Critical Analysis of a Rapid 4-compartment Model in Hispanic Adults:Effect of Age and Level of Body Fatness

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ABSTRACT In response to PAR-16-439, Support of Competitive Research (SCORE) Pilot Project Award (SC1), the PI is proposing a study that seeks to systematically evaluate a rapid 4-compartment (4C) model in a diverse sample of Hispanic adults. Testing will consist of one visit to the Exercise Physiology Laboratory at Texas A&M International University. The PI will recruit Hispanic men (n = 150) and women (n = 150) ages 18-79 years in Laredo Texas for this study. Participants will be block recruited to ensure equal distribution of age, sex, and BMI groups. A criterion 4C model will be determined using deuterium oxide for total body water (TBW), dual energy X-ray absorptiometry (DXA) for bone mineral content (BMC), and underwater weighing for body volume (BV). A rapid 4C model will be determined using DXA for BV and BMC and bioimpedance analysis (BIA) for TBW. The DXA- derived BV equation recently developed by the PI (1) in a group of young Hispanic adults (18-45 years) will be utilized to compute BV for the rapid 4C model. Validity will be established by comparing the %Fat, fat mass (FM), and fat-free mass (FFM) of the rapid 4C model against the criterion 4C model. The FFM density, (DFFM), bone mineral (MoFFM), total body water (TBWFFM), and residual (RFFM) will also be calculated in the rapid and criterion 4C model and compared against the cadaver reference values of Brozek et al. (2). The PI recently revealed that the FFM characteristics of young- and middle-aged Hispanic adults (18-55 years) significantly differs from non-Hispanic Whites and cadaver reference values of Brozek et al. (2). This is a significant finding since the cadaver reference values of Brozek et al. (2) are employed in stand-alone methods such as BIA. Nonetheless, further evaluations need to establish whether variations in FFM characteristics exist among Hispanic adults who vary in age and level of body fatness. Collectively, findings from the proposed study will help establish whether a rapid 4C model can be used in a diverse sample of Hispanic adults and whether the assumptions employed in stand-alone assessments such as BIA (73% TBWFFM) are violated.