rss_2.0Sciendo RSS Feed for Journal of Electrical Bioimpedancehttps://sciendo.com/journal/JOEBhttps://www.sciendo.comhttps://sciendo-parsed-data-feed.s3.eu-central-1.amazonaws.com/6408752b627d370c6a673ecb/cover-image.jpghttps://sciendo.com/journal/JOEB140216https://sciendo.com/article/10.2478/joeb-2023-0003<abstract> <title style='display:none'>Abstract</title> <p>The aim of the proposed study is to reveal the correlations between the dynamics of Respiratory Rate (RR) and Heart Rate (HR) during intermittent physical work at maximum power on a cycle ergometer. The stage of investigating the General functional athlete readiness (GFAR) was conducted using the sports standard “R-Engine” and the cycle ergometer in 16 volunteers (10 men, 6 women) whose average age was 21±1.17 years. To determine the athletic potential of the volunteers in this study, we used our own Coefficient of Anaerobic Capacity (CANAC Q, beats). Continuous registration of the heart rate and respiratory rate of volunteers in the maximum power sports test was performed by the “RheoCardioMonitor” system with a module of the athlete functional readiness based on the method of Transthoracic electrical impedance rheography (TEIRG). The degree of correlation of functional indicators (M, HRM, GFAR) with CANAC Q in all experimental series of the study group as a whole (n=80) was at a very high level, which confirmed the effectiveness of using the Coefficient of Anaerobic Capacity (CANAC Q) in assessing the general functional athlete readiness of the volunteers. CANAC Q is measured in “beats” of the heart and is recorded very accurately using the method of transthoracic electrical impedance rheography (TEIRG). For this reason, as a promising sports PSM-system, CANAC Q can replace the methods for determining the functional athlete readiness by blood lactate concentration and maximum oxygen consumption.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2023-00032023-05-26T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2023-0002<abstract> <title style='display:none'>Abstract</title> <p>This study evaluated the influence of novel beverage formulations on bioimpedance- and urine-based hydration markers. Thirty young healthy adults (n=16 females, n=14 males; age: 23.2±3.7 years; BMI: 24.3±3.3 kg/m²) participated in a randomized, double-blind, placebo-controlled, crossover study. Participants completed three conditions with baseline bioimpedance, urine, and body mass assessments, followed by ingestion of one liter of a test beverage over a 30-minute period. The three beverages were: active hydration formulation in still (AFstill) or sparkling (AFspark) water and a still water control. The active formulations were identical in concentrations of alpha-cyclodextrin and complexing agents. Following beverage ingestion, bioimpedance assessments were performed every 15 minutes for two hours, followed by final urinary and body mass assessments. The primary bioimpedance outcomes were phase angle at 50 kHz, resistance of the extra-cellular compartment (R₀), and resistance of the intracellular compartment (Ri). Data were analyzed using linear mixed effects models, Friedman tests, and Wilcoxon tests. Statistically significant changes in phase angle values were observed at 30 (p=0.004) and 45 minutes (p=0.024) following the initiation of beverage ingestion in the AFstill condition as compared to the reference model (i.e., control condition at baseline). Although differences between conditions were not statistically significant at later time points, the data were consistent with AFstill having greater elevations in phase angle throughout the monitoring period. At the 30-minute time point only, statistically significant differences in R₀ for AFspark (p&lt;0.001) and in Ri for AFstill (p=0.008) were observed. When averaged across post-ingestion time points, there was a trend (p=0.08) for Ri differences between conditions. The net fluid balance was greater than zero, indicating retention of ingested fluid, for AFstill (p=0.02) and control (p=0.03), with a trend for AFspark (p=0.06). In conclusion, an active formulation containing alpha-cyclodextrin in still water demonstrated potential benefits for enhancing hydration markers in humans.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2023-00022023-04-26T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2023-0001ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2023-00012023-03-02T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0021<abstract> <title style='display:none'>Abstract</title> <p>This paper describes the proof of concept for a wearable device that measures skin conductance, to provide a way of quantifying an individual’s physiological stress response to external stimuli. Important goals of the project were to have reliable measurements that correlate with the external stimuli, as well as a small footprint and low power consumption to facilitate battery powered operation.</p> <p>These goals were accomplished using a STM32L476 micro-controller to generate an AC sine voltage across two solid gel electrodes placed in the palm of the hand, converting the resulting current to a voltage with a trans-impedance amplifier, which was then sampled and processed digitally in a lock-in amplifier, to eliminate signals differing from the desired (reference) frequency and phase. The output of the lock-in amplifier represents the skin conductance and was transmitted over USB to a computer with software for serial capture.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00212023-01-14T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0019<abstract> <title style='display:none'>Abstract</title> <p>Diabetic peripheral neuropathy (DPN) may lead to several changes in the skin, and some of these may influence the skin impedance spectrum. In the present study we have developed a prototype solution for skin impedance spectroscopy at selected skin sites (big toe pulp, heel and toe ball) that was tested in a pilot study on five patients with DPN and five healthy controls. At the big toe, most of the controls had markedly lower impedance than the DPN group, especially in the range of 1-100 kHz. The separation between the groups seems to be weaker at the heel and weakest at the toeball. The results may indicate that monitoring of the skin impedance spectrum may be a method for detection of skin changes associated with DPN, encouraging further studies with the big toe sensor in particular.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00192023-01-14T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0020<abstract> <title style='display:none'>Abstract</title> <p>Fast and reliable bioimpedimetric measurements are of growing importance in many practical applications. In this work we used a measurement method in time domain by processing the step response of the biological system under test. In order to decrease the data volume and computation time while retaining all relevant information the step response is sampled non-uniformly. Consequently, fast Fourier transform cannot be directly used for spectrum calculation and non-conventional data processing algorithms for transforming measured data into the frequency domain are required.</p> <p>In this paper we present corresponding computational methods. They are split into two groups. The first group is oriented on calculating the local approximation of the measured step response with a set of proper functions and calculating its spectrum via analytical Fourier transform, thus yielding a relatively versatile approach for estimating the impedance spectrum. In this case, the choice of approximating functions that suit known a priori properties of the measured signals are of great importance.</p> <p>A second group of methods relies on the evaluation of important signal parameters directly in the time domain. In this case we use a priori information about the measurement object in the form of an underlying model. After that the model is fitted to the measured data and thus, parameter values are extracted.</p> <p>Practical aspects, advantages and drawbacks of all considered data processing steps are revealed when applying them to the measurements made with real biological objects.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00202023-01-14T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0018<abstract> <title style='display:none'>Abstract</title> <p>It is necessary to evaluate the total deoxyribonucleic acid (DNA) concentration in gene expression assays. The existing techniques require equipment that is expensive for many labs in developing countries. Portable and inexpensive equipment is needed for easy and economical DNA quantification. Electrical bioimpedance spectroscopy (EBiS) is a non-invasive and inexpensive technique for examining the electrical properties of biological materials. The aim of this study was to explore a potential correlation between the measurement of total DNA extracted from human samples by UV-Vis spectrophotometry and EBiS. Hence, after quantifying the total DNA extracted from each sample by UV-Vis spectroscopy, EBiS was recorded and a possible correlation between the two measurements was analyzed. Considering the bioimpedance phase parameter at 5.24 MHz, a significant correlation was found with total DNA, especially when the concentration was below 100 ng/μL (Spearman coefficient = 0.82, p&lt;0.005). Additional experiments are warranted to confirm these findings.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00182023-01-14T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0017<abstract> <title style='display:none'>Abstract</title> <p>Correct food labeling is a legal requirement and helps consumers to make informed purchasing choices. Mislabeling defrosted meat as fresh is illegal in the EU. However, there are no standardized technologies to authenticate fresh versus defrosted meat. We address this by testing if bioimpedance-based measurements can separate defrosted meat from refrigerated-only meat at the end of shelf life, i.e., when also fresh meat shows deterioration. Pork sirloin samples from 20 pigs were first tested at 12 days postmortem (‘fresh group’). This time point was chosen to represent a typical use-by date for refrigerated storage of fresh pork. Then, all samples were transferred to a -24°C freezer for 3 days and thawed for 2 days before final testing (‘frozen-thawed group’).</p> <p>Bioimpedance analyses (BIA) were done in a frequency range of [10²-10⁶ Hz]. Weight, pH and electrode positioning were assessed to test for potential confounding effects. Statistics for treatment dependent differences were based on the established P_y parameter and phase angle, which were extracted from the BI spectra. We found that using bioimpedance testing with tetrapolar electrodes, P_y and phase angle allowed almost complete separation of fresh and previously frozen samples. However, within the whole sample population, there was some overlap between the spectra of fresh and frozen samples. Yet, based on P_y, only one fresh sample (5% of N_total=20) fell in the lowest P_y class with all the frozen samples. We used a multifactorial design that allowed to test the effects of potential confounding factors, such as electrode positioning and meat quality parameters. We found a relatively low explained variance for the P_y parameter, indicating that confounding effects from other factors or quality defects in fresh pork may affect the detection capacity of bioimpedance-based authentication of fresh pork. Our data, therefore, suggest that reliable fresh-label authentication with bioimpedance testing should be based on testing a small number of samples to represent a specific lot of pork that is to be inspected.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00172023-01-14T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0014<abstract> <title style='display:none'>Abstract</title> <p>Bioelectrical impedance analysis (BIA) reference values are based on supine assessments. Little is known regarding the effects of time course shifts in body water compartments after assuming a supine position. The aim of this study was to characterize these effects and provide recommendations regarding the optimal waiting time to perform BIA. Thirty-eight healthy adults underwent BIA via the RJL Quantum Legacy analyzer immediately upon lying down and every 5 minutes for 15 minutes. Differences in resistance (R), reactance (Xc), intracellular (ICW), extracellular (ECW), total body water (TBW), body fat percentage (%BF), and phase angle (PhA) were assessed. There were small but significant increases in R, Xc, and %BF (all p&lt;0.001), as well as small but significant decreases in ICW, ECW, and TBW (all p&lt;0.001) over 15 minutes. No difference was observed for PhA (p=0.065). Average values changed over 15 minutes by +7.14Ω, +1.36Ω, -0.2L, -0.2L, -0.4L, +0.05° and +0.1% for R, Xc, ICW, ECW, TBW, PhA and %BF, respectively. BIA measurements are affected by shifts in body water compartments after assuming a supine position, but these differences lack clinical significance in healthy adults. Technicians working with healthy adults can perform BIA within 15 minutes after participants assume a supine position.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00142023-01-08T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0016<abstract> <title style='display:none'>Abstract</title> <p>Probing deep regions of the lung using electrical impedance is very important considering the need for a low cost and simple technique, particularly for the low and medium income countries. Because of complexity and cost, Electrical Impedance Tomography is not suitable for this envisaged application. The simple Tetrapolar Impedance Measurement (TPIM) technique employing four electrodes is the age old technique for bioelectrical measurements. However, it has its limitations in respect of organ localisation and depth sensitivity using skin surface electrodes. Recently, a new 6-electrode TPIM with two current electrodes but two pairs of appropriately connected potential electrodes positioned on the front and back of the thorax, proposed by one of the authors, came with a promise. However, this work gave a qualitative proposal based on concepts of physics and lacked a quantitative evaluation. In order to evaluate the method quantitatively, the present work employed finite element method based COMSOL Multiphysics software and carried out simulation studies using this new 6-electrode TPIM and compared the results with those from 4-electrode TPIM, with electrodes applied either on the front or at the back of the thorax for the latter. Initially, it carried out a sensitivity distribution study using a simple rectangular volume conductor which showed that the 6-electrode TPIM gives better depth sensitivity throughout the lung region. Next it used a near life like thorax model developed by another of the authors earlier. Using this model, extensive studies were carried out to quantify the overall sensitivity over a target lung region, the contribution of the target lung to the total measured impedance, and several other parameters. Through these studies, the 6-electrode TPIM was established on a stronger footing for probing deep regions of the lungs.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00162023-01-08T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0015<abstract> <title style='display:none'>Abstract</title> <p>The image reconstruction in electrical impedance tomography (EIT) has low accuracy due to the approximation error between the measured voltage change and the approximated voltage change, from which the object cannot be accurately reconstructed and quantitatively evaluated. A voltage approximation model based on object-oriented sensitivity matrix estimation (OO-SME model) is proposed to reconstruct the image with high accuracy. In the OO-SME model, a sensitivity matrix of the object-field is estimated, and the sensitivity matrix change from the background-field to the object-field is estimated to optimize the approximated voltage change, from which the approximation error is eliminated to improve the reconstruction accuracy. Against the existing linear and nonlinear models, the approximation error in the OO-SME model is eliminated, thus an image with higher accuracy is reconstructed. The simulation shows that the OO-SME model reconstructs a more accurate image than the existing models for quantitative evaluation. The relative accuracy (RA) of reconstructed conductivity is increased up to 83.98% on average. The experiment of lean meat mass evaluation shows that the RA of lean meat mass is increased from 7.70% with the linear model to 54.60% with the OO-SME model. It is concluded that the OO-SME model reconstructs a more accurate image to evaluate the object quantitatively than the existing models.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00152023-01-08T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0013<abstract> <title style='display:none'>Abstract</title> <p>Cardiovascular disease (CVD) represents the leading cause of mortality worldwide. In order to diagnose CVDs, there are a range of detection methods, among them, the impedance cardiography technique (ICG). It is a non-invasive and low-cost method. In this paper, we highlight recent advances and developments of the CDVs diagnosis mainly by the ICG method. We considered papers published during the last five years (from 2017 until 2022). Based on this study, we expressed the need for an ICG database for the different CDVs.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00132022-12-25T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0012<abstract> <title style='display:none'>Abstract</title> <p>The significant drop in estrogen levels during menopause increases the cardiovascular risks, one of which is cerebrovascular atherosclerosis. Research on rheoencephalography (REG) parameters for the early diagnosis of cerebrovascular atherosclerotic lesions is of great interest to scientists because of its ease of implementation, low cost, and non-invasiveness. The objectives of study are to evaluate the vascular tone, cerebral circulation flow in each hemisphere of the brain of menopausal women, and some associated factors through waveform characteristics and parameters in REG. A controlled cross-sectional descriptive study was conducted on a group of patients including 80 menopausal women and a control group of 46 menstruating women. All patients were measured REG in the frontal-occipital leads by VasoScreen 5000 impedance REG meter. In menopausal women, the percentage of sharp waves, the percentage of clear side waves, and the average REG were all lower than in the control group (p&lt;0.01). The mean conduction time and mean slope ratio was lower than the control group (p&lt;0.001). The mean peak time was higher than the control group (p&lt;0.01). The mean elasticity index (alpha/T) was higher than the control group (p&lt;0.001). Menopausal women have increased vascular tone, the highest in the group of women 50-60 years old, menopause &lt;5 years, having a habit of eating red meat; and decreased blood flow intensity, the highest in the group of women &lt;50 years old. However, the difference was statistically significant only in the left hemisphere (p&lt;0.05). Vascular hypertonia in menopausal women with central obesity was higher than in the non-obese group in both hemispheres (p&lt;0.05). In conclusion, menopausal women had atherosclerosis in both hemispheres of the brain, which was clearly shown in the rate of increased vascular tone. Central obesity may increase the risk of vascular hypertonia 3.75 times in the right and 5.44 times in the left hemisphere.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00122022-12-18T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0011<abstract><title style='display:none'>Abstract</title><p>The following case study demonstrates that the effectiveness of Deep Tissue Massage (DTM) can be monitored in real time with bioimpedance. DTM techniques are used as a medical treatment to help reduce swelling of the calves of congestive heart failure patients. Bioimpedance monitoring shows immediately how fluid is redistributed within the intravascular, interstitial and intracellular fluid compartments, and how long the redistribution lasts. Bioimpedance spectroscopy, as used in this study, is a non-invasive procedure that can be used to monitor compartment fluid volumes and changes during many fluid management procedures.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00112022-11-23T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0010<abstract><title style='display:none'>Abstract</title><p>Extensive bioelectrical impedance analysis (BIA) data have the potential of health monitoring and the assessment of health risks at the population level. The importance of BIA data lies in their availability and abundance for many countries. In Russia, mass BIA data are generated by the national network of health centers (HCs). Our aim was to describe the structure and capabilities of the updated HCs’ BIA database. Upon several requests between 2012 and 2020, 369 HCs representing all Federal districts of Russia and 60 out of 85 Federal subjects in them, submitted raw bioimpedance data which were obtained using the same type of BIA instrument, namely ABC-01 ‘Medas’ (SRC Medas, Russia). After application of strict selection criteria, 2,429,977 BIA measurement records were selected that formed the updated 2010-2019 HCs’ database. Various slices of the BIA data are described according to spatiotemporal, demographic and other characteristics. Reference curves of the bioimpedance phase angle according to age and sex are presented. Limitations and prospects for further work are outlined. We believe that, after appropriate sampling, the database can be utilized to study biological, geographical, social and other associations of the bioimpedance and body composition parameters, for generating updated national references, international comparisons and data standardization.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00102022-11-23T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0009<abstract><title style='display:none'>Abstract</title><p>With better quality of life, obesity is becoming a worldwide disease due to over-eating and sedentary lifestyle. Therefore, daily monitoring of the glucose and body fat percentage (%) is vital to keep track of one’s health. Currently, separated devices are required to monitor each parameter at home and some are still invasive to measure the glucose level. In this study, a portable band-shaped bioimpedance system is proposed to measure both parameters. The system is battery run with two main modules: the current source and the voltage recording, with minimal design to fit into a band of 150 mm x 40 mm in dimension. The impedance is measured at the frequency of 1 kHz at 30 kHz sampling frequency and in 1000 signal cycles to flatten noises. The final average impedance is calculated and evaluated in correlation with the body fat and the fasting glucose. The system was tested on 21 volunteers and 4 locations were picked for the impedance measurement: the arm under the triceps, the side of the belly, the back on one side and the thigh under the bicep femoris. The results show promising results with the arm being the best location for predicting the body fat (correlation coefficient: 0.89, 95% CI: 0.73-0.95), while the thigh impedance best correlated with the fasting glucose (correlation coefficient: 0.92, 95% CI: 0.81-0.97). These preliminary results indicate the feasibility and capacity of the proposed system as a home-based, portable and convenient system in monitoring the body fat and glucose. The system’s performance will be verified and replicated in a future larger study.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00092022-11-04T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0008<abstract> <title style='display:none'>Abstract</title> <p>At present, there are no hardware or biochemical systems that allow to assess the severity of post-COVID syndrome in vivo. The hardware of the proposed biotechnical system is based on routine transthoracic electrical impedance rheography, which makes it possible to register the frequency characteristics of the patient's bioimpedance response to controlled stress stimulation, thereby simultaneously fixing the characteristics of his productive heart, the state of the hemomicrocirculatory bed, the efficiency of the gas transport function of his blood, and also reliably assess personal reactivity and adaptive potential. Subsequent mathematical approximation of the obtained biometric data by an original neural network makes it possible to rank the results obtained and automatically generate a program of medical rehabilitation for a particular patient, depending on the severity of his post-COVID syndrome. The study results proved two reliable physiological signs confirming the presence of latent post-COVID complications: a decrease in the base impedance value for light exercise and an increase in the length of the systolic arc of the rheocardiogram.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00082022-09-09T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0007<abstract><title style='display:none'>Abstract</title> <sec id="j_joeb-2022-0007_s_005"> <title style='display:none'>Background</title> <p>Bioimpedance analysis (BIA) is a readily available tool to assess body composition in a clinical setting. BIA has received little attention in orthopaedics and namely joint arthroplasty. This study aims to quantify changes in body composition in the immediate peri-operative period following total joint arthroplasty.</p></sec> <sec id="j_joeb-2022-0007_s_006"> <title style='display:none'>Methods</title> <p>Adults scheduled for elective total joint arthroplasty were recruited to participate. Patients underwent BIA scans in the immediate peri-operative period: pre-operative on their day of surgery, post-operative day 0, and post-operative day 1.</p></sec> <sec id="j_joeb-2022-0007_s_007"> <title style='display:none'>Results</title> <p>67 patients were enrolled to undergo BIA scans. Mean age was 62.64 ± 10.28 years old, and 49.2% were females. The all-supine cohort exhibited a 0.36 ± 0.61 kg increase in dry lean mass (<italic>p</italic> &lt; 0.001) and 1.30 ± 2.14 kg increase in lean body mass on postoperative day 0 (<italic>p</italic> &lt; 0.001). Patients received to 1.16 ± 0.58 kg of fluid mass, on average.</p></sec> <sec id="j_joeb-2022-0007_s_008"> <title style='display:none'>Conclusion</title> <p>BIA is a rapid, portable tool that allows for body composition analysis of an inpatient surgical population. This study demonstrated that BIA can detect net fluid changes and may approximate implant mass following total joint arthroplasty. This may aid surgeons in interpreting post-operative body composition changes.</p></sec> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00072022-09-09T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0005<abstract> <title style='display:none'>Abstract</title> <p>This study aimed to evaluate the changes in impedance and estimates of body composition variables obtained from segmental multi-frequency bioelectrical impedance analysis (SMFBIA) following acute hydration change. All participants (N = 11 active adults) had SMFBIA measurements at baseline (euhydration), post-dehydration, and post-hyperhydration in an experimental repeated-measures design. Dehydration and hyperhydration trials were randomized with the opposite treatment given 24 h later. Dehydration was achieved via a heat chamber of 40 °C and 60% relative humidity. Hyperhydration was achieved by drinking lightly-salted water (30 mmol·L^-1 NaCl; 1.76 g NaCl·L^-1) within 30 min. Post-measurements were taken 30 min after each treatment. Despite changes in mass post-dehydration (Δ = -2.0%, p &lt; 0.001) and post-hyperhydration (Δ = 1.2%, p &lt; 0.001), SMFBIA estimates of total body water (TBW) did not change significantly across trials (p = 0.507), leading to significant differences (p &lt; 0.001) in SMFBIA-estimates of body fat percentage across trials. Dehydration resulted in a significant (p &lt; 0.001) 8% decrease in limb impedances at both 20 kHz and 100 kHz. Hyperhydration increased limb impedances only slightly (1.5%, p &gt; 0.05). Impedance changes in the trunk followed an opposite pattern of the limbs. SMFBIA failed to track acute changes in TBW. Divergent impedance changes suggest the trunk is influenced by fluid volume, but the limbs are influenced by ion concentration.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00052022-06-25T00:00:00.000+00:00https://sciendo.com/article/10.2478/joeb-2022-0006<abstract> <title style='display:none'>Abstract</title> <p>Fat-free mass (FFM) estimation has dramatic importance for body composition evaluation, often providing a basis for treatment of obesity and muscular dystrophy. However, current methods of FFM estimation have several drawbacks, usually related to either cost-effectiveness and equipment size (dual-energy X-ray absorptiometry (DEXA) scan) or model limitations. In this study, we present and validate a new FFM estimation model based on hand-to-hand bioimpedance analysis (BIA) and arm volume. Forty-two participants underwent a full-body DEXA scan, a series of anthropometric measurements, and upper-body BIA measurements with the custom-designed wearable wrist-worn impedance meter. A new two truncated cones (TTC) model was trained on DEXA data and achieved the best performance metrics of 0.886 ± 0.051 r², 0.052 ± 0.009 % mean average error, and 6.884 ± 1.283 kg maximal residual error in FFM estimation. The model further demonstrated its effectiveness in Bland-Altman comparisons with the skinfold thickness-based FFM estimation method, achieving the least mean bias (0.007 kg). The novel TTC model can provide an alternative to full-body BIA measurements, demonstrating an accurate FFM estimation independently of population variables.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/joeb-2022-00062022-06-25T00:00:00.000+00:00en-us-1