Within-day variability of whole-body and segmental bioelectrical impedance in a standing position

Cook with Different Pots, but Similar Taste? Comparison of Phase Angle Using Bioelectrical Impedance Analysis According to Device Type and Examination Posture

Bioelectrical impedance analysis (BIA) is gaining popularity as a tool for body composition assessment. Although BIA has been studied and validated in different populations, age groups, and clinical settings, including critically ill patients, there are concerns about BIA reproducibility and reliability for different device types and postures. This study aimed to evaluate the reliability of BIA using different devices, postures, and lead types. Cross-sectional observational data were collected from 74 healthy volunteers (32 women, 42 men). We used two types of devices, three types of postures (standing, sitting, and lying), and two lead types (clamp lead and adhesive lead) to measure the whole-body phase angle (phA) at a single frequency of 50 kHz. The measurements were validated using the intraclass correlation coefficient (ICC) and Bland-Altman plot analysis. All phA measurements recorded using the two types of devices, three different postures, and two types of leads were equivalent (mean ICC = 0.9932, 95% confidence interval (CI) 0.9905-0.0053, p < 0.001). The average mean difference in phA was 0.31 (95% CI 0.16-0.46). The largest phA value was measured using BWA with an adhesive-type lead in the supine position. There were no differences between the standing and sitting positions. We compared the consistency and reliability of phA using two devices, two lead types, and three postures. Seven different phA were interchangeable in healthy volunteers.

Comparison of Dual-Energy X-ray Absorptiometry and Bioelectrical Impedance Analysis in the Assessment of Body Composition in Women with Anorexia Nervosa upon Admission and Discharge from an Inpatient Specialist Unit

Assessment of body composition is fundamental in diagnosis and treatment of anorexia nervosa (AN). The gold standard dual-energy X-ray absorptiometry (DXA) is expensive and not universally available. Bioelectrical impedance analysis (BIA) is a non-invasive, inexpensive method relative to DXA. We compared DXA and BIA in the assessment of fat-free mass (FFM), fat mass (FM), and body fat percentage (BF%) in women with AN upon admission (ANT1) and discharge (ANT2) from an inpatient specialist unit with a referent healthy control (HC) group. The study population consisted of 31 ANT1, 25 ANT2, and 52 HC women with median age of 21 years. Body composition was measured by DXA and Tanita foot-to-foot BIA. Comparison between the two methods was done using Bland–Altman analysis, Pearson’s correlation coefficient, Lin’s concordance correlation coefficient, and linear regression. The mean difference (bias) in FM and BF% values obtained by DXA and BIA in ANT1 (FM: +1.01 kg, BF%: +2.26%) and ANT2 (FM: +1.49 kg, BF%: +1.66%) were comparable to HC (FM: −1.32 kg, BF%: −2.29%) although in opposite directions. Less bias was observed in FFM values in ANT1 (−0.46 kg) and ANT2 (−0.86 kg) than in HC (+2.03 kg); however, the limits of agreement between the two methods were wider in ANT1 and ANT2 than in HC for all measurements. No association was observed between age, percentage of total body water, and the time spent on the inpatient specialist unit with the difference in estimates of body composition between DXA and BIA. Comparison of DXA and BIA suggests that DXA should remain the gold standard for measuring body composition; the development of more specific BIA equations is required to improve validity and precision of BIA in patients with AN. Despite ease and cost in both BIA access and operation, the suitability of BIA in a low bodyweight eating disorders population remains questionable.

Prediction and discrimination of skeletal muscle function by bioelectrical impedance vector analysis using a standing impedance analyzer in healthy Taiwanese adults

Background

Bioelectrical impedance vector analysis (BIVA) has been used for prediction of muscle performance. However, little is known about BIVA in Asian adults, and even less is known about using standing BIVA devices. Standing impedance analyzer allows quicker and more convenient way to gather data than conventional supine analyzer and is more suitable for clinical practice. This study aimed to investigate the relations between muscle function and BIVA parameters measured with a standing impedance analyzer in healthy Taiwanese adults.

Methods

A total of 406 healthy subjects (age 34.5 ± 17.3 years, body mass index 24.1 ± 4.1 kg/m²) were recruited for BIVA and handgrip strength (HGS) measurements. Impedance parameters, including resistance (R) and reactance (Xc), were measured and normalized to body size by dividing by height (H). The resulting phase angle (PhA) was calculated. HGS in the dominant, left, and right hands were referred to as HGS_DH, HGS_LH, and HGS_RH, respectively. All subjects were divided into 5 grades according to HGS.

Results

Muscle strength in the dominant, right, and left arms was correlated with variables in the order of sex, weight, age, height, Xc/H, and R/H (all, p < 0.001). Using all 6 variables, the determination coefficients were 0.792, 0.782, and 0.745, respectively, whereas the standard errors of estimates were 56.89, 58.01, and 56.67 N for HGS_DH, HGS_LH, and HGS_RH, respectively. HGS was positively correlated with PhA, and negatively correlated with Xc/H and R/H.

Conclusions

BIVA parameters measured with a standing impedance analyzer and anthropometric variables can predict and discriminate muscle function with good performance in healthy Asian adults.

Comparison of Bioelectrical Impedance Analysis and Dual Energy X-ray Absorptiometry for Total and Segmental Bone Mineral Content with a Three-Compartment Model

Modern bioelectrical impedance analysis (BIA) provides a wide range of body composition estimates such as fat mass (FM), lean body mass (LBM), and body water, using specific algorithms. Assuming that the fat free mass (FFM) and LBM can be accurately estimated by the 8-electrode BIA analyzer (BIA_8MF; InBody230, Biospace), the bone mineral content (BMC) may be calculated by subtracting the LBM from the FFM estimates based on the three-compartment (3C) model. In this cross-sectional study, 239 healthy Taiwanese adults (106 male and 133 female) aged 20-45 years were recruited for BIA and dual-energy X-ray absorptiometry (DXA) measurements of the whole body and body segments, with DXA as the reference. The results showed a high correlation between BIA_8MF and DXA in estimating total and segmental LBM, FM and percentage body fat (r = 0.909-0.986, 0.757-0.964, and 0.837-0.936, respectively). For BMC estimates, moderate to high correlations (r = 0.425-0.829) between the two methods were noted. The percentage errors and pure errors for BMC estimates between the methods ranged from 33.9% to 93.0% and from 0.159 kg to 0.969 kg, respectively. This study validated that BIA_8MF can accurately assesses LBM, FM and body fat percentage (BF%). However, the estimation of segmental BMC based on the difference between FFM and LBM in body segments may not be reliable by BIA_8MF.

Effects of procedure, upright equilibrium time, sex and BMI on the precision of body fluid measurements using bioelectrical impedance analysis

BACKGROUND/OBJECTIVES

Extensive work has addressed the validity of bioimpedance (BIA) measurements and the effect of posture on fluid homeostasis. However, limited research has investigated effects of subject preparation. This study aimed to determine the precision of total body water (TBW) and extracellular water (ECW) measurements using a stand-on multifrequency BIA (MFBIA seca mBCA 514/515), in three pre-test procedures: supine, sitting, and following walking, with specific reference to the influence of sex and body mass index (BMI).

SUBJECTS/METHODS

Fifty three healthy, ambulatory men (n=26, age:32.5±9.4 years) and women (n=27, age:35.2±10.3 years) received repeat MFBIA measurements (six measurements from 0 to 15 min). Agreement and precision were evaluated for each condition and paired time points.

RESULTS

Significant TBW sex differences from supine posture were observed for walking (females) and sitting (males) postures. For BMI (⩽24.9 kg m^-2) significant TBW differences from supine were observed for both sitting and walking and significant ECW differences from sitting were also observed with both supine and walking. There was no significant effect of sex or BMI (⩾25.0 kg m^-2) on ECW measures. Irrespective of sex or BMI, there was close agreement in TBW and ECW precision over the three protocols.

CONCLUSIONS

Practitioners can have confidence in the precision of TBW and ECW measurements within a 15 min time period and pre-testing conditions (supine, sitting or walking) in healthy subjects, though must be cautious in assessments when pre-test postures change. Further research to examine the impact of pre-testing procedures on stand-on MFBIA BIA measurements, including subjects with fluid disturbance, is warranted.

Hand-to-Hand Model for Bioelectrical Impedance Analysis to Estimate Fat Free Mass in a Healthy Population

This study aimed to establish a hand-to-hand (HH) model for bioelectrical impedance analysis (BIA) fat free mass (FFM) estimation by comparing with a standing position hand-to-foot (HF) BIA model and dual energy X-ray absorptiometry (DXA); we also verified the reliability of the newly developed model. A total of 704 healthy Chinese individuals (403 men and 301 women) participated. FFM (FFM_DXA) reference variables were measured using DXA and segmental BIA. Further, regression analysis, Bland–Altman plots, and cross-validation (2/3 participants as the modeling group, 1/3 as the validation group; three turns were repeated for validation grouping) were conducted to compare tests of agreement with FFM_DXA reference variables. In male participants, the hand-to-hand BIA model estimation equation was calculated as follows: FFM^m_HH = 0.537 h²/Z_HH − 0.126 year + 0.217 weight + 18.235 (r² = 0.919, standard estimate of error (SEE) = 2.164 kg, n = 269). The mean validated correlation coefficients and limits of agreement (LOAs) of the Bland–Altman analysis of the calculated values for FFM^m_HH and FFM_DXA were 0.958 and −4.369–4.343 kg, respectively, for hand-to-foot BIA model measurements for men; the FFM (FFM^m_HF) and FFM_DXA were 0.958 and −4.356–4.375 kg, respectively. The hand-to-hand BIA model estimating equation for female participants was FFM^F_HH = 0.615 h²/Z_HH − 0.144 year + 0.132 weight + 16.507 (r² = 0.870, SEE = 1.884 kg, n = 201); the three mean validated correlation coefficient and LOA for the hand-to-foot BIA model measurements for female participants (FFM^F_HH and FFM_DXA) were 0.929 and −3.880–3.886 kg, respectively. The FFM_HF and FFM_DXA were 0.942 and −3.511–3.489 kg, respectively. The results of both hand-to-hand and hand-to-foot BIA models demonstrated similar reliability, and the hand-to-hand BIA models are practical for assessing FFM.

Comparison of Standing Posture Bioelectrical Impedance Analysis with DXA for Body Composition in a Large, Healthy Chinese Population

Bioelectrical impedance analysis (BIA) is a common method for assessing body composition in research and clinical trials. BIA is convenient but when compared with other reference methods, the results have been inconclusive. The level of obesity degree in subjects is considered to be an important factor affecting the accuracy of the measurements. A total of 711 participants were recruited in Taiwan and were sub-grouped by gender and levels of adiposity. Regression analysis and Bland-Altman analysis were used to evaluate the agreement of the measured body fat percentage (BF%) between BIA and DXA. The BF% measured by the DXA and BIA methods (Tanita BC-418) were expressed as BF%DXA and BF%BIA8, respectively. A one-way ANOVA was used to test the differences in BF% measurements by gender and levels of adiposity. The estimated BF%BIA8 and BF%DXA in the all subjects, male and female groups were all highly correlated (r = 0.934, 0.901, 0.916, all P< 0.001). The average estimated BF%BIA8 (22.54 ± 9.48%) was significantly lower than the average BF%DXA (26.26 ± 11.18%). The BF%BIA8 was overestimated in the male subgroup (BF%DXA< 15%), compared to BF%DXA by 0.45%, respectively. In the other subgroups, the BF%BIA8 values were all underestimated. Standing BIA estimating body fat percentage in Chinese participants have a high correlation, but underestimated on normal and high obesity degree in both male and female subjects.

Body composition and functional assessment of nutritional status in adults: a narrative review of imaging, impedance, strength and functional techniques

The accurate and valid assessment of body composition is essential for the diagnostic evaluation of nutritional status, identifying relevant outcome measures, and determining the effectiveness of current and future nutritional interventions. Developments in technology and our understanding of the influences of body composition on risk and outcome will provide practitioners with new opportunities to enhance current practice and to lead future improvements in practice. This is the second of a two-part narrative review that aims to critically evaluate body composition methodology in diverse adult populations, with a primary focus on its use in the assessment and monitoring of under-nutrition. Part one focused on anthropometric variables [Madden and Smith (2016) J Hum Nutr Diet 29: 7-25] and part two focuses on the use of imaging techniques, bioelectrical impedance analysis, markers of muscle strength and functional status, with particular reference to developments relevant to practice.

Measuring body composition using the bioelectrical impedance method can predict the outcomes of gemcitabine-based chemotherapy in patients with pancreatobiliary tract cancer

In order to examine the effect on body composition of anticancer drug treatments, the body composition rate in patients being treated with gemcitabine (GEM)-based chemotherapy was measured over time on an outpatient basis with a simple body composition monitor using the bioelectrical impedance (BI) method. The results revealed a significant reduction in the body fat rate (P=0.01) over the course of treatment in patients with pancreatobiliary tract cancer who became unable to continue GEM-based chemotherapy due to progressive disease or a decreased performance status. Meanwhile, no changes were observed in the body composition of control patients with urothelial carcinoma receiving GEM-based chemotherapy. In association with the adverse reactions to GEM and the hematotoxicity profile, a decreased white blood cell count was more likely to occur in body fat-dominant patients (mean fat rate, 25.8%; mean muscle rate, 26.2%), whereas a decreased blood platelet count was more likely to occur in skeletal muscle-dominant patients (mean fat rate, 23.3%; mean muscle rates, 28.7%). The correlation between body composition parameters and the relative dose intensity (RDI) associated with GEM administration was also analyzed. The results revealed a positive correlation between the RDI and basal metabolism amount (P=0.03); however, the RDI did not correlate with the body fat rate, skeletal muscle rate or body mass index (P=0.61, P=0.14 and P=0.20, respectively). In conclusion, the body composition rate measurement using the BI method over time may be useful for predicting the outcome of GEM-based chemotherapy and adverse events in patients with pancreatobiliary tract cancer. In particular, the present findings indicate that the changes in body fat rate may be helpful as an adjunct index for assessing potential continuation of chemotherapy and changes in physical conditions.

Predicting body composition using foot-to-foot bioelectrical impedance analysis in healthy Asian individuals

Background

The objectives of this study were to develop a regression model for predicting fat-free mass (FFM) in a population of healthy Taiwanese individuals using standing foot-to-foot bioelectrical impedance analysis (BIA) and to test the model’s performance in predicting FFM with different body fat percentages (BF%).

Methods

We used dual-energy X-ray absorptiometry (DXA) to measure the FFM of 554 healthy Asian subjects (age, 16–75 y; body mass index, 15.8–43.1 kg/m²). We also evaluated the validity of the developed multivariate model using a double cross-validation technique and assessed the accuracy of the model in an all-subjects sample and subgroup samples with different body fat levels.

Results

Predictors in the all-subjects multivariate model included height²/impedance, weight, year, and sex (FFM = 13.055 + 0.204 weight + 0.394 height²/Impedance – 0.136 age + 8.125 sex (sex: Female = 0, Male = 1), r² = 0.92, standard error of the estimate = 3.17 kg). The correlation coefficients between predictive FFM by BIA (FFM_BIA) and DXA-measured FFM (FFM_DXA) in female subjects with a total-subjects BF%_DXA of <20 %, 20 %–30 %, 30 %–40 % and >40 % were r = 0.87, 0.90, 0.91, 0.89, and 0.94, respectively, with bias ± 2SD of 0.0 ± 3.0 kg, −2.6 ± 1.7 kg, −1.5 ± 2.8 kg, 0.5 ± 2.7 kg, and 2.0 ± 2.9 kg, respectively. The correlation coefficients between FFM_BIA and FFM_DXA in male subjects with a total-subjects BF%_DXA of <10 %, 10 %–20 %, 20 %–30 %, and >30 % were r = 0.89, 0.89, 0.90, 0.93, and 0.91, respectively, with bias ± 2SD of 0.0 ± 3.2 kg, −2.3 ± 2.5 kg, −0.5 ± 3.2 kg, 0.4 ± 3.1 kg, and 2.1 ± 3.2 kg, respectively.

Conclusions

The standing foot-to-foot BIA method developed in this study can accurately predict FFM in healthy Asian individuals with different levels of body fat.

The effect of acute fluid consumption following exercise-induced fluid loss on hydration status, percent body fat, and minimum wrestling weight in wrestlers

Acute fluid consumption (approximately 1 L) has been shown to reduce urine specific gravity (Usg) among subjects after an overnight fast, yet it is unknown if Usg may be reduced among subjects who have experienced exercise-induced fluid loss. The purpose of this study was to examine the effect of acute fluid consumption on Usg, body mass, percent body fat (%BF), and minimum wrestling weight (MWW) following an exercise-induced fluid loss protocol. National Collegiate Athletic Association coaches' perceptions of the weight certification program (WCP) were also evaluated. Twelve men wrestlers (19.8 ± 1.14 years) were tested prepractice (PRE), postpractice (POST), and 1 hour after consuming 1 L of water (PFC). Percent body fat was measured by skinfolds (SF), air displacement plethysmography (ADP), and multifrequency and leg-to-leg bioelectrical impedance analysis to calculate MWW. Urine specific gravity measurements significantly increased above PRE (1.013 ± 0.006) at the POST (1.019 ± 0.007; p = 0.017) and PFC (1.022 ± 0.008; p = 0.025) assessments; however, POST and PFC were not significantly different (p = 0.978) from one another. The %BF values were similar (p > 0.05) at each assessment point when using SF and ADP. When compared with PRE, MWW significantly reduced at the POST assessment when using SF (67.2 ± 8.4 vs. 65.7 ± 8.2 kg; p < 0.001) and ADP (66.6 ± 9.1 vs. 64.8 ± 9.0 kg; p = 0.001), reflecting the reduction in body mass observed after exercise. Forty-seven National Collegiate Athletic Association coaches completed the questionnaire and 2 central themes emerged: (a) concerns with the 1.5% weight loss plan and (b) wrestlers using strategies in an attempt to circumvent the WCP. Exercise-induced fluid loss followed by acute fluid consumption equal to 1 L was ineffective in reducing Usg.

Development of an equation for estimating appendicular skeletal muscle mass in Japanese older adults using bioelectrical impedance analysis

AIM

Bioelectrical impedance analysis has been reported to have high reliability and accuracy in assessing body composition. However, equations for estimating appendicular skeletal muscle mass are population-specific, and few have been developed for older Japanese adults. Thus, the purpose of the present study was to develop and validate an estimate equation for appendicular skeletal muscle mass using bioelectrical impedance analysis.

METHODS

A total of 250 older adults aged 65 years and older participated in this study. Appendicular skeletal muscle mass was measured using dual-energy X-ray absorptiometry, and bioelectrical resistance was measured using a multifrequency bioelectrical impedance analyzer. Multiple regression analysis was applied to derive sex-specific estimation formulae using bioelectrical impedance analysis, and a Bland-Altman analysis was used to test agreement.

RESULTS

The cross-validation results showed that the slopes and intercepts of the regression lines were approximately one and zero, respectively, and the coefficients of determination and standard errors of the estimate of the newly developed equations were similar between the two groups. Thus, the single sex-specific equations were developed using all participants as follows. Men: appendicular skeletal muscle mass=0.197 × (impedance index) +0.179 × (weight) -0.019 (R(2)  =0.87, standard error of the estimate=0.98 kg). Women: appendicular skeletal muscle mass=0.221 × (impedance index) +0.117 × (weight) +0.881 (R(2)  =0.89, standard error of the estimate=0.81 kg).

CONCLUSION

These new equations offer a valid option for assessing appendicular skeletal muscle mass in older Japanese adults.

Bioelectrical phase angle and impedance vector analysis--clinical relevance and applicability of impedance parameters

BACKGROUND & AIMS

The use of phase angle (PhA) and raw parameters of bioelectrical impedance analysis (BIA) has gained attention as alternative to conventional error-prone calculation of body composition in disease. This review investigates the clinical relevance and applicability of PhA and Bioelectrical Impedance Vector Analysis (BIVA) which uses the plot of resistance and reactance normalized per height.

METHODS

A comprehensive literature search was conducted using Medline identifying studies relevant to this review until March 2011. We included studies on the use of PhA or BIVA derived from tetrapolar BIA in out- and in-patient settings or institutionalized elderly.

RESULTS

Numerous studies have proven the prognostic impact of PhA regarding mortality or postoperative complications in different clinical settings. BIVA has been shown to provide information about hydration and body cell mass and therefore allows assessment of patients in whom calculation of body composition fails due to altered hydration. Reference values exist for PhA and BIVA facilitating interpretation of data.

CONCLUSION

PhA, a superior prognostic marker, should be considered as a screening tool for the identification of risk patients with impaired nutritional and functional status, BIVA is recommended for further nutritional assessment and monitoring, in particular when calculation of body composition is not feasible.

The effect of acute fluid consumption on measures of impedance and percent body fat estimated using segmental bioelectrical impedance analysis

BACKGROUND/OBJECTIVES

To determine the effect of acute fluid consumption on measures of impedance and percent body fat (%BF) estimated using segmental bioelectrical impedance analysis (SBIA).

SUBJECTS/METHODS

Seventy-six healthy, recreationally active adults (41 women; 35 men) volunteered to participate in this study (mean+/-s.d.; age, 21.0+/-1.6 years; body mass index, 25.0+/-3.2 kg/m2). Subjects had their body composition assessed on three separate occasions. After a baseline measurement, subjects consumed 591 ml of water (H2O), a carbohydrate/electrolyte drink (CHOE) or received nothing (CON). Subjects were reassessed 20, 40 and 60 min following (POST) the baseline measure in each fluid condition.

RESULTS

Twenty minutes after drinking a H2O or CHOE beverage, %BF (1.1 and 1.2%), impedance (12 and 14 Omega) and body mass increased significantly (P<0.001). During the CON trial, %BF (0.3 and 0.5%) and impedance (7 and 11 Omega) also increased significantly above baseline values at 40 and 60 min POST. However, the normal hourly variability was significantly (P<0.009) less than the observed fluid-induced %BF alterations. The greatest %BF increases were observed in the lightest subjects, who were women. Fluid type had no effect on the magnitude of change POST.

CONCLUSIONS

Twenty minutes after drinking, %BF estimates increased approximately 1.0% due to elevations in impedance and body mass. As such, we recommend adhering to the pretest fluid restriction guideline to avoid fluid-induced alterations in SBIA body composition measures. In addition, use of a consistent testing schedule may minimize normal %BF variation over time.