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Bio-impedance Spectroscopy (BIS) is a technique that allows tissue analysis to diagnose a variety of diseases, such as medical imaging, cancer diagnosis, muscle fatigue detection, glucose measurement, and others under research. The development of CMOS integrated circuit front-ends for bioimpedance analysis is required by the increasing use of wearable devices in the healthcare field, as they offer key features for battery-powered wearable devices. These features include high miniaturization, low power consumption, and low voltage power supply. A key circuit in BIS systems is the current source, and one of the most common topology is the Enhanced Howland Current Source (EHCS). EHCS is also used when the current driver is driven by a pseudo-random signal like discrete interval binary sequences (DIBS), which, due to its broadband nature, requires high performance operational amplifiers. These facts lead to the need for a current source more compatible with DIBS signals, ultra-low power supply, standard CMOS integrated circuit, output current amplitude independent of input voltage amplitude, high output impedance, high load capability, high output voltage swing, and the possibility of tetra-polar BIS analysis, that is a pseudotetra-polar in the case of EHCS. The objective of this work is to evaluate the performance of the Switching CMOS Current Source (SCMOSCS) over EHCS using a Cole-skin model as a load using SPICE simulations (DC and AC sweeps and transient analysis). The SCMOSCS demonstrated an output impedance of more than 20 MΩ, a ± 2.5 V output voltage swing from a +3.3 V supply, a 275 µA current consumption, and a 10 kΩ load capacity. These results contrast with the + 1.5 V output voltage swing, the 3 kΩ load capacity, and the 4.9 mA current of the EHCS case.

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Introduction: In areas with limited access to healthcare systems, Resting Energy Expenditure (REE) estimation is performed using predictive equations to calculate an individual's caloric requirement. One problem is that these equations were validated in populations with different characteristics from those in Latin America, such as race, height, or body mass, leading to potential errors in the prediction of this parameter. Objective: To determine the REE using predictive formulas compared with bioimpedance in Peruvians. Materials and methods: A comparative analytical cross-sectional study with secondary database analysis of the CRONICAS cohort. Results: we worked with a total of 666 subjects. The Mjeor equation was the one with the highest rating of 0.95, a lower mean absolute percentage error (MAPE) of 4.69%, and equivalence was found with the REE values. In the multiple regression, it was observed that the Mjeor equation was the one that least overestimated the REE, increasing 0.77 Kcal/day (95% CI: 0.769-0.814; p<0.001) for each point that increased the REE determined by bioimpedance. The strength of association between Mjeor and bioimpedance was 0.9037. Furthermore, in the regression of the data (weight, height, age) in the Mjeor equation it was observed that the coefficients obtained were the same as those used in the original equation. Conclusions: The Mjeor equation seems to be the most adequate to estimate the REE in the Peruvian population. Future prospective studies should confirm the usefulness of this formula with potential utility in primary health care(AU)

Introducción: En zonas con acceso limitado a sistemas de salud, la estimación del Gasto Energético en Reposo (GER) se realiza utilizando ecuaciones predictivas para calcular el requerimiento calórico de un individuo. Uno de los problemas es que estas ecuaciones fueron validadas en poblaciones con características diferentes a las latinoamericanas, como raza, talla o masa corporal, lo que conlleva a potenciales errores en la predicción de este parámetro. Objetivo: Determinar el GER mediante fórmulas predictivas comparadas con la bioimpedancia en peruanos. Materiales y métodos: Estudio transversal analítico comparativo con análisis secundario de base de datos de la cohorte CRONICAS. Resultados: Se trabajó con un total de 666 sujetos. La ecuación de Mjeor fue la que obtuvo la puntuación más alta de 0,95, un error medio porcentual absoluto (MAPE) inferior de 4,69%, y se encontró equivalencia con los valores del GER. En la regresión múltiple, se observó que la ecuación de Mjeor fue la que menos sobreestimó el GER, aumentando 0,77 Kcal/día (IC 95%: 0,769-0,814; p<0,001) por cada punto que aumentaba el GER determinado por bioimpedancia. La fuerza de asociación entre Mjeor y bioimpedancia fue de 0,9037. Además, en la regresión de los datos (peso, talla, edad) de la ecuación de Mjeor se observó que los coeficientes obtenidos eran los mismos que los utilizados en la ecuación original. Conclusiones: La ecuación de Mjeor parece ser la más adecuada para estimar el GER en la población peruana. Futuros estudios prospectivos deberán confirmar la utilidad de esta fórmula para su potencial utilidad en la atención primaria de salud(AU)

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OBJECTIVE: The search for other indicators to assess the weight status of individuals is important as it may provide more accurate information and assist in personalized medicine.This work is aimed to develop a machine learning predictions of weigh status derived from bioimpedance measurements and other physical parameters of healthy infant juvenile cohort from the Southern Cuba Region, Santiago de Cuba. METHODS: The volunteers were selected between 2002 and 2008, ranging in age between 2 and 18 years old. In total, 393 female and male infant and juvenile individuals are studied. The bioimpedance parameters are obtained by measuring standard tetrapolar whole-body configuration. A classification model are performed, followed by a prediction of other bioparameters influencing the weight status. RESULTS: The results obtained from the classification model indicate that fat-free mass, reactance, and corrected resistance primarily influence the weight status of the studied population. Specifically, the regression model demonstrates that other bioparameters derived from impedance measurements can be highly accurate in estimating weight status. CONCLUSION: The classification and regression predictive models developed in this work are of the great importance for accessing to the weigh status with high accuracy of younger individuals at the Oncological Hospital in Santiago de Cuba, Cuba.

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BACKGROUND: Phase angle (PhA), obtained from the bioimpedance analysis, is widely used in clinical situations and in sports. This study evaluated the association between PhA with body composition and physical performance of handball athletes. METHODS: 43 national-level players (22.19 ± 3.86 years) of both sexes were evaluated regarding anthropometry, body composition, squat (SJ) and countermovement (CMJ) jumps, handgrip strength, and cardiorespiratory fitness. RESULTS: We verified a correlation between PhA of the whole body and fat-free mass (r = 0.511), body mass index (r = 0.307), and body fat % (r = -0.303). There was a positive correlation between PhA of the whole body and SJ (r = 0.376), CMJ (r = 0.419), and handgrip for the dominant hand (r = 0.448). Moreover, PhA of the upper limbs was more strongly correlated with handgrip for the dominant (r = 0.630) and non-dominant hand (r = 0.575) compared to PhA of the whole body considering both sexes. Similarly, segmental PhA had a stronger significant correlation with SJ (r = 0.402) and handgrip for the dominant hand (r = 0.482) in males, as well as CMJ (r = 0.602) in females, compared to PhA of the whole body. CONCLUSION: PhA of the whole body was positively related to fat-free mass, body mass index, body fat %, and lower- and upper-limbs strength in handball athletes. Segmental PhA might be used as a tool for estimating lower and upper limbs performance considering the sex, in preference to the PhA of the whole body.

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To evaluate the association of standardized phase angle (SPA) with nutritional status, functional parameters, and postoperative outcomes in surgical cancer patients. This prospective study includes 59 cancer patients from Pelotas (Brazil) admitted for elective cancer surgery. We obtained the phase angle through Bioelectrical Impedance Analysis (BIA) and standardized it according to the population's reference values. We estimated the muscle mass using BIA for later calculation of the Skeletal Muscle Index (SMI) and performed handgrip strength (HGS) and gait speed (GS) tests. We used the Patient-Generated Subjective Global Assessment (PG-SGA) to assess the nutritional status. Postoperative complications and duration of hospital stay were evaluated as the outcomes. The prevalence of malnutrition in the sample was 28.8%, according to ASG-PPP. SPA was statistically lower in patients with malnutrition, with lower HGS and reduced GS. For postoperative outcomes, patients with severe complications and those with prolonged hospitalization also had lower SPA values. The greater the number of functional alterations in patients, the lower the SPA value, mainly when associated with reduced muscle mass assessed by BIA, suggesting that muscle mass reduction plays an important role in the association between functional alterations and phase angle in patients with cancer. According to the parameters used in this study, low SPA value was associated with impaired nutritional and functional status and negative outcomes in the analyzed sample.

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OBJECTIVE: The search for other indicators to assess the weight and nutritional status of individuals is important as it may provide more accurate information and assist in personalized medicine. This work is aimed to develop a machine learning predictions of weigh status derived from bioimpedance measurements and other physical parameters of healthy younger volunteers from Southern Cuba Region. METHODS: A pilot random study at the Pediatrics Hospital was conducted. The volunteers were selected between 2002 and 2008, ranging in age between 2 and 18 years old. In total, 776 female and male volunteers are studied. Along the age and sex in the cohort, volunteers with class I obesity, overweight, underweight and with normal weight are considered. The bioimpedance parameters are obtained by measuring standard tetrapolar whole-body configuration. The bioimpedance analyser is used, collecting fundamental bioelectrical and other parameters of interest. A classification model are performed, followed by a prediction of the body mass index. RESULTS: The results derived from the classification leaner reveal that the size, body density, phase angle, body mass index, fat-free mass, total body water volume according to Kotler, body surface area, extracellular water according to Kotler and sex largely govern the weight status of this population. In particular, the regression model shows that other bioparameters derived from impedance measurements can be associated with weight status estimation with high accuracy. CONCLUSION: The classification and regression predictive models developed in this work are of the great importance to assist the diagnosis of weigh status with high accuracy. These models can be used for prompt weight status evaluation of younger individuals at the Pediatrics Hospital in Santiago de Cuba, Cuba.

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Objective. Blood C-reactive protein (CRP) and the electrical bioimpedance spectroscopy (EBIS) variables phase angle (PhA) and impedance ratio (IR) have been proposed as biomarkers of metainflammation in overweight/obesity. CRP involves taking blood samples, while PhA and IR imply a less-than-2-minute-non-invasive procedure. In this study, values for these variables and percent body fat mass (PBFM) were obtained and compared before and immediately after a colon cleansing protocol (CCP), aimed at modulating intestinal microbiota and reducing metainflammation, as dysbiosis and the latter are intrinsically related, as well as along a period of 8 weeks after it.Approach. 20 female volunteers (20.9-24.9 years old) participated: 12 in an overweight group (OG), and 8 in a lean group (LG). TheOGwas divided in two subgroups (n= 6, each): control (CSG) and experimental (ESG). TheESGunderwent a 6-day CCP at week 2, while 5 volunteers in theCSGunderwent it at week 9.Main results.Pre/post-CCP mean values for the variables in theOGwere: PBFM (34.3/31.3%), CRP (3.7/0.6 mg dl-1), PhA (6.9/7.5°) and IR*10 (0.78/0.77). CalculatedR2correlation factors among these variables are all above 0.89. The favourable changes first seen in theESGwere still present 8 weeks after the CCP.Significance.(a) the CCP drastically lowers meta-inflammation, (b) EBIS can be used to measure metainflammation, before and after treatment, (c) for microbiota modulation, CCP could be a good alternative to more drastic procedures like faecal microbiota transplantation; (d) reestablishing eubiosis by CCP could be an effective coadjutant in the treatment of overweight young adult women.

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This study proposes a multiclass model to classify the severity of knee osteoarthritis (KOA) using bioimpedance measurements. The experimental setup considered three types of measurements using eight electrodes: global impedance with adjacent pattern, global impedance with opposite pattern, and direct impedance measurement, which were taken using an electronic device proposed by authors and based on the Analog Devices AD5933 impedance converter. The study comprised 37 participants, 25 with healthy knees and 13 with three different degrees of KOA. All participants performed 20 repetitions of each of the following five tasks: (i) sitting with the knee bent, (ii) sitting with the knee extended, (iii) sitting and performing successive extensions and flexions of the knee, (iv) standing, and (v) walking. Data from the 15 experimental setups (3 types of measurements×5 exercises) were used to train a multiclass random forest. The training and validation cycle was repeated 100 times using random undersampling. At each of the 100 cycles, 80% of the data were used for training and the rest for testing. The results showed that the proposed approach achieved average sensitivities and specificities of 100% for the four KOA severity grades in the extension, cyclic, and gait tasks. This suggests that the proposed method can serve as a screening tool to determine which individuals should undergo x-rays or magnetic resonance imaging for further evaluation of KOA.

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Objective. Bioimpedance spectroscopy (BIS) is a popular technique for the assessment of body composition in children and adults but has not found extensive use in babies and infants. This due primarily to technical difficulties of measurement in these groups. Although improvements in data modelling have, in part, mitigated this issue, the problem continues to yield unacceptably high rates of poor quality data. This study investigated an alternative data modelling procedure obviating issues associated with BIS measurements in babies and infants.Approach.BIS data are conventionally analysed according to the Cole model describing the impedance response of body tissues to an appliedACcurrent. This approach is susceptible to errors due to capacitive leakage errors of measurement at high frequency. The alternative is to model BIS data based on the resistance-frequency spectrum rather than the reactance-resistance Cole model thereby avoiding capacitive error impacts upon reactance measurements.Main results.The resistance-frequency approach allowed analysis of 100% of data files obtained from BIS measurements in 72 babies compared to 87% successful analyses with the Cole model. Resistance-frequency modelling error (percentage standard error of the estimate) was half that of the Cole method. Estimated resistances at zero and infinite frequency were used to predict body composition. Resistance-based prediction of fat-free mass (FFM) exhibited a 30% improvement in the two-standard deviation limits of agreement with reference FFM measured by air displacement plethysmography when compared to Cole model-based predictions.Significance.This study has demonstrated improvement in the analysis of BIS data based on the resistance frequency response rather than conventional Cole modelling. This approach is recommended for use where BIS data are compromised by high frequency capacitive leakage errors such as those obtained in babies and infants.

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Electrical bioimpedance is a non-invasive and radiation-free technique that was proposed to be used in different clinical areas, however, its practical use is limited due to its low capacity to discriminate between tissues. In order to overcome this limitation, our research group proposes to incorporate the contrast media into the electrical bioimpedance procedure. The main objective of the present study was to assess the crystalloid solutions as a possible contrast media to discriminate between different tissue types in the bioimpedance technique. Two medical-grade crystalloid solutions (Hartmann and NaCl 0.9%) were injected into three biological ex vivo models: kidney, liver, and brain. BIOPAC system was used to acquire bioimpedance data before and after the injections. The data was adjusted to the Debye electrical model. The analysis of measured values showed substantial bioimpedance disparities in tissues subjected to isotonic solutions. The NaCl solution exhibited more pronounced changes in electrical parameters compared to the Hartmann solution. Similarly, NaCl solution displayed superior discriminatory capabilities among tissues, with variations of 465%, 157%, and 206%. Distinct spectral modifications were identified, with tissues demonstrating unique responses at each frequency of analysis relative to untreated tissue. Variations in bandwidth alterations were discernible among tissues, providing clear distinctions. In conclusion, the research showed that the crystalloid solution exhibited greater sensitivity and superior tissue contrast at specific frequencies. This study's findings underscore the feasibility of implementing crystalloid solutions to enhance tissue discrimination, similar to the effects of contrast agents.

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BACKGROUND & AIMS: Malnutrition is common in older individuals with end-stage renal disease on maintenance dialysis. Whether nutritional supplementation may improve skeletal muscle mass (SMM) and survival rate in this population is uncertain. We aimed to analyze the effect of a year of nutritional supplementation on muscle mass and survival rate in older patients on hemodiafiltration. METHODS: In this observational study, older patients (≥65 years old) on maintenance hemodiafiltration were selected to receive nutritional counselling + nutritional supplementation (N = 85, Supp+) or nutritional counselling alone (N = 47, Supp-) and followed for 1 year. The outcomes were a change in SMM and sarcopenia diagnosis. The secondary outcome was 1-year mortality rate. Nutritional parameters included calf circumference, body mass index, anthropometric measurements, subjective global assessment, and handgrip strength (HGS). Data were evaluated using GLM for repeated measures with adjustment for covariates (age and diabetes). RESULTS: Malnutrition was found in 50.8% of patients. At baseline, patients from the Supp+ group were older and had worse nutritional parameters including hand grip strength, calf circumference, anthropometric findings and sarcopenia (all p values < 0.05). During the follow-up, there was no significant change in sarcopenia (from 50.8% to 58.3%, p = 0.108), and there was a more pronounced decrease in the SMM index in the Supp-group (p = 0.049), with a significant intervention interaction (p = 0.030). Twenty deaths occurred, 7 (35%) in the Supp- and 13 (65%) in the Supp+ group (p = 0.540). SMM index (relative risk 0.90, p = 0.030) and age (relative risk 1.07, p = 0.046) were independently associated with higher mortality rates. CONCLUSION: Nutritional supplementation in older and malnourished individuals undergoing hemodiafiltration mitigates the loss of the SMM index and benefits survival rate.

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El diagnóstico por bioimpedancia (BIA) y el ángulo de fase (AnF), como indicador, permiten monitorear el estado físico, de salud y nutricional en adultos mayores. El objetivo de este estudio fue establecer la relación entre la condición física y valores de fase angular por bioimpedancia en un grupo de adultos mayores sedentarios. Participaron voluntariamente 24 adultos mayores sedentarios (21 mujeres y 3 hombres). A cada participante se les midió bioimpedancia, fuerza de presión manual y test de 6 minutos del Senior Fitness Test (SFT). Posteriormente se analizaron los resultados, correlacionando el ángulo de fase (AnF) y condición física cardiorrespiratoria según sexo y el AnF con la fuerza de presión manual. El 71% presentó una media de AnF por debajo de la referencia (4,5º ± 0,4), específicamente, el 67% de los hombres y el 62% de las mujeres. La correlación entre AnF y capacidad física cardiorrespiratoria arrojó un valor de R2= 0,50; p<0,0001. La asociación entre AnF y fuerza de presión manual fue de R2=0,35; p=0,0023. Se encontró una relación significativa entre una prueba de condición física cardiorrespiratoria y AnF y entre la fuerza de presión manual y AnF. Es de importancia clínica incluir parámetros objetivos de valoración celular en adultos mayores como el AnF.

The diagnosis by bioimpedance (BIA) and the phase angle (PhA) are indicators, that allow monitoring of the physical health and nutritional status of older adults. The objective of this study was to establish the relationship between physical fitness and phase angle values by bioimpedance in a group of sedentary older adults. 24 elderly sedentary volunteers participated (21 women and 3 men). Each participant underwent bioimpedance, manual dynamometry, and the 6-minute Senior Fitness Test (SFT). Subsequently, the results were analyzed, making a correlation between PhA and cardiorespiratory physical condition, another between PhA and cardiorespiratory physical condition according to sex and finally an association between PhA and handgrip strength. R71% presented a PhA mean below the reference (4.5º ± 0.4), specifically 67% of men and 62% of women. The correlation between PhA and cardiorespiratory fitness showed a value of R2= 0.50; p<0.0001. The association between PhA and handgrip strength was R2=0.35; p=0.0023. A significant relationship was found between a cardiorespiratory fitness test and PhA and between handgrip strength and PhA. It is of clinical importance to include objective cellular assessment parameters in older adults such as PhA.

O diagnóstico por bioimpedância (BIA) e ângulo de fase (AnF), como indicador, permitem monitorar o estado físico, de saúde e nutricional de idosos. O objetivo deste estudo foi estabelecer a relação entre a condição física e os valores da fase angular por bioimpedância em um grupo de idosos sedentários. Participaram voluntariamente 24 idosos sedentários (21 mulheres e 3 homens). Cada participante foi medido bioimpedância, força de pressão manual e teste de 6 minutos do Senior Fitness Test (SFT). Posteriormente, os resultados foram analisados, correlacionando o ângulo de fase (AnF) e a condição física cardiorrespiratória de acordo com o sexo e o AnF com a força de pressão manual. 71% apresentaram média do LAn abaixo da referência (4,5º ± 0,4), sendo 67% dos homens e 62% das mulheres. A correlação entre o LAn e a aptidão cardiorrespiratória deu um valor de R2= 0,50; p<0,0001. A associação entre LAn e força de pressão manual foi R2=0,35; p=0,0023. Encontrou-se relação significativa entre teste de aptidão cardiorrespiratória e NF e entre força de pressão manual e NF. É de importância clínica incluir parâmetros objetivos de avaliação celular em adultos mais velhos, como AnF.

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INTRODUCTION: Severe forms of COVID-19 are more common in patients with abnormal fat distribution, particularly high visceral adiposity. The patient's muscle strength may be reduced during the acute phase of the infection. Electrical bioimpedance (BIA) is a non-invasive method for measuring body compartments and estimating visceral fat area (VFA) that can be used at the bedside. OBJECTIVE: To assess the association between several body composition parameters, primarily high adipose tissue and high VFA, in patients with and without a diagnosis of COVID-19 infection, and whether it worsened the severity parameters. METHODS: This retrospective cohort study was conducted in a private hospital in the city of São Paulo from March 2020 to August 2021. The demographic and clinical data was collected from medical reports. Body composition is assessed using the InBODY® model S10 bioelectrical impedance device and a Jamar® digital hydraulic manual dynamometer with a scale from 0 to 90 kg is used to measure handgrip strength (HGS). RESULTS: A total of 96 patients with a mean age of 69.1 years (SD 15) were divided into two groups of 48 individuals, with and without COVID-19 infection. Body mass index (odds ratio [OR]: 4.47, 95% confidence interval [CI]: 1.69, 11.83), fat mass (OR: 2.03, 95% CI: 0.48, 8.55), and VFA (OR: 1.08, 95% CI: 0.33, 3.53) were all higher in the infection group. When COVID-19 patients were evaluated, those with higher VFA had longer hospital stays (OR: 0.99, 95% CI: 0.97, 1.01) and used more vasoactive drugs (p = 0.043). Patients with COVID-19 with poor handgrip strength were 3.29 times more likely to require a prolonged intensive care unit (ICU) stay. CONCLUSION: The study concluded that excess weight and body fat are significantly associated with COVID-19 involvement, but the severity is primarily related to a greater area of visceral fat. The use of bioimpedance for visceral fat measurement was effective, as it is a simple method performed in the hospital setting that does not require the use of radiation.

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La composición corporal engloba una serie de variables relacionadas con la salud e influye en la condición física. A pesar de ello, existe poca evidencia sobre sus efectos en la capacidad operativa en militares. El objetivo de este estudio fue relacionar la composición corporal, la condición física y la capacidad operativa de militares chilenos. Participaron 57 militares chilenos (26,9 ± 4,8 años), con especialización operativa en infantería. La composición corporal fue evaluada con bioimpedancia octopolar estimando masa libre de grasa, tejido muscular y tejido adiposo, entre otras variables. También se realizaron las siguientes pruebas de condición física: 5000 m planos, dominadas, abdominales y flexibilidad, así como cuatro pruebas específicas de actividades operativas militares específicas (situación de combate simulado). Los resultados mostraron un porcentaje de tejido muscular de 45,4 ± 2,9 % (IC95%: 44,6 - 46,2), mientras que el porcentaje de tejido adiposo fue de 20,3 ± 4,9 % (IC95%: 14,7 - 17,3). Se encontraron correlaciones negativas de pequeña magnitud entre el tiempo de carrera (5000 m) y el tejido muscular (%) (r = -0,275) y positiva con el tejido adiposo (%) (r = 0,294). Sin embargo, se observaron correlaciones de alta magnitud entre dominadas y tejido muscular (%) (r = 0,517) y tejido adiposo (%) (r = -0,558). El tejido adiposo se relacionó negativamente con la capacidad aeróbica, fuerza de brazos(??) y fuerza resistencia abdominal, mientras que el tejido muscular se relacionó positivamente con estas mismas variables. No se apreciaron correlaciones entre la composición corporal y la capacidad operativa militar (p<0,05). Se concluye que la composición corporal y la condición física no se relacionan con la capacidad operativa militar en situación de combate en especialistas en infantería, pero si la composición corporal se relaciona con la fuerza y la capacidad cardiorrespiratoria.

SUMMARY: Body composition encompasses a series of variables that are health-related and influence physical condition. Nevertheless, there is little evidence on its effects on the operational capacity of the military. The objective of this study was to relate the body composition, the physical condition and the operational capacity of the Chilean military. Fifty-seven Chilean soldiers (26.9 ± 4.8 years) participated, with operational specialization in infantry. Body composition was evaluated with octopolar bioimpedance, estimating fat- free mass, muscle tissue, and adipose tissue, among other variables. The following physical condition tests were also carried out: 5000 m flat, pull-ups, abdominals and flexibility, as well as four specific tests of specific military operational activities (simulated combat situation). The results showed a percentage of muscle tissue of 45.4 ± 2.9 % (95%CI: 44.6 - 46.2), while the percentage of adipose tissue was 20.3 ± 4.9 % (95%CI). : 14.7-17.3). Negative correlations of small magnitude were found between race time (5000 m) and muscle tissue (%) (r = -0.275) and positive with adipose tissue (%) (r = 0.294). However, high magnitude correlations were observed between pull-ups and muscle tissue (%) (r = 0.517) and adipose tissue (%) (r = -0.558). Adipose tissue was negatively related to aerobic capacity, arm strength, and abdominal endurance strength, while muscle tissue was positively related to these same variables. No correlations were found between body composition and military operational capacity (p<0.05). It is concluded that body composition and physical condition are not related to military operational capacity in combat situations in infantry specialists, but body composition is related to strength and cardiorespiratory capacity.

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BACKGROUND: In 2019, cirrhosis accounted for 2.4% of global deaths. The projection for 2030 is an increase in this index. In recent years, hospitalization costs have escalated by 36% for compensated cirrhosis and 24% for decompensated cirrhosis. Therefore, it is necessary to identify a tool capable of predicting the mortality of these patients according to their clinical condition and consequently extending their survival time. Different studies have shown that the phase angle (PA) can be a feasible method in clinical practice, with the potential to guide assertive patient management in the therapeutic of chronic liver disease. AIM: To evaluate the prognostic role of PA in cirrhotic patients over a 15-year follow-up period. METHODS: Retrospective cohort study with 129 cirrhotic patients of both sexes over 18 years old. Diagnosis of cirrhosis by liver biopsy. The first year of data collection was 2007, and data regarding outcomes was collected in 2023. Data were gathered from medical records, such as esophageal varices (EV), EV bleeding, ascites, spontaneous bacterial peritonitis (SBP), encephalopathy, laboratory findings and PA. The cut-off value for the PA was 5.4°, a value described in 2012 by Fernandes et al for 129 patients evaluated in this study and the cut-off points for the Brazilian population presented in percentiles (P), as described by Mattiello et al. The mortality was assessed using the PA percentile through Kaplan-Meier curves and multivariate binary logistic regression models. RESULTS: Patients were divided into two groups according to the PA 5.4th (PA > 5.4°, n = 40; PA ≤ 5.4°, n = 89) PA percentile (< P50, n = 56; ≥ P50 n = 73). The percentile classification was more accurate in identifying long-term deaths than the 5.4º PA. Patients with < P50 had a higher number of relevant complications such as ascites, SBP, liver encephalopathy and HCC. PA is strongly correlated with serum albumin (P < 0.001), International Normalized Ratio (P = 0.01), total bilirubin (P = 0.02) and direct bilirubin (P = 0.003). PA is correlated with survival time (P < 0.001) and length of stay (P = 0.02). Logistic regression analysis shows that an increase of 1° in PA enlarges the cirrhotic patient's chance of survival by 17.7%. CONCLUSION: PA is a good predictor of morbidity and mortality for cirrhotic patients. The PA by percentile showed greater sensitivity in predicting mortality compared to the cut-off point of 5.4º.

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RESUMEN Objetivo: Determinar la asociación entre edad, género, carrera profesional y antecedentes personales como DM2, HTA y obesidad con respecto al % GC en estudiantes de pregrado de una universidad pública peruana. Materiales y métodos: Estudio descriptivo, analítico, transversal. Se evaluaron estudiantes de carreras de salud, educación y ciencias sociales de la Universidad Nacional de Trujillo (UNT). El % GC fue estimado mediante el método de bioimpedancia; para el análisis bivariado se usó, en caso de distribución normal t-student o ANOVA, y para aquellos sin distribución normal, U de Mann-Whitney o Kruskal Wallis. Para determinar la correlación entre variables numéricas y % GC se usó la prueba de Pearson o de Spearman, según distribución de normalidad. Para el análisis multivariado se aplicó regresión lineal múltiple. Se obtuvo el consentimiento informado de cada participante, con aprobación del Comité de Ética n°. 2019/CE/FAC/ENF. Resultados: Participaron 390 estudiantes. La mediana de edad fue 19 años [18-20], 72,6 % fueron género femenino, la mayoría de salud (58,7 %). El antecedente personal más frecuente fue obesidad (10,77 %). La mediana del % GC fue 26,35 % [20,78-30,2]. En el análisis bivariado se evidenció asociación significativa entre % GC con factores género (p<0,001), antecedente personal de HTA (p=0,041), y obesidad (p<0,001). En el análisis multivariado permanecieron con asociación significativa género (p<0,001) siendo mayor %GC en las mujeres, y antecedente personal de obesidad (p<0.001). Conclusiones: El género femenino y antecedente de obesidad fueron factores asociados a % GC en universitarios, grupo poblacional en riesgo que requiere programas de estilos de vida saludable.

ABSTRACT Objective: To determine the association between age, gender, professional career, and personal history of diabetes, hypertension, and obesity, concerning % GC in undergraduate students of a Peruvian public university. Methods: Descriptive, analytical, cross-sectional study. Students of health, education, and social sciences of the National University of Trujillo were evaluated. For bivariate analysis, t-student or ANOVA was used in the case of normal distribution, and for those without normal distribution, Mann-Whitney U or Kruskal Wallis was used. Pearson's or Spearman's test was used to determine the correlation between numerical variables and % GC, according to normal distribution. For multivariate analysis, multiple linear regression was applied. Informed consent was obtained from each participant, with approval from the Ethics Committee n°. 2019/CE/FAC/ENF. Results: 390 students participated. The median age was 19 years [18-20], 72.6 % were female, and most were healthy (58.7 %). The most frequent personal history was obesity (10.77 %). The median % GC was 26.35 % [20.78-30.2]. In the bivariate analysis, there was a significant association between % GC with gender (p<0.001), personal history of HTA (p=0.041), and obesity (p<0.001). In the multivariate analysis remained with significant association with gender (p<0.001) being higher % GC in women, and personal history of obesity (p<0.001). Conclusions: Female gender and history of obesity were factors associated with % GC in university students, a population group at risk that requires healthy lifestyle programs.

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Head and neck cancer (H&NC) is a diverse category of tumors related to malignancies in the common aerodigestive pathway, with high metabolic rate, poor nutritional and treatment outcomes, and elevated mortality despite the best standard treatment. Herein, we focus on determining how the phase angle (PA) differs across sex as a predictor of poor prognosis, low quality-of-life (QoL) scores, and mortality in patients with head and neck cancer. This follow-up study presents a sex-differential analysis in a prospective cohort of 139 head and neck cancer patients categorized by sex as male (n = 107) and female (n = 32). Patients were compared in terms of nutritional, biochemical, and quality-of-life indicators between low and normal PA in women (<3.9° (n = 14, 43.75%) and ≥3.9°) and men (<4.5° (n = 62, 57.9%) and ≥4.5°). Our results show that most patients were in locally advanced clinical stages (women: n = 21 (65.7%); men: n = 67 (62.6%)) and that patients with low PA had a lower punctuation in parameters such as handgrip strength, four-meter walking speed, albumin, C-reactive protein (CRP), and CRP/albumin ratio (CAR), as well as the worst QoL scores in functional and symptomatic scales in both the male and female groups. A comparison between sexes revealed significant disparities; malnourishment and tumor cachexia related to an inflammatory state was more evident in the women's group.

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SUMMARY: Athletes differ among themselves and one of the main differences is observed in relation to body shape and composition. Achieving top sports performance requires more standardization in the processes of training and development of a unique methodology for individualizing the control specific adaptation of athletes. The aim of this study is to establish reference data for the most sensitive variables to define the amount and structure of body fat in female athletes in individual sports. The sample included 895 females, divided in: a control group (Cont) of young females (N = 688); International (N = 113), and National level female athletes (N = 94) in 13 individual sports. Four variables described the structureof of body fat: Percentage of body fat (PBF), Body Fat Mass Index (BFMI), Protein Fat Index (PFI) and Index of Body Composition (IBC). Results showed that considering the control group, female athletes have all examined Body Fat variables statistically significantly different (BFMI and PBF are lower, p = 0.011 and p = 0.000, while PFI and IBC are higher, p = 0.000, respectively). Female athletes are also statistically significantly different in relation to the level of competition (p = 0.000), and the investigated variables are responsible for 17.7 % of the variability of the difference between the groups. Competitively more successful female athletes have higher IBC (lower percentage of fat per overall body volume, p = 0.013), as well as, a statistically significantly higher protein mass in relation to body fat mass (PFI, p = 0.018). The most sensitive variables for defining body fat differences between the examined individual sports were IBC, with an influence of 37.9 %, then PFI (32.4 %), then PBF (22.8 %), and finally BFMI, with an influence of 11.4 % on the differences. Based on the results of this study, IBC and PFI are variables that have shown useful scientific-methodological potential for research in the future.

Los deportistas difieren entre sí y una de las principales diferencias se observa en relación a la forma y composición corporal. Alcanzar el máximo rendimiento deportivo requiere una mayor estandarización en los procesos de entrenamiento y en el desarrollo de una metodología única para individualizar el control de adaptación específico de los atletas. El objetivo de este estudio fue establecer datos de referencia de las variables más sensibles para definir la cantidad y estructura de la grasa corporal en mujeres deportistas en deportes individuales. La muestra estuvo compuesta por 895 mujeres, divididas en: un grupo control (Cont) de mujeres jóvenes (N = 688); Atletas femeninas de nivel internacional (N = 113) y nacional (N = 94) en 13 deportes individuales. Cuatro variables describieron la estructura de la grasa corporal: Porcentaje de grasa corporal (PBF), Índice de Masa Grasa Corporal (BFMI), Índice de Proteína Grasa (PFI) e Índice de Composición Corporal (IBC). Los resultados mostraron que, considerando el grupo control, todas las atletas tuvieron diferecias estadísticamente significativas respecto a las variables de grasa corporal (BFMI y PBF son más bajos, p = 0,011 y p = 0,000, mientras que PFI e IBC son más altos, p = 0,000, respectivamente). En relación al nivel de competencia, las atletas femeninas presentan diferencias estadísticamente significativas (p = 0,000), y las variables investigadas son responsables por el 17,7 % de la variabilidad de la diferencia entre los grupos. Las atletas femeninas competitivamente más exitosas tienen un IBC más alto (menor porcentaje de grasa por volumen corporal total, p = 0,013), así como una masa proteica estadísticamente más alta en relación con la masa de grasa corporal (PFI, p = 0,018). Las variables más sensibles para definir las diferencias de grasa corporal entre los deportes individuales examinados fueron IBC, con una influencia del 37,9 %, luego PFI (32,4 %), a seguir PBF (22,8 %) y finalmente BFMI, con una influencia del 11,4 % en las diferencias. En base a los resultados de este estudio, IBC y PFI son las variables que han mostrado un potencial científico-metodológico útil para la investigación en el futuro.

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INTRODUCTION: Hemodialysis is life-sustaining in kidney failure. However, proper regulation of body fluids depends on an accurate estimate of target weight. This trial aims to compare clinical endpoints between target weight estimation guided by bioimpedance spectroscopy and usual care in hemodialysis patients. METHODS: This is an open-label, parallel-group, controlled trial that randomized, through a table of random numbers, adult patients on maintenance hemodialysis to target weight estimation based on monthly clinical evaluation alone or added to evaluation by bioimpedance twice a year. The primary outcome was survival, and the secondary outcomes were the rate of hospital admissions, change in blood pressure (BP), and antihypertensive drugs load. Participants were followed for 2 years. Survival analysis was performed using Kaplan-Meier estimator and Log-rank test, and hospital admissions were analyzed by the incidence-rate ratio. FINDINGS: One hundred and ten patients were randomized to the usual care (52) or bioimpedance (58) groups, with a mean age of 57.4 (15.4) years, 64 (58%) males. There was no difference between the groups at baseline. Survival was not significantly different between groups (log-rank test p = 0.68), but the trial was underpowered for this outcome. There was also no difference between the groups in the change in systolic or diastolic BP or in the number of antihypertensive drugs being used. The incidence rate of hospital admissions was 3.1 and 2.1 per person-year in usual care and bioimpedance groups, respectively, with a time-adjusted incidence rate ratio of 1.48 (95% CI: 1.20-1.82, p = 0.0001) and attributable fraction of risk among exposed individuals of 0.32 (95% CI: 0.17-0.45). DISCUSSION: The inclusion of bioimpedance data to guide the estimation of target weight in hemodialysis patients had no detectable impact on survival or BP control, but significantly reduced the incidence rate of hospital admissions. The study was registered at ClinicalTrials.gov Identifier: NCT05272800.

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ABSTRACT Objective To develop and validate predictive equations to estimate the body composition of women with grade III obesity, using the body mass index (BMI) as a predictive variable. Methods This cross-sectional study involved 104 patients treated at the hospital of the Universidade Federal do Rio de Janeiro randomly divided into two groups, the Equation Group, used to generate regression equations, and the Validation Group, used to validate the equations. Body fat mass (BFM), body fat percentage (BFP), skeletal muscle mass (SMM), fat-free mass (FFM) and total body water content (TBW) were valuated employing the bioimpedance method (InBody® 230). Results Polynomial equations exhibited the best fit and a general trend of results normalized by height squared presenting higher coefficients of determination (r2) was noted, positively affecting equation validations. Only one exception was observed, since the body fat percentage index (BFPI) resulted in an even lower correlation with BMI. Only these variables exhibited low r2 (0.11 to 0.29), while r2 values ranged from 0.51 to 0.94 for the other results. Conclusion Except for the BFP and BFPI, body composition can be estimated by the application of predictive BMI-based models. The equations employed for the indices normalized by the square of height were better predictors, while the use of equations that do not employ this normalization should consider the caveat that individuals with extreme BMI values (40 to 76 kg/m2) present greater estimate deviations in relation to the measured values.

RESUMEN Objetivo Desarrollar y validar ecuaciones predictivas para estimar la composición corporal de mujeres con obesidad III, utilizando el índice de masa corporal (IMC) como variable predictiva. Métodos Este estudio transversal involucró a 104 pacientes atendidos por el Hospital Universitario de la Universidad Federal de Río de Janeiro, divididos aleatoriamente en dos grupos. La masa de grasa corporal (MGC), el porcentaje de grasa corporal (PGC), la masa musculoesquelética (MME), la masa libre de grasa (MLG) y el contenido de agua total (ACT) fueron valorados por el método de bioimpedancia (InBody® 230). Resultados Las ecuaciones polinómicas presentaron un mejor ajuste y se observó una tendencia general de resultados normalizados, con mayores coeficientes de determinación (r2), lo cual afectó positivamente las validaciones de las ecuaciones. Se observó apenas una excepción, en relación con el PGC, pues el índice de porcentaje de grasa corporal (IPGC) tuvo una correlación menor con el IMC. Estas variables exhibieron un r2 bajo (0,11 a 0,29). Los valores de r2 oscilaron entre 0,51 y 0,94 para los demás resultados. Conclusión Con excepción del PGC y el IPGC, la composición corporal puede estimarse por medio de la aplicación de modelos predictivos basados en el IMC. Las ecuaciones empleadas por los índices normalizados por el cuadrado de la estatura fueron mejores predictores, en tanto que el uso de las ecuaciones que no emplean esa normalización debe considerar la advertencia de que individuos con valores extremos de IMC (40 a 76 kg/m2) presentan una mayor estimación de las desviaciones en relación con los valores medidos.