Journal of Electrical Bioimpedance Feed

Electromagnetic validation of a multichannel coplanar four-electrode bioimpedance sensing platform for perfused 3D tumor-on-chip systems

Mon, 12 Oct 2026 00:00:00 GMT

Three-dimensional tumor-on-chip systems better reproduce the spatial organization of tumor cells within extracellular-matrix-based microenvironments than conventional two-dimensional cultures, yet their integration with quantitative, non-destructive monitoring tools remains limited. Electrical bioimpedance provides a label-free approach for real-time assessment of living 3D tissues, but its implementation in perfused millimeter-scale microfluidic environments requires rigorous electrical and geometrical validation.In this study, we designed and electromagnetically validated an integrated coplanar four-electrode bioimpedance sensor embedded within a perfused 3D tumor-on-chip platform compatible with collagen-based hydrogels. Three-dimensional finite-element simulations were used to compute sensitivity fields and quantify the effective measurement volume. Calibration with conductivity standards showed quantitative agreement between experimental measurements and numerical predictions, with relative deviations below 10%, enabling reliable extraction of the cell constant. Chamber height was identified as the dominant geometrical parameter affecting impedance magnitude, whereas lateral misalignment had limited impact. Temperature-dependent conductivity changes induced impedance drifts of up to 25% during thermal equilibration, highlighting the need for strict temperature control.Acellular collagen I hydrogels exhibited concentration-dependent impedance variations, while increased gel loading before chamber closure modified impedance, likely through matrix compression and reorganization. These results demonstrate that the extracellular matrix significantly contributes to the measured electrical response. In static 3D cultures, embedding pancreatic cancer cells within collagen I produced a reproducible decrease in impedance magnitude at 10 kHz compared with acellular controls, confirming a measurable cell-dependent baseline shift. Under continuous perfusion, gradual cellular evolution did not generate a reproducible impedance trajectory, whereas Triton X-100-induced cell disruption increased impedance toward the acellular collagen I baseline.Overall, this study demonstrates that coplanar impedance sensing can detect cell-dependent baseline differences and strong endpoint perturbations in millimeter-scale 3D tumor models. However, dynamic impedance variations under perfusion remain influenced by matrix, thermal, geometrical, and conductive-pathway contributions, emphasizing the need for careful calibration before biological interpretation.

A biomimetic anthropomorphic leg phantom for wearable bioimpedance sensing in lymphedema monitoring

Fri, 11 Sep 2026 00:00:00 GMT

This study aims to develop a reproducible, biomimetic, anthropomorphic leg phantom as a controlled platform for the development and evaluation of wearable sensors for low-frequency bioimpedance monitoring of lymphedema. As a proof of concept, a 20-cm multilayer model was developed to establish and characterise the materials and fabrication approach required for future full-scale sensor validation. Electrical and mechanical characterisation of polyvinyl alcohol cryogel (PVA-C) and PVA-based fat and muscle phantoms was performed. The influence of freeze-thaw cycle number and duration on electrical properties and Shore hardness was investigated to support large-scale multilayer fabrication. Muscle anisotropy was reproduced via directional structuring. Reproducibility of electrical properties and long-term stability of PVA-C hydrogels were evaluated under refrigerated, vacuum-sealed storage. A practical methodology for assembling multilayer anthropomorphic leg phantoms was implemented. Electrical properties remained stable across the investigated freeze/thaw conditions, whereas Shore hardness increased with the number of cycles. Two 20-cm-high, three-layer anthropomorphic leg phantoms, representing healthy and stage 2 pathological condition, were fabricated using 3D-printed moulds integrating bone, muscle, and fat. Interfacial bonding between the layers provided mechanical cohesion and electrical continuity. Bioimpedance measurements showed consistent differences between the healthy and lymphedema-mimicking configurations. The methodology enables fabrication and assembly of multilayer anthropomorphic leg phantoms with electrical stability and mechanical cohesion. This proof-of-concept provides a basis for the development of a full-scale anthropomorphic model and its subsequent integration with wearable bioimpedance sensing technologies for lymphedema monitoring.

Ultrasound-guided structural fusion enhances the interpretability of electrical impedance tomography for layered tissue imaging

Fri, 04 Sep 2026 00:00:00 GMT

Electrical Impedance Tomography (EIT) provides low-cost functional impedance imaging, whereas ultrasound offers high-resolution morphological visualization. In this study, a hybrid Ultrasound–EIT (EIT–US) fusion framework is developed for soft-tissue characterization in layered ex vivo biological phantoms using controlled chicken tissue models. A custom EIT acquisition system recorded 208 boundary voltage measurements per acquisition across three tissue layers and multiple frequency–voltage conditions, with experiments repeated across three anatomical tissue configurations. Five FEM-based reconstruction methods—Back Projection (BP), Gauss–Newton (GN), Tikhonov regularization (TIK), GREIT, and a linearized EIDORS-like approach—were implemented within a stand-alone MATLAB framework. Ultrasound images acquired using a GE VScan Air CL probe (musculoskeletal mode) were integrated with EIT reconstructions through a multimodal fusion pipeline incorporating impedance imaging, ultrasound texture–echogenicity mapping, and statistical correlation analysis. Quantitative evaluation demonstrated consistent layer differentiation with moderate structural–electrical agreement (r ≈ 0.37–0.45). ESI increased by more than 60% at the evaluated layer interfaces during the fusion approach compared to EIT-only reconstructions, along with an increase in boundary detection performance (AUC improvement of approximately 0.13–0.15). Structural similarity (SSIM) of the fused images relative to ultrasound boundaries ranged from 0.71 to 0.78, indicating preserved spatial coherence. Frequency and voltage variations influenced reconstruction stability and contrast recovery. Overall, multimodal fusion improved the structural interpretability of EIT by anchoring conductivity distributions to ultrasound-derived morphological boundaries. These results indicate that incorporating ultrasound-derived structural priors improves the interpretability of EIT reconstructions by providing spatial context to conductivity distributions. This framework provides a practical experimental approach for integrating complementary electrical and acoustic sensing modalities, with potential relevance to future low-cost and portable soft-tissue imaging systems.

Measurement error in bioimpedance spectroscopy: The role of electrode type and analyzer

Tue, 25 Aug 2026 00:00:00 GMT

Bioimpedance spectroscopy (BIS) is a non-invasive method used to assess body composition in a variety of settings. Although BIS has been reported as an accurate measure of body composition, the magnitude of within-day technical error associated with different BIS devices and electrode types remains unknown. Therefore, the purpose of this study was to assess the technical error of measurement (TEM) between single-tab and double-tab electrodes across two BIS devices for resistance, reactance, phase angle, total body water, fat-free mass, and fat mass. One hundred and four adults reported to the laboratory for a single visit, undergoing twelve different assessments utilizing single- and double-tab electrodes on two BIS analyzers of the same model. The within-day technical error was assessed as the absolute and relative TEM for each of the variables. The results indicated that intra-analyzer assessments displayed the lowest amount of error for all the variables (relative TEM = 0.05 – 0.28%) while the largest TEMs were observed for comparisons between single-tab and double-tab assessments (relative TEM = 1.04 – 3.68%), except for reactance. For reactance alone, the TEMs were greatest for the inter-analyzer comparison with double-tab electrodes (absolute TEM = 1.07 Ω; relative TEM = 1.68%). While all assessments displayed relatively low technical error, the present results reinforce the importance of consistently using the same analyzer and electrode type to minimize errors when assessing body composition using BIS, particularly when seeking to identify subtle changes in BIS output.

Magnetic induction spectroscopy (MIS) as potential non-contact label-free technique for DNA amplification follow-up

Tue, 18 Aug 2026 00:00:00 GMT

Gene amplification and detection techniques such as polymerase chain reaction (PCR) or quantitative PCR (qPCR) require the use of fluorescent reagents and probes or dyes. Both PCR and qPCR must be performed by trained personnel. The aim of this work was to assess the potential use of magnetic induction spectroscopy (MIS) as a non-contact, label-free and easy-to-use technique to detect gene amplification in final PCR products. We extracted Deoxyribonucleic Acids (DNA) from samples of mouse tissue and processed it for gene amplification through PCR. We considered six different biological samples for the exploration of four genotypes and their corresponding blank controls. In every sample, we carried out MIS measurements in two stages (before and after PCR) in the range of 0.073 to 1.125 MHz and compared the differences. The results indicate a MIS magnitude differential pattern in the range of 500 to 650 kHz, which warrants the potential use of the MIS technique for the development of a fully contactless, label-free biosensor and capable of detecting DNA directly from PCR products.

Examining within-session test-retest reliability of four bioimpedance devices among adults across a wide age range

Sat, 08 Aug 2026 00:00:00 GMT

Bioimpedance is increasingly growing in clinical utility for within-session monitoring; however, many studies neglect to report the test-retest reliability of their devices. The purpose of this study was to examine the within-session test-retest reliability of whole-body bioelectrical variables measured by four common bioimpedance devices among adults. Ninety-six adults (age = 46.1 ± 21.7yrs, female = 63.5%, BMI = 26.4 ± 5.2 kg/m2) were tested in the morning-time on each device after providing a urine sample to confirm euhydration in addition to 10 minutes of passive rest in each device’s respective testing position (standing or supine). Each device assessed whole-body impedance, resistance, reactance, and phase angle in duplicate with approximately 10 seconds between trials; bioelectrical variables were extracted at 5, 50, 250, 500, and 1000 kHz as available from each device. Reliability was assessed using intraclass correlation coefficients (ICC2,1) and coefficients of variation (CV). At 5, 50, and 250 kHz, reliability across devices and measures was excellent (ICC2,1 > 0.90, CV = 0.78 ± 0.55%). Precision at 500 kHz for PhA (CV = 5.41%) and Xc (CV = 4.9%) was low and approaching low, respectively. Measures of Xc and PhA at higher frequencies (500 and 1000 kHz) may be less precise, but further research is needed to confirm, particularly with 1000 kHz where negative Xc values may limit the interpretability of CVs. Clinicians, researchers, and practitioners using these devices for within-session monitoring of raw bioelectrical variables should ideally test the reliability of their own devices but may use the data within this manuscript as a point of reference.

Evaluation of indirect methods for estimating body fat in dogs using electrical bioimpedance and morphometry

Tue, 28 Jul 2026 00:00:00 GMT

Canine obesity causes metabolic issues and reduces quality of life. Assessing adiposity remains challenging due to limited indirect and reference methods. Electrical bioimpedance (BIA) is a proposed tool, but agreement between morphometric and BIA equations, and the body condition score (BCS) role, remains poorly explored in heterogeneous canine populations.ObjectiveTo evaluate agreement among indirect methods (BCS, morphometry, BIA) for estimating canine body fat and assess BIA's viability for nutritional evaluation.Materials and methodsA cross-sectional study included 17 healthy dogs from Villamaría, Colombia. Body condition was assessed using 5- and 9-point scales. Morphometric variables and single-frequency 50 kHz BIA parameters (resistance, reactance, phase angle) were recorded. Body fat percentage (%BF) was estimated using four established equations. Method agreement was evaluated via Bland–Altman analysis and Lin's concordance correlation coefficient (CCC). Differences in bioelectrical parameters and lipid profiles between obese and lean dogs were analyzed using independent t-tests.ResultsMorphometric methods showed the highest agreement (CCC = 0.759). Conversely, comparisons involving BIA-derived equations exhibited low or negative agreement, with Bland–Altman analyses revealing wide limits of agreement. Obese dogs had higher resistance and lower phase angles than lean dogs, though differences were not statistically significant (p > 0.05). This lack of significance must be interpreted cautiously due to the small sample size, particularly the obese group (n = 4). HDL cholesterol was significantly lower in obese dogs (p = 0.030), with no differences in total cholesterol.ConclusionThe evaluated indirect methods showed poor agreement and are not clinically interchangeable. Without a reference method like DEXA, accuracy cannot be determined. While raw BIA parameters aligned physiologically with body condition, their use remains preliminary and requires validation in larger, reference-controlled studies.

Evaluating the Impact of hydration on electrodermal activity: A Comparison between AC bioimpedance and DC skin potential metrics

Thu, 23 Jul 2026 00:00:00 GMT

This study evaluates the comparative sensitivity and stability of tonic and phasic electrodermal activity (EDA) parameters, specifically skin conductance (SC), susceptance (SS), and potential (SP), following a localized moisturizer intervention. Utilizing a single-group pretest-posttest design (N = 55), the research demonstrates that AC bioimpedance-based metrics (SC and SS) exhibit distinct response dynamics compared to conventional DC-based measures. Tonic-level analysis revealed that SCL and SSL produced nearly identical relative percentage increases (52.6%) compared to SPL (34.46%). While SCL provided the largest absolute change, SSL emerged as the most statistically stable indicator across the cohort, characterized by a highly uniform signal-to-noise ratio (d = 1.23). Phasic analysis revealed that Skin Susceptance Responses (ΔSSRs) demonstrated a highly pronounced downward shift following the intervention, characterized by a −70.2% change from baseline. This negative shift was significantly divergent from the potential response (p < 0.001, d = −0.55), highlighting a distinct directional sensitivity for ΔSSRs under these experimental conditions. These findings suggest that AC-based EDA parameters are highly responsive to the resistive and capacitive shifts within the stratum corneum interface. The results suggest that for applications evaluating localized skin surface changes, a multimodal approach incorporating AC bioimpedance-based metrics may provide a highly responsive framework for detecting acute alterations at the electrode-skin interface compared with traditional potential-based measurements.

FEM-based volume estimation using electrode catheter measurements

Wed, 17 Jun 2026 00:00:00 GMT

Cardiovascular diseases are the leading cause of death worldwide, and accurate assessment of left ventricular volume (LVV) is crucial for diagnosis, therapy guidance, and long-term monitoring in these patients. Existing clinical techniques either require substantial resources, depend strongly on operator expertise, or lack the precision required for continuous monitoring. In this work we investigate the feasibility of a finite-element– method-based (FEM) algorithm for estimating volume and catheter offset from catheter-based admittance measurements to provide the basis for a new LVV estimation method. The present paper describes the underlying ventricle FEM model, a sensitivity-guided selection of informative 4-electrode configurations, and a constrained Gauss–Newton estimation algorithm. The algorithm was evaluated using numerical simulations and measurements obtained with a dynamic 3D-printed ventricle phantom with controllable volume changes. In both simulation and experiment, the reduced measurement set achieved volume reconstructions comparable to the full measurement set. In the phantom experiments, volume estimation errors of approximately 3–4% were observed over a wide range of volumes. These results demonstrate the feasibility of FEM-based parameter estimation and show that a small number of optimized electrode configurations can provide sufficient information for robust volume estimation. While the present study uses simplified geometries and a controlled phantom setup, the proposed approach provides a methodological basis for future investigations using more realistic anatomical models and biological experiments.

Elicitation and habituation of the electrodermal activity responses: Implications for neurophysiological applications

Wed, 17 Jun 2026 00:00:00 GMT

Electrodermal activity (EDA) serves as a reliable indicator of sympathetic activation for the measurement of emotional arousal. Despite extensive use of EDA in psychophysiological and neurophysiological research, little is known about how repeated stimulus presentation influences EDA responses, particularly when more than one parameter is measured simultaneously. This study examined the influence of repeated stimulus presentation on three EDA parameters (SCRs, SPRs, and SSRs). A total of sixty healthy subjects participated in the study. They were exposed to four external stimuli: sound, image, taste, and smell. Each of the four stimuli was repeated five times to investigate the effect of their repetition on SCRs, SPRs, and SSRs. Significant (p < 0.001) impacts of repeated stimulus presentation and introducing a novel stimulus on three EDA parameters were observed. The study results indicated that SCRs, SPRs, and SSRs were reduced following stimulus repetitions and habituation, exhibiting exponential decay, and they recovered following a change in stimulus category. This suggests that using different stimuli may better preserve physiological reactivity by limiting within-trial habituation. This information should be considered in neurotechnological applications, such as amygdala function, where repeated presentation of the same stimulus may inadvertently decrease amygdala activation, potentially mimicking volitional downregulation.

Lack of clinical Interchangeability between electrical impedance myography and multifrequency bioimpedance: Functional and physiological validation in young adults

Thu, 21 May 2026 00:00:00 GMT

Body composition is a fundamental health marker that distinguishes fat mass from lean mass.ObjectiveTo determine the agreement between electrical impedance myography (EIM) and multifrequency bioelectrical impedance analysis (BIA) for body fat estimation, and to assess how muscle quality markers correlate with functional strength.Materials and MethodsAn observational, cross-sectional study evaluated 53 university students. Body fat percentage (BF%), muscle mass, phase angle, and active cell mass were measured via BIA (Biody Expert ZM II). Segmental BF% and muscle quality (MQ) were assessed via EIM (Skulpt AIM). Functional strength was measured by dynamometry. Statistical analysis utilized Spearman’s correlation and Bland-Altman agreement.ResultsEIM reports higher values for BF% by 3.65% compared to BIA, exhibiting wide limits of agreement (−5.20% to 12.51%). Functional grip strength showed strong positive correlations with BIA-derived muscle mass p= 0.821, p < 0.001) and active cell mass (p= 0.804, p < 0.001). Conversely, the EIM-derived MQ index showed no significant correlation with strength (p = 0.745).ConclusionsEIM reports higher body fat values compared to BIA and lacks clinical interchangeability due to individual variability. BIA compartments strongly predict functional muscle strength, whereas proprietary EIM quality indices do not.

Bioimpedance-based evaluation of relative leaf age in mango twigs using electrical impedance spectroscopy

Thu, 26 Mar 2026 00:00:00 GMT

This study proposes a non-destructive method for estimating the relative age of mango leaves using electrical impedance spectroscopy (EIS) and a modified double-shell equivalent circuit model. Impedance measurements were conducted on six mango varieties using five leaves per variety representing different positions along the twig. The Nyquist plots showed increasing circular arc diameters with leaf position, indicating higher charge transfer resistance in older leaves. Fitting results revealed that R1 increased while C1 decreased systematically with leaf age. Spearman correlation analysis confirmed a strong positive correlation between R1 and leaf position and a strong negative correlation for C1, whereas n1 showed no significant relationship. Linear regression yielded high coefficients of determination for most varieties. The selection of R1 and C1 as electrical indicators was supported by their low fitting errors, strong correlations, and consistent regression performance. These results demonstrate that EIS provides a rapid and reliable non-destructive approach for assessing the physiological age of mango leaves.

Feasibility of electrochemical impedance spectroscopy for in situ detection of water stress in plants

Tue, 17 Mar 2026 00:00:00 GMT

Electrochemical impedance spectroscopy (EIS) has been widely applied to bioimpedance measurements in human and animal systems; however, its potential for direct plant monitoring remains less explored. This study uses Komatsuna (Brassica rapa) to examine the feasibility of using EIS for in situ detection of plant water stress.Impedance spectra are measured noninvasively and analyzed using an equivalent circuit model designed to separate plant-related electrical properties from the electrode–plant interface. Changes in the low-frequency impedance region were observed under both irrigation and drying conditions, while the high-frequency response remained relatively stable. In particular, variations in the extracellular resistance parameter (Ro) preceded visible water-stress symptoms and continued even after visual changes became indistinguishable. Although the number of tested plants was limited, these results suggested the potential of EIS as a rapid and cost-effective tool for early, in situ assessment of plant water status. The present study provides a proof-of-concept for extending bioimpedance-based approaches to plant systems, with implications for precision agriculture and plant physiology research.

Finite element modeling of human thorax for electrical bioimpedance based monitoring of pulmonary fluid accumulation

Sun, 15 Mar 2026 00:00:00 GMT

Monitoring fluid accumulation in the lungs is critical in conditions such as pulmonary edema and pneumonia. Current diagnostic modalities, including auscultation, chest X-ray, computed tomography, magnetic resonance imaging, and ultrasonography, either involve ionizing radiation or are not suitable for continuous long-term monitoring. This study investigated the feasibility of a non-invasive, non-ionizing electrical impedance–based approach for continuous assessment of pulmonary fluid accumulation using computational modeling. Firstly, CT images of human subjects were used to build a simplified thorax model. Different parts of human thorax including airways, left and right lungs, and soft tissue were segmented using a segmentation software Materialise Mimics® and imported into COMSOL Multiphysics® for finite element analysis. Tetrapolar transfer impedance was computed at multiple vertical electrode positions under baseline (air-filled lung) and fluid-accumulation conditions. The results demonstrated a measurable reduction in impedance in the presence of fluid, particularly at electrode levels corresponding to the fluid-filled lower lobes. A linear relationship between impedance and fluid volume was observed (R2 = 0.9972 for the left lung and R2 = 0.9998 for the right lung), with sensitivities of −466.74 mΩ/100 mL and −754.75 mΩ/100 mL, respectively. For clinically relevant fluid accumulations (≥300 mL), the predicted impedance change exceeded 2 Ω, indicating practical detectability. Frequency-domain analysis (5–1000 kHz) further demonstrated consistent impedance contrast across the investigated range. These findings suggest that tetrapolar electrical impedance measurements have the potential for continuous monitoring of pulmonary fluid changes and provide a foundation for future experimental validation in human subjects.

When measurement outpaces meaning: Bioimpedance in Organ-on-Chip systems

Wed, 07 Jan 2026 00:00:00 GMT

Toe digit pulsation measurement by impedance plethysmography in miniaturized devices: An early feasibility test

Wed, 31 Dec 2025 00:00:00 GMT

This early feasibility test explores impedance plethysmography (IPG) for detecting toe pulse waves using a setup suited for miniaturized devices. Conventional tests often miss micro-circulatory impairment, which is critical for wound healing and limb survival. We designed a flexible 3D-printed clamp with Ag/AgCl electrodes positioned on the inner big toe to target the lateral plantar digital artery. 50 kHz impedance measurements were performed on a healthy volunteer using 3D-printed electrode clamp for a tetrapolar configuration. Custom designed flexible electrodes were tested with and without contact gel. Preliminary results suggest that IPG can capture distal pulsatile signals, motivating further exploration of the potential for early detection of peripheral vascular dysfunction.

Using neuromorphic computing in prediction of GABA concentration – a pilot study

Mon, 29 Dec 2025 00:00:00 GMT

Neuromorphic computing has the potential to facilitate detection of GABA concentration levels in the brain, and offers energy-efficient, real-time machine learning processing possibilities. To study whether neuromorphic computing can be used for GABA concentration detection, dielectric relaxation spectroscopy was used to acquire permittivity data of different concentrations of GABA solution. Thereafter, two different machine learning models were compared (Feedforward neural network (FFNN) and convolutional neural network (CNN)) for accuracy in prediction of GABA concentration from dielectric properties. The CNN model was then converted to spiking Neural Networks (SNNs), which showed promising results for energy efficiency and real-time processing capabilities. The system incorporates Tkinter, a Python interface to the Tcl/Tk GUI toolkit for seamless data transfer between the neuromorphic chip and the measurement system, ensuring flexibility and scalability in a user-friendly system.

Changes in bioelectrical and non-bioelectrical variables associated with overweight after a weight-loss program based on intestinal microbiota modulation

Wed, 17 Dec 2025 00:00:00 GMT

ObjectiveTo assess changes in clinical and bioelectrical impedance analysis (BIA) variables associated with overweight, after a 6-day weight-loss protocol based on intestinal microbiota modulation.MethodsA group of 12 young overweight women (OG) were randomly assigned to either a control subgroup (COG, n=6) or an experimental subgroup (EOG, n=6), while, for comparison, eight lean healthy women served as reference (LG). The intervention combined a liquid diet, probiotics, psyllium, bentonite, and a daily open-system trans-anal irrigation. 23 clinical variables not involving BIA (type BIA-0: 12 physical, 9 chemical and 2 biological), and 21 variables obtained by BIA were measured at 4 time points (T1-T4), in a time lapse of 10 weeks. 11 BIA variables were designed as BIA-1, i.e., proper bioimpedance variables, and 10 as BIA-2, i.e., those calculated by a combination of BIA-0 and BIA-1 variables. Intestinal microbiota (IMB) modulation was explored via two biological variables: Firmicutes/Bacteroidota ratio and Akkermansia muciniphila relative prevalence. All variables (except age and height) were also divided in two subtypes: “+”, those usually higher in overweight people, whose median values were expected to decrease after the intervention (a total of 26), and “−”, those usually lower in overweight people, whose medians values were expected to increase with the intervention (a total of 16).Resultsall 42 variables susceptible to changes with the intervention changed in a favorable direction (their median values moved towards those of the LG), with 32 of the changes showing statistical significance.ConclusionsIn this pilot study, a multimodal microbiota-oriented protocol was associated with consistent and, mostly, clinically meaningful improvements of bioelectrical and physiological markers in overweight young women. Changes in BIA parameters seem to mirror the physiological changes detected in BIA-0 variables. Larger and longer trials are warranted to confirm these findings.

Cycling exercise efficiency and economy: Exploring the role of phase angle

Fri, 12 Dec 2025 00:00:00 GMT

BackgroundPhase angle (PhA), derived from bioelectrical impedance analysis (BIA), is considered a non-invasive marker of cellular health and membrane integrity. Whether PhA relates to muscular efficiency during exercise remains unclear.MethodsThis pilot study investigated the association between PhA and delta efficiency (DE), gross efficiency (GE), and exercise economy (EC) during submaximal cycling in 30 healthy young adults (15 females, mean age 21.4 ± 3.8 years). Whole-body and lower-body PhA were assessed using multifrequency BIA. Participants completed a graded cycling test (20–80 W) with energy expenditure determined via indirect calorimetry. DE, GE, and EC were calculated using standard procedures, and associations with PhA were examined using Pearson correlations, median-split group comparisons, and multivariable linear regression models adjusting for sex and fat-free mass.ResultsNeither whole-body nor lower-body PhA was significantly correlated with DE, GE, or EC (all p > 0.05). Group comparisons based on PhA medians showed no significant differences in performance indicators. The largest observed correlation was between whole-body PhA and GE (r = −0.32, p = 0.081). Regression models adjusting for sex and fat-free mass confirmed that PhA did not independently predict DE, GE, or EC.ConclusionsPhA did not predict submaximal cycling efficiency or economy in healthy young adults. These findings suggest that cellular health, as reflected by PhA, may not directly influence muscular energetics under steady-state conditions. Future studies with larger samples and mechanistic measurements are warranted to clarify this relationship.

Effects of acute essential amino acid intake on post-prandial raw bioimpedance and fluid shifts between healthy young and older adults: An exploratory pilot study

Fri, 28 Nov 2025 00:00:00 GMT

IntroductionAge-related anabolic resistance can lead to reduced muscle mass but can be costly and timely to diagnose. Multi-frequency bioelectrical impedance analysis could potentially be used as a non-invasive tool for the assessment of anabolic resistance as changes in frequency-dependent impedance values may reflect fluid shifts occurring with nutrient uptake. This exploratory pilot study evaluated the effects of acute essential amino acid (EAA) intake on raw bioimpedance and fluid shifts in healthy young adults (YA, n=5) and older adults (OA, n=7).MethodsParticipants completed a five-hour protocol with multifrequency bioelectrical impedance analysis (MF-BIA) at baseline and every 30 minutes post-consumption of a 10 g EAA beverage. Whole-body and segmental values for impedance (Z), resistance (R), reactance (Xc), phase angle (PhA), and body water compartments were assessed.ResultsYA demonstrated significantly higher Z, R, Xc, and PhA values compared to OA (p<0.05), particularly in the leg segments and at 50 kHz. Time effects revealed declines in R (p=0.013) and Xc (p=0.002) following EAA ingestion, consistent with postprandial fluid shifts. Fluid analysis showed significant group differences only for ECW/ICW ratio (p=0.001–0.004) with OA > YA and increases in TBW, ICW, and ECW over time.ConclusionRaw bioimpedance values distinguished between age groups and reflected acute responses to nutrient intake. These findings suggest MF-BIA may be sensitive to short-term physiological changes and, with further validation, could support assessments of muscle quality and nutritional responsiveness.