The bioelectrical impedance analysis (BIA) international database: aims, scope, and call for data.

BACKGROUND: Bioelectrical impedance analysis (BIA) is a technique widely used for estimating body composition and health-related parameters. The technology is relatively simple, quick, and non-invasive, and is currently used globally in diverse settings, including private clinicians' offices, sports and health clubs, and hospitals, and across a spectrum of age, body weight, and disease states. BIA parameters can be used to estimate body composition (fat, fat-free mass, total-body water and its compartments). Moreover, raw measurements including resistance, reactance, phase angle, and impedance vector length can also be used to track health-related markers, including hydration and malnutrition, and disease-prognostic, athletic and general health status. Body composition shows profound variability in association with age, sex, race and ethnicity, geographic ancestry, lifestyle, and health status. To advance understanding of this variability, we propose to develop a large and diverse multi-country dataset of BIA raw measures and derived body components. The aim of this paper is to describe the 'BIA International Database' project and encourage researchers to join the consortium. METHODS: The Exercise and Health Laboratory of the Faculty of Human Kinetics, University of Lisbon has agreed to host the database using an online portal. At present, the database contains 277,922 measures from individuals ranging from 11 months to 102 years, along with additional data on these participants. CONCLUSION: The BIA International Database represents a key resource for research on body composition.

Effect of Physical Training on Body Composition in Brazilian Military.

The military are selected on the basis of physical standards and are regularly involved in strong physical activities, also related to particular sports training. The aims of the study were to analyze the effect of a 7-month military training program on body composition variables and the suitability of specific 'bioelectrical impedance vector analysis' (spBIVA), compared to DXA, to detect the changes in body composition. A sample of 270 male Brazilian cadets (19.1 ± 1.1 years), composed of a group practicing military physical training routine only (MT = 155) and a group involved in a specific sport training (SMT = 115), were measured by body composition assessments (evaluated by means of DXA and spBIVA) at the beginning and the end of the military routine year. The effect of training on body composition was similar in SMT and MT groups, with an increase in LST. DXA and spBIVA were correlated, with specific resistance (Rsp) and reactance (Xcsp) positively related to fat mass (FM), FM%, LST, and lean soft tissue index (LSTI), and phase angle positively related to LST and LSTI. Body composition variations due to physical training were recognized by spBIVA: the increase in muscle mass was indicated by the phase angle and Xcsp increase, and the stability of FM% was consistent with the unchanged values of Rsp. Military training produced an increase in muscle mass, but no change in FM%, independently of the sample characteristics at baseline and the practice of additional sports. SpBIVA is a suitable technique for the assessment of body composition in military people.

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 (%FMDXA) and fat-free mass index (FFMIDXA = 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 %FMDXA in the whole body and all body segments, and the phase angle was correlated with FFMIDXA, 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.

Interpopulation Similarity of Sex and Age-Related Body Composition Variations Among Older Adults.

The aim of the study was to analyze sex and age-related body composition variations among older adults from the Brazilian, Italian, and Mexican population. A cross-sectional analysis was conducted in 1103 community-dwelling older adults (634 women and 469 men), aged 60 to 89 years, living in Brazil (n = 176), Italy (n = 554), and Mexico (n = 373). Anthropometric measurements were taken, BMI was calculated, and impedance measurements were obtained (resistance, R, reactance, Xc). Specific bioelectrical impedance vector analysis (specific BIVA) was applied, with the specific vector defined by impedance, or vector length (Z = (Rsp2 + Xcsp)0.5), and phase angle (PA = arctan Xc/R 180/π). Population, sex, and age differences in anthropometric and bioelectrical variables were evaluated by means of a two way ANOVA. The mean bioelectrical vectors were graphed by confidence ellipses and statistically compared by the Hotelling's T2 test. The three population groups showed differences in body mass and composition (p < 0.001): the Brazilian sample was characterized by greater body dimensions, longer vectors (higher relative content of fat mass), and lower phase angles (lower skeletal muscle mass). Men were taller and heavier than women (p < 0.001) but had a similar BMI (p = 0.102). They also had higher phase angle (higher skeletal muscle mass) (p < 0.001) and lower vector length (lower %FM) (p < 0.001). In the three population groups, the oldest individuals showed lower anthropometric and phase angle values with respect to the youngest ones (p < 0.001), whereas the vector length did not change significantly with age (p = 0.665). Despite the differences between sexes and among populations, the trend of age-related variations was similar in the Brazilian, Italian, and Mexican older adults.

Phase angle and bioelectrical impedance vector analysis in the evaluation of body composition in athletes.

AIMS: To analyze the association of classic and specific bioelectrical impedance vector analysis (BIVA) and phase angle with reference techniques for the assessment of body composition in athletes. METHODS: 202 athletes of both sexes (men: 21.5 ± 5.0; women: 20.7 ± 5.1) engaged in different sports were evaluated during the in-season period. Bioelectrical resistance (R, ohm) and reactance (Xc, ohm) were obtained with a phase-sensitive 50 kHz bioelectrical impedance analysis device. The classic and specific BIVA procedures, which respectively correct bioelectrical values for body height (R/H and Xc/H, ohm/m) and body geometry (Rsp and Xcsp, ohm cm), were applied. Dual energy X-ray absorptiometry was used as the reference method to assess fat-mass (FM), fat-free mass (FFM) and %FM. Deuterium dilution and bromide dilution where used as the criterion method for total body water (TBW) and extracellular water (ECW), respectively. Intracellular water (ICW) was calculated as TBW minus ECW. RESULTS: Specific bioelectrical values (Rsp, Xcsp, Zsp) were positively correlated with FM and %FM (%FM; Zsp men: r = 0.569, p < 0.001; Zsp women: r = 0.773, p < 0.001). Classic values (R/H, Xc/H, Z/H) were negatively correlated with FM and FFM, but were correlated with %FM only in men (Z/H men: r = -0.214, p = 0.013; Z/H women: r = 0.218, p = 0.097). As to body fluid, classic BIVA showed strong associations (Z/H men: r = -0.880, p < 0.001; Z/H women: r = -0.829, p < 0.001) with TBW, whereas Zsp was not correlated. Phase angle was negatively correlated with ECW/ICW ratio in both sexes (men: r = -0.493, p < 0.001; women: r = -0.408, p < 0.001) and positively with ICW (men: r = 0.327, p < 0.001; women: r = 0.243, p = 0.080). CONCLUSIONS: Specific BIVA turns out to be more accurate for the analysis of %FM in athletes, while it does not correctly evaluate TBW, for which classic BIVA appears to be a suitable approach. Phase angles, and hence both BIVA approaches, can detect ECW/ICW changes.

Total body and arm bioimpedance in patients with Alzheimer's disease.

PURPOSE OF THE RESEARCH: To analyse body composition of patients with Alzheimer's disease (AD) using total body and localized specific bioelectrical impedance vector analysis (specific BIVA). METHOD: 127 patients (50 men, 78.2±6.3years; 77 women, 81.4±6.8years) with mild to moderate stages of AD were selected from the Geriatric Division, SS. Trinità Hospital of Cagliari (Italy). A sample of 135 healthy age-matched individuals (74 men, 77.4±5.3years; 61 women, 80.4±5.5years) was chosen as control group. Anthropometric measurements were taken and body mass index (BMI) was calculated. Bioelectrical measurements were taken on the right side of the body for both the whole-body and the arm, using a BIA 101 analyser (Akern). Body composition was assessed by means of specific bioelectrical impedance vector analysis (specific BIVA). The comparison between patients and the control group was performed by two-factor analysis of variance and Hotelling's T2 test. RESULTS: In comparison with the control group, patients with AD showed similar anthropometric characteristics, including BMI, but lower lean tissue mass and higher percent fat mass, as indicated by the lower phase angles and longer specific vectors. The same body composition peculiarities were detected considering only the right arm. CONCLUSION: Patients with AD show characteristics - lower lean mass/higher percent fat mass - that can be detected by both total body and localized bioimpedance approaches. This suggests the possibility of a new, quicker and simpler procedure for body composition assessment.

Specific BIVA recognizes variation of body mass and body composition: Two related but different facets of nutritional status.

OBJECTIVE: The aim of this study was to demonstrate the different information provided by body mass index (BMI) in combination with specific bioelectrical impedance vector analysis (specific BIVA) in the measure of relative body fat. METHODS: Anthropometric and bioelectrical values and dual-energy x-ray absorpitometry measurements from a sample of 1590 US adults of both sexes were retrieved from the National Health and Nutrition Examination Survey 2003-2004. The sample distribution of the BMI of each sex was divided into deciles. Quartiles were calculated for percent fat mass (FM%) after stratifying by BMI deciles. Body composition and bioelectrical characteristics of groups below the first and above the third quartile were compared using analysis of variance and the Hotelling's T-square test. RESULTS: BMI and specific BIVA showed a different accuracy in detecting body composition variations: BMI showed similar values in groups represented by different FM percentages, whereas the bioelectrical differences were statistically significant. The mean impedance vectors corresponding to cases below the first FM% quartiles were shorter and located on the left side of the ellipses (the region of higher fat-free mass), whereas those above the third FM% quartiles were on the right and toward the upper pole (the region of higher FM%). CONCLUSIONS: Specific BIVA is a technique for the evaluation of body composition which can add relevant information regarding BMI.

A new, effective and low-cost three-dimensional approach for the estimation of upper-limb volume.

The aim of this research was to validate a new procedure (SkanLab) for the three-dimensional estimation of total arm volume. SkanLab is based on a single structured-light Kinect sensor (Microsoft, Redmond, WA, USA) and on Skanect (Occipital, San Francisco, CA, USA) and MeshLab (Visual Computing Lab, Pisa, Italy) software. The volume of twelve plastic cylinders was measured using geometry, as the reference, water displacement and SkanLab techniques (two raters and repetitions). The right total arm volume of thirty adults was measured by water displacement (reference) and SkanLab (two raters and repetitions). The bias and limits of agreement (LOA) between techniques were determined using the Bland-Altman method. Intra- and inter-rater reliability was assessed using the intraclass correlation coefficient (ICC) and the standard error of measurement. The bias of SkanLab in measuring the cylinders volume was -21.9 mL (-5.7%) (LOA: -62.0 to 18.2 mL; -18.1% to 6.7%) and in measuring the volume of arms' was -9.9 mL (-0.6%) (LOA: -49.6 to 29.8 mL; -2.6% to 1.4%). SkanLab's intra- and inter-rater reliabilities were very high (ICC >0.99). In conclusion, SkanLab is a fast, safe and low-cost method for assessing total arm volume, with high levels of accuracy and reliability. SkanLab represents a promising tool in clinical applications.

Effect of influenza-induced fever on human bioimpedance values.

BACKGROUND AND AIMS: Bioelectrical impedance analysis (BIA) is a widely used technique to assess body composition and nutritional status. While bioelectrical values are affected by diverse variables, there has been little research on validation of BIA in acute illness, especially to understand prognostic significance. Here we report the use of BIA in acute febrile states induced by influenza. METHODS: Bioimpedance studies were conducted during an H1N1 influenza A outbreak in Venezuelan Amerindian villages from the Amazonas. Measurements were performed on 52 subjects between 1 and 40 years of age, and 7 children were re-examined after starting Oseltamivir treatment. Bioelectrical Impedance Vector Analysis (BIVA) and permutation tests were applied. RESULTS: For the entire sample, febrile individuals showed a tendency toward greater reactance (p=0.058) and phase angle (p=0.037) than afebrile individuals, while resistance and impedance were similar in the two groups. Individuals with repeated measurements showed significant differences in bioimpedance values associated with fever, including increased reactance (p<0.001) and phase angle (p=0.007), and decreased resistance (p=0.007) and impedance (p<0.001). CONCLUSIONS: There are bioelectrical variations induced by influenza that can be related to dehydration, with lower extracellular to intracellular water ratio in febrile individuals, or a direct thermal effect. Caution is recommended when interpreting bioimpedance results in febrile states.

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.

Specific bioelectrical impedance vector reference values for assessing body composition in the Italian elderly.

OBJECTIVE: To obtain specific bioelectrical impedance vector reference values for the healthy elderly Italian population, and to study age- and sex-related differences in body composition. DESIGN: The study group consisted of 560 healthy individuals (265 men and 295 women) aged 65 to 100 y, whose anthropometric (height, weight, and calf, arm and waist circumferences) and bioelectrical measurements (resistance [R] and reactance [Xc], at 50 kHz and 800 µA) were recorded. R (Ω) and Xc (Ω) values were standardized for stature (H, m) to obtain the classic bioelectrical values. Specific values (resistivity [Rsp] and reactivity [Xcsp], Ω·cm) were obtained by multiplying R and Xc by a correction factor (A/L) that includes an estimate of the cross-sectional area of the body (A=0.45 arm area+0.10 waist area+0.45 calf area), where L=1.1H. RESULTS: Descriptive statistics were: Rsp (391.8±57.9), Xcsp (42.6±9.9), Zsp (394.2±58.2), phase angle (6.2°±1.2) in men; Rsp (462.0±80.1), Xcsp (47.9±11.2), Zsp (464.6±80.5), phase angle (5.9°±1.0) in women. The Xcsp and phase angle values showed a significant age-related decrease in both sexes, but especially in men, possibly relating to a gradual loss of muscle mass. Women's Rsp and Zsp values tended to drop, attributable to their declining proportion of fat mass. A declining sexual dimorphism was also apparent. CONCLUSIONS: Specific tolerance ellipses can be used for reference purposes for the Italian population when assessing body composition in gerontological practice and for epidemiological purposes.

Accuracy of specific BIVA for the assessment of body composition in the United States population.

BACKGROUND: Bioelectrical impedance vector analysis (BIVA) is a technique for the assessment of hydration and nutritional status, used in the clinical practice. Specific BIVA is an analytical variant, recently proposed for the Italian elderly population, that adjusts bioelectrical values for body geometry. OBJECTIVE: Evaluating the accuracy of specific BIVA in the adult U.S. population, compared to the 'classic' BIVA procedure, using DXA as the reference technique, in order to obtain an interpretative model of body composition. DESIGN: A cross-sectional sample of 1590 adult individuals (836 men and 754 women, 21-49 years old) derived from the NHANES 2003-2004 was considered. Classic and specific BIVA were applied. The sensitivity and specificity in recognizing individuals below the 5(th) and above the 95(th) percentiles of percent fat (FMDXA%) and extracellular/intracellular water (ECW/ICW) ratio were evaluated by receiver operating characteristic (ROC) curves. Classic and specific BIVA results were compared by a probit multiple-regression. RESULTS: Specific BIVA was significantly more accurate than classic BIVA in evaluating FMDXA% (ROC areas: 0.84-0.92 and 0.49-0.61 respectively; p = 0.002). The evaluation of ECW/ICW was accurate (ROC areas between 0.83 and 0.96) and similarly performed by the two procedures (p = 0.829). The accuracy of specific BIVA was similar in the two sexes (p = 0.144) and in FMDXA% and ECW/ICW (p = 0.869). CONCLUSIONS: Specific BIVA showed to be an accurate technique. The tolerance ellipses of specific BIVA can be used for evaluating FM% and ECW/ICW in the U.S. adult population.

Elderly subjects with type 2 diabetes show altered tissue electrical properties.

OBJECTIVE: The aim of the present research was to show the characteristics of body composition in a sample of elderly subjects with type 2 diabetes compared with healthy controls matched by age and body mass index (BMI) by bioelectrical impedance vector analysis. METHODS: The sample consisted of 144 free-living patients (84 women and 60 men) with type 2 diabetes 60 to 84 y old and 209 age-matched controls (116 women and 93 men). Anthropometric measurements (weight; height; upper arm, hip, waist, and calf circumferences; biceps; triceps; and subscapular and suprailiac skinfolds) were taken. Blood samples for the assessment of plasma glucose and glycated hemoglobin were collected. The BMI, upper arm muscular area, and waist-to-hip ratio were calculated. Bioelectrical impedance vector analysis was applied. The analysis was performed in the entire diabetic sample and the healthy BMI-matched groups. RESULTS: Compared with healthy subjects, patients had greater weight (P < 0.01 in women), higher BMI (P < 0.01 in women), smaller muscular area (P < 0.01 in men), and thicker skinfolds (P < 0.01 in women and men). Female and male patients showed larger phase angles (P < 0.01). Moreover, female patients showed a shorter vector length and lower resistance (P < 0.01) and male patients showed a higher reactance (P < 0.01). The BMI-matched analysis confirmed that patients were characterized by larger phase angles. CONCLUSIONS: Older patients with type 2 diabetes were characterized by peculiar anthropometric and bioelectrical patterns, which can be related to their smaller appendicular muscular area and lower extracellular/intracellular water ratio.

The potential of classic and specific bioelectrical impedance vector analysis for the assessment of sarcopenia and sarcopenic obesity.

PURPOSE: The aim of this paper is to investigate whether bioelectrical impedance vector analysis (BIVA) can be a suitable technique for the assessment of sarcopenia. We also investigate the potential use of specific BIVA as an indicator of sarcopenic obesity. SUBJECTS AND METHODS: The sample comprised 207 free-living elderly individuals of both sexes, aged 65 to 93 years. Anthropometric and bioelectrical measurements were taken according to standard criteria. The "classic" and "specific" BIVA procedures, which respectively correct bioelectrical values for body height and body geometry, were used. Dual energy X-ray absorptiometry (DXA) was used as the reference method for identifying sarcopenic and obese sarcopenic individuals. Bioelectrical and DXA values were compared using Student's t-test and Hotelling's T(2) test, as well as Pearson's correlation coefficient. RESULTS: According to classic BIVA, sarcopenic individuals of both sexes showed higher values of resistance/height (R/H; p < 0.01) and impedance/height (Z/H; p < 0.01), and a lower phase angle (p < 0.01). Similarly, specific BIVA showed significant differences between sarcopenic and nonsarcopenic individuals (men: T(2) = 15.7, p < 0.01; women: T(2) = 10.7, p < 0.01), with the sarcopenic groups showing a lower specific reactance and phase angle. Phase angle was positively correlated with the skeletal muscle mass index (men: r = 0.52, p < 0.01; women: r = 0.31, p < 0.01). Specific BIVA also recognized bioelectrical differences between sarcopenic and sarcopenic obese men (T(2) = 13.4, p < 0.01), mainly due to the higher values of specific R in sarcopenic obese individuals. CONCLUSION: BIVA detected muscle-mass variations in sarcopenic individuals, and specific BIVA was able to discriminate sarcopenic individuals from sarcopenic obese individuals. These procedures are promising tools for screening for presarcopenia, sarcopenia, and sarcopenic obesity in routine practice.

Body composition variations in ageing.

Age-related physiological variations of body composition concern both the fat-free mass (FFM) and the fat mass (FM). These variations expose the elderly person to the risk of malnutrition and could lead to conditions of disability. This paper aims to review the current state of knowledge on body composition in the aged population. The pattern of qualitative variations in body composition in old age is fairly well defined. In adulthood, the physiological variation of body mass involves a first increasing phase followed by a decreasing trend. The reduction is due mainly to the loss of fat-free mass, especially muscle mass. Total body water and bone mass also decrease. Fat mass tends to decrease and the reduction seems to be due mainly to the loss of subcutaneous fat. The quantitative aspects of the age of onset, rate and intensity of the physiological variations are still not completely clear. This poor quantitative definition is due to the variable and multifactorial phenomenology of ageing, the heterogeneity of assessment techniques and sampling models, and the limited number of empirical observations in oldest-old individuals.

Assessment of nutritional status in the Amazigh children of Amizmiz (Azgour Valley, High Atlas and Morocco).

The Berbers of the High Atlas (Amazigh) live in very severe socio-economic and climatic conditions, which expose children to the risk of malnutrition. In this study we used anthropometry and bioelectrical impedance analysis for the assessment of nutritional status. Height, weight and bioelectrical parameters were taken on 71 children (28 boys and 43 girls). Height and BMI were standardized using the 2007 WHO reference. The results show that 36.6% of the children were classified as stunted and 8.5% as wasted. Based on the Bioelectrical Impedance Vector Analysis, children from the High Atlas had an adequate body cell mass, but a high risk of dehydration (42.3%).

Assessment of nutritional status in free-living elderly individuals by bioelectrical impedance vector analysis.

OBJECTIVE: The aim of the present research was to examine bioelectrical vector changes in relation to nutritional status in a sample of healthy free-living elderly people. METHODS: The study group consisted of 170 men and women 70 to 99 y of age. Anthropometric and bioelectrical (resistance and reactance, 50 kHz, 800 muA) measurements were taken. Bioelectrical impedance vector analysis was applied. Nutritional status was determined by the Mini-Nutritional Assessment. Bioelectrical characteristics of normal and undernourished individuals were compared statistically with Hotelling's T(2) test and graphically with 95% probability confidence ellipses. RESULTS: The impedance and multidimensional approaches showed a clear association. Undernourished subjects had a smaller phase angle (men 5.2 +/- 1.3 versus 5.7 +/- 1.0 degrees, P = 0.027; women 5.0 +/- 1.0 versus 5.4 +/- 0.9 degrees, P = 0.065) than normally nourished subjects. CONCLUSION: Bioelectrical impedance vector analysis represents a promising indicator of nutritional status, suitable in screening programs and clinical practice.