Bioelectrical impedance methods in clinical research: a follow-up to the NIH Technology Assessment Conference

Exosomes isolated from metabolically unhealthy normal weight and overweight phenotypes deteriorate the ER/PR positive breast cancer behavior

Purpose

Obesity has been linked to a higher risk of postmenopausal breast cancer Yet, research indicates an opposite correlation between obesity and premenopausal breast cancer risk. Various obesity phenotypes based on metabolic health could play a significant part. This study aims to assess how plasma exosomes taken from women with varying obesity phenotypes impact MCF-7 cell migration, matrix metalloproteinase-2 activity, and apoptosis.

Methods

The characterization of isolated exosomes and their internalization into MCF-7 cells was evaluated. The treatment of MCF-7 cells with exosomes isolated from different groups was done. Migration, the activity of MMP-2, mRNA expression of Bax and Bcl-2, protein expression of p-53 and Thr55 p-p53, and apoptosis were assessed.

Results

Isolated exosomes from unhealthy obese individuals increase MCF-7 cell migration. Regarding MMP activities, unhealthy normal weight and overweight and healthy obese groups isolated exosomes increase the MMP-2 activity than the treated group with exosomes isolated from counterpart groups. Furthermore, unhealthy normal weight and overweight and healthy obese obtained exosomes decrease apoptosis compared to counterpart groups.

Conclusion

Altogether, plasma exosomes derived from both unhealthy individuals with normal weight and overweight status, as well as those with unhealthy obesity, negatively impacted the behavior of estrogen/progesterone receptor-positive breast cancer cells.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01295-1.

Defining Overweight and Obesity by Percent Body Fat instead of Body Mass Index

OBJECTIVE

Thresholds for overweight and obesity are currently defined by body mass index (BMI), a poor surrogate marker of actual adiposity (percent body fat, %BF). Practical modern technologies provide estimates of %BF but medical providers need outcome-based %BF thresholds to guide patients. This analysis determines %BF thresholds based on key obesity-related comorbidities, exhibited as metabolic syndrome (MetSyn). These limits were compared to existing BMI thresholds of overweight and obesity.

DESIGN

Correlational analysis of data from cross sectional sampling of 16,918 adults (8,734 men and 8,184 women) from the US population, accessed by the National Health and Nutrition Examination Survey (NHANES) public use datasets.

RESULTS

Individuals measured by BMI as overweight (BMI>25 kg/m2) and with obesity (BMI>30 kg/m2) included 5% and 35% of individuals with MetSyn, respectively. For men, there were no cases of MetSyn below 18%BF, %BF equivalence to "overweight" (i.e., 5% of MetSyn individuals) occurred at 25%BF, and "obesity" (i.e., 35% of MetSyn individuals) corresponded to 30%BF. For women, there were no cases of MetSyn below 30%BF, "overweight" occurred at 36%BF, and "obesity" corresponded to 42%BF. Comparison of BMI to %BF illustrates the wide range of variability in BMI prediction of %BF, highlighting the potential importance of using more direct measures of adiposity to manage obesity-related disease.

CONCLUSIONS

Practical methods of body composition estimation can now replace the indirect BMI assessment for obesity management, using threshold values provided from this study. Clinically relevant "overweight" can be defined as 25 and 36% BF for men and women, respectively, and "obesity" is defined as 30 and 42% BF for men and women.

Metabolically healthy/unhealthy obesity and breast cancer: A possible role of plasma-derived extracellular vesicles on the cancerous behavior of triple-negative breast cancer

PURPOSE

Obesity has known detrimental effects on breast cancer (BC) development and progression. However, it's essential to consider the obesity phenotype based on metabolic health. This study aims to evaluate the impact of circulating extracellular vesicles (EVs) from women with metabolically healthy or unhealthy normal weight, overweight, and obesity on MDA-MB-231 cell migration, invasion, and apoptosis.

METHODS

Plasma EVs were isolated from different obesity phenotypes in women. EVs were characterized and EVs uptake by MDA-MB-231 cells was assessed. MDA-MB-231 cell lines were treated with EVs obtained from various studied groups, and migration, invasion, MMP-2 and MMP-9 activity, Bax and Bcl-2 mRNA expression, p-53 and Thr55 p-p53 protein expression, and apoptosis were assessed.

RESULTS

EVs from obese individuals, regardless of phenotype, increased invasion and MMP-2 activity compared to healthy normal-weight EVs. Normal-weight EVs led to higher invasion under unhealthy conditions. BC cell migration was enhanced by EVs from healthy obese individuals compared to healthy normal-weight EVs. EVs from unhealthy obese women exhibited significantly lower p53/p-p53 levels and reduced apoptosis compared to healthy obese groups.

CONCLUSION

It appears that EVs from both normal-weight women with unhealthy conditions and those with obesity or overweight, irrespective of metabolic status, worsened the cancerous behavior of TNBC cells. Therefore, considering metabolic health, in addition to BMI, is crucial for understanding obesity-related disorders.

Effects of "Football and Nutrition for Health" program on body composition, physical fitness, eating behaviours, nutritional knowledge, and psychological status among 7 to 10 years school children

Introduction

Noncommunicable diseases and obesity are between the major health threat due to consumption of unhealthy foods and limited time spent on physical activities, a situation of particular concern among children. Since children spend most of their time at school, this study intends to investigate the effect of a school intervention program, which combines recreational football and nutrition education, on body composition, physical fitness, physical activity, blood pressure and heart rate, eating behaviours, nutritional knowledge, and psychological status in elementary school children.

Methods

A total of 67 children, between 7 and 10 years old, were allocated into three groups: the Football Group (FG) which held 2 weekly sessions of 60 min of recreational football, the Nutrition and Football Group (NFG) which held 2 sessions per week of 60 min of recreational football plus 60 min of nutritional education and the Control Group (CG) which maintained its usual curriculum. The intervention lasted 12 weeks. All measurements were collected before and after the intervention.

Results

Intervention groups significantly (p < 0.05) improved BMI Z-score, rest heart rate, horizontal jump and shuttle test, physical activity level, and psychosocial health. The NFG group significantly decreased (p < 0.05) waist-to-height ratio and blood pressure, and significantly increased (p < 0.05) nutritional knowledge, fruit, and fish consumption. While FG significantly decreased (p < 0.05) the percentage of fat mass and significantly increased (p < 0.05) muscle mass and performance in the 20 m sprint.

Discussion

The results have shown to improve nutritional status, explosive strength, aerobic and neuromuscular fitness, as well as increase the level of physical activity. The nutritional education sessions contributed to increase nutritional knowledge and to improve the consumption of healthy food groups in a ludic-educational way. The "Football and Nutrition for Health" program was able to induce short-term improvements in several health markers, highlighting the role of the school curriculum in children's health.

Effects of Physical Activity and Nutrition Education on the Gut Microbiota in Overweight and Obese Children

Childhood obesity continues to represent a growing challenge, and it has been associated with gut microbiota dysbiosis. This study examines the gut microbiota composition in overweight and obese school children and assesses whether a 12-week multidisciplinary intervention can induce changes in the gut microbiota. The intervention, which combined recreational football and nutritional education, was implemented among 15 school children, aged 7-10 years, with a Body Mass Index ≥ 85th percentile. The children were assigned into two groups: Football Group (n = 9) and Nutrition and Football Group (n = 6). Faecal samples were collected at the beginning and end of the program and analysed by sequencing the 16S rRNA gene. Over the intervention, a significant decrease was found collectively for Bifidobacterium genera (p = 0.011) and for Roseburia genera in the Football Group (p = 0.021). The relative abundance of Roseburia (p = 0.002) and Roseburia faecis (p = 0.009) was negatively correlated with moderate to vigorous physical activity (MVPA), while Prevotella copri was positively correlated with MVPA (p = 0.010) and with the daily intake of protein (p = 0.008). Our findings suggest that a multidisciplinary intervention was capable of inducing limited but significant positive changes in the gut microbiota composition in overweight and obese school children.

Noninvasive Monitoring to Detect Dehydration: Are We There Yet?

The need for hydration monitoring is significant, especially for the very young and elderly populations who are more vulnerable to becoming dehydrated and suffering from the effects that dehydration brings. This need has been among the drivers of considerable effort in the academic and commercial sectors to provide a means for monitoring hydration status, with a special interest in doing so outside the hospital or clinical setting. This review of emerging technologies provides an overview of many technology approaches that, on a theoretical basis, have sensitivity to water and are feasible as a routine measurement. We review the evidence of technical validation and of their use in humans. Finally, we highlight the essential need for these technologies to be rigorously evaluated for their diagnostic potential, as a necessary step to meet the need for hydration monitoring outside of the clinical environment.

Future lines of research on phase angle: Strengths and limitations

Bioelectrical impedance analysis (BIA) is the most widely used technique in body composition analysis. When we focus the use of phase sensitive BIA on its raw parameters Resistance (R), Reactance (Xc) and Phase Angle (PhA), we eliminate the bias of using predictive equations based on reference models. In particular PhA, have demonstrated their prognostic utility in multiple aspects of health and disease. In recent years, as a strong association between prognostic and diagnostic factors has been observed, scientific interest in the utility of PhA has increased. In the different fields of knowledge in biomedical research, there are different ways of assessing the impact of a scientific-technical aspect such as PhA. Single frequency with phase detection bioimpedance analysis (SF-BIA) using a 50 kHz single frequency device and tetrapolar wrist-ankle electrode placement is the most widely used bioimpedance approach for characterization of whole-body composition. However, the incorporation of vector representation of raw bioelectrical parameters and direct mathematical calculations without the need for regression equations for the analysis of body compartments has been one of the most important aspects for the development of research in this area. These results provide new evidence for the validity of phase-sensitive bioelectrical measurements as biomarkers of fluid and nutritional status. To enable the development of clinical research that provides consistent results, it is essential to establish appropriate standardization of PhA measurement techniques. Standardization of test protocols will facilitate the diagnosis and assessment of the risk associated with reduced PhA and the evaluation of changes in response to therapeutic interventions. In this paper, we describe and overview the value of PhA in biomedical research, technical and instrumental aspects of PhA research, analysis of Areas of clinical research (cancer patients, digestive and liver diseases, critical and surgical patients, Respiratory, infectious, and COVID-19, obesity and metabolic diseases, Heart and kidney failure, Malnutrition and sarcopenia), characterisation of the different research outcomes, Morphofunctional assessment in disease-related malnutrition and other metabolic disorders: validation of PhA with reference clinical practice techniques, strengths and limitations. Based on the detailed study of the measurement technique, some of the key issues to be considered in future PhA research. On the other hand, it is important to assess the clinical conditions and the phenotype of the patients, as well as to establish a disease-specific clinical profile. The appropriate selection of the most critical outcomes is another fundamental aspect of research.

The impact of bariatric surgery procedures on the modulation of cardiometabolic risk factors in patients with severe obesity: a 12-month follow-up

Objective

To evaluate the effects of one anastomosis gastric bypass (OAGB), Roux-en-Y gastric bypass (RYGB), and sleeve gastrectomy (SG) on cardiometabolic risk factors (CMRFs) in patients with severe obesity.

Methods

This retrospective cohort study included patients with severe obesity who had undergone OAGB, RYGB, or SG between 2015 and 2017 and follow-up assessments over 12-months.

Results

Among 485 included patients, anthropometric measurements, body composition, fasting blood glucose (FBG), lipid profile, and comorbidities were significantly improved for all three procedures throughout the follow-up period. Weight, % total weight loss (%TWL), body mass index, fat mass and fat mass to fat-free mass ratio improvements were higher with RYGB and OAGB than SG. There were no significant differences between procedures in all other variables. A significant trend toward remission rate of dyslipidemia and type 2 diabetes mellitus was observed with all three procedures, with no significant difference between the three groups. %TWL statistically correlated with fat mass, FBG, and triglycerides.

Conclusions

OAGB, RYGB, and SG had a beneficial impact on CMRFs and comorbidities during 12 months of follow-up. Of note, RYGB and OAGB may result in better outcomes, particularly anthropometric and body composition indices. Further large-sample, long-term follow-up studies are required to expand on the present findings.

Breaking of Sitting Time Prevents Lower Leg Swelling-Comparison among Sit, Stand and Intermittent (Sit-to-Stand Transitions) Conditions

BACKGROUND

Sitting or standing during prolonged periods is related to leg swelling. It is unknown if interrupting sedentary behavior can attenuate lower leg swelling. We aimed to examine if adding sit-to-stand transitions prevents lower leg swelling as compared with uninterrupted motionless standing and sitting, using localized bioelectrical impedance raw parameters.

METHODS

Twenty adults participated in this crossover randomized controlled trial and acted out three conditions: (1) uninterrupted, motionless standing; (2) uninterrupted motionless sitting; (3) sit-to-stand transitions (1 min sitting followed by 1 min standing). Localized resistance (R), reactance (Xc), impedance (Z) and phase angle (PhA) were assessed at baseline, at 10 min and at 20 min for each condition.

RESULTS

For sitting and standing conditions, R and Xc values decreased after 10 and 20 min. Uninterrupted sitting resulted in the highest decrease in R (ΔSit - ΔStand = -9.5 Ω (4.0), p = 0.019; ΔSit - ΔInt = -11.6 Ω (4.0), p = 0.005). For standardized R (R/knee height), sitting was the condition with a greater decrease (ΔSit - ΔStand = -30.5 Ω/m (13.4), p = 0.025; ΔSit - ΔInt = -35.0 Ω/m (13.5), p = 0.011).

CONCLUSIONS

Interrupting sedentary behavior by changing from sit to stand position during short periods may be effective at preventing leg swelling.

Bioimpedance spectroscopy: Is a picture worth a thousand words?

Volume status can be difficult to assess in dialysis patients. Peripheral edema, elevated venous pressure, lung crackles, and hypertension are taught as signs of fluid overload, but sensitivity and specificity are poor. Bioimpedance technology has evolved from early single frequency to multifrequency machines which apply spectroscopic analysis (BIS), modeling data to physics-based mixture theory. Bioimpedance plots can aid the evaluation of hydration status and body composition. The challenge remains how to use this information to manage dialysis populations, particularly as interventions to improve over hydration, sarcopenia, and adiposity are not without side effects. It is therefore of no surprise that validation studies for BIS use in peritoneal dialysis patients are limited, and results from clinical trials are inconsistent and conflicting. Despite these limitations, BIS has clinical utility with potential to accurately evaluate small changes in body tissue components. This article explains the information a BIS plot ("picture") can provide and how it can contribute to the overall clinical assessment of a patient. However, it remains the role of the clinician to integrate information and devise treatment strategies to optimize competing patient risks, fluid and nutrition status, effects of high glucose PD fluids on membrane function, and quality of life issues.

The diagnostic value of phase angle, an integrative bioelectrical marker, for identifying individuals with dysmobility syndrome: the Korean Urban-Rural Elderly study

Low phase angle, a non-invasive bioimpedance marker, is associated with elevated odds of dysmobility syndrome and its components. Phase angle (estimated cutoffs: < 4.8° in men; < 4.5° in women) can be used to detect dysmobility syndrome in community-dwelling older adults as a simple, integrative screening tool.

INTRODUCTION

Dysmobility syndrome uses a score-based approach to predict fracture risk that incorporates the concepts of osteoporosis, sarcopenia, and obesity. Low phase angle (PhA), a simple, non-invasive bioelectrical impedance marker, was associated with low lean mass, high fat mass, and poor muscle function. We aimed to investigate the association between PhA and dysmobility syndrome, with the exploration of the diagnostic cutoffs.

METHODS

In a community-dwelling Korean older adult cohort, dysmobility syndrome was defined as the presence of ≥ 3 of the following components: osteoporosis, low lean mass, falls in the preceding year, low grip strength, high fat mass, and poor timed up and go performance.

RESULTS

Among the 1825 participants (mean age 71.6, women 66.7%), subjects were classified into sex-stratified PhA tertiles. The prevalence of dysmobility syndrome increased from the highest PhA tertile group to the lowest (15.50 to 2.45% in men; 33.41 to 12.25% in women, P for trend < 0.001). The mean PhA values decreased as the dysmobility score increased (5.33° to 4.65° in men; 4.76° to 4.39° in women, P for trend < 0.001). Low PhA (cutoff: < 4.8° in men; < 4.5° in women) was associated with twofold elevated odds of dysmobility syndrome after adjusting for age, sex, and conventional risk factors. Low PhA improved the identification of individuals with dysmobility syndrome when added to the conventional risk model (area under the curve, 0.73 to 0.75, P = 0.002).

CONCLUSION

Low PhA was associated with dysmobility syndrome and its components, independent of age, sex, body mass index, nutritional status, and inflammation.

Effects of the Consumption of Low-Fat Cooked Ham with Reduced Salt Enriched with Antioxidants on the Improvement of Cardiovascular Health: A Randomized Clinical Trial

The aim of the study was to analyze how cardiovascular risk factors can be modified using nutritionally improved cooked ham enriched with a pool of antioxidants to influence relevant metabolic targets. Sixty-five untreated subjects (49.2% males, 50.8% females, mean age 40.92 ± 9.03 years) with total cholesterol level ≥180 mg/dL or LDL cholesterol ≥130 mg/dL participated in a 8-weeks randomized, double-blind controlled trial. Participant in the intervention group (51.5% males, 48.5% females, mean age 41.6 ± 9.8 years and mean BMI 25.1 ± 3.6 kg/m²) consumed cooked ham enriched with antioxidants (100 g/d) and controls (49.9% males, 53.1% females, mean age 40.2 ± 8.3 years and mean BMI 26.3 ± 3.2 kg/m²) received placebo. At 8 weeks, oxidized LDL decreased significantly between experimental and placebo groups (p < 0.036). Experimental group differences were also significant (p < 0.05). Similar findings in malondialdehyde, total cholesterol, high-sensitivity C-reactive protein, and interleukin 6 were observed in the intervention group. Significant between-group differences in these variables were also found, except for total cholesterol and interleukin 6. The effects on inflammation and oxidation support the direct action of these antioxidants on the etiopathogenic factors of atheromatous plaque. We also observed an improvement in the lipid profiles among the subjects.

Systemic circulating inflammatory burden and periodontitis in adolescents

OBJECTIVES

To analyze the association between systemic inflammatory burden of cardiovascular disease (CVD) risk and periodontitis in adolescents, including mediating pathways triggered by their common risk factors.

MATERIALS AND METHODS

Using a population-based sample study (n = 405) of Brazilian adolescents (17-18 years old), direct and mediation pathways triggered by "Socioeconomic Status," "Adiposity," Smoking, and "Blood Pressure" were modelled for the association between the "Systemic Circulating Inflammatory Burden of CVD Risk" (IL-1β, IL-6, IL-8, TNF-α) and the "Initial Periodontitis" (bleeding on probing (BoP), probing depth (PD) ≥ 4 mm, clinical attachment loss (CAL) ≥ 4 mm), both as continuous latent variables, using structural equation modeling. Sensitivity analysis was performed for the outcomes "Gingivitis" (visible plaque; BoP); "Moderate Periodontitis" (PD ≥ 5 mm and CAL ≥ 5 mm) and periodontitis (CDC-AAP case definition).

RESULTS

Higher "Systemic Circulating Inflammatory Burden of CVD Risk" was directly associated with higher "Initial Periodontitis" (standardized coefficient [SC] = 0.178, P value < 0.001). Lower "Socioeconomic Status" (SC = - 0.022, P value = 0.015) and Smoking (SC = 0.030, P value = 0.021) triggered the "Initial Periodontitis", mediated by "Systemic Circulating Inflammatory Burden of CVD Risk". Sensitivity analysis showed a dose-response relationship between "Systemic Circulating Inflammatory Burden of CVD Risk" and "Moderate Periodontitis" (SC = 0.323, P value = 0.021).

CONCLUSIONS

"Systemic Circulating Inflammatory Burden of CVD Risk" appeared as an underlying mechanism of early periodontal breakdown in adolescents, also triggered by social vulnerability and smoking.

CLINICAL RELEVANCE

The association between periodontitis and CVD in adulthood seems to establish much earlier in life than had been previously studied, giving impetus to preventive approaches focused on their common risk factors.

Simple Wireless Impedance Pneumography System for Unobtrusive Sensing of Respiration

This extended paper presents the development and implementation at a prototype level of a wireless, low-cost system for the measurement of the electrical bioimpedance of the chest with two channels using the AD5933 in a bipolar electrode configuration to measure impedance pneumography. The measurement device works for impedance measurements ranging from 1 Ω to 1800 Ω. Fifteen volunteers were measured with the prototype. We found that the left hemithorax has higher impedance compared to the right hemithorax, and the acquired signal presents the phases of the respiratory cycle with variations between 1 Ω, in normal breathing, to 6 Ω in maximum inhalation events. The system can measure the respiratory cycle variations simultaneously in both hemithorax with a mean error of -0.18 ± 1.42 BPM (breaths per minute) in the right hemithorax and -0.52 ± 1.31 BPM for the left hemithorax, constituting a useful device for the breathing rate calculation and possible screening applications.

Correlation of resting heart rate with anthropometric factors and serum biomarkers in a population-based study: Fasa PERSIAN cohort study

Background

There is a positive association between raised resting heart rate (RHR), and all causes of mortality and shorter life expectancy. Several serum biomarkers and some anthropometric factors can affect the resting heart rate. This study aimed to investigate the determinants of resting heart rate in a large random sample of the Iranian population.

Material and methods

It is a standardized, retrospective study and the subjects were chosen from the baseline survey of the Prospective Epidemiological Research Study in IrAN (PERSIAN) Fasa non-communicable disease cohort study. It was conducted from winter 2014 to summer 2019 and after obtaining informed consent from a random sample, all the eligible subjects were enrolled. All anthropometric factors and biologic laboratory factors were collected and analyzed by implement smoothly clipped absolute deviation (SCAD) linear regression and SCAD quantile regression. The comparisons between males and females were done via independent T-test.

Results & conclusion

A total number of 9975 persons from 35 to 90 years old were included. The overall median resting heart rate was 74 (interquartile range:66–80). Mean age has no important difference between males and females (P = 0.79) but, resting heart rate was significantly higher in females (76.6 versus 71.4, P < 0.001). All anthropometric factors except wrist circumference were higher in females (P < 0.05). Age has an adverse effect on resting heart rate and also, there was a direct association between resting heart rate and systolic blood pressure and blood glucose. Alpha-blockers (coefficient = 5.2) and Beta1-blockers (coefficient = − 2.2) were the most effective drugs with positive and negative effects on resting heart rate respectively. Lower hemoglobin, obesity, and more body mass index, and more low-density lipoprotein were associated with more resting heart rate.

Continuing the monitoring of this sample via our cohort study and put to action multinational prospective researches with large sample sizes and long follow-ups can lead to more precise results and better scientific judgments.

Wireless Low-Cost Bioimpedance Measurement Device for Lung Capacity Screening

This paper presents the development and implementation at a prototype level of a wireless, low-cost system for the measurement of the electrical bio-impedance of the chest with two channels using the AD5933 in a bipolar electrode configuration to measure lung volume variation. 15 volunteers were measured with the prototype, and the acquired signal presents the phases of the respiratory cycle, useful for the breathing rate calculation and for possible screening applications.

A Randomized, Double-Blind, Placebo Controlled Trial to Determine the Effectiveness a Polyphenolic Extract (Hibiscus sabdariffa and Lippia citriodora) in the Reduction of Body Fat Mass in Healthy Subjects

The location and quantity of body fat determine the health risks, limiting people with obesity. Recently, polyphenols have attracted the attention of the scientific community because of their potential use for the reduction of obesity. A proprietary formula comprised of a blend of Lippia citriodora and Hibiscus sabdariffa has been recognized for its high content of polyphenols, powerful antioxidant molecules that may prevent weight gain and could be helpful for the treatment of obesity, as proven previously by in vivo models. The aim of the present study is to determine if the supplementation with Lippia citriodora and Hibiscus sabdariffa is useful for the treatment of obesity and/or weight control in subjects without a controlled diet. The intake of the extract for 84 days reduced body weight, the body mass index, and the fat mass measured with both bioimpedance and densitometry. This decrease in fat mass was observed to a greater extent, being significant, in the fat mass of the trunk (chest and torso).

Correlation Between Muscle Structures and Electrical Properties of the Tibialis Anterior in Subacute Stroke Survivors: A Pilot Study

Electrical impedance myography (EIM) is a non-invasive diagnostic tool that assesses the muscle inherent properties, whereas ultrasonography can assess the alteration in muscle architecture. This study aimed to combine EIM with ultrasonography to assess the changes of the tibialis anterior (TA) muscle properties during passive plantar/dorsiflexion in stroke survivors. Fifteen patients with subacute stroke were recruited. The muscle structures were simultaneously assessed by EIM and ultrasonography at five different extension angles (−10°, 0°, 10°, 20°, and 30°) of the ankle joint. The EIM parameters measured were resistance (R), reactance (X), and phase angle (θ). The parameters recorded by ultrasonography were pennation angle (PA), muscle thickness (MT), and fascicle length (FL). Two-way repeated ANOVA was performed to compare the differences between the affected and unaffected sides as well as the parameters that changed with joint angle. Linear correlation analysis was conducted to assess the association between muscle parameters and clinical scores. The results showed that as the ankle was passively plantarflexed, the θ (P = 0.003) and PA (P < 0.001) values decreased, and the X (P < 0.001), R (P < 0.001), and FL (P < 0.001) values increased. Significant correlations were found between the FL and R values (r = 0.615, P = 0.015), MT and R values (r = 0.522, P = 0.046), and FL and θ values (r = 0.561, P = 0.03), as well as between the PA and the Fugl–Meyer Assessment of Lower Extremity score (r = 0.615, P = 0.015), the R and the Modified Ashworth Scale (MAS) score (r = 0.58, P = 0.023), and the PA and the manual muscle testing (MMT) score (r = −0.575, P = 0.025). This study demonstrated a correlation between the EIM and the ultrasonography parameters at different joint angles. Therefore, both methods could jointly be applied in patients with stroke to detect changes in the muscle inherent properties and muscle architecture. This could assist clinicians to quantitatively evaluate the muscle condition in people with subacute stroke. The study was registered on the Chinese Clinical Trial Registry (trial registration number: ChiCTR-IOR-17012299, http://www.chictr.org.cn/showprojen.aspx?proj=19818).

Clinical Trial Registration Number: ChiCTR-IOR-17012299.

Towards personalized hydration assessment in patients, based on measurement of total body electrical resistance: Back to basics

BACKGROUND & AIMS

Assessment of tissue hydration by conventional bioelectrical impedance analysis (BIA) has produced conflicting results because of flaws in the algorithms that are used to translate measurements of total body electrical resistance (TBER) into liters of body water. This type of error can be eliminated by a return to the TBER measurement itself, without attempting to convert Ohms into liters of body water. Aims of this study were to quantify tissue hydration based on TBER, to establish TBER normal values (TBER_norm), to improve the prediction of TBER_norm values in individual patients, and to evaluate this approach in patients on hemodialysis (HD).

METHODS

TBER_norm values were obtained in 213 healthy controls and corrected for body height (H-TBER_norm). Inter-individual H-TBER_norm variability was reduced by correction for arm muscle cross-sectional area (AMA). Performance of this approach was evaluated in 94 patients on HD.

RESULTS

H-TBER_norm was inversely related to AMA. Correction for AMA reduced the H-TBER_norm standard deviation by 31% in men and 23% in women. When applied to patients on HD, H-TBER changes within subjects were inversely related to ultrafiltration volumes, with a mean R² of 0.95 ± 0.04 in men and 0.93 ± 0.07 in women. Clinically significant H-TBER increments occurred after volume reductions of 0.39 ± 0.25 L in men and 0.37 ± 0.18 L in women.

CONCLUSIONS

TBER measurements, corrected for height and AMA, have the potential to become an objective and sensitive method to assess hydration in patients. Its clinical value remains to be shown in intervention studies.

Dehydration assessment via a portable, single sided magnetic resonance sensor

PURPOSE

Undiagnosed dehydration compromises health outcomes across many populations. Existing dehydration diagnostics require invasive bodily fluid sampling or are easily confounded by fluid and electrolyte intake, environment, and physical activity limiting widespread adoption. We present a portable MR sensor designed to measure intramuscular fluid shifts to identify volume depletion.

METHODS

Fluid loss is induced via a mouse model of thermal dehydration (37°C; 15-20% relative humidity). We demonstrate quantification of fluid loss induced by hyperosmotic dehydration with multicomponent T2 relaxometry using both a benchtop NMR system and MRI localized to skeletal muscle tissue. We then describe a miniaturized (~1000 cm³ ) portable (~4 kg) MR sensor (0.28 T) designed to identify dehydration-induced fluid loss. T2 relaxometry measurements were performed using a Carr-Purcell-Meiboom-Gill pulse sequence in ~4 min.

RESULTS

T2 values from the portable MR sensor exhibited strong (R² = 0.996) agreement with benchtop NMR spectrometer. Thermal dehydration induced weight loss of 4 to 11% over 5 to 10 h. Fluid loss induced by thermal dehydration was accurately identified via whole-animal NMR and skeletal muscle. The portable MR sensor accurately identified dehydration via multicomponent T2 relaxometry.

CONCLUSION

Performing multicomponent T2 relaxometry localized to the skeletal muscle with a miniaturized MR sensor provides a noninvasive, physiologically relevant measure of dehydration induced fluid loss in a mouse model. This approach offers sensor portability, reduced system complexity, fully automated operation, and low cost compared with MRI. This approach may serve as a versatile and portable point of care technique for dehydration monitoring.

Bioelectrical impedance analysis does not detect an increase in total body water following isotonic fluid consumption

PURPOSE

To determine if single-frequency foot-to-foot bioelectrical impedance analysis (BIA) can detect acute changes in total body water (TBW) following consumption of isotonic saline. All participants ate a sodium-free meal at 4 h prior to the data collection visit and had euhydration confirmed using urine specific gravity at the beginning of the experimental visit. Subjects drank 466 mL of isotonic saline (Na⁺ 140 mmol·L^-1) following baseline measures. Blood sampling and BIA were performed at baseline and every 30 min for 3 h after saline consumption. Ten healthy participants completed this study. Plasma volume (5%Δ, p < 0.001) and serum sodium concentration (1%Δ, p < 0.001) increased by 60 min and 90 min, respectively. Body mass (p < 0.001) displayed a biphasic response increasing to a peak at 30 min (+0.38Δkg) and then decreasing to its minimum at 180 min (-0.35Δkg). BIA impedance (p = 0.678) was unaffected by the saline administration. BIA-derived TBW (p = 0.039) decreased from baseline starting at 150 min (0.21Δkg). Novelty Athletes and coaches wishing to achieve hyperhydration can do so through the consumption of isotonic fluid. 50 kHz foot-to-foot BIA-derived TBW is inadequate for measuring hyperhydration. Future studies should examine the physiological and performance effects of such a hyperhydration protocol.

Classification of Hydration in Clinical Conditions: Indirect and Direct Approaches Using Bioimpedance

Although the need to assess hydration is well recognized, laboratory tests and clinical impressions are impractical and lack sensitivity, respectively, to be clinically meaningful. Different approaches use bioelectrical impedance measurements to overcome some of these limitations and aid in the classification of hydration status. One indirect approach utilizes single or multiple frequency bioimpedance in regression equations and theoretical models, respectively, with anthropometric measurements to predict fluid volumes (bioelectrical impedance spectroscopy-BIS) and estimate fluid overload based on the deviation of calculated to reference extracellular fluid volume. Alternatively, bioimpedance vector analysis (BIVA) uses direct phase-sensitive measurements of resistance and reactance, measured at 50 kHz, normalized for standing height, then plotted on a bivariate graph, resulting in a vector with length related to fluid content, and direction with phase angle that indexes hydration status. Comparison with healthy population norms enables BIVA to classify (normal, under-, and over-) and rank (change relative to pre-treatment) hydration independent of body weight. Each approach has wide-ranging uses in evaluation and management of clinical groups with over-hydration with an evolving emphasis on prognosis. This review discusses the advantages and limitations of BIS and BIVA for hydration assessment with comments on future applications.

Body Composition Technology: Implications for the ICU

Malnutrition continues to be highly prevalent in hospitalized and critically ill patients and is associated with significant morbidity and mortality. Additionally, survivors of critical illness have an increased risk for sarcopenia, which leads to weakness and physical debilitation that can persist for years. Nutrition risk assessment tools have been developed and validated in critically ill patients but have limitations. Variables such as body weight, body mass index, weight change, or percentage of food intake can be difficult to obtain in critically ill patients and may be misleading given changes in body composition, such as an increase in body water. Assessment of body composition through new techniques provides a unique opportunity to counter some of these limitations and develop improved methods of nutrition risk assessment based on objective data. The present manuscript provides a review of the most commonly available clinical technology for assessment of body composition (bioimpedance, computed tomography, and ultrasound), including data from trials in critically ill patients highlighting the benefits and weaknesses of each modality.

Prevalence of rheumatoid cachexia in rheumatoid arthritis: a systematic review and meta-analysis

BACKGROUND

Low muscle mass occurs in patients with rheumatoid arthritis without weight loss; this condition is referred as rheumatoid cachexia. The aim of the current study was to perform a systematic review with meta-analysis to determine the rheumatoid cachexia prevalence.

METHODS

A systematic review with meta-analysis of observational studies published in English, between 1994 and 2016, was conducted using MEDLINE (via PubMed) and other relevant sources. Search strategies were based on pre-defined keywords and medical subject headings. The methodological quality of included studies was assessed using the Newcastle-Ottawa Scale. Meta-analysis was used to estimate the prevalence, and because studies reported different methods and criteria to estimate body composition and prevalence of rheumatoid cachexia, subgroup analyses were performed. Meta-regression adjusted for the 28-joint disease activity score and disease duration (years) was performed (significance level at P ≤ 0.05).

RESULTS

Of 136 full articles (one duplicate publication) screened for inclusion in the study, eight were included. The estimated overall prevalence of rheumatoid cachexia was 19% [95% confidence interval (CI) 07-33%]. This prevalence was 29% (95% CI 15-46%) when body composition was measured by dual-energy X-ray absorptiometry. When the diagnostic criteria were fat-free mass index below the 10th percentile and fat mass index above the 25th percentile, rheumatoid cachexia prevalence was 32% (95% CI 14-52%). The 28-joint disease activity score and disease duration had no influence on the estimated prevalence of rheumatoid cachexia (P > 0.05). Most studies were rated as having moderate methodological quality.

CONCLUSIONS

Meta-analysis showed a prevalence of rheumatoid cachexia of 15-32%, according to different criteria, demonstrating that this condition is a frequent comorbidity of rheumatoid arthritis. To better understand its clinical impact, more studies using standardized definitions and prospective evaluations are urgently needed.

Influence of maternal adiposity, preterm birth and birth weight centiles on early childhood obesity in an Indigenous Australian pregnancy-through-to-early-childhood cohort study

Childhood obesity rates are higher among Indigenous compared with non-Indigenous Australian children. It has been hypothesized that early-life influences beginning with the intrauterine environment predict the development of obesity in the offspring. The aim of this paper was to assess, in 227 mother-child dyads from the Gomeroi gaaynggal cohort, associations between prematurity, Gestation Related-Optimal Weight (GROW) centiles, maternal adiposity (percentage body fat, visceral fat area), maternal non-fasting plasma glucose levels (measured at mean gestational age of 23.1 weeks) and offspring BMI and adiposity (abdominal circumference, subscapular skinfold thickness) in early childhood (mean age 23.4 months). Maternal non-fasting plasma glucose concentrations were positively associated with infant birth weight (P=0.005) and GROW customized birth weight centiles (P=0.008). There was a significant association between maternal percentage body fat (P=0.02) and visceral fat area (P=0.00) with infant body weight in early childhood. Body mass index (BMI) in early childhood was significantly higher in offspring born preterm compared with those born at term (P=0.03). GROW customized birth weight centiles was significantly associated with body weight (P=0.01), BMI (P=0.007) and abdominal circumference (P=0.039) at early childhood. Our findings suggest that being born preterm, large for gestational age or exposed to an obesogenic intrauterine environment and higher maternal non-fasting plasma glucose concentrations are associated with increased obesity risk in early childhood. Future strategies should aim to reduce the prevalence of overweight/obesity in women of child-bearing age and emphasize the importance of optimal glycemia during pregnancy, particularly in Indigenous women.

Assessing Hand Muscle Structural Modifications in Chronic Stroke

The purpose of the study is to assess poststroke muscle structural alterations by examining muscular electrical conductivity and inherent electrophysiological properties. In particular, muscle impedance and compound muscle action potentials (CMAP) were measured from the hypothenar muscle bilaterally using the electrical impedance myography and the electrophysiological techniques, respectively. Significant changes of muscle impedance were observed in the paretic muscle compared with the contralateral side (resistance: paretic: 27.54 ± 0.97 Ω, contralateral: 25.46 ± 0.91 Ω, p < 0.05; phase angle: paretic: 8.81 ± 0.61°, contralateral: 10.79 ± 0.69°, p < 0.05). In addition, impedance changes correlated moderately with the CMAP amplitude in the paretic hand (phase angle: r = 0.66, p < 0.05; reactance: r = 0.58, p < 0.05). The study discloses significant muscle rearrangements as a result of fiber loss or atrophy, fat infiltration or impaired membrane integrity in chronic stroke.

Chiarello P. Estimation of Body Composition and Water Data Depends on the Bioelectrical Impedance Device

Overweight, obese and chronic kidney disease patients have an altered and negative body composition being its assessment important. Bioelectrical impedance analysis is an easy-to-operate and low-cost method for this purpose. This study aimed to compare and correlate data from single- and multi-frequency bioelectrical impedance spectroscopy applied in subjects with different body sizes, adiposity, and hydration status. It was a cross-sectional study with 386 non-chronic kidney disease volunteers (body mass index from 17 to 40 kg/m2), 30 patients in peritoneal dialysis, and 95 in hemodialysis. Bioelectrical impedance, body composition, and body water data were assessed with single- and multi-frequency bioelectrical impedance spectroscopy. Differences (95% confidence interval) and agreements (Bland-Atman analyze) between devices were evaluated. The intraclass correlation coefficient was used to measure the strength of agreement and Pearson's correlation to measure the association. Regression analyze was performed to test the association between device difference with body mass index and overhydration. The limits of agreement between devices were very large. Fat mass showed the greatest difference and the lowest intraclass and Pearson's correlation coefficients. Pearson's correlation varied from moderate to strong and the intraclass correlation coefficient from weak to substantial. The difference between devices were greater as body mass index increased and was worse in the extremes of water imbalance. In conclusion, data obtained with single- and multi-frequency bioelectrical impedance spectroscopy were highly correlated with poor agreement; the devices cannot be used interchangeably and the agreement between the devices was worse as body mass index and fat mass increased and in the extremes of overhydration.

New anthropometric indices or old ones: Which is the better predictor of body fat?

BACKGROUND

The percent and distribution of body fat are important factors in the pathogenesis of numerous diseases. Our aim was to investigate common anthropometric indices in their relationship with body fat content.

METHODS

In a cross-sectional study 1360 healthy individuals (580 men and 780 women) in a cluster sampling, from Ahvaz, Iran, body fat content (using bioelectrical impedance) and anthropometric measurements [weight, waist circumference, a body shape index, abdominal volume index, body adiposity index, conicity, body mass index, hip circumference, waist to hip ratio and waist to height ratio] was obtained. The ROC curve analysis was used to compare each index with body fat percent.

RESULTS

Significant difference was found between men and women in all anthropometric parameters (p < 0.001). Women displayed higher percentages in the overweight and obese categories (33.6% vs. 32.9% and 26.4% vs. 22.1%, respectively). In both men and women, the strongest correlations were seen between body fat percent and BMI, AVI and WHtR (r>7.9 and p<0.001). BMI, WHtR and AVI in men and BAI, BMI and WHtR in women showed the most accuracy for estimating body fat percent, respectively.

CONCLUSION

All anthropometric parameters could predict body fat percent with relatively good power, however BMI, WHtR and AVI are more powerful predictors. Based on our findings, we suggest using the AVI and WHtR instead of other indexes, as they are better able to assess the accumulation of fat in the abdominal area and are able to more accurately assess body fat percent, which are indicators of chronic disease.

Electrical Impedance Myography for Evaluating Paretic Muscle Changes After Stroke

Electrical impedance myography (EIM) was used to assess the paretic muscle intrinsic electrical properties post stroke. Twenty-seven subjects with chronic hemiparesis participated in this study. Muscle impedance was measured by applying high-frequency, low-intensity alternating current to biceps brachii muscles. Major EIM parameters, resistance ( ), reactance ( ), phase angle ( ), and electrical anisotropy ratios (AR) of the three parameters, were examined at 50 kHz. Statistical analysis demonstrated significant reduction of reactance, phase angle, AR of resistance, and AR of reactance in the paretic muscle compared with the contralateral side (Paretic X: , contralateral X: , and p < 0.001; Paretic : , contralateral : 14.5 ± 0.82°, and p < 0.001; Paretic AR of R: 0.969 ± 0.013, contralateral AR of R: 1.008 ± 0.011, and p < 0.02; and Paretic AR of X: 0.981 ± 0.066, contralateral AR of X: 1.114 ± 0.041, and p < 0.02). Correlation analysis, however, did not show any significant relationship between EIM parameters and clinical assessments. Findings of this paper indicated significant changes in the muscular intrinsic electrical properties after stroke, possibly related to structural modifications induced by loss of muscle fibers or fat infiltration as well as changes in the quality of cell membranes post stroke.

Slightly superior performance of bioimpedance spectroscopy over single frequency regression equations for assessment of total body water

Electrical bioimpedance has been used for several decades to assess body fluid distribution and body composition by using single frequency and bioimpedance spectroscopic (BIS) techniques. It remains uncertain whether BIS methods have better performance compare to single frequency regression equations. In this work the performance of two BIS methods and four different 50 kHz single frequency prediction equations was studied in a data set of wrist-to-ankle tetrapolar BIS measurements (5-1000 kHz) together with reference values of total body water obtained by tritium dilution in 92 patients. Data were compared using regression techniques and Bland-Altman plots. The results of this study showed that all methods produced similarly high correlation and concordance coefficients, indicating good accuracy as a method. Limits of agreement analysis indicated that the population level performance of Sun's prediction equations was very similar to the performance of both BIS methods. However, BIS methods in practice have slightly better predictive performance than the single-frequency equations as judged by higher correlation and the limits of agreement from the Bland-Altman analysis. In any case, the authors believe that an accurate evaluation of performance of the methods cannot be done as long as the evaluation is done using Bland-Altman analysis, the commonly accepted technique for this kind of performance comparisons.

Stratification of Fat-Free Mass Index Percentiles for Body Composition Based on National Health and Nutrition Examination Survey III Bioelectric Impedance Data

BACKGROUND

Loss of protein mass and lower fat-free mass index (FFMI) are associated with longer length of stay, postsurgical complications, and other poor outcomes in hospitalized patients. Normative data for FFMI of U.S. populations do not exist. This work aims to create a stratified FFMI percentile table for the U.S. population using the large bioelectric impedance analysis data obtained from National Health and Nutrition Examination Surveys (NHANES).

METHODS

Fat-free mass (FFM) was calculated from the NHANES III bioelectric impedance analysis and anthropometric data for males and females ages 12 to >90 years for 3 race/ethnicities (non-Hispanic white, non-Hispanic black, and Mexican American). FFM was normalized by subject height to create an FFMI distribution table for the U.S.

POPULATION

Selected percentiles were obtained by age, sex, and race/ethnicity. Data were collapsed by race/ethnicity before and after removing obese and underweight participants to create an FFMI decile table for males and females 12 years and older for the healthy-weight U.S.

POPULATION

RESULTS

FFMI increased during adolescent growth but stabilized in the early 20s. The FFMI deciles were similar by race/ethnicity, with age group remaining relatively stable between ages 25 and 80 years. The FFMI deciles for males and females were significantly different.

CONCLUSIONS

After eliminating the obese and extremely thin, FFMI percentiles remain stable during adult years allowing creation of age- and race/ethnicity-independent decile tables for males and females. These tables allow stratification of individuals for nutrition intervention trials to depict changing nutrition status during medical, surgical, and nutrition interventions.

Assessment of Postresuscitation Volume Status by Bioimpedance Analysis in Patients with Sepsis in the Intensive Care Unit: A Pilot Observational Study

Background. Bioimpedance analysis (BIA) is a novel method of assessing a patient's volume status. Objective. We sought to determine the feasibility of using vector length (VL), derived from bioimpedance analysis (BIA), in the assessment of postresuscitation volume status in intensive care unit (ICU) patients with sepsis. Method. This was a prospective observational single-center study. Our primary outcome was feasibility. Secondary clinical outcomes included ventilator status and acute kidney injury. Proof of concept was sought by correlating baseline VL measurements with other known measures of volume status. Results. BIA was feasible to perform in the ICU. We screened 655 patients, identified 78 eligible patients, and approached 64 for consent. We enrolled 60 patients (consent rate of 93.8%) over 12 months. For each 50-unit increase in VL, there was an associated 22% increase in the probability of not requiring invasive mechanical ventilation (IMV) (p = 0.13). Baseline VL correlated with other measures of volume expansion including serum pro-BNP levels, peripheral edema, and central venous pressure (CVP). Conclusion. It is feasible to use BIA to predict postresuscitation volume status and patient-important outcomes in septic ICU patients. Trial Registration. This trial is registered with clinicaltrials.gov NCT01379404 registered on June 7, 2011.

Double product break point estimates ventilatory threshold in individuals with type 2 diabetes

[Purpose] To verify the identification of the anaerobic threshold through the double product breakpoint (DPBP) method for individuals with type 2 diabetes. [Subjects and Methods] Nine individuals with T2D (7 females; age=63.2 ± 8.9 y) and 10 non-diabetic (ND) (7 females; age=58.3 ± 7.8 y) performed an incremental exercise test on a cycle ergometer. Heart rate (HR), blood pressure (BP) and expired gas were measured at the end of each stage. The ventilatory threshold (VT) and DPBP were considered as the exercise intensities above which an over proportional increases in VE and DP were observed in relation to increasing workload. [Results] No differences were observed between the workloads, HR and VO2 corresponding to the AT identified respectively by VT and DPBP. For the T2D, strong correlations between VT and DBPB workloads (r=0.853), HR (r=0.714), and VO2 (r=0.863) were found. These relationships were similar to those found for the control group (r=0.923; r=0.881; and r=0.863, respectively). [Conclusion] These results demonstrate that the DPBP enables for the prediction of AT and correlated well the VT in both the T2D and ND participants.

Different displacement of bioimpedance vector due to Ag/AgCl electrode effect

BACKGROUND/OBJECTIVES

Bioelectrical impedance vector analysis (BIVA) is increasingly used in clinical research to assess soft tissue hydration. It is known that physical characteristics of electrodes, such as low intrinsic impedance, low electrode/skin contact impedance and type of gel, affect the reliability of noninvasive bioimpedance assessments. The aim of this study was to determine the effect of intrinsic impedance of electrode on the bioimpedance vector displacement in RXc graph.

SUBJECTS/METHODS

The intrinsic impedance is measured in nine pregelled disposable Ag/AgCl electrodes usually used for bioimpedance measures. The BIVA method is performed on 35 healthy volunteers using a 50 kHz phase-sensitive bioimpedance analyzer (BIA 101 Anniversary) with the lowest intrinsic impedance electrode and highest. The individual bioimpedance vector is plotted on the bivariate normal interval of reference population. The differences in the mean bioimpedance vectors obtained with each electrode are plotted, with their 95% confidence ellipses, on the dRXc graph. The paired one-sample Hotelling's T²-test is used to compare the differences of the mean bioimpedance vectors.

RESULTS

We found large variability in intrinsic resistance (11-665 Ω) and reactance (0.25-2.5 Ω) values of the electrodes analyzed and significant displacement (P<0.05) of bioimpedance vector positions in healthy adults according to the paired one-sample Hotelling's T²-test.

CONCLUSIONS

A robust study of all physical characteristics of commercial Ag/AgCl electrodes is necessary to reach consensus on pregelled Ag/AgCl electrodes valid for bioimpedance measurement. This information will enable BIVA users to avoid systemic errors when performing BIVA assessments, specifically when these measurements are used for clinical interpretations.

Proposal of new body composition prediction equations from bioelectrical impedance for Indonesian men

BACKGROUND/OBJECTIVES

Bioelectrical impedance analysis (BIA) is one of the most affordable and feasible body composition assessment techniques for clinical and field settings. However, it is important to use an equation appropriate for the study population. This study aimed to propose and validate prediction equations to estimate body composition using BIA for Indonesian men.

SUBJECTS/METHODS

Total body water (TBW), fat-free mass (FFM) and fat mass (FM) were determined using the deuterium dilution technique in 292 Indonesian males. Participants were divided equally into development and validation groups to develop prediction equations and to cross-validate the proposed prediction equations, respectively. In addition, selected prediction equations using BIA were cross-validated.

RESULTS

The proposed BIA equations were valid in our cross-validation samples. The best performance equations obtained from the absolute measure of body composition (TBW, FFM and FM) showed that r ranged between 0.89 and 0.91 and standard error of the estimate=1.8-2.6 kg. Cross-validation analysis indicated that the proposed equations had a bias of 0.1-0.3 kg, pure error of 1.3-1.8 kg and limits of agreement (mean difference±1.96 s.d.) of -0.26 to 0.13±4.09 to 5.59 kg. Among existing prediction equations examined, those by Deurenberg et al. (1989) and Lukaski et al. (1987) significantly overestimated FM by 4.0 and 3.2 kg, respectively, whereas the equation by Deurenberg et al. (1991) significantly (P<0.001) underestimated FFM by 5.0 kg compared with the reference FFM.

CONCLUSIONS

The new BIA prediction equations may provide more precise and accurate estimation of body composition in Indonesian men than the existing equations.

Body Composition Tools for Assessment of Adult Malnutrition at the Bedside: A Tutorial on Research Considerations and Clinical Applications

Because of the key role played by the body's lean tissue reserves (of which skeletal muscle is a major component) in the response to injury and illness, its maintenance is of central importance to nutrition status. With the recent development of the Academy of Nutrition and Dietetics/American Society for Parenteral and Enteral Nutrition diagnostic framework for malnutrition, the loss of muscle mass has been recognized as one of the defining criteria. Objective methods to evaluate muscle loss in individuals with acute and chronic illness are needed. Bioimpedance and ultrasound techniques are currently the best options for the clinical setting; however, additional research is needed to investigate how best to optimize measurements and minimize error and to establish if these techniques (and which specific approaches) can uniquely contribute to the assessment of malnutrition, beyond more subjective evaluation methods. In this tutorial, key concepts and statistical methods used in the validation of bedside methods to assess lean tissue compartments are discussed. Body composition assessment methods that are most widely available for practice and research in the clinical setting are presented, and clinical cases are used to illustrate how the clinician might use bioimpedance and/or ultrasound as a tool to assess nutrition status at the bedside. Future research needs regarding malnutrition assessment are identified.

A knitted garment using intarsia technique for Heart Rate Variability biofeedback: Evaluation of initial prototype

Heart rate variability (HRV) biofeedback is a method based on paced breathing at specific rate called resonance frequency by giving online feedbacks from user respiration and its effect on HRV. Since the HRV is also influence by different factors like stress and emotions, stress related to an unfamiliar measurement device, cables and skin electrodes may cover the underling effect of such kind of intervention. Wearable systems are usually considered as intuitive solutions which are more familiar to the end-user and can help to improve usability and hence reducing the stress. In this work, a prototype of a knitted garment using intarsia technique is developed and evaluated. Results show the satisfactory level of quality for Electrocardiogram and thoracic electrical bioimpedance i.e. for respiration monitoring as a part of HRV biofeedback system. Using intarsia technique and conductive yarn for making the connection instead of cables will reduce the complexity of fabrication in textile production and hence reduce the final costs in a final commercial product. Further development of garment and Android application is ongoing and usability and efficiency of final prototype will be evaluated in detail.

Which method to use for a fast assessment of body fat percentage?

Body position affects body water distribution and in turn the accuracy of bioelectrical impedance analysis (BIA), which may consequently distort conclusions about an individual's body composition.We compared body fat percentage (BFP) obtained with leg-to-leg-BIA (LL) and hand-to-leg-BIA (HL) with the reference values.The BFPs of 97 individuals were determined with an LL- (Tanita TBF 215GS, Japan) and HL- (Akern, STA/BIA, Italy) BIA-analyser and with reference skinfold thickness (SF) measurements. Each subject was measured upright with the LL-analyser, and upright and supine with the HL-analyser, both before and after 20 min of supine rest. The one-way ANOVA for repeated measures (HL-BIA), Student's t-test (LL-BIA), intraclass correlation coefficients, and Bland-Altman's plots were used for statistical analysis.BFPs determined with HL/LL BIA in upright/supine positions differ significantly. Compared to the SF method, HL-BIA mostly overestimates, while LL-BIA mostly underestimates BFP. Agreement between anthropometrically determined BFP and HL/LL-BIA determined BFP is better with HL for both sexes, and generally better in females than males.HL-BIA-determined estimates of BFP are more similar to reference values than LL-BIA. However, for both BIA methods, BIA-determined estimates of BFP are significantly affected by body position. Consequently, different BIA methods will classify approximately one fifth of subjects into the erroneous body-fat-content category, which calls for urgent standardization.

New specific bioelectrical impedance vector reference values for assessing body composition in the Italian-Spanish young adult population

OBJECTIVE

Specific bioelectrical impedance vector analysis (spBIVA) is a recently proposed technique for the analysis of body composition. The aim of this study was to apply spBIVA to a sample of Italian and Spanish young adults and to define the new bioelectrical references for this Western Mediterranean population.

METHODS

A sample of 440 individuals (220 from Italy, 220 from Spain; 213 men, 227 women) aged 18-30 years was considered. Anthropometric (height, weight, relaxed upper arm, waist, and calf girths) and bioelectrical (resistance, reactance; 50 kHz, 800 μA) measurements were taken. In order to verify the need for new references, specific bioelectrical values were compared to the reference values for U.S. adults and Italian elderly by tolerance ellipses and Student's t test.

RESULTS

The mean specific bioelectrical values (resistivity, Rsp, and reactivity, Xcsp, Ohm·cm) were: Rsp (332.7 ± 41.7 Ω·cm), Xcsp (44.4 ± 6.8 Ω·cm), Zsp (335.6 ± 41.9 Ω·cm) and phase (7.6 ± 0.8°) in men; Rsp (388.6 ± 60 Ω·cm), Xcsp (43.7 ± 7.5 Ω·cm), Zsp (391.0 ± 60.3 Ω·cm) and phase (6.4 ± 0.7°) in women. Italo-Spanish bioelectrical vectors were mainly distributed (>90%) in the lower part of the tolerance ellipses for U.S. young adults, due to a shorter impedance (P < 0.001), indicative of a lower percent fat mass. Compared to Italian elders, they were mainly located in the left side (>90%), due to a higher phase (P < 0.001), indicative of higher body cell mass.

CONCLUSIONS

These population and age-related differences indicate the need for new specific tolerance ellipses that can be used as references for assessing body composition in young adults from Western Mediterranean populations.

Dehydration: physiology, assessment, and performance effects

This article provides a comprehensive review of dehydration assessment and presents a unique evaluation of the dehydration and performance literature. The importance of osmolality and volume are emphasized when discussing the physiology, assessment, and performance effects of dehydration. The underappreciated physiologic distinction between a loss of hypo-osmotic body water (intracellular dehydration) and an iso-osmotic loss of body water (extracellular dehydration) is presented and argued as the single most essential aspect of dehydration assessment. The importance of diagnostic and biological variation analyses to dehydration assessment methods is reviewed and their use in gauging the true potential of any dehydration assessment method highlighted. The necessity for establishing proper baselines is discussed, as is the magnitude of dehydration required to elicit reliable and detectable osmotic or volume-mediated compensatory physiologic responses. The discussion of physiologic responses further helps inform and explain our analysis of the literature suggesting a ≥ 2% dehydration threshold for impaired endurance exercise performance mediated by volume loss. In contrast, no clear threshold or plausible mechanism(s) support the marginal, but potentially important, impairment in strength, and power observed with dehydration. Similarly, the potential for dehydration to impair cognition appears small and related primarily to distraction or discomfort. The impact of dehydration on any particular sport skill or task is therefore likely dependent upon the makeup of the task itself (e.g., endurance, strength, cognitive, and motor skill).