Monitoring Change of Body Fluid during Physical Exercise using Bioimpedance Spectroscopy and Finite Element Simulations

Abstract

Athletes need a balanced body composition in order to achieve maximum performance. Especially dehydration reduces power and endurance during physical exercise. Monitoring the body composition, with a focus on body fluid, may help to avoid reduction in performance and other health problems. For this, a potential measurement method is bioimpedance spectroscopy (BIS). BIS is a simple, non-invasive measurement method that allows to determine different body compartments (body fluid, fat, fat-free mass). However, because many physiological changes occur during physical exercise that can influence impedance measurements and distort results, it cannot be assumed that the BIS data are related to body fluid loss alone. To confirm that BIS can detect body fluid loss due to physical exercise, finite element (FE) simulations were done. Besides impedance, also the current density contribution during a BIS measurement was modeled to evaluate the influence of certain tissues on BIS measurements. Simulations were done using CST EM Studio (Computer Simulation Technology, Germany) and the Visible Human Data Set (National Library of Medicine, USA). In addition to the simulations, BIS measurements were also made on athletes. Comparison between the measured bioimpedance data and simulation data, as well as body weight loss during sport, indicates that BIS measurements are sensitive enough to monitor body fluid loss during physical exercise.

A Galvanic Coupling Method for Assessing Hydration Rates

“…The electrical conduction at this frequency is affected by the amount of water solute available in the tissue spaces. Loss of body fluid, for example, during exercise could cause up to 6% increase in muscle impedance [8]. Thus, by coupling a low frequency electrical signal galvanically on the body, the signal passing through the tissue will vary in attenuation to the changes in the water level.…”

Effects of Intense Physical Activity with Free Water Replacement on Bioimpedance Parameters and Body Fluid Estimates

“…A limitation of this study was the lack of control over temperature of the skin surface that is increased by physical activity. Beckmann [22] and Röthlingshöfer [23] reported that even after a recovery time of 15 minutes the temperature of skin remained high. In this study, the reduction in fat percentage immediately after the exercise is a result of changes in body fluids, because, according Saunders et al [24] a small change in balance of body fluids can be incorrectly interpreted by BIA, in form of changes in adipose tissue of athletes.…”

“…In this study, the reduction in fat percentage immediately after the exercise is a result of changes in body fluids, because, according Saunders et al [24] a small change in balance of body fluids can be incorrectly interpreted by BIA, in form of changes in adipose tissue of athletes. Moreover, ionic losses resulting from the physical activity [23] can infer an erroneous reading of an increase in fat free mass, resulting from increased ICF.…”

Extraction of Cole parameters from the electrical bioimpedance spectrum using stochastic optimization algorithms

“…For instance, it has been successfully used in characterization of body tissues for early disease diagnosis [31], determination of body water content [13,18,32], and muscle and cardiovascular activity [17]. In most of the applications, the measured bioimpedance spectrum needs to be computationally processed to extract useful information contained in it.…”