New bioelectrical impedance vector references and phase angle centile curves in 4,367 adults: The need for an urgent update after 30 years.

BACKGROUND & AIMS: The bioelectrical impedance vector analysis (BIVA) represents a qualitative analysis of body composition. The vector, defined by resistance (R) and reactance (Xc) standardized by stature, can be evaluated compared to the 50%,75%, and 95% tolerance ellipses representative of the reference populations. The tolerance ellipses for healthy adults have been provided in 1995 and were developed by mixing underage, adult, and elderly subjects, possibly misrepresenting the actual adult population. The current multicentric, cross-sectional study aimed to provide new tolerance ellipses specific for the general adult population and as a secondary aim to present centile curves for the bioelectrical phase angle. METHODS: R, Xc, and phase angle were measured in 2137 and 2230 males and females using phase-sensitive foot-to-hand analyzers at 50 kHz. A minimum of 35 subjects were included for each sex and age category from 18 to 65 years. RESULTS: The new mean vectors showed a leftward shift on the R-Xc graph with respect to the former reference values (males: F = 75.3; p < 0.001; females: F = 36.6, p < 0.001). The results provided new 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, and 97th percentile curves for phase angle, identifying time point phases of decrement (males: -0.03° per year at 33.0-51.0 years and -0.05° per year after 51 years; females: -0.03° per year from 37.2 to 57.9 years). CONCLUSIONS: Compared to the original references, the new data are characterized by a different distribution within the R-Xc graph with a higher phase angle. Thirty years after the BIVA invention, the current study presents new tolerance ellipses and phase angle reference values for the adult population.

Reference Percentiles for Bioelectrical Phase Angle in Athletes.

The present study aimed to develop reference values for bioelectrical phase angle in male and female athletes from different sports. Overall, 2224 subjects participated in this study [1658 males (age 26.2 ± 8.9 y) and 566 females (age 26.9 ± 6.6 y)]. Participants were categorized by their sport discipline and sorted into three different sport modalities: endurance, velocity/power, and team sports. Phase angle was directly measured using a foot-to-hand bioimpedance technology at a 50 kHz frequency during the in-season period. Reference percentiles (5th, 15th, 50th, 85th, and 95th) were calculated and stratified by sex, sport discipline and modality using an empirical Bayesian analysis. This method allows for the sharing of information between different groups, creating reference percentiles, even for sports disciplines with few observations. Phase angle differed (men: p < 0.001; women: p = 0.003) among the three sport modalities, where endurance athletes showed a lower value than the other groups (men: vs. velocity/power: p = 0.010, 95% CI = -0.43 to -0.04; vs. team sports: p < 0.001, 95% CI = -0.48 to -0.02; women: vs. velocity/power: p = 0.002, 95% CI = -0.59 to -0.10; vs. team sports: p = 0.015, 95% CI = -0.52 to -0.04). Male athletes showed a higher phase angle than female athletes within each sport modality (endurance: p < 0.01, 95% CI = 0.63 to 1.14; velocity/power: p < 0.01, 95% CI = 0.68 to 1.07; team sports: p < 0.01, 95% CI = 0.98 to 1.23). We derived phase angle reference percentiles for endurance, velocity/power, and team sports athletes. Additionally, we calculated sex-specific references for a total of 22 and 19 sport disciplines for male and female athletes, respectively. This study provides sex- and sport-specific percentiles for phase angle that can track body composition and performance-related parameters in athletes.

Generalized bioelectric impedance-based equations underestimate body fluids in athletes.

The current study aimed: (i) to external validate total body water (TBW) and extracellular water (ECW) derived from athlete and non-athlete predictive equations using radioisotope dilution techniques as a reference criterion in male and female athletes; (ii) in a larger sample, to determine the agreement between specific and generalized equations when estimating body fluids in male and female athletes practicing different sports. A total of 1371 athletes (men: n = 921, age 23.9 ± 1.4 y; women: n = 450, age 27.3 ± 6.8 y) participated in this study. All athletes underwent bioelectrical impedance analyses, while TBW and ECW were assessed with dilution techniques in a subgroup of 185 participants (men: n = 132, age 21.7 ± 5.1 y; women: n = 53, age 20.3 ± 4.5 y). Two specific and eight generalized predictive equations were tested. Compared to the criterion methods, no mean bias was observed using the athlete-specific equations for TBW and ECW (-0.32 to 0.05, p > 0.05) and the coefficient of determination ranged from R2  = 0.83 to 0.94. The majority of the generalized predictive equations underestimated TBW and ECW (p < 0.05); R2 ranged from 0.66 to 0.89. In the larger sample, all the generalized equations showed lower TBW and ECW values (ranging from -6.58 to -0.19, p < 0.05) than specific predictive equations; except for TBW in female power/velocity (one equation) athletes and team sport (two equations). The use of generalized BIA-based equations leads to an underestimation of TBW, and ECW compared to athlete-specific predictive equations. Additionally, the larger sample indicates that generalized equations overall provided lower TBW and ECW compared to the athlete-specific equations.

Classic Bioelectrical Impedance Vector Reference Values for Assessing Body Composition in Male and Female Athletes.

Bioimpedance standards are well established for the normal healthy population and in clinical settings, but they are not available for many sports categories. The aim of this study was to develop reference values for male and female athletes using classic bioimpedance vector analysis (BIVA). In this study, 1556 athletes engaged in different sports were evaluated during their off-season period. A tetrapolar bioelectrical impedance analyzer was used to determine measurements of resistance (R) and reactance (Xc). The classic BIVA procedure, which corrects bioelectrical values for body height, was applied, and fat-free mass, fat mass, and total body water were estimated. In order to verify the need for specific references, classic bioelectrical values were compared to the reference values for the general male and female populations. Additionally, athletes were divided into three groups: endurance, velocity/power, and team sports. In comparison with the general healthy male and female populations, the mean vectors of the athletes showed a shift to the left on the R-Xc graph. Considering the same set of modalities, BIVA confidence graphs showed that male and female endurance athletes presented lower body fluids, fat mass, and fat-free mass than other sets of modalities. This study provides BIVA reference values for an athletic population that can be used as a standard for assessing body composition in male and female athletes.

Body composition and bone mineral density in Huntington's disease.

OBJECTIVE: Understanding the body composition (BC) of patients with Huntington's disease (HD) could help to delay disease progression and improve treatment efficacy. The aim of this study was to assess BC parameters, including bone mineral density (BMD), and to find new biomarkers that can be early indicators for weight loss in patients with HD. METHODS: Twenty-one age- and sex-matched patients with HD and 29 healthy controls (CT) were enrolled. For each patient, body weight (BW), height, and body mass index (BMI) were evaluated. BC and BMD were measured by dual-energy x-ray absorptiometry. Subsamples were created according to sex and percent fat mass (FM) (obese and nonobese). All analyses were carried out using SPSS version 23. RESULTS: In all comparisons, BMD and T-score were lower in the HD group, but were not correlated with lean body mass (LBM) or FM. In the HD group, LBM and truncal fat were mostly reduced, except in women with HD whose BC appeared to be less affected by the disease than men. Furthermore, LBM (r = 0.80) and truncal fat (r = 0.68) were better correlated with BW than BMI (r = 0.56). CONCLUSION: Complete BC assessment can be crucial for preventive interventions and prognosis definition in patients with HD. New biomarkers such as BMD, LBM, and truncal fat can be early indicators of weight loss in patients with HD.

Effect of anti IL-12/23 on body composition: results of bioelectrical impedance analysis in Caucasian psoriatic patients.

BACKGROUND: Bioelectrical impedance analysis (BIA) is an inexpensive, non-invasive and fast method to assess body composition. Little is known of the interaction between anti IL 12/23 treatment and body composition. The aim of this study was to evaluate 6- and 12-month changes in body weight, Body Mass Index (BMI) and body composition assessed by BIA in psoriatic patients treated with anti-IL-12/23. RESEARCH DESIGN AND METHODS: Demographic and clinical data were collected for each enrolled patient. Physical examination, anthropometric assessment, Psoriasis Area and Severity Index (PASI) assessment and body composition by BIA (single-frequency 50 kHz), were assessed at baseline and at 6 and 12 months of treatment. RESULTS: A significant decrease in body weight, compared to baseline, in BMI, Fat Mass at month 6 and a significant increase at month 12 for body cellular mass (BCM) and Phase Angle (PhA) were observed. In addition, a significant increase was found for intracellular water. CONCLUSION: At baseline, psoriatic patients showed a lower BCM and a lower mean PhA score. During ustekinumab treatment, the mean PhA and BCM scores increased with an improvement in psoriatic disease. Thus, ustekinumab can be an effective drug for improving not only psoriasis but also the general clinical status of patients.

Body composition analysis to study long-term training effects in elite male water polo athletes.

BACKGROUND: Elite water polo athletes undergo heavy training programs throughout the year, but especially to prepare major competitions, such as the Olympic Games (OG). Optimal athletic performance is a result of many factors, including proper management of the intensity and volume of training, nutrition and recovery between training sessions. When training is excessive in relation to recovery may occur nonfunctional overreaching (NFO). NFO can degenerate into overtraining syndrome resulting in a decrease in athletic performance, with likely changes in body weight and body composition. The aim of this study was to evaluate the relationship between body composition and the tolerance to intense training supported by diet meal plans and to highlight any difference between athletes selected for the OG and not selected ones. METHODS: Twenty-one male elite water polo athletes, 26 to 34 years of age, participated in the study. For three months before the Olympics, athletes have carried out an intense training period based on a detailed program. Only 13 athletes participated to OG (OA), 8 were excluded (NOA). Body weight and height were measured and Body Mass Index was calculated. BC and phase angle was evaluated at the half of first (T0), second (T1), and third (T2) month of training. Also blood analyses were collected at T0 and food intake assessed in all the evaluations. Measurements were carried out at three selected time points throughout the training period (12 weeks), which marked variations in the volume and intensity of the training load. RESULTS: Data analyses showed no statistical difference among the three measurements performed for body weight, body composition and phase angle in all OA group. Furthermore, there was not statistically significant differences between the OA and NOA group for weight, body mass index, body composition and phase angle. CONCLUSIONS: Results of the present study encourage the use of body composition by bioelectrical impedance monitoring system for high-level athletes involved in long and intense training periods to prevent body dehydration and overtraining syndrome. Body cell mass monitoring provides a valuable help to evaluate the effects of training and to prevent any decrease in the performance level.

Body composition in clinical practice.

Nutritional status is the results of nutrients intake, absorption and utilization, able to influence physiological and pathological conditions. Nutritional status can be measured for individuals with different techniques, such as CT Body Composition, quantitative Magnetic Resonance Imaging, Ultrasound, Dual-Energy X-Ray Absorptiometry and Bioimpendance. Because obesity is becoming a worldwide epidemic, there is an increasing interest in the study of body composition to monitor conditions and delay in development of obesity-related diseases. The emergence of these evidence demonstrates the need of standard assessment of nutritional status based on body weight changes, playing an important role in several clinical setting, such as in quantitative measurement of tissues and their fluctuations in body composition, in survival rate, in pathologic condition and illnesses. Since body mass index has been shown to be an imprecise measurement of fat-free and fat mass, body cell mass and fluids, providing no information if weight changes, consequently there is the need to find a better way to evaluate body composition, in order to assess fat-free and fat mass with weight gain and loss, and during ageing. Monitoring body composition can be very useful for nutritional and medical interventional. This review is focused on the use of Body Composition in Clinical Practice.

PP065. Assessment of total vascular resistance and total body water in normotensive women during the first trimester of pregnancy in order to predict hypertensive complications.

INTRODUCTION: In pregnancy there is an increase in maternal cardiac output (CO) and a reduction in total vascular resistance (TVR). Abnormalities of this adaptive mechanisms lead to numerous disorders of pregnancy. Moreover the mother's body water composition undergoes important modifications in total body water (TBW), extracellular and intracellular body water (EBW, IBW). OBJECTIVES: Aim of the study is to identify a group of patients at high risk of developing hypertensive complications of pregnancy in frist trimester. METHOD: To investigate hemodynamic changes and distribution of body water during the frist trimester of pregnancy, we conducted an observational study. We evaluated CO, TVR and Time Flow Corrected (TFc) with the USCOM system, a non invasive method. Patients were, also, subjected to BIA (Body Impedance Assessment). RESULTS: We enrolled 120 healthy pregnant women. 20 patients, were excluded for bad signal. Absolute values of haemodynamic and body impedance measures are shown in Fig. 1. Patients were divided in two groups:Group A with TVR>1200 dyne and Group B with TVR<1200 dyne. CO values were higher in group B. There wasn't significant differences in TBW, haematocrit, TFc and WBI (water balance index: TBW/Hct) between the two groups. CONCLUSION: Our results show that at costant values of TBW, Hct and WBI,we can find difference in term of TVR and CO in the first trimester of pregnancy. These parameters may improve the accuracy of screening in clinical practice.

Longitudinal study of total body potassium in healthy men.

OBJECTIVES: Total body potassium (TBK) is an index of fat-free mass and an accurate measure of body cell mass (BCM). To date, however, no longitudinal studies have evaluated body composition using TBK in aging healthy adults. The purpose of this study was to assess TBK and BCM in healthy men over a 21-year period, and to evaluate changes with age. DESIGN: A 21-year longitudinal, prospective, observational study evaluating TBK and BCM and their relationship to changes with aging and body mass index (BMI). SUBJECTS: Body composition of 133 healthy Italian men, 20 to 66 years of age, was measured by whole-body counting of (40)K. TBK was calculated by using this formula: (40)K × 8.474. BCM was calculated from TBK by using this formula: BCM (kg) = 0.00833 × TBK (mmol). RESULTS: The prevalence of overweight and obesity increased significantly from baseline to end of study (p < 0.01), with no change in TBK observed over the 21-year period. BCM summaries were tested to determine if any was a good predictor of BMI after age 30. Participants with a low maximum BCM (<27 kg) at an early age tended to exhibit decreased BMI as they aged, whereas those with a high maximum BCM (>27 kg) at an early age tended to show increased BMI as they aged. CONCLUSION: Despite an overall increase in the incidence of overweight and obesity over the 21-year period, a high maximum BCM at an early age was a predictor of an increase in BMI as men got older.

The effect of marathon on mRNA expression of anti-apoptotic and pro-apoptotic proteins and sirtuins family in male recreational long-distance runners.

BACKGROUND: A large body of evidence shows that a single bout of strenuous exercise induces oxidative stress in circulating human lymphocytes leading to lipid peroxidation, DNA damage, mitochondrial perturbations, and protein oxidation.In our research, we investigated the effect of physical load on the extent of apoptosis in primary cells derived from blood samples of sixteen healthy amateur runners after marathon (a.m.). RESULTS: Blood samples were collected from ten healthy amateur runners peripheral blood mononuclear cells (PBMCs) were isolated from whole blood and bcl-2, bax, heat shock protein (HSP)70, Cu-Zn superoxide dismutase (SOD), Mn-SOD, inducible nitric oxide synthase (i-NOS), SIRT1, SIRT3 and SIRT4 (Sirtuins) RNA levels were determined by Northern Blot analysis. Strenuous physical load significantly increased HSP70, HSP32, Mn-SOD, Cu-Zn SOD, iNOS, GADD45, bcl-2, forkhead box O (FOXO3A) and SIRT1 expression after the marathon, while decreasing bax, SIRT3 and SIRT4 expression (P < 0.0001). CONCLUSION: These data suggest that the physiological load imposed in amateur runners during marathon attenuates the extent of apoptosis and may interfere with sirtuin expression.

Use of vibration exercise in spinal cord injury patients who regularly practise sport.

The aim of this study was to evaluate the applicability and effects of mechanical vibration on body composition and mechanical properties of the arm in patients with spinal cord injury (SCI). For this purpose, ten volunteers with thoracic SCI were recruited. Measurements were performed before and after a period of treatment with mechanical vibration applied during forearm flexion in isometric condition. The subjects were tested performing forearm flexion (both right and left side) with increasing loads, corresponding to 5, 8, 10 and 15% of their own body weight. Average velocity (AV), average force (AF) and average power (AP) were calculated. The Functional Independence Measure was used to evaluate daily autonomy at baseline. Total body and segmental (arms) body composition, fat mass, fat-free mass, and bone mineral density, were studied by dual energy X-ray absorptiometry. Functional measurements (AV, AF, AP) and body composition were measured at three time points: after a medical examination and interview (T0); after an interval of 12 weeks without physical therapy or training (T1); and finally after a further 12-week period during which the patients performed segmental vibration exercise (T2). The results showed statistically significant increases in AV and AP on the right (dominant) side (p<0.05); AF also increased, but without the difference reaching statistical significance. Total body composition, did not change whereas the bone mineral density of the arms was higher after treatment, but again without the difference reaching statistical significance.

Effect of supplementation of calcium and vitamin D on bone mineral density and bone mineral content in peri- and post-menopause women; a double-blind, randomized, controlled trial.

BACKGROUND: Osteoporosis is a serious global health problem for the future, that is why improving diagnostic methods and prevention of this disease could be helpful. OBJECTIVES: To assess the effects of calcium supplementations combined with Vitamin D on bone mineral density (BMD) and bone mineral content (BMC) in a representative sample of peri- and post-menopausal women in a double-blind, a randomized, controlled trial was untaken. DESIGN: A total of 120 women aged over 45 were included in a randomised placebo-controlled, double-blind trial on the effect of a daily dietary supplementation of calcium and Vitamin D on bone mineral density and bone mineral content; over a 30-month period. METHODS: Dietary intake assessment; dual-energy X-ray absorptiometry to measure total body and segmental bone mineral density and bone mineral content at beginning of the study and every 15 months were undertaken. RESULTS: There was no significant change in dietary calcium or Vitamin D intakes in either of the treatment groups during the 30-month intervention period. The change in total BMD in the calcium group was significantly different from that in the placebo group (P <0.005). The placebo group lost a total BMD at a rate of about 0.4% per year. There was an inverse correlation between BMD and age. CONCLUSIONS: The effect of calcium and Vitamin D supplementation on bone mineral density of calcium has been demonstrated in this group of young adult women. Our results showed the positive effect of calcium and Vitamin D supplementation in women both peri- and post-menopausal status; for this reason a supplementation of calcium and Vitamin D should be recommended as a strategic option in helping to prevent early postmenopausal bone loss.

Total body water estimation and maternal cardiac systolic function assessment in normal and gestational hypertensive pregnant women.

BACKGROUND: The importance of establishing correlations between cardiac function (cardiac output and stroke volume) and total body water (TBW) content in normal and hypertensive pregnancy focuses primarily on their potential relevance in treatment. Total body water content and cardiac function were evaluated in 25 normotensive (N) and 22 gestational hypertensive (GH) pregnant women matched for age, gestational age, and pre-pregnancy body mass index (BMI) during the third trimester of gestation. MATERIAL/METHODS: Patients underwent maternal echocardiography, bioelectrical impedance analysis (BIA), and hematocrit (Hct) evaluation, and the water balance index (WBI), i.e. the ratio of total body water to hematocrit, was computed. Hematocrit showed significantly lower values in normal than in GH women (31.9+/-2.2% vs. 36.2+/-2.5%; p<0.001). RESULTS: There was no difference in TBW between the two groups. The WBI was higher in normal than in GH women (1.35+/-0.20 l.kg-1.m-2 vs. 1.19+/-0.18 l.kg-1.m-2; p<0.001). Normal subjects showed a higher stroke volume than GH patients (78.0+/-9.7 ml vs 67.9+/-10.2 ml; p=0.001). Atrial function was also higher in normal than in GH women (left atrial fractional area change: 57.4+/-5.1% vs. 42.5+/-7.5%; p<0.001). Correlation was found between stroke volume and WBI (r=0.93, p<0.0001). CONCLUSIONS: Maternal cardiac function and the water balance index are strongly related and might help in comprehending the mechanisms of adaptation in physiologic and hypertensive pregnancy.

Body cell mass measured by total body potassium in normal-weight and obese men and women.

OBJECTIVE: Total body potassium (TBK) concentration is linearly correlated with the size of the body cell mass (BCM). The aim of this study was to compare BCM in normal-weight and obese individuals. METHODS: 271 individuals (207 males, 64 females), 20 to 67 years of age, participated in this study. Subjects were separated by body mass index (BMI): BMI < 25 kg/m(2) (BMI-L) and BMI > 25 kg/m(2) (BMI-H). (40)K was assessed using a whole-body counter and BCM was calculated. RESULTS: BCM and TBK were significantly greater in men, with a trend to be greater in women in BMI-H compared to men in BMI-L. TBK/body weight was significantly lower, while TBK/height was significantly greater for men and women in BMI-H compared to men and women in BMI-L. Fat-free mass (FFM) was significantly greater for men in BMI-H, with no significant differences in FFM between the two groups of women. CONCLUSIONS: The healthy obese subjects in the present study had a greater BCM than the non-obese subjects. These results indicate that it is important to assess BCM in obese individuals because it could influence the type of weight loss regimen that will be used in order to preserve BCM.

Segmental bioelectrical impedance analysis.

PURPOSE OF REVIEW: The bioelectrical impedance analysis method is a non-invasive, rapid accurate and practical method for assessing body composition. During last decade evidence has been gathered that supports the use of this method to monitor hydration status. This review critically examines different approaches and applications of segmental bioelectrical impedance analysis in the healthy and clinical situations. RECENT FINDINGS: Segmental bioelectrical impedance analysis may be useful to assess appendicular lean body mass, to estimate muscle volume and to investigate possible relationships between muscle size and strength in a limited segment of the limb. The method may become a tool for the bedside detection of fluid accumulation in critical care. SUMMARY: This is a review of segmental bioelectrical impedance. The preponderance of the published applications of bioelectrical impedance analysis focused on applications in a healthy population and in the field indicate the validity of the methods. A short description of the set-up of the segmental method is also given. This review discusses the application of segmental bioelectrical impedance analysis in children in different ethnic populations, in clinical situations. We also examine the application of the method to assessing body composition, and monitoring rapid changes in internal fluid balance in the field of haemodialysis and during surgery.

Nifedipine-induced changes in body composition in hypertensive patients at term.

BACKGROUND: There are few studies on the effect of nifedipine on fluid homeostasis during pregnancy. OBJECTIVE: To assess the variation of body composition at term in patients with normal pregnancy and patients with gestational hypertension (GH) treated with nifedipine. METHODS: Seventeen healthy patients with singleton pregnancies and 12 non-proteinuric patients with gestational hypertension treated with nifedipine were enrolled consecutively from our University Hospital from January 2000 to January 2001. Two evaluations were performed (anthropometric measurements, bioelectric impedance analysis (BIA) at 5, 50 and 100kHz and hematocrit), the first at 36.4+/-3.2 weeks' gestation, the second at 2.1+/-1.6 days of puerperium. The BIA measurements included: fat mass (FM, kg), fat-free mass (FFM, kg), extra-cellular water (ECW, Lt), intra-cellular water (ICW, Lt), total body water (TBW, Lt). Values were analyzed as mean+/-S.D. and statistical analysis was performed by using the Student's t-test for unpaired data. RESULTS: Birthweights were significantly lower in the gestational hypertensive patients (3472.7+/-266.4g versus 2735.8+/-575.9g, P<0.001). At the first study time, systolic and diastolic blood pressure were significantly higher in the hypertensive patients than in control group, notwithstanding the therapy. Interestingly we found pre-delivery and post-delivery TBW higher in gestational hypertensive patients versus the control patients (44.48+/-9.12Lt versus 36.60+/-5.07Lt, P<0.001 and 40.69+/-4.31Lt versus 37.30+/-4.35Lt, P=0.016, respectively). TBW loss after delivery was greater among hypertensive patients (3.79+/-4.81Lt versus -0.70+/-0.72Lt, P<0.001). CONCLUSIONS: Bioelectrical impedance analysis is a practical tool in the follow-up of anti-hypertensive therapy at term gestation. Moreover, nifedipine increases TBW in gestational hypertensive patients, reverting the pathophisiological pattern, yet described elsewhere.