Segmental bioelectrical impedance analysis: an update

Validity between dual-energy x-ray absorptiometry and bioelectrical impedance for segmental fat analysis and a novel low-cost model developed using anthropometry in young adults

BACKGROUND

Accurate body fat distribution assessment is essential for managing cardiovascular disease and metabolic disorders. Although several methods are available for segmental fat analysis, few studies have examined the validity of affordable methods such as Bioelectrical Impedance Analysis (BIA) against the reference method, Dual-Energy X-ray Absorptiometry (DXA). This study aimed to assess the validity of BIA as compared to DXA for segmental fat mass assessment, and to develop anthropometric multivariate regression models that offer a cost-effective alternative for health professionals in clinical and public health settings.

METHODS

Cross-sectional study that included 264 young adults (161 males, mean age = 23.04 ± 5.61 years; and 103 females, mean age = 22.29 ± 5.98 years). Segmental fat mass was measured using DXA and BIA, and anthropometric measurements were collected following the ISAK protocol.

RESULTS

Significant differences were found between DXA and BIA for segmental fat mass (p < 0.001). Sex significantly influenced the results (p < 0.05), while BMI and hydration status had no significant impacts. The Bland-Altman analysis revealed significant differences (p < 0.001) between BIA and DXA for fat mass in the upper and lower limbs. Trunk fat mass also differed significantly in males and females (p < 0.001), except for the overall sample (p = 0.088). Anthropometric multivariate regression models showed a high predictive accuracy for both females (R²=0.766-0.910; p < 0.001) and males (R²=0.758-0.887; p < 0.001). Key predictors of segmental fat mass included body mass (r = 0.606-0.867; p < 0.001), skinfold thickness (r = 0.688-0.893; p < 0.001), and waist girth (r = 0.883 - 0.810; p < 0.001). Peripheral skinfolds were highly predictive for upper and lower limbs, while waist girth was relevant for trunk fat mass.

CONCLUSIONS

DXA and BIA are not interchangeable for segmental fat analysis due to the significant differences observed. However, the anthropometric multivariate regression models developed provide a cost-effective and reliable alternative for predicting segmental fat mass in clinical settings where DXA is unavailable.

TRIAL REGISTRATION

Not applicable.

Compared to dual-energy X-ray absorptiometry, bioelectrical impedance effectively monitors longitudinal changes in body composition in children and adolescents with obesity during a lifestyle intervention

Accurate and efficient body composition assessment is essential for diagnosing and monitoring childhood obesity in clinical and research settings. This study evaluated the agreement between bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA) in assessing body composition and its changes during a long-term lifestyle intervention in children and adolescents with obesity. We hypothesized that BIA is comparable to DXA in tracking longitudinal changes in body composition in this population. The study included 92 children and adolescents 5 to 17 years of age (mean 10.5 ± 2.9 years) classified as obese at the time of measurement (body mass index-standard deviation score ≥ 2 SD). From January 1, 2014, to December 31, 2017, they participated in a lifestyle intervention at Randers Regional Hospital. Body composition was assessed using BIA and DXA at baseline and follow-up (mean 20.5 ± 9.3 months). Bland-Altman plots, correlation- and concordance analyses were used to evaluate the agreement between methods. Bland-Altman plots demonstrated wide limits of agreement without significant bias for longitudinal changes in fat mass (FM), FM%, fat-free mass (FFM), and FFM% (0.39 kg (CI -0.14, 0.93), -0.39% (CI -1.06, 0.26), -0.21 kg (CI -0.73, 0.31), and 0.39% (CI -0.27, 1.05), respectively). Correlations between methods for changes in FM, FM%, FFM, and FFM% were 0.93, 0.83, 0.88, and 0.83, respectively. In cross-sectional assessments, BIA underestimated FM and FM% and overestimated FFM and FFM% compared to DXA. Conclusively, BIA effectively monitors longitudinal changes in body composition at a group level in a pediatric population with obesity. However, caution is needed for individual assessments.

Development and clinical application of bioelectrical impedance analysis method for body composition assessment

Obesity, which is characterized by excessive body fat, increases the risk of chronic diseases, such as type 2 diabetes, cardiovascular diseases, and certain cancers. Sarcopenia, a decline in muscle mass, is also associated with many chronic disorders and is therefore a major concern in aging populations. Body composition analysis is important in the evaluation of obesity and sarcopenia because it provides information about the distribution of body fat and muscle mass. It is also useful for monitoring nutritional status, disease severity, and the effectiveness of interventions, such as exercise, diet, and drugs, and thus helps assess overall health and longevity. Computed tomography, magnetic resonance imaging, and dual-energy X-ray absorptiometry are commonly used for this purpose. However, they have limitations, such as high cost, long measurement time, and radiation exposure. Instead, bioelectrical impedance analysis (BIA), which was introduced several decades ago and has undergone significant technological advancements, can be used. It is easily accessible, affordable, and importantly, poses no radiation risk, making it suitable for use in hospitals, fitness centers, and even at home. Herein, we review the recent technological developments and clinical applications of BIA to provide an updated understanding of BIA technology and its strengths and limitations.

Reliability, biological variability, and accuracy of multi-frequency bioelectrical impedance analysis for measuring body composition components

Introduction

Bioelectrical impedance analysis (BIA) systems are gaining popularity for use in research and fitness assessments as the technology improves and becomes more affordable and easier to use. Multifrequency BIA (MF-BIA) may improve accuracy and precision using octopolar contacts for segmental analyses.

Purpose

Evaluate reliability, biological variability, and accuracy of component measures (total body water, mass, and composition) of commercially available MF-BIA system (InBody 770, Cerritos, California, USA).

Methods

Fourteen healthy military-age adults were assessed by MF-BIA in duplicate on five laboratory visits across 3 weeks (10 measures each). Participants were evaluated at the same time of day after refraining from strenuous exercise (> 48 h), alcohol consumption (> 24 h), and caffeine, nicotine, and food (> 10 h). Systematic error (test-retest reliability) and biological variability (day-to-day reliability) were summarized by intraclass correlation coefficient (ICC) values determined for body mass (fat, fat-free, total) and body water (extracellular, intracellular, total). Body composition measurements derived from BIA on the second visit were also tested for accuracy compared to dual-energy x-ray absorptiometry (DXA).

Results

Test-retest reliability was very high for all measurements of whole-body water and mass (ICC ≥ 0.999) and high for regional body water and mass (ICC 0.973-1.000). Biological variability was observable with very minor differences between tests (same day) for total and regional body water (0.0-0.2 L) and total and regional body mass measurements (0.0-0.2 kg); while between day differences were slightly higher (0.0-0.5 L and 0.1-0.7 kg). Compared to DXA, the MF-BIA whole-body measures showed an offset in %BF (Bias -4.0 ± 2.8%; Standard error of the estimate (SEE), 2.6%), an overprediction for total body fat-free mass (Bias 2.8 ± 2.1 kg; SEE 2.2 kg) and an underprediction of total body fat mass (Bias -2.9 ± 2.0 kg; SEE 1.9 kg).

Conclusion

Under controlled conditions with fit and healthy men and women, this MF-BIA system has high methodological reliability and demonstrates stable day-to-day measurements of major body composition components. Previously reported ~3% body fat offset compared to criterion methods was again confirmed. Precision of the InBody 770 shows consistency and supports further testing of this specific device as a new military standards method and suitability across a wider range of %BF.

Comparing Device-Generated and Calculated Bioimpedance Variables in Community-Dwelling Older Adults

Despite BIA emerging as a clinical tool for assessing older adults, it remains unclear how to calculate whole-body impedance (Z), reactance (Xc), resistance (R), and phase angle (PhA) from segmental values using modern BIA devices that place electrodes on both sides of the body. This investigation aimed to compare both the whole-body and segmental device-generated phase angle (PhADG) with the phase angle calculated using summed Z, Xc, and R from the left, right, and combined sides of the body (PhACalc) and to compare bioelectric variables between sides of the body. A sample of 103 community-dwelling older adults was assessed using a 50 kHz direct segmental multifrequency BIA device. Whole-body PhACalc values were assessed for agreement with PhADG using 2.5th and 97.5th quantile nonparametric limits of agreement and Spearman's rho. Bioelectrical values between sides of the body were compared using Wilcoxon rank and Spearman's rho. A smaller mean difference was observed between PhADG and right PhACalc (-0.004°, p = 0.26) than between PhACalc on the left (0.107°, p = 0.01) and on the combined sides (0.107°, p < 0.001). The sum of Z, R, and PhACalc was significantly different (p < 0.01) between the left (559.66 ± 99.55 Ω, 556.80 ± 99.52 Ω, 5.51 ± 1.5°, respectively) and the right sides (554.60 ± 94.52 Ω, 552.02 ± 94.23 Ω, 5.41 ± 0.8°, respectively). Bilateral BIA values do not appear to be interchangeable when determining whole-body measurements. Present data suggest that using right-sided segmental values would be the most appropriate choice for calculating whole-body bioelectrical variables.

Efficacy of Split Versus Full-Body Resistance Training on Strength and Muscle Growth: A Systematic Review With Meta-Analysis

ABSTRACT

Ramos-Campo, DJ, Benito-Peinado, PJ, Caravaca, LA, Rojo-Tirado, MA, and Rubio-Arias, JÁ. Efficacy of split versus full-body resistance training on strength and muscle growth: a systematic review with meta-analysis. J Strength Cond Res 38(7): 1330-1340, 2024-No previous study has systematically compared the effect of 2 resistance training routines commonly used to increase muscle mass and strength (i.e., split [Sp] and full-body [FB] routines). Our objective was to conduct a systematic review and meta-analysis following PRISMA guidelines to compare the effects on strength gains and muscle growth in healthy adults. 14 studies (392 subjects) that compared Sp and FB routines in terms of strength adaptations and muscle growth were included. Regarding the effects of the Sp or FB routine on both bench press and lower limbs strength, the magnitude of the change produced by both routines was similar (bench press: mean difference [MD] = 1.19; [-1.28, 3.65]; p = 0.34; k = 14; lower limb: MD = 2.47; [-2.11, 7.05]; p = 0.29; k = 14). Concerning the effect of the Sp vs. FB routine on muscle growth, similar effects were observed after both routines in the cross-sectional area of the elbow extensors (MD = 0.30; [-2.65, 3.24]; p = 0.84; k = 4), elbow flexors (MD = 0.17; [-2.54, 2.88]; p = 0.91; k = 5), vastus lateralis (MD = -0.08; [-1.82, 1.66]; p = 0.93; k = 5), or lean body mass (MD = -0.07; [-1.59, 1.44]; p = 0.92; k = 6). In conclusion, the present systematic review and meta-analysis provides solid evidence that the use of Sp or FB routines within a resistance training program does not significantly impact either strength gains or muscle hypertrophy when volume is equated. Consequently, individuals are free to confidently select a resistance training routine based on their personal preferences.

Assessment of Changes in Body Composition After 3 Months of Dulaglutide Treatment

Background

Changes in body composition accompanied by glucagon-like peptide 1 receptor agonist (GLP-1RA) induced weight loss have drawn much attention. However, fewer studies have reported body composition changes in patients receiving dulaglutide therapy in Chinese population.

Methods

A total of 70 overweight/obese type 2 diabetes mellitus (T2DM) patients who received dulaglutide therapy were included. Clinical data were collected. Visceral fat area (VFA) and body composition were also measured. Changes in clinical indicators and body composition of patients before and after intervention were also analyzed. Correlation analysis and multiple linear regression model were used to evaluate the association between hemoglobin A1C (HbA1c) and body composition.

Results

The results showed that body weight (BW), VFA, body fat (BF), lean body mass (LBM), skeletal muscle mass (SMM) and water content were reduced after 3 months dulaglutide intervention. The lean body mass percentage (LBMP) and skeletal muscle mass percentage (SMMP) significantly increased. Moreover, there was no significant difference in bone mineral quality (BMQ) after the intervention. The multiple linear regression model revealed that the % change in BF was independently associated with % change in HbA1c (β = 0.449, t = 3.148, p=0.002).

Conclusion

These results indicate that dulaglutide intervention does not cause muscle and bone mass loss while inducing weight loss, and % change in BF was independently associated with improved glucose control during dulaglutide therapy. This study offers some positive results to support the clinical application of dulaglutide.

Ketogenic Diet: A Nutritional Therapeutic Tool for Lipedema?

PURPOSE OF REVIEW

This review aims to provide an overview of the current evidence on the efficacy, also considering the anti-inflammatory properties and safety of very low-calorie ketogenic diet (VLCKD) as a potential treatment for lipedema, particularly in the context of obesity.

RECENT FINDINGS

Lipedema is a chronic disease characterized by abnormal and painful fat buildup on the legs and/or arms. It is often misdiagnosed as obesity or lymphedema. However, although lipedema and obesity can coexist, unlike obesity, lipedema usually affects the legs and thighs without affecting the feet or hands, and the abnormal deposition of adipose tissue in lipedema is painful. The current lifestyle interventions are often unsuccessful in the management of lipedema. There is no consensus on the most effective nutritional approach for managing lipedema. Recent studies have suggested that VLCKD may be an effective treatment for lipedema, demonstrating that it is also superior to other nutritional approaches such as Mediterranean diet or intermittent fasting. Lipedema is a chronic and debilitating disease characterized by abnormal and painful accumulation of adipose tissue in the legs. VLCKD has been shown to be an effective treatment for lipedema, especially in the context of obesity, due to its anti-inflammatory properties. However, further research is needed to determine the long-term safety and efficacy of VLCKD as a treatment for lipedema.

The role of segmental bioelectrical impedance technique in the assessment of intraperitoneal ultrafiltration volume with peritoneal dialysis patients

OBJECTIVE

To investigate the role of segmental bioelectrical impedance technique (SBIA) in the assessment of intraperitoneal ultrafiltration volume with peritoneal dialysis patients.

METHOD

We selected the patients at the Department of Nephrology of the First Affiliated Hospital of Zhengzhou University and measured the segmental bioelectrical impedance by a German Fresenius body composition analyzer (the Fresenius whole body composition measurement (BCM) machine was used as a segmental machine in this study). An alternating current (5 kHz, 0.05-0.7 mA) was continuously released during the measurement. The released current penetrated the peritoneal cavity on both sides of the body, from which the segmental resistance at a frequency of 5 kHz was obtained from the multifrequency data (R5/Ω). Baseline BIA measurements were initiated after the patient entered the supine position for 5-10 min, then dialysate was instilled into the peritoneal cavity. BIA measurements were performed at 10-min intervals during the retention of dialysate in the abdomen and finally ended when dialysate drainage was complete. Real-time intraperitoneal volume estimated by SBIA (IPVSBIA)and ultrafiltration volume estimated by SBIA(UFVSBIA) was calculated. At the same time, the actual ultrafiltration volume at the end of peritoneal dialysis was weighed and measured (UFVMEA).

RESULTS

A total of 30 patients were included in the study, 9 patients withdrew from the study due to subjective factors during the measurement process, and 21 patients completed the study. The correlation coefficient R2 of UFVSBIA and UFVMEA was 0.21 (p < 0.05). Bland-Altman analysis showed that the bias of UFVSBIA to the actual UFVMEA was 0.12 L, and the 95% agreement limit was between -0.5 L and 0.74 L, which confirmed that UFVSBIA measured by electrical impedance method and UFVMEA measured by weighing method were in good agreement. The time required to reach the maximum ultrafiltration volume (UFVSBIA) was 108 ± 68 min, and the mean value of the maximum ultrafiltration volume (Max UFVSBIA) was 1.16 ± 0.60 L.

CONCLUSION

The segmental bioelectrical impedance technique can be used to assess the intraperitoneal ultrafiltration volume of peritoneal dialysis patients in real-time and effectively. This method may guide the dialysis fluid retention time and the maximum ultrafiltration volume in PD patients.

Association of sarcopenia, pre-sarcopenia, and dynapenia with the onset and progression of locomotive syndrome in Japanese older adults: a cross-sectional study

BACKGROUND

Sarcopenia commonly occurs in older adults with motor disorders requiring long-term care, and the clinical features of sarcopenia are associated with locomotive syndrome. Dynapenia is the age-related loss of muscle strength. However, the association of sarcopenia and dynapenia with the onset and progression of locomotive syndrome in older adults remains unknown. The current study aimed to determine the association of sarcopenia, pre-sarcopenia, and dynapenia with the onset and progression of locomotive syndrome in Japanese older adults.

METHODS

This study included older females (n = 264, 73.9 ± 5.8 years) and males (n = 92, 76.3 ± 6.1 years). Sarcopenia was defined as low muscle function and mass; pre-sarcopenia was defined as low muscle mass with normal muscle function; and dynapenia was defined as low muscle function without low muscle mass. Locomotive syndrome (stage 0-2) severity was determined using the stand-up test, the two-step test, and the 25-question geriatric locomotive function scale. Logistic regression analysis was performed to determine the relationship between sarcopenia category and locomotive syndrome stages.

RESULTS

Age (1.208, 95% confidence interval (CI) 1.124-1.298), sex (2.455, 95% CI 1.241-4.856), and BMI (1.211, 95% CI 1.077-1.361) were significant variables for determining locomotive syndrome stage ≥ 1, whereas pre-sarcopenia (0.543, 95% CI 0.331-0.891) and sarcopenia (1.664, 95% CI 1.005-2.755) were significant variables for determining locomotive syndrome stage 2.

CONCLUSIONS

Only sarcopenia was associated with locomotive syndrome progression, while low muscle mass or low muscle function was not associated with locomotive syndrome. Gaining muscle mass accompanied by an increased muscle function for older adults is warranted to prevent locomotive syndrome progression in the super-aged society.

High precision but systematic offset in a standing bioelectrical impedance analysis (BIA) compared with dual-energy X-ray absorptiometry (DXA)

Bioelectrical impedance analysis (BIA) provides a practical method of body composition estimation for field research and weight management programmes, with devices and algorithms that have improved in recent years. We compared suitability of a commercial BIA system that uses multi-frequency-based proprietary algorithms (InBody 770, Cerritos, California, USA) and a laboratory-based validated single-frequency system (Quantum IV, RJL Systems, Clinton Township, Michigan, USA) with dual-energy X-ray absorptiometry (DXA) (iDXA, GE Lunar, Madison, Wisconsin, USA). Volunteers included fit non-obese active duty US Marines (480 men; 315 women), assessed by DXA and the two BIA systems. Both RJL and InBody BIA devices predicted DXA-based fat-free mass (FFM) (mean absolute error (MAE) 2.8 and 3.1 kg, respectively) and per cent body fat (%BF) (MAE 3.4% and 3.9%, respectively), with higher correlations from the InBody device (r²=0.96 (%BF) and 0.84 (FFM)) versus the RJL (r²=0.92 (%BF) and 0.72 (FFM)). InBody overpredicted FFM (bias +2.7, MAE 3.1 kg) and underpredicted %BF (bias -3.4 and MAE 3.9%) versus the RJL. A 3% correction factor applied to the InBody device results provided values very close to the DXA measurements. These findings support the application of modern BIA systems to body composition goals of maximum %BF and minimum lean body mass for both men and women.

A Bioelectrical Impedance Analysis for the Assessment of Muscle Atrophy in Patients with Chronic Inflammatory Demyelinating Polyneuropathy

Objective Muscle atrophy is observed in a subset of patients with chronic inflammatory demyelinating polyneuropathy (CIDP). Its manifestation is associated with a poor functional prognosis and poor response to immunomodulatory therapies. We evaluated muscle atrophy in patients with CIDP using a bioelectrical impedance analysis (BIA). Methods We enrolled 12 patients with CIDP for a BIA of muscle atrophy. Of these 12 patients, 10 were diagnosed with typical CIDP, 1 with multifocal acquired demyelinating sensory and motor neuropathy, and 1 with distal acquired demyelinating symmetric neuropathy. All 12 patients underwent a series of assessments and evaluations, including a BIA and computed tomography (CT). A correlation was found between the skeletal muscle mass determined by the BIA and that found using CT of the muscles. Results The BIA provided values for each patient's skeletal muscle mass index (SMI) ranging from 4.1 to 8.1 kg/m². Four of the patients with CIDP had SMI values below the threshold for sarcopenia. CT of the patients' muscles provided scores indicating grades of muscle atrophy in the upper and lower extremities. A comparison of the outcomes from these two measures showed a good correlation between their muscle atrophy ratings (p <0.05). Conclusions We found that a BIA and muscle CT provided muscle atrophy assessments of equivalent accuracy. Therefore, a BIA can be a simple alternative to muscle CT that is suitable for regular use in daily clinical practice as a reliable tool for assessing muscle atrophy in patients with CIDP.

Estimation of fluid status using three multifrequency bioimpedance methods in hemodialysis patients

INTRODUCTION

Segmental eight-point bioimpedance has been increasingly used in practice. However, whether changes in bioimpedance analysis components before and after hemodialysis (HD) using this technique in a standing position is comparable to traditional whole-body wrist-to-ankle method is still unclear. We aimed to investigate the differences between two eight-point devices (InBody 770 and Seca mBCA 514) and one wrist-to-ankle (Hydra 4200) in HD patients and healthy subjects in a standing position.

METHODS

Thirteen HD patients were studied pre- and post-HD, and 12 healthy subjects once. Four measurements were performed in the following order: InBody; Seca; Hydra; and InBody again. Electrical equivalent models by each bioimpedance method and the fluid volume estimates by each device were also compared.

FINDINGS

Overall, total body water (TBW) was not different between the three devices, but InBody showed lower extracellular water (ECW) and higher intracellular water (ICW) compared to the other two devices. When intradialytic weight loss was used as a surrogate for changes in ECW (∆ECW) and changes in TBW (∆TBW), ∆ECW was underestimated by Hydra (-0.79 ± 0.89 L, p < 0.01), InBody (-1.44 ± 0.65 L, p < 0.0001), and Seca (-0.32 ± 1.34, n.s.). ∆TBW was underestimated by Hydra (-1.14 ± 2.81 L, n.s.) and InBody (-0.52 ± 0.85 L, p < 0.05) but overestimated by Seca (+0.93 ± 3.55 L, n.s.).

DISCUSSION

Although segmental eight-point bioimpedance techniques provided comparable TBW measurements not affected by standing over a period of 10-15 min, the ECW/TBW ratio appeared to be significantly lower in InBody compared with Seca and Hydra. Results from our study showed lack of agreement between different bioimpedance devices; direct comparison of ECW, ICW, and ECW/TBW between different devices should be avoided and clinicians should use the same device to track the fluid status in their HD population in a longitudinal direction.

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.

Body Composition Characteristics of Community-Dwelling Older Adults With Dynapenia or Sarcopenia

This study aimed to determine the differences in muscle and fat masses of the arm and leg between older adults with dynapenia, sarcopenia, or presarcopenia and normal individuals. The percent body fat, lean body mass, and skeletal mass index were measured with bioelectrical impedance analysis. Muscle function was evaluated using grip strength and walking speed. Participants were classified into four categories. Dynapenia was defined as low muscle function with normal muscle mass. Sarcopenia was defined as the presence of both low muscle mass and low muscle function. Presarcopenia was defined as low muscle mass with normal muscle function. Control was defined as normal muscle mass and function. Multivariate analyses of variance were performed separately for women and men to test the main effect of sarcopenia category on body composition. Among the 356 enrolled participants, 270 were women, and 86 were men. In older women, the dynapenia and sarcopenia groups had significantly less muscle mass in the leg than the control group. In older men, the dynapenia group demonstrated a higher body fat mass in the leg than the control group. These results suggest that different strategies are necessary to prevent dynapenia in women and men.

Accuracy of Estimated Bioimpedance Parameters with Octapolar Segmental Bioimpedance Analysis

The validity of the impedance parameters of the five body segments estimated using octapolar segmental bioelectrical impedance analysis (OS-BIA) has not been confirmed. This study aimed to verify the accuracy of the resistance (R), reactance (Xc), and phase angle of each five-body segment. The accuracy of the OS-BIA at 50 kHz was measured based on the direct tetrapolar segmental BIA. The differences in the estimated impedance parameters of the five body segments were compared to those measured from the OS-BIA in elderly men (N = 73) and women (N = 63). The estimated 50 kHz-R (Ω) was significantly higher than the measured 50 kHz-R in the right and left arms, and lower than the measured 50 kHz-R of the trunk, right leg, and left leg (all, p < 0.05). The estimated 50 kHz-phase angles in all the five body segments were significantly lower than the measured ones (all, p < 0.05). The findings suggest that the estimated impedance parameters, R, Xc, and phase angle of the trunk, were remarkedly underestimated, limiting the assessment of the physiological state of the organs in the body. Therefore, further intensive research is needed in the field of estimated segmental BIA in the future.

Individualized body geometry correction factor (KB) for use when predicting body composition from bioimpedance spectroscopy

OBJECTIVE

Prediction of body composition from bioimpedance spectroscopy (BIS) measurements using mixture theory-based biophysical modelling invokes a factor (K_B) to account for differing body geometry (or proportions) between individuals. To date, a single constant value is commonly used. The aim of this study was to investigate variation in KB across individuals and to develop a procedure for estimating an individualized K_Bvalue.

APPROACH

Publicly available body dimension data, primarily from the garment industry, were used to calculate K_Bvalues for individuals of varying body sizes across the life-span. The 3-D surface relationship between weight, height and K_B, was determined and used to create look-up tables to enable estimation of K_Bin individuals based on height and weight. The utility of the proposed method was assessed by comparing body composition predictions from BIS using either a constant K_Bvalue or the individualized value.

RESULTS

Computed KB values were well fitted to height and weight by a 3-D surface (R2 = 0.988). Body composition was predicted more accurately compared to reference methods when using individualized K_Bthan a constant value in infants and children but improvement in prediction was less in adults particularly those with high body mass index.

SIGNIFICANCE

Prediction of body composition from BIS and mixture theory is improved by using an individualized body proportion factor in those of small body habitus, e.g. children. Improvement is small in adults or non-existent in those of large body size. Further improvements may be possible by incorporating a factor to account for trunk size, i.e., waist circumference.

Reference Data of Phase Angle Using Bioelectrical Impedance Analysis in Overweight and Obese Chinese

INTRODUCTION

Phase angle (PhA) is a ratio of reactance and resistance {arctangent (reactance (Xc)/resistance (R)) × (180°/π)}, which can be obtained by bioelectrical impedance analysis (BIA). PhA indicates cellular health and integrity, and it is also considered as a prognostic tool in medical disorders and an indicator of nutritional status (especially of muscle quality) in patients with obesity. However, PhA has limited usefulness in clinical practice because of a lackness of reference values for Chinese overweight and obese populations. The main aim of this study was to show PhA reference data in different age and BMI groups by sex. In addition, we also study the association of age, sex, and BMI on PhA.

METHODS

A total of 1729 overweight and obese participants were included in this study. PhA and body composition were measured using segmental multifrequency BIA. Differences in mean values for variables were tested by one-way analysis of variance. Multiple regression analysis was used to assess the associations of PhA with age, sex and BMI.

RESULTS

Multiple regression analysis showed that age, sex and BMI were significant (P < 0.05) independent influence factors of PhA in Chinese overweight and obese adults when age and BMI were continues variables. The mean PhA value for all participants was 5.5°. Mean BMI, age, weight, height and 50kHz-PhA were significantly higher (P < 0.001) in male participants than female ones. In age groups and BMI groups, mean 50kHz-PhA was significantly higher (P < 0.005) in male participants than female ones. When age groups and BMI groups were categorical variables, multiple regression analysis showed that different age groups (46-55 years and ≥ 56 years) had a significantly lower (P < 0.005) PhA as compared with the baseline group (18-25 years) and different BMI groups (≥ 28 kg/m²) had a significantly higher (P < 0.05) PhA as compared with the baseline group (24-27.9 kg/m²).

CONCLUSION

PhA differed according to age, sex and BMI. Reference data in this study can be taken into consideration when deriving the reference values for overweight and obese Chinese populations.

Can Muscle Mass Be Maintained with A Simple Resistance Intervention in the Older People? A Cluster Randomized Controlled Trial in Thailand

The aging population is rapidly increasing worldwide. Sarcopenia is a common and important health problem among older people. The prevalence of sarcopenia among older Thai adults is increasing. Exercise intervention for sarcopenia prevention may significantly improve muscle strength, body balance, and muscle mass. Therefore, this study aimed to investigate the effects of a simple resistance intervention (SRI) program in preventing sarcopenia on physiological outcomes among community-dwelling older Thai adults. This study was a 12-week randomized controlled trial, which included 80 community-dwelling older adults in Chiang Mai, Thailand, who were randomly assigned into control (40 participants who performed usual exercise) and intervention (40 participants who performed the SRI program) groups. The SRI program was a home-based program consisting of 30 min of resistance exercise three times/week for 12 weeks, health education on sarcopenia. After 12 weeks, all physiological outcomes were measured and were significantly improved in the intervention group compared with baseline; hand grip, skeletal muscle mass index, and walking speed were significantly improved in the intervention group compared with the control group. Based on our results, the SRI program may prevent muscle weakness in community-dwelling older people in Thailand.

Differences of body composition and physical strength among Japanese and Thai older adults living in Chiang Mai, Thailand: an inter-ethnic cross-sectional study

BACKGROUND

The number of adults aged over 65 years is rapidly increasing in several Southeast Asian countries. Muscle mass decreases with age, leading to sarcopenia. The primary objective of this study was to determine whether differences exist in the body composition and physical strength, according to ethnicity, among community-dwelling Japanese and Thai older adults living in Chiang Mai Province, Thailand.

METHODS

A survey was conducted in February and March 2019. Japanese and Thai adults aged ≥ 60 years living in Chiang Mai Province were recruited through community clubs. Participants completed a self-administered questionnaire that enabled collection of data on age, sex, educational background, marital status, annual income, current medical conditions, smoking and alcohol consumption, and exercise habits. Measurements were collected on height, weight, body composition, blood pressure, hand grip, and walking speed for 6 m. Body composition was measured using a standing-posture 8-electrode multifrequency bioimpedance analysis analyzer. Hand grip of each hand was measured with the patient in the standing position using a digital grip dynamometer. Multivariable logistic regression was used to determine factors associated with skeletal muscle mass index (SMI).

RESULTS

Of the total 119 participants, 47 were Japanese (26 men, 21 women) and 72 were Thai (16 men, 56 women). The prevalence of a low SMI was 3/26 (12%), 1/21 (5%), 6/16 (38%), and 5/56 (9%) among Japanese men, Japanese women, Thai men, and Thai women, respectively. The prevalence of low muscle strength was 2/26 (8%), 2/21 (10%), 3/16 (19%), and 13/56 (23%) among Japanese men, Japanese women, Thai men, and Thai women, respectively. There were significant differences between ethnic groups in body mass index for both sexes, percentage body fat in women, SMI in men, and average grip strength in men. Ethnic group, sex, age, and body mass index were independent predictors of SMI.

CONCLUSIONS

Ethnicity had a clinically important effect on body composition and physical strength among older Japanese and Thai adults living in a similar environment.

Good performance of bioimpedance in early pregnancy to predict preeclampsia

INTRODUCTION

Preeclampsia (PE) affects 2-8% of pregnancies and is one of the main causes of maternal morbidity and mortality worldwide. Early identification of pregnant women at higher risk for PE would allow the use of interventions to reduce adverse maternal and perinatal outcomes.

OBJECTIVE

To assess the ability of bioelectrical impedance analysis (BIA) in pregnancy to predict the development of PE.

METHODS

This prospective cohort involved healthy nulliparas who underwent BIA at 17-20 weekś gestation and were followed until delivery. We used univariate and multivariate logistic regression to assess the ability of BIA measures to predict the occurrence of PE. We used an adjusted regression model to estimate the probability of developing PE, the Hosmer-Lemeshow test to assess the adequacy of the final model, and ROC curves to assess the sensitivity and specificity of different BIA measures in the prediction of PE.

RESULTS

Twelve (6.1%) of the 196 participants developed PE. In the final multivariate model, the following BIA measures were associated with the occurrence of PE: extracellular water/intracellular water ≤ 0.618, skeletal muscle mass ≥ 25 Kg, and body fat percentage ≥ 44%. The combination of these three measures had a predictive accuracy of 83.7%, a sensitivity of 83.3%, a specificity of 83.7%, and a negative predictive value of 98.7% for PE.

CONCLUSION

BIA done on nulliparous women at 17-20 weekś gestation has a good accuracy and high negative predictive value for the risk of developing PE.

Iron Beats Electricity: Resistance Training but Not Whole-Body Electromyostimulation Improves Cardiometabolic Health in Obese Metabolic Syndrome Patients during Caloric Restriction-A Randomized-Controlled Study

Caloric restriction (CR) and exercise are cornerstones in the treatment of obesity and cardiometabolic disorders. Recently, whole body electromyostimulation (WB-EMS) has emerged as a more time-efficient alternative to traditional resistance training (RT). However, the effects of WB-EMS compared to RT on cardiometabolic health in obese metabolic syndrome (MetS) patients performed during CR are still unclear. In total, 118 obese MetS patients (52.7 ± 11.8 years, BMI: 38.1 ± 6.9 kg/m²) undergoing CR over 12 weeks (aim: −500 kcal deficit/day) were randomly allocated to either WB-EMS, single-set RT (1-RT), 3-set RT (3-RT) or an inactive control group (CON). Primary outcome was MetS severity (MetS z-score). Secondary outcomes were body composition, muscle strength and quality of life (QoL). All groups significantly reduced body weight (~3%) and fat mass (~2.6 kg) but only 1-RT and 3-RT preserved skeletal muscle mass (SMM). All exercise groups increased muscle strength in major muscle groups (20–103%). However, only the two RT-groups improved MetS z-score (1-RT: −1.34, p = 0.003; 3-RT: −2.06, p < 0.001) and QoL (1-RT: +6%, p = 0.027; 3-RT: +12%, p < 0.001), while WB-EMS and CON had no impact on these outcomes. We conclude that traditional RT has superior effects on cardiometabolic health, SMM and QoL in obese MetS patients undergoing CR than WB-EMS.

Bioimpedance analysis as a tool for hemodynamic monitoring: overview, methods and challenges

Recent advances in hemodynamic monitoring have seen the advent of non-invasive methods which offer ease of application and improve patient comfort. Bioimpedance Analysis or BIA is one of the currently employed non-invasive techniques for hemodynamic monitoring. Impedance Cardiography (ICG), one of the implementations of BIA, is widely used as a non-invasive procedure for estimating hemodynamic parameters such as stroke volume (SV) and cardiac output (CO). Even though BIA is not a new diagnostic technique, it has failed to gain consensus as a reliable measure of hemodynamic parameters. Several devices have emerged for estimating CO using ICG which are based on evolving methodologies and techniques to calculate SV. However, the calculations are generally dependent on the electrode configurations (whole body, segmental or localised) as well as the accuracy of different techniques in tracking blood flow changes. Blood volume changes, concentration of red blood cells, pulsatile velocity profile and ambient temperature contribute to the overall conductivity of blood and hence its impedance response during flow. There is a growing interest in investigating limbs for localised BIA to estimate hemodynamic parameters such as pulse wave velocity. As such, this paper summarises the current state of hemodynamic monitoring through BIA in terms of different configurations and devices in the market. The conductivity of blood flow has been emphasized with contributions from both volume and velocity changes during flow. Recommendations for using BIA in hemodynamic monitoring have been mentioned highlighting the suitable range of frequencies (1 kHz-1 MHz) as well as safety considerations for a BIA setup. Finally, current challenges in using BIA such as geometry assumption and inaccuracies have been discussed while mentioning potential advantages of a multi-frequency analysis to cover all the major contributors to blood's impedance response during flow.

Phase Angle Cut-Off Points and Their Association With Sarcopenia and Frailty in Adults of 50-64 Years Old and Older Adults in Mexico City

Background: In recent studies, the usefulness of the phase angle (PA) to assess geriatric conditions such as sarcopenia and frailty has been evaluated. However, there are no useful cut-off points for clinical research and/or practice. Objective: To analyze PA cut-off points associated with sarcopenia and frailty in adults of 50-64 years old and older adults in Mexico City. Design: Cross-sectional analysis of the FraDySMex cohort study (Frailty, Dynapenia, and Sarcopenia in Mexican Adults). Setting and Participants: 498 people were included, 78.7% women, aged 71.1 ± 9.5 years. Methods: The sarcopenia measurements were made according to the European Working Group on Sarcopenia in Older People (EWGSOP) (2019) (by dynamometer to evaluate hand grip strength and dual energy X-ray absorptiometry (DXA) for appendicular muscle mass), and the frailty through the physical frailty phenotype with cut-off points adjusted to the Mexican population. The PA was evaluated by bioelectrical impedance analysis (BIA), tetrapolar to 50 Hz, other variables such as socio-demographic, comorbidity, cognitive status, and functional dependence were evaluated. Results: The prevalence of frailty was 10.6% and sarcopenia 10.0%. The mean of the PA was 4.6° ± 0.70°. The PA cut-off point for frailty in adults 50 to 64 years was ≤4.3° [sensitivity (S) = 91.95%, specificity (Sp) 66.77%, AUROC (Area Under the Receiver Operating Characteristic) curve = 0.9273 95% CI (0.8720-0.9825)]; the PA cut-off point for sarcopenia was ≤4.3 [S = 91.95%, Sp = 66.77%, AUROC = 0.9306 95% CI (0.8508-1.000)]. The PA cut-off for frailty in adults ≥ 65 years was ≤4.1° [S = 72.37%, Sp 71.43%, AUROC = 0.7925 95%, CI (0.7280-0.8568)] for sarcopenia was ≤4.1° [S = 72.76%, Sp 73.81%, AUROC = 0.7930 95% CI (0.7272-0.8587)]. These cut-off points showed a significant association between PA with frailty (OR 4.84; 95% CI 2.61-8.99) and sarcopenia (OR 8.44; 95% CI 3.85-18.4) after adjusted by age, sex, BMI, comorbidity index and cognitive impairment. Conclusions and Implications: These cut-off points of PA could be useful for the screening of sarcopenia and frailty in Mexican adults of 50 years and older in centers that have BIA.

Segmental body composition estimated by specific BIVA and dual-energy X-ray absorptiometry

AIMS

The aim of this study was to analyse the association between specific bioelectric impedance vector analysis (BIVA) and dual-energy X-ray absorptiometry (DXA) to assess segmental body composition using DXA as the reference technique.

METHODS

The sample comprised 50 young active students who practised or played different sports (25 men, age: 24.37 ± 4.79 y; 25 women, age: 24.32 ± 4.43 y) from the National Institute of Physical Education of Catalonia (INEFC). Anthropometric data (height, weight, arm, waist, and calf circumferences) and bioelectrical measurements (R, ohm; Xc, ohm) were recorded. Body composition was analysed with specific BIVA. DXA was used as the reference method to assess body composition of the whole-body, the trunk, and the limbs. The percentage of fat mass (%FM_DXA) and fat-free mass index (FFMI_DXA = FFM/length²) were calculated. The agreement between specific BIVA and DXA was evaluated by a depth-depth analysis, two-way ANOVA, and Pearson's correlations.

RESULTS

The depth-depth analysis showed a good agreement between DXA and BIVA (F = 14.89, p < 0.001) in both sexes and all body segments. Specific vector length (Zsp; i.e. indicative of %FM) was correlated with %FM_DXA in the whole body and all body segments, and the phase angle was correlated with FFMI_DXA, with he trunk in women as the only exception. Specific BIVA demonstrated to balance the effect of body size on bioelectrical measurements in both whole and segmental approaches.

CONCLUSIONS

Segmental specific BIVA and DXA provided a consistent evaluation of body composition in both sexes, of the whole body and each body segment. The indices %FM and FFMI obtained with DXA were correlated to vector length and phase angle in each segment, respectively. Specific BIVA represents a promising technique for monitoring segmental body composition changes in sport science and clinical applications.

Feasibility of segmental bioelectrical impedance analysis for mild- to moderate-degree breast cancer-related lymphedema: Correlation with circumferential volume measurement and phase angle

ABSTRACT

Segmental multi-frequency bioelectrical impedance analysis (s-MFBIA) has been adopted recently to evaluate the volume of breast cancer-related lymphedema (BCRL). This procedure uses the segmental phase angle (s-PhA) as an indicator of cellular integrity. In the smaller-built Asian population, the BCRL often has a small volume difference and can be overlooked by tape circumference volume measurement (TVM). This study aimed to investigate the clinical feasibility of s-MFBIA for the assessment of lymphedema severity compared with TVM and evaluate the association between lymphedema severity and cellular integrity of the affected arm based on s-PhA values for a patient with mild- to moderate-degree BCRL.Segmental PhA and extracellular water (ECW)/total body water (TBW) ratio of bilateral arms were measured using InBody S10, an s-MFBIA device, in 128 BCRL patients. Inter-limb volume ratio was measured using TVM. The inter-limb ECW/TBW ratio was correlated with inter-limb volume ratio. Inter-limb ECW/TBW ratio and inter-limb volume ratio were then correlated with inter-limb PhA ratio to demonstrate the association between lymphedema severity and arm cellular integrity.The inter-limb ECW/TBW ratio and inter-limb volume ratio were positively correlated (r = 0.654, P < .001). The same result was obtained after adjusting for age, body mass index, postoperative survival, and duration of lymphedema (r = 0.636, 0.653, 0.652, and 0.648, P < .001). The inter-limb PhA ratio demonstrated significant negative correlation with inter-limb ECW/TBW ratio and inter-limb volume ratio (r = -0.896, -0.562, P < .001).s-MFBIA has high consistency with the conventional TVM method, and its relation to cellular integrity by segmental PhA enables better understanding of the cellular state of the affected limb in mild- to moderate-degree BCRL. Therefore, it is clinically feasible for severity assessment and monitoring of mild- to moderate-degree BCRL in smaller-built Asian patients.

Bilateral Asymmetries Assessment in Elite and Sub-Elite Male Futsal Players

This study aimed to investigate morphological, functional, and neuromuscular asymmetries on futsal players’ lower limbs at different competitive levels. Sixteen male elite futsal players from the Spanish National Futsal League and thirteen male sub-elite futsal players from the third division participated in this study. Morphological asymmetry was assessed through bioelectrical impedance (fat-mass (g and %) and lean-mass (g)). Functional asymmetry was assessed by means of a 20-s static unipedal balance test. Finally, neuromuscular asymmetry was assessed using tensiomiography tests on both the rectus femoris (RF) and biceps femoris (BF) of each participant. The three tests conducted did not reveal significant bilateral asymmetries in elite players. On the other hand, sub-elite players showed significant bilateral asymmetry in fat-mass percentage between dominant and non-dominant limbs (+6%; CI95%: 1 to 11; ES: 0.88; p = 0.019). They also showed higher bilateral asymmetry in the delay time of the RF (+13%; CI95%: 7 to 21; ES: 1.3; p < 0.05). However, the static unipedal balance test (p > 0.05) did not evidence asymmetries regardless of the level of the participants. Elite futsal players do not develop bilateral asymmetries in lower limbs in the studied parameters. On the contrary, sub-elite players are likely to develop morphological and neuromuscular asymmetries between their dominant leg and non-dominant leg.

Development of a Segmental Bioelectrical Impedance Spectroscopy Device for Body Composition Measurement

Whole-body bioelectrical impedance analysis for measuring body composition has been well-explored but may not be sensitive enough to changes in the trunk compared to changes in the limbs. Measuring individual body segments can address this issue. A segmental bioelectrical impedance spectroscopy device (SBISD) was designed for body composition measurement and a prototype was implemented. Compensation was performed to adjust the measured values to correct for a phase difference at high frequencies and to counteract the hook effect when measuring the human body. The SBISD was used to measure five subjects and was compared against three existing analyzers. For most segmental measurements, the SBISD was within 10% of the R₀ and R_∞ values determined with a Bodystat Multiscan 5000 and an Impedimed SFB7. The impedance values from the third reference device, a Seca 514, differed significantly due to its eight-electrode measuring technique, meaning impedance measurements could not be compared directly.

Chronic Standing Desk Use and Arterial Stiffness

Background: Sedentary activity and sitting for at least 10 hours per day can increase the risk for cardiovascular disease by more than 60%. Use of standing desks may decrease sedentary time and improve cardiovascular health. Acute standing lowers pulse wave velocity (PWV), but chronic effects remain unknown. The purpose of this study was to determine the effect of chronic standing desk use on arterial stiffness versus seated controls. Methods: A total of 48 adults participated in this study. Twenty-four participants qualified as seated desk users (age 41 [10] y, body mass index 25 [4] kg/m2) and 24 as standing desk users (age 45 [12] y, body mass index 25 [5] kg/m2). Arterial stiffness was assessed as PWV within the aorta, arm, and leg. Results: Carotid–femoral PWV (cfPWV) was not different between seated (6.6 [1.3] m/s) and standing (6.9 [1.3] m/s) groups (P = .47). Similarly, there were no differences in arm or leg PWV between groups (P = .13 and P = .66, respectively). A secondary analysis of traditional factors of age and aerobic fitness revealed significant differences in cfPWV in seated and standing desk participants. Age also significantly influenced cfPWV across conditions. Conclusions: Standing for >50% of a workday did not affect PWV. Consistent with previous research, fitness and age are important modulators of arterial stiffness.

Evaluation of one year of frequent dialysis on fluid load and body composition using calf bioimpedance technique

OBJECTIVE

The primary aim of this study was to evaluate the effect of increased frequency of dialysis (FHD) on change in fluid status and body composition using segmental bioimpedance.

APPROACH

Twelve stable HD patients were switched from 3 times/week to 6 times/week HD (FHD). Systolic blood pressure (SBP), body mass and body mass index (BMI) were measured pre- and post-HD. Calf resistance (R ₅) at 5 kHz was measured using a multifrequency bioimpedance device (Hydra 4200). Calf resistivity (ρ  =  R ₅ * area/length), normalized resistivity (CNR  =  ρ/BMI) and calf extracellular volume (cECV) were calculated. Fat mass was measured by Futrex body composition analyzers (Futrex 6100, Futrex Tech, Inc.). All measurements were performed at baseline (BL) and monthly for up to one year.

MAIN RESULTS

Nine patients completed one year of FHD. Compared to BL, body weight and cECV decreased, and CNR increased significantly by the first month but did not change thereafter. SBP pre-HD decreased significantly by the end of the first month with further reduction until month 12. Additionally, antihypertensive medication decreased significantly from baseline by month 4 and remained stable from month 6 throughout the rest of the study. The post-HD CNR in five of nine patients reached the range of normal (>18.5 10^-2 * Ohm * m³ kg^-1 for males and  >19.1 10^-2 * Ohm * m³ kg^-1 for females) after 1 year FHD. In patients who returned to 3 times/week dialysis, CNR decreased significantly in the first week, and this was associated with increases in body weight and SBP.

SIGNIFICANCE

Reduction of fluid overload with no alteration of body composition was observed in this study. Accordingly, improving fluid status was confirmed by reducing BP and use of antihypertensive drugs together with increase in CNR. Measurement of fluid status by CNR in hemodialysis patients is a new method to quantitatively assess hydration potentially creating a target for volume of fluid removal.

Assessment of Plasma Resistivity as a Surrogate for Extracellular Fluid Resistivity: Analytical Performance and Impact of Fluid Composition

Bio-electrical impedance analysis (BIA) is frequently used to assess body composition in man. Its accuracy in patients is limited, possibly because the employed algorithms are based on the assumption that total body electrical resistance (TBER) is exclusively related to body water volume, and that variation in fluid composition and its effect on fluid resistivity can be ignored. This may introduce substantial calculation errors. The aim of this study was to develop an objective method to assess plasma resistivity (ρ_plasma) based on measurements by a conductivity probe, as a surrogate for extracellular fluid resistivity (ρ_e). Sample measurements were standardized at body temperature. Analytical variation was 0.6% within runs and 0.9% between runs. The critical difference, i.e. the smallest difference needed to consider changes within individuals significant, was 1.8% for measurements within runs and 4.3% for measurements between runs. The normal range was defined by a mean ± SD of 66.9 ± 1.8 Ω cm. Multiple regression demonstrated that ρ_plasma was inversely related to plasma sodium and chloride concentrations, and positively related to total protein (overall R² = 0.92, p < 0.001). In conclusion, ρ_plasma measurements were sufficiently robust to be useful as a tool to examine and improve the validity of BIA in clinical settings.

Predictors of Discordance in the Assessment of Skeletal Muscle Mass between Computed Tomography and Bioimpedance Analysis

Computed tomography (CT) and bioimpedance analysis (BIA) can assess skeletal muscle mass (SMM). Our objective was to identify the predictors of discordance between CT and BIA in assessing SMM. Participants who received a comprehensive medical health check-up between 2010 and 2018 were recruited. The CT and BIA-based diagnostic criteria for low SMM are as follows: Defined CT cutoff values (lumbar skeletal muscle index (LSMI) <1 standard deviation (SD) and means of 46.12 cm²/m² for men and 34.18 cm²/m² for women) and defined BIA cutoff values (appendicular skeletal muscle/height² <7.0 kg/m² for men and <5.7 kg/m² for women). A total of 1163 subjects were selected. The crude and body mass index (BMI)-adjusted SMM assessed by CT were significantly associated with those assessed by BIA (correlation coefficient = 0.78 and 0.68, respectively; p < 0.001). The prevalence of low SMM was 15.1% by CT and 16.4% by BIA. Low SMM diagnosed by CT was significantly associated with advanced age, female gender, and lower serum albumin level, whereas low SMM diagnosed by BIA was significantly associated with advanced age, female gender, and lower BMI (all p < 0.05). Upon multivariate analysis, age >65 years, female and BMI <25 kg/m² had significantly higher risks of discordance than their counterparts (all p < 0.05). We found a significant association between SMM assessed by CT and BIA. SMM assessment using CT and BIA should be interpreted cautiously in older adults (>65 years of age), female and BMI <25 kg/m².

Bioelectrical impedance analysis for body composition assessment: reflections on accuracy, clinical utility, and standardisation

Bioelectrical impedance analysis is an extremely popular method for assessment of body composition. Despite its wide-spread use over the past thirty years, its accuracy and clinical value is still questioned. Most frequently, criticisms focus on its purported poor absolute accuracy and that different impedance analysers or prediction equations fail to measure body composition identically. This perspective review highlights that the magnitude of errors associated with impedance methods are not dissimilar to those observed for so-called gold standard methods. It is argued that the focus on statistically significant but small differences between methods can obscure operational equivalence and that such differences may be of minor clinical significance. Finally, the need for better standardization of protocols and the need for consensus on what is a minimal clinically important difference between methods is highlighted.

Body weight difference between dual-energy X-ray absorptiometry and multi-frequency bioelectrical impedance analysis attenuates the equivalence of body-composition assessment

BACKGROUND/OBJECTIVES

Low agreement of body-composition analysis (BCA) using dual-energy X-ray absorptiometry (DXA) and multi-frequency bioelectrical impedance analysis (MF-BIA) has been reported. We examined whether this discrepancy is influenced by the precision of body weight (BW) measurement using DXA.

SUBJECTS/METHODS

This cross-sectional study enrolled 1353 participants aged 53-83 years. A whole-body DXA scan and an eight-polar tactile-electrode impedance-meter using four electronic frequencies of 5, 50, 250, and 500 kHz were employed for BCA. The level of agreement between BW estimated using DXA and actual BW (WgtA) was calculated. The agreement of BCA parameters using DXA and MF-BIA across WgtA groups was also assessed.

RESULTS

DXA incorrectly estimated BW, especially in men. In total, 13.5%, 5.1%, and 5.6% of the participants had BW bias levels of 2%, 3%, and ≥4%, respectively. Correlations of BCA parameters measured using DXA and MF-BIA, including body fat mass, percent body fat, and lean body mass (LBM), were gradually reduced, whereas the root mean square error was increased in accordance with the reduction in WgtA. DXA provided a lower LBM amount compared to MF-BIA and this difference increased significantly across groups with poor WgtA.

CONCLUSIONS

Lower WgtA greatly contributed to the difference in BCA measured using DXA and MF-BIA.

Electrical Properties Assessed by Bioelectrical Impedance Spectroscopy as Biomarkers of Age-related Loss of Skeletal Muscle Quantity and Quality

Skeletal muscle, in addition to being comprised of a heterogeneous muscle fiber population, also includes extracellular components that do not contribute to positive tensional force production. Here we test segmental bioelectrical impedance spectroscopy (S-BIS) to assess muscle intracellular mass and composition. S-BIS can evaluate electrical properties that may be related to muscle force production. Muscle fiber membranes separate the intracellular components from the extracellular environment and consist of lipid bilayers which act as an electrical capacitor. We found that S-BIS measures accounted for ~85% of the age-related decrease in appendicular muscle power compared with only ~49% for dual-energy x-ray absorptiometry (DXA) measures. Indices of extracellular (noncontractile) and cellular (contractile) compartments in skeletal muscle tissues were determined using the Cole-Cole plot from S-BIS measures. Characteristic frequency, membrane capacitance, and phase angle determined by Cole-Cole analysis together presented a S-BIS complex model that explained ~79% of interindividual variance of leg muscle power. This finding underscores the value of S-BIS to measure muscle composition rather than lean mass as measured by DXA and suggests that S-BIS should be highly informative in skeletal muscle physiology.

Developing and Validating an Age-Independent Equation Using Multi-Frequency Bioelectrical Impedance Analysis for Estimation of Appendicular Skeletal Muscle Mass and Establishing a Cutoff for Sarcopenia

Background: Appendicular skeletal muscle (or lean) mass (ALM) estimated using dual-energy X-ray absorptiometry (DXA) is considered to be a preferred method for sarcopenia studies. However, DXA is expensive, has limited portability, and requires radiation exposure. Bioelectrical impedance analysis (BIA) is inexpensive, easy to use, and portable; thus BIA might be useful in sarcopenia investigations. However, a large variety of models have been commercially supplied by different companies, and for most consumer products, the equations estimating ALM are not disclosed. It is therefore difficult to use these equations for research purposes. In particular, the BIA equation is often age-dependent, which leads to fundamental difficulty in examining age-related ALM loss. The aims of the current study were as follows: (1) to develop and validate an equation to estimate ALM using multi-frequency BIA (MF-BIA) based on theoretical models, and (2) to establish sarcopenia cutoff values using the equation for the Japanese population. Methods: We measured height (Ht), weight, and ALM obtained using DXA and a standing-posture 8-electrode MF-BIA (5, 50, 250 kHz) in 756 Japanese individuals aged 18 to 86-years-old (222 men and 301 women as developing equation group and 97 men and 136 women as a cross validation group). The traditional impedance index (Ht²/Z₅₀) and impedance ratio of high and low frequency (Z₂₅₀/Z₅) of hand to foot values were calculated. Multiple regression analyses were conducted with ALM as dependent variable in men and women separately. Results: We created the following equations: ALM = (0.6947 × (Ht²/Z₅₀)) + (-55.24 × (Z₂₅₀/Z₅)) + (-10,940 × (1/Z₅₀)) + 51.33 for men, and ALM = (0.6144 × (Ht²/Z₅₀)) + (-36.61 × (Z₂₅₀/Z₅)) + (-9332 × (1/Z₅₀)) + 37.91 for women. Additionally, we conducted measurements in 1624 men and 1368 women aged 18 to 40 years to establish sarcopenia cutoff values in the Japanese population. The mean values minus 2 standard deviations of the skeletal muscle mass index (ALM/Ht²) in these participants were 6.8 and 5.7 kg/m² in men and women, respectively. Conclusion: The current study established and validated a theoretical and age-independent equation using MF-BIA to estimate ALM and provided reasonable sarcopenia cutoff values.

Bioimpedance to screen for abdominal fat in patients with breast cancer treatment-related lymphedema

BACKGROUND

One of the dreaded complications after the treatment of breast cancer is lymphedema. Therapies used in the treatment of breast cancer such as surgery, radiotherapy, hormone therapy and chemotherapy may be adversely affected by obesity.

AIM

The objective of this study was to use bioimpedance to assess abdominal fat in women with breast cancer treatment-related lymphedema and suggest this as a screening method.

METHODS

Forty-five female patients with clinical diagnosis of breast cancer treatment-related lymphedema were evaluated in this quantitative cross-sectional study. A control group, composed of 38 patients with varicose veins and women attending a social support group, was matched for age and body mass index (BMI). All participants were submitted to a bioimpedance evaluation (In Body S 10), with particular attention being paid to abdominal fat and their BMI. The unpaired t -test, Fisher Exact test and Mann-Whitney test were used for statistical analysis and an alpha error of 5%.

RESULTS

There was no significant difference (p -value = 0.23) in the mean BMI between the study group (27.79 kg∕m2) and the control group (28.80 kg∕m2). The mean abdominal circumference, a measure of abdominal fat, of the women in the study group was 130.54 cm2 and for the control group it was 102.24 cm2 (p -value = 0.0037). Thus the study group had more abdominal fat (p -value = 0.0003). Moreover, on comparing obese patients in the two groups, the study group had more abdominal fat (p -value = 0.02). However, no significant difference was observed comparing non-obese patients (p -value = 0.6). The comparison of obese patients with non-obese patients in the control group identifies an association between obesity and abdominal fat (p -value < 0.04).

CONCLUSION

Overweight and obese women with breast cancer treatment-related lymphedema are more likely to have increased abdominal fat than the general population with bioimpedance.