Total body electrical conductivity

W. H. Van Itallie, T. B. (1983) Measurement of total body electrical conductivity a new method for estimation of body composition. Am. J. Clin. Nutr. 37, 735-739. 

Baumgartner. R.N. (1996) Electrical Impedance and Total Body Electrical Conductivity, in Human Body Composition (Roche, A.F., Heymsfield, S.B., and Lohman, T.G., eds.) pp. 91-93, Human Kinetics, Champaign, IL. 

Swan, J.E., Parrish, F.C., Jr., Wiegand, B.R., Larsen, S.T., Baas, T.J., and Berg, E.P. (2001) Total Body Electrical Conductivity (TOBEC) Measurement of Compositional Differences in Hams, Loins, and Bellies from Conjugated Linoleic Acid (CLA)-Fed Stress-Genotype Pigs, J. Anim. Sci. 79,1475-1482. 

Abbreviations CLA, conjugated linoleic add BMI, body mass index BC, body composition % BF, percentage of body fat M, men W, women DEXA, dual energy X-ray absorptiometry TOBEC, total body electrical conductivity BIS, bioimpedance spectroscopy NR, not reported SAD, sagittal abdominal diameter. 

Isotope dilution bility of total body water, total body potassium, total body electrical conductivity, and dualenergy X-ray absorptiometry Expensive and needs specialized equipment mineral content, fat mass, and lean body mass Noninvasive, safe... 

Measurements of either total body electrical conductivity (TOBEC) or bioelectrical impedance (BIE) are used mainly in research, but as the equipment becomes more widely available these methods will become the methods of preference for routine estimation of body fat. 

Baumgartner RN (1996). Electrieal impedance and total body electrical conductivity, hr Roche AF, Heymsfield SB, Lohman TG (eds). Human Body Composition. Human Kinetics Champaign, IL. pp 79—107... 

U = untrained (no previous resistance training in the last 3 months) T = trained (undergoing some form of resistance training prior to study). ° DEXA = dual-energy x-ray absorptiometry HW = hydrostatic weighing SF = skin-fold thickness TOBC = total body electrical conductivity. 

Bioelectrical impedance. This technique involves connecting electrodes to the hands and feet and passing a mild electric current through the body. Most organs and tissues conduct the electric current, as they contain water and salts. However, adipose tissue contains only about 14% water, by weight, and does not readily conduct electricity. The results give an indication of total body fat. 

A question that some students ask is why, while water is not an electrical conductor, it is dangerous to expose damp hands or in general a damp body, to mains electricity, for example in a bathroom. The explanation is that dry skin has a resistance of 100 000 ohms or more, while wet skin may have a resistance of only 1000 ohms. Such a low resistance of the wet skin allows current to pass into the body more easily and give a greater electric shock. Note also that pure water should be contrasted with natural water (such as tap water), which has various substances dissolved in it, among which are electrolytes. Hence natural water has some electric conductivity, which depends on the concentration of the water in various electrolytes. Electrical conductivity measurements of natural waters are used to predict the salinity, major solute concentrations, and total dissolved solids concentrations of natural waters. 

We will now consider a second example which illustrates the electrostatic induction phenomenon. First of all, let us suppose that a conductive body of arbitrary shape is situated within the region of influence of an electric field Eq as shown in Fig. 1.9. Under the action of the field, the positive and negative charges residing inside the conductor move in opposite directions. As consequence of this movement, electric charges accumulate on both sides of the conductor. In so doing, they create a secondary electric field, which is directed in opposite direction to the primary field inside the conductor. The induced surface charges distribute themselves in such a way that the total electric field inside the conductor disappears, that is ... 

---