Journal of Electrical Bioimpedance最新文献

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.

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.

Objective: To 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.

Methods: A 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).

Results: all 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.

Conclusions: In 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.

Background: Phase 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.

Methods: This 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.

Results: Neither 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.

Conclusions: PhA 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.

Introduction: Age-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).

Methods: Participants 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.

Results: YA 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.

Conclusion: Raw 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.

Cell membrane capacitance (Cm) is considered a measure of cellular health. This study evaluated the relationship between bioimpedance spectroscopy-measured Cm and multicomponent model reference-measured body composition variables from air displacement plethysmography and dual-energy x-ray absorptiometry in a sample of 226 young adult athletes. Men (3.00 ± 0.62 nF) had greater (p < 0.001) Cm than women (1.90 ± 0.36 nF). Variables indicative of lean mass, such as fat-free mass index, had a strong (r > .70) direct relationship with Cm. The Cm relationship was moderate for measures related to body mass and bone health (r = .30 to .60) and weak (r < .20) for fat mass. The relationship between Cm and body composition variables is strongest for the fat-free components.

Motivation: Anorexia Nervosa (AN) is characterized by a severe reduction in caloric intake resulting in substantial weight loss. Methods to evaluate muscle loss specifically during AN or following a weight recovery intervention are difficult to administer and expensive.

Purpose: To evaluate the utility of electrical impedance myography (EIM) to assess changes to muscle mass during simulated AN and different durations of weight recovery in rats.

Methods: Female Sprague-Dawley rats (n=11/group, total of 66 rats, 8 weeks old) were divided into simulated AN or healthy control conditions. Simulated AN included 30 days of 50-60% food restriction. Following AN intervention, rats were further subdivided into recovery cohorts which included five, fifteen, or thirty days of ab libitum food consumption to elicit weight gain. EIM was assessed at various stages of weight loss and recovery and correlated to metrics of muscle mass.

Results: Various EIM parameters detected changes in muscle mass both during simulated AN and following weight restoration. The resistance parameter produced the most consistent results during simulated AN and following various stages of weight recovery. Moreover, the resistance parameter had the highest correlation with gastrocnemius mass (r = ~0.50, p<0.05). Maximal tetanic plantar flexion was also analyzed but did not correlate with any EIM parameters.

Conclusion: EIM can non-invasively detect changes to muscle mass during AN and following various states of weight recovery.

This study used predictive models to explore the link between bioparameters at characteristic frequency and their positions within tolerance ellipses in a southern Cuban cohort. The database includes 367 individuals (235 females, 132 males) aged 18-86. Among them, 61 had cancer, while 306 were healthy. After balancing the data, the analysis used 16 bioimpedance-based characteristics along with other anthropometric and location factors. The results showed that characteristic frequency bioparameters (Zc, θc, Xcc, and Rc) are key for assessing health and location. There was a strong agreement between experimental and predicted values for Zc, θc, Xcc, and Rc across various categories. Cancer patients showed higher Zc and slightly lower θ _c and Xcc values, attributed to unbalanced body composition and cell membrane deterioration. Females exhibited higher Zc and Xcc values, indicating better cell membrane integrity. Predictions are consistent across quartiles and percentiles, with lower θ _c observed in higher quartiles and centiles where more cancer patients are located. Variations in Rc values across different BIVA statuses demonstrated the model's robustness in estimating impedance parameters in diverse physiological conditions. These predictive models are significant for assigning locations without developing BIVA methods, enhancing clinical assessments and health monitoring.

Body physique assessment is important for various fields of science and practice, including anthropology, medicine, sports nutrition and pedagogy. The classic Heath-Carter method is complex and multi-step, while bioelectrical impedance analysis makes it easier and faster to evaluate this parameter. The purpose of this study is a comparative analysis of the anthropometric method and bio-electrical impedance analysis in assessing the somatotype. Differences and a low degree of agreement were found between these methods in determining the somatotype.

Study design: Studies were carried out at the Department of Anatomy and Biological Anthropology of the Russian University of Sports "SCOLIPE" (Russia) and the morphological departments of the medical faculties of Osh State University (OshSU) of the Kyrgyz Republic from February to April 2024.

Results: Bioelectrical impedance analysis quickly and more significantly speeds up the process of assessing a person's body type.

Conclusion: Bioimpe-dance analysis shows an increased level of mesomorphy scores in both males and females, and the difference in males is more pronounced. On the other hand, endomorphy scores were lower when assessing the somatotype using the anthropometric method.