Fat-free Mass Bioelectrical Impedance Analysis Predictive Equation for Athletes using a 4-Compartment Model

Abstract

Bioelectrical impedance analysis equations for fat-free mass prediction in healthy populations exist, nevertheless none accounts for the inter-athlete differences of the chemical composition of the fat-free mass. We aimed to develop a bioimpedance-based model for fat-free mass prediction based on the four-compartment model in a sample of national level athletes; and to cross-validate the new models in a separate cohort of athletes using a 4-compartment model as a criterion. There were 142 highly trained athletes (22.9±5.0 years) evaluated during their respective competitive seasons. Athletes were randomly split into development (n=95) and validation groups (n=47). The criterion method for fat-free mass was the 4-compartment model. Resistance and reactance were obtained with a phase-sensitive 50 kHz bioimpedance device. Athletic impedance-based models were developed (fat-free mass=− 2.261+0.327*Stature2/Resistance+0.525*Weight+5.462*Sex, where stature is in cm, Resistance is in Ω, Weight is in kg, and sex is 0 if female or 1 if male). Cross validation revealed R2 of 0.94, limits of agreement around 10% variability and no trend, as well as a high concordance correlation coefficient. The new equation can be considered valid thus affording practical means to quantify fat-free mass in elite adult athletes.

Assessment of Body Composition in Athletes: A Narrative Review of Available Methods with Special Reference to Quantitative and Qualitative Bioimpedance Analysis

“…For this reason, a previous review called for action by the scientific community, since such regression equations were not available [ 23 ]. Most recently, some regression equations have been proposed for athletes, distinguishing the male and female population [ 24 , 25 , 26 ]. Similarly, new elements for a qualitative analysis in sport-specific populations have been developed [ 30 , 31 , 32 , 33 , 34 , 35 , 36 ].…”

“…This may have led to inaccurate values, generating doubts about the accuracy and usefulness of BIA in athletes [ 23 , 27 , 28 ]. These perplexities have pushed researchers to develop specific equations [ 24 , 25 , 26 ] or use alternative evaluation approaches [ 31 , 45 , 56 , 78 , 109 , 110 ].…”

“…Current application of BIS and BIA aims to predict body composition parameters for inclusion in multicomponent models. However, only single-frequency BIA has been used to develop prediction equations to estimate different body composition parameters in athletes [ 24 , 25 , 26 ].…”

Bioimpedance Vector Patterns Changes in Response to Swimming Training: An Ecological Approach

“…BIVA was carried out using the classic methods, e.g., normalizing VL, R, and Xc for height (H) in meters. The R-Xc z score graph was used to plot the BIVA data of the swimmers separated by gender; in this approach, the mean bioimpedance vectors are considered in relation to their specific reference population [27] Total body water (TBW), ECW, ICW, as well as fat-free mass (FFM) and fat mass (FM) were calculated using specific equation for athletes [28,29].…”

Specific Bioelectrical Impedance Vector Analysis Identifies Body Fat Reduction after a Lifestyle Intervention in Former Elite Athletes

“…At the molecular level, the four-compartment model is considered the "gold standard" for the assessment of FM [5]. Given that this model combines the use of several techniques, due to the assessment of bone mineral content by dual-energy X-ray absorptiometry (DXA); total body water by isotopes dilution, bioelectrical impedance analysis (BIA), or bioelectrical impedance spectroscopy (BIS); and body volume by air displacement plethysmography, it requires considerable time and high costs, as well as highly qualified personnel.…”