged 12-14 y). RESULTS: Age-adjusted %BF ADP and %BF BIA were significantly higher in swimmers than footballers. ADP correlates better with DXA than with BIA (r = .84 vs r = .60, P < .001). %BF was lower when measured by DXA and BIA than ADP (P < .001), and the bias was higher when comparing ADP versus BIA than ADP versus DXA. The intraclass correlation coefficients between DXA and ADP showed a good to excellent agreement (r = .67-.79), though it was poor when BIA was compared with ADP (r = .26-.49). The ranges of agreement were wider when comparing BIA with ADP than DXA with ADP. CONCLUSION: DXA and BIA seem to underestimate %BF in young male athletes compared with ADP. Furthermore, the bias significantly increases with %BF in the BIA measurements. At the individual level, BIA and DXA do not seem to predict %BF precisely compared with ADP in young athletic populations.This work was done as part of the PRO-BONE
study. It has received funding from the European Union Seventh
Framework Programme (FP7/2007-2013) under grant agreement
no. PCIG13-GA-2013-618496. M.V.N-F. received a PhD
Student Internships Abroad scholarship from the National
Council for Scientific and Technological Development
(CNPq; process: 200340/2015-8) and a Brazilian PhD Student
scholarship from the São Paulo Research Foundation (FAPESP;
process. 2016/18436-8 and 2017/11732-3). E.U-G. received a
PhD scholarship from Universidad de Castilla-La Mancha
(2014/10340). A.C.F.M. received a postdoctoral scholarship
from the São Paulo Research Foundation (FAPESP; process:
2014/13367-2 and 2015/14319-4)
