Interrater Reliability For Dxa And Bia Analysis For Measuring Total And Regional Lean Mass

Abstract

Dual-energy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) are capable of assessing total and regional body composition using different technologies. DXA is considered more reliable than BIA to evaluate body composition, while BIA is a more cost-efficient and portable option. The agreement between these measures has not been determined in Rugby athletes. PURPOSE: To assess the interrater reliability between two devices that are capable of assessing total and regional lean mass in rugby athletes. METHODS: Body composition was measured in sixteen male rugby players (21.1 ± 1.6 years; 88.3 ± 14.2 kg; 1.78 ± 0.06 m) prior to the onset of their competitive season. Total body estimates of percent fat (%FAT), fat mass (FM), and lean mass (LM) were determined by DXA (Lunar iDXA) and BIA (InBody 770). Regional LM estimates were also determined for the arms and legs from both devices. To assess the agreement between DXA and BIA on these measures, intraclass correlation coefficients (ICC), 95% limits of agreement (95% LOA), and coefficients of variation (CV%) were calculated. RESULTS: The agreement between DXA and BIA for total body estimates of %FAT (ICC2,1 = 0.81, 95% LOA = 0.91 - 1.34%, CV% = 10.5%), FM (ICC2,1 = 0.48, LOA = 0.63 - 0.92 kg, CV% = 10.1%) and LM (ICC2,1 = 0.67, LOA = 0.92 – 1.00, CV% = 2.3%) was variable, while regional values for lean arm mass (ICC3,1 = 0.91, 95% LOA = 0.93 – 1.06%, CV% = 3.3%) and lean leg mass (ICC3,1 = 0.89, 95% LOA = 1.05 – 1.15%, CV% = 2.4%) agreement was consistent. CONCLUSION: These data suggest that the interrater reliability between DXA and BIA is high when estimating total and regional lean mass, but not for estimating fat mass or body fat percentage. Although limited by the cross-sectional nature of the study design, our findings suggest it may be possible to use these devices interchangeably for tracking total and regional lean mass.