Equivalence of information from single frequency v. bioimpedance spectroscopy in bodybuilders

Abstract

In bioelectrical impedance spectroscopy (BIS), it is assumed that the current path is only extracellular at the lowest frequencies and that it is both extra-and intracellular at the highest frequencies. We tested validity of BIS assumptions in bodybuilders who have an increased intracellular volume due to hypertrophy of muscle fibres. The study was observational cross-sectional in a study group of thirty professional bodybuilders compared with thirty control subjects. Resistance (R) and reactance (Xc) vector components fitting the Cole's arc with BIS (SFB3 analyser) were compared with components at 50 kHz frequency. The average Cole's arc in bodybuilders was significantly smaller and shifted to the left in the R -Xc plane (both R and Xc values were smaller at any individual frequency). The ratio of Xc at 5 kHz and Xc at the characteristic frequency was 70 % in bodybuilders and 64 % in control subjects, indicating a huge intracellular flow of the electric current at low frequencies in both groups (expected ratio close to 0 if the current path was extracellular). As a consequence of a common path, the correlation coefficient between R values at 50 kHz and at other frequencies (from 0 to infinity) was 0·94 to 1·00. The correlation between total body water estimated with BIS or with R at 50 kHz was 0·98. Hence, there was equivalence between information provided by the vector components R and Xc at 50 kHz and that provided by 496 correlated vectors that were measured with BIS.

Effect of ketogenic mediterranean diet with phytoextracts and low carbohydrates/high-protein meals on weight, cardiovascular risk factors, body composition and diet compliance in Italian council employees

“…Body composition was assessed using bioelectrical impedance analysis (BIA Akern Bioresearch, Pontassieve, FI, Italy) which is a non-invasive and portable method for the estimation of fluid compartments, fat and fat-free mass in healthy subjects. Bioelectrical impedance analysis was chosen for the analysis of body composition due to its reliability, safety, convenience and non-invasiveness making it optimal for the routine monitoring of body composition during the ketogenic diet [25,26]. The experimental design is showed in Figure 1.…”

Effect of resistance training on phase angle in older women: A randomized controlled trial

“…Considering the potential health-related implications, PhA has been investigated as a means to assess nutritional status (Zhang et al, 2014). In the areas of exercise science and sports medicine, PhA has often been analyzed in cross-sectional observational (Piccoli et al, 2007) and prospective (Mascherini et al, 2015;Matias et al, 2015) studies. Cross-sectional studies have shown that the PhA can be affected by physical activity (Dittmar, 2003;Torres et al, 2008;Koury et al, 2014;Mala et al, 2015).…”

Comparison of Bioimpedance and Clinical Methods for Dry Weight Prediction in Maintenance Hemodialysis Patients

“…In fact, studies had shown that using BCS equations in MHD patients could achieve physiological fluid status and better control of hypertension [26,27]. However, it was found that the BISA used in DW BCS did not provide any improvement over single-frequency measurement at 50 kHz for the estimation of hydration status [28,29]. The equivalence of information from single versus multifrequency bioimpedance was due to tissue anisotropy.…”