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BIA method is a technology measuring the volume of a conductor through its length and impedance . Hoffer applied this method to the human body to calculate body water through measured impedance. In 1969 Hoffer’s study reported a high correlation between body water and height2/resistance, and to this day it has been the basic impedance index for the analysis of body composition.
RJL Corporation of the United States first commercialized the impedance measuring instrument in 1979. The introduction of the impedance measuring device used a simple method of measuring the impedance by attaching polar electrodes to the hand and foot of the subjects while lying down, providing a useful method for the study of BIA. Until then, analysis of the body composition was done through dissection, under water body density method, where one had to enter a water tank fully undressed while holding their breath, or by using the extremely expensive DEXA. Comparably, BIA was easier, faster, cheaper, and noninvasive, thus attracting the attention of researchers.

After the commercialization of the impedance measuring device by the RJL Systems Corporation, numerous studies were performed by body composition researchers, nutritionists, and doctors until the mid-1980’s. The impedance measuring device used during this period used a mono-frequency, measuring the resistance from the wrist to the ankle (Whole Body Impedance). Whole body impedance measuring method using mono-frequency contains a problem because the body composition as well as the body shape affect the impedance. In order to overcome such limitations, researchers corrected the values for age, gender, and other factors and the following equation was utilized.

TBW = C1 x heght2/R + C2 x weight + C3 x age + C4 x gender + C5 *C1-C5 are constants.
Although the BIA technology was adequate for healthy individuals, there were many skeptical reports that “BIA was not accurate.” This meant that it was not suitable for those truly in need of body composition analysis such as children, elderly, severely obese patients, and athletes. The BIA method in the late 1980’s used empirical data of the average person in its calculations to provide the analysis. Those who were not of the average body type did not recieve accurate results. As a solution to such emerging problems, multifrequency technology and impedance measurements specific to different body segments were provided as an alternative method.
Many engineers concentrated on the study of multifrequency technology and segmental impedance technology in order to solve the problems with BIA. With Chumlea et al. continuing the study of segmental impedance, numerous researchers concentrated on the multifrequency study. Through this process BIA method development continued.
Kichul Cha, Andrew G. Hill, Jan D. Rounds and Douglas W. Wilmore, Multifrequency bioelectrical impedance fails to quantify sequestration of abdominal fluid, J. Appl. Phyiol . 78(2): 739-739, 1995
Richard N Baumgartner, W Cameron C humlea, and Alex F Roche, Estimation of body composition from bioelectrical impedance of body segments, Am J Clin Nutr 50:221-6, 1989.
In the early nineties, Kichul Cha, a bioengineering major at Harvard University, reported an article pointing out the fundamental problem of BIA. This article concluded that in order to accurately analyze the trunk, which comprises half the human body, the impedance must be measured with extreme precision.
For such ultra-precise body segment analysis a direct segmental measuring method was necessary. The trunk has a high metabolism and thus low impedance. Accuracy was not achieved through existing methods. Kichul Cha developed an 8- polar impedance method for the first time in history. This technique required an individual to attach all electrodes, and by use of an internal switch, the impedance values can directly measure the individual body segments. This technology is able to achieve a high level of accuracy without using statistical data such as age and gender. It can be applied to those with a unique physique, overcoming limitations of the existing BIA.
Kichul Cha, Andrew G. Hill, Jan D. Rounds, and Douglas W. Wilmore, Multifrequency bioelectrical impedance fails to quantify sequestration of abdominal fluid. , J.Appl.Physiol. Vol.78(2):736-739, 1995.
Kichul Cha, Ramona G Faris, Elaine F Brown and Douglas W Wilmore, An electronic method for rapid measurement of haematocrit in blood samples, Physiol Meas, Vol 15, 129 ? 137, 1994.
Kichul Cha, Glenn M. Chertow, Jorge Gonzalez, J. Michael Lazarus, and Douglas W. Wilmore, Multifrequency bioelectrical impedance estimates the distribution of body water, J.Appl.Physiol. Vol.79(4):1316-1319, 1995.
In 1996 Biospace developed the InBody using multi-frequency BIA technology in which the trunk and limbs are analyzed separately, and extra cellular fluid is accurately measured. BIA became a reality. InBody was distributed in Korea where the BIA method was still unfamiliar and “body fat” was not as well known as it is today. Today InBody is becoming the most preferred device by the world’s leading researchers and numerous domestic and international SCI level articles utilizing InBody are common.
A Sartorio, M Malavolti, F Agosti, PG Marinone, O Caiti, N Battistini and G Bedogni, Body water distribution in severe obesity and its assessment from eight-polar bioelectrical impedance analysis. Eur. J. Clin. Nutr. 1-6, 2004.

M. Malavolti, C. Mussi, M.Poli, A. L. Fantuzzi, G. Salvioli, N. Battistini and G. Bedogni, Cross-calibration of 8-polar Bioelectrical Impedance Analysis vs Dual-Energy X-ray Absorptiometry for the assessment of Total and Appendicular Body Composition in Healthy Subjects aged 21-82y. Annals of Human Biology 30(4): 380-391, 2003.

Colon J. Carati, Sandy N. Anderson, Bren J. Gannon, Neil B. Piller, Treatment of Postmastectomy Lymphedema with Low-Level Laser Therapy. Cancer 98: 1114-22, 2003.

Bedogni, G., M. Malavolti, S. Severi, M. Poli, C. Mussi, A.L. Fantuzzi, and N. Battistini. Accuracy of an eight-point tactile-electrode impedance method in the assessment of total body water. Eur. J. Clin. Nutr. 56: 1143-1148, 2002.

Lee, S., J., Song, G., Kim, K., Lee and M., Kim. Assessment of total body water from anthropometry-based equations using bioelectrical Impedance as reference in Korean adult control and haemodialysis subsjects. Nephrol. Dial. Ransplant. 16: 91-97, 2001.

Toda Y , T. Toda, A. Kato, F. Toda and N. Segal. A Decline in Lower Extremity Lean Body Mass per Body Weight Is Characteristic of Women with Early Phase Osteoarthritis of the Knee. J.Rheumatol. 27: 2449-2454, 2000.

Toda Y. and T. Kobayashi. The Usefulness of Walking for Preventing Sarcopenia in Dieting Postme-nopausal Women Complaining of knee Pain. Ann. N.Y. Acad. Sci. 904: 610-613, 2000.