Reference values for the phase angle of the electrical bioimpedance: Systematic review and meta-analysis involving more than 250,000 subjects

Comparison of bioelectrical impedance analysis-derived phase angle in individuals with different weight status

OBJECTIVE

Obesity is characterized not only by an increase of fat mass but also by alterations in skeletal muscle. Bioimpedance analysis (BIA)-derived phase angle (PhA) may provide specific information on the inherent characteristics of fat-free mass, and is widely used as an index of poor nutritional status. The aim of this study was to describe whether and to what extent PhA varies depending on age, sex, and body mass index (BMI) in individuals with different weight status.

METHODS

We selected 1877 participants for this retrospective study (two weight status groups): 983 individuals with obesity (age 40 ± 13.9 y; BMI 39.5 ± 7.2 kg/m²) and 894 controls (age 40 ± 13.3 y; BMI 24.6 ± 2.7 kg/m²). Anthropometry and PhA at 50 kHz for the whole body were performed in all participants.

RESULTS

PhA was greater in men than in women, although a decline of PhA was observed with age, which was linear in women and occurred in men after 40 y of age. On the other hand, no significant differences were observed with increasing BMI in either sex; lower values might be observed when BMI >50 kg/m².

CONCLUSIONS

A more detailed appraisal of BIA-derived PhA in obesity is reported in the present study, providing basic data that might be taken into consideration in prevention and clinical nutrition. Further studies are needed to explore differences of PhA in individuals with different weight status.

Nutritional status of patients with COVID-19 one year post-ICU stay: a prospective observational study

Objective

Patients discharged from the Intensive Care Unit (ICU) often suffer from physical complaints and poor nutritional intake, which negatively affect nutritional status (NS). Our aim was to describe NS of patients with COVID-19 one year post-ICU stay.

Research Methods & Procedures

Observational study of adult patients with COVID-19 one year post-ICU. NS assessment (nutrient balance, body composition and physical status) was performed. Nutritional intake and nutrition-related complaints were examined. Nutritional requirements were determined with indirect calorimetry and body composition with bio-electrical impedance. Fat-free mass index (FFMI) and fat mass index (FMI) were calculated. Physical status was determined with handgrip strength (HGS), 6-minute walk test, and 1-minute sit to stand test (1MSTST). Descriptive statistics and paired sample t-tests were used for analysis.

Results

We included 48 patients (73% male; median age 60 years [IQR 52;65]). Median weight loss during ICU stay was 13%. One year post-ICU 12% weight was regained. Median BMI was 26 kg/m² and 23% was obese (BMI>30 kg/m² and high FMI). Of the patients, 50% had high FMI and 19% had low FFMI. Median reported nutritional intake was 90% of measured resting energy expenditure. Nutrition-related complaints were seen in 16%. Percentages of normal values reached in physical tests were 92% of HGS, 95% of 6 minute walking distance and 79% of 1MSTST.

Conclusion(s)

Despite almost fully regained weight and good physical recovery in adult patients one year post-ICU stay, NS remained impaired due to elevated FMI, even though reported nutritional intake was below the estimated requirements.

Bioelectrical impedance analysis in patients with breast cancer-related lymphedema before and after lymphaticovenular anastomosis

OBJECTIVE

Bioelectrical impedance analysis (BIA) as a measure of lymphedema has been gaining popularity because of its measurement simplicity and noninvasiveness. This study was performed to investigate the effectiveness of BIA for assessment of the outcomes of lymphaticovenular anastomosis (LVA) in patients with breast cancer-related lymphedema.

METHODS

This study involved 25 patients with unilateral breast cancer-related lymphedema who underwent LVA. Segmental multifrequency BIA and conventional circumferential volume measurement were performed preoperatively and 6 months postoperatively from June 2018 to June 2021 at Hiroshima University Hospital International Center for Lymphedema. The patients' clinicopathological data, operative details, and preoperative and postoperative BIA results were investigated.

RESULTS

Segmental multifrequency BIA and circumferential volume measurement were strongly correlated in the lymphedema-affected upper limb both before and after LVA. The interlimb volume, interlimb extracellular water ratio (r = 0.784; P < .001), and interlimb extracellular water/total body water ratio were positively correlated (r = 0.612; P < .01), whereas the phase angle was negatively associated (r = -0.556; P < .01).

CONCLUSIONS

Segmental multifrequency BIA can be a useful tool for assessing the severity of lymphedema and monitoring the outcomes of LVA.

Association of Phase Angle with Overall Survival in Patients with Cancer: A Prospective Multicenter Cohort Study

Low phase angle (PhA) is related with poor clinical status of cancer patients. The objective of this study was to establish sex- and age-specific cutoff points and examine the association between PhA and overall survival (OS) in Chinese cancer patients. This cohort study included data on 1,814 patients with cancer from December 2013 to October 2020. The association between low PhA and overall survival was analyzed using the Kaplan-Meier method and Cox regression model. Among 1,814 participants, there were 993 (54.70%) male and 821 (45.30%) female patients. The optimal cutoff points of low PhA were 4.8°, 4.2°, 4.4°, and 3.8° for the young male, elderly male, young female, and elderly female, respectively. Low PhA was independently associated with poorer OS in young female, elderly female and male (HR: 1.59, 95% CI: 1.08-2.34; HR: 1.65, 95% CI: 1.03-2.67; HR: 2.00, 95% CI: 1.45-2.75). In addition, low PhA was demonstrated to be an adverse prognostic factor in patients with lung cancer, colorectal cancer, and esophagus cancer (HR: 1.85, 95% CI: 1.39-2.47; HR: 2.05, 95% CI: 1.13-3.70; HR: 2.92, 95% CI: 1.49-5.71). Based on cutoff points, low PhA was associated with worse prognosis in patients with cancer.

Impact of Exercise and Cognitive Stimulation Therapy on Physical Function, Cognition and Muscle Mass in Pre-Frail Older Adults in the Primary Care Setting: A Cluster Randomized Controlled Trial

OBJECTIVES

Multicomponent exercise program have shown to improve function and cognition in older adults but studies on pre-frail older adults in the primary care setting are limited. This study aimed i) to evaluate impact of 6 months exercise (Ex) versus complementary effect of 3 months of cognitive stimulation therapy (CST) to 6 months of Ex (Ex+CST) on physical function, muscle mass and cognition versus control group at 3, 6 and 12 months ii) inflammatory biomarkers such as Interleukin-6 (IL-6) and Tumor Necrosis Factor Alpha (TNF-α).

DESIGN

Cluster randomised control trial.

SETTING AND INTERVENTION

Pre-frail older adults ≥ 65 years attending primary care clinic. Two intervention groups i) Ex 6 months ii) CST 3 months with Ex 6 months.

MEASUREMENTS

At 0, 3, 6 and 12 months, questionnaires (on demographics, physical function, cognition, and depression) were administered and physical function assessment (gait speed, short physical performance battery (SPPB) test, handgrip strength, five times sit-to-stand (5x-STS)) was conducted. Muscle mass and its surrogates such as phase angle and body cell mass were measured using bioelectrical impedance analysis machine. Inflammatory biomarkers were measured at 0 and 3 months.

RESULTS

Data from 190 participants was analysed at 3 months (111 control, 37 Ex and 41 Ex+CST). At 3 months, significant improvement in cognition was seen only in the Ex+CST group whereas improvements in depression, gait speed, SPPB and 5x-STS were seen in both the Ex and Ex+CST groups. At 6 months, the Ex+CST group improved in cognition and depression whereas improvement in frailty and muscle mass indices were seen in both the interventions groups. At 12 months, both the interventions groups had better perceived health, gait speed and less decline in muscle mass compared with control groups. Both the Ex and Ex+CST had significant association with TNF-α at 3 months (β -2.71 (95% CI -4.80 - -0.62); p = 0.012 and β -1.74 (95% CI -3.43 - -0.06); p = 0.043 respectively).

CONCLUSION

Combined Ex+CST had significant improvement in cognition whereas the intervention groups improved in depression, physical function, muscle mass, frailty, perceived health and TNF-α levels. With growing evidence of the benefits of multicomponent interventions at primary care level, incorporating it into mainstream care with action plans on long-term sustainability and scalability should be a priority for every country.

The Role of Standardized Phase Angle in the Assessment of Nutritional Status and Clinical Outcomes in Cancer Patients: A Systematic Review of the Literature

Compared with the phase angle (PA), the predictive ability of the standardized phase angle (SPA) in assessing nutritional status and clinical outcomes in cancer patients remains uncertain. This review aimed to assess (1) the relationship between SPA and nutritional status and clinical outcomes (including complications and survival) in cancer patients; (2) the predictive ability of SPA alone and in comparison with the predictive ability of PA; and (3) the cut-off value of SPA in cancer patients. Studies that addressed the relationship of SPA use to nutritional status, complications, and survival in cancer patients were searched and identified from six electronic databases (PubMed, Medline, CINAHL, Embase, Web of Science, and the Cochrane Library). The included studies were considered to meet the following criteria: English studies with original data that reflected the effects of SPA on nutritional status and clinical outcomes (including complications and survival) and reported a cut-off value of SPA in cancer patients aged ≥18. Thirteen studies that included a total of 2787 participants were evaluated. Five studies assessed the relationship between SPA and nutritional status, and four of them reported a positive relationship between SPA and nutritional status in cancer patients, even considering SPA as a predictor. Twelve studies assessed the relationship between SPA and clinical outcomes in cancer patients. Two-thirds of the studies that evaluated complications reported the predictive ability of SPA; 30% of survival studies reported a positive relationship, 40% reported SPA as a predictor, and 30% reported no relationship. The standard cut-off value for SPA has not yet been determined. Data from the selected studies suggest that SPA might be a predictor of nutritional status. Further studies are needed to determine the value of SPA in predicting nutritional status and clinical outcomes in cancer patients.

Diagnostic and prognostic utility of phase angle in patients with cancer

Patients with cancer experience dynamic and longitudinal changes in nutritional status and body composition along the disease trajectory. They often want to know about their outlook with regard to treatment outcomes and overall survival. One of the commonly used measures for body composition is bioelectrical impedance analysis (BIA). BIA is an easy-to-use, quick, inexpensive, noninvasive, and reproducible technique that is often incorporated in daily clinical practice. Phase angle (PA), which is derived from BIA, is an indicator of cell membrane health and integrity. Higher PA values reflect better cell function, higher muscle mass, and lower fat mass. PA is also thought to be a proxy of water distribution (ratio between extracellular water [ECW] and intracellular water [ICW]) and body cell mass. In this narrative review, we discuss studies examining the diagnostic and prognostic value of PA regarding nutritional status, body composition and physical function, complications of cancer treatments, overall survival, symptoms, and quality of life (QOL) in patients with cancer. The literature suggests that PA is moderately to strongly correlated with body composition and physical function but only weakly correlated with nutritional status, complications, survival, symptoms, and QOL. Furthermore, the PA cutoff values vary significantly according to study and patient population with the diversity of bioelectrical impedance technology and electrode composition and placement. Thus, PA has yet to be routinely incorporated into clinical practice for patients with cancer. Future research is needed to determine how to translate scientific understanding of PA to clinical practice.

Role of phase angle in older adults with focus on the geriatric syndromes sarcopenia and frailty

Age-related changes in body composition reflect an increased risk for disease as well as disability. Bioimpedance analysis is a safe and inexpensive bed side method to measure body composition, but the calculation of body compartments with BIA is hampered in older adults. Phase angle, a raw parameter derived from bioimpedance analysis, is free from calculation-inherent errors. It declines with age and disease and is highly predictive of a variety of clinical outcomes as well as mortality. This review summarizes the current evidence linking the phase angle to geriatric syndromes such as malnutrition, sarcopenia and frailty and also investigates whether the phase angle reacts to interventions. Since the majority of studies show an association between the phase angle and these geriatric syndromes, a low phase angle is not suitable to exclusively indicate a specific condition. It does not inform on the underlying cause and as such, a low phase angle mainly indicates increased risk. Phase angle decline over time is reflected by deterioration of e.g. frailty status. It reacts to physical training and detraining, but studies investigating whether these induced changes are also associated with improved outcome are missing.

Prognostic value of phase angle and bioelectrical impedance vector in critically ill patients: A systematic review and meta-analysis of observational studies

BACKGROUND AND AIMS

Assessment of the raw parameters derived from bioelectrical impedance analysis (BIA) has gained emphasis in critically ill patients. The phase angle (PhA) reflects the integrity of the cell membrane, and bioelectrical impedance vector analysis (BIVA) is indicative of patients' hydration status. The aim of this study was to investigate whether these parameters are associated with clinical outcomes in the intensive care unit (ICU) setting.

METHODS

We conducted a systematic review with meta-analysis. We searched PubMed, Embase, Scopus and Web of Science for all published observational studies without language restrictions up to April 2022. Two reviewers independently performed study selection and data extraction. We judged the risk of bias by the Newcastle-Ottawa Scale and the certainty of evidence by the GRADE approach. Mortality was the primary outcome. Secondary outcomes included ICU length of stay, hospital length of stay, duration of mechanical ventilation, nutritional risk, and malnutrition. A meta-analysis with a random-effect model was performed to combine data on R version 3.6.2.

RESULTS

Twenty-seven studies were included in the systematic review (4872 participants). Pooled analysis revealed that patients with low PhA had a higher risk of death (14 studies; RR = 1.82, 95% CI 1.46 to 2.26; I² = 42%) and spent more days in ICU (6 studies; MD = 1.79, 95% CI 0.33 to 3.24, I² = 69%) in comparison to patients with normal PhA. The pooled analysis also showed higher PhA values in survivors compared to non-survivor patients (12 studies; MD = 0.75°, 95% CI 0.60° to 0.91°, I² = 31%). Overhydration defined by BIVA was not a predictor of mortality (4 studies; RR = 1.01, 95% CI 0.70 to 1.46; I² = 0%). More than 40% of primary studies were classified with a high risk of bias, and the quality of evidence ranged from low to very low.

CONCLUSIONS

This meta-analysis revealed, with limited evidence, that low PhA was associated with higher mortality and ICU length of stay, while overhydration identified by BIVA was not a predictor of death in critically ill patients.

Decrease phase angle one year after Roux-en-Y bypass and sleeve gastrectomy is related to risks to protein nutritional status

BACKGROUND & AIMS

Phase angle (PhA) has been used as an indicator of nutritional status. However, the significance of PhA reduction after bariatric surgery is less known. This study evaluated PhA and its relation with biochemical parameters and prognostic inflammatory and nutritional indices at a one-year follow-up of patients subjected to Roux-en-Y bypass (RYGB) or sleeve gastrectomy (SG).

METHODS

Our final sample consisted of 25 patients subjected to RYGB and 11 to SG. Body mass index, fat-free mass, fat mass, PhA, serum transthyretin (TTR), albumin, C-reactive protein, alpha-1-acid glycoprotein, and prognostic inflammatory and nutritional indices were evaluated at four time points: before and approximately two, six, and 12 months after RYGB or SG. One-way repeated measures ANOVA or the Friedman test with Tukey's post hoc test was used depending on data distribution. The correlation between PhA and biochemical parameters and indices were evaluated using Spearman's or Pearson's correlation coefficients.

RESULTS

Except for serum albumin, all parameters significantly decreased over time (p < 0.001). Only the RYGB group showed transthyretinTR values below reference ones. Prognostic indices significantly decreased in both groups (p < 0.001). We found a significant positive correlation of PhA with TTR in both RYGB (r = 0.475; p < 0.001) and SG (r = 0.457; p < 0.001).

CONCLUSIONS

Data suggest that at a one-year follow-up after bariatric surgery, lower PhA values might indicate a concomitant loss of visceral protein and a worsening of protein nutritional status.

Effects of exercise programs on phase angle in older adults: A systematic review and meta-analysis

The purpose of this study was to calculate the effects of exercise programs on phase angle (PhA) in older people. A systematic review was undertaken in multiple electronic databases in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement guidelines for the purposes of selecting randomized controlled trials that measured the effects of the exercise programs on PhA in older adults on 31 March 2022. We carried out a random-effect meta-analysis for the effects of exercise programs on PhA. Additionally, we analysed the differences between subgroups in terms of weekly frequency, number of sets and repetitions, and duration of interventions. Studies were methodological assessed through the PEDro scale where one had excellent, ten had good, and three had poor methodological quality. For the purposes of the study, fourteen studies met the criteria for inclusion. However, four studies did not have enough information to be included in the quantitative analysis. The remaining ten articles revealed moderate effects on PhA in favour of intervention groups (p=0.009, SMD=0.72 [0.46-0.99], I2=54%). The meta-analysis also showed that interventions lasting twelve weeks are more successful in generating positive effects on PhA as opposed to eight weeks (SMD's=0.79 vs. 0.64, respectively). These results indicate that resistance training (RT) is an effective and safe to improve PhA in the older people, especially through RT programs lasting from eight to twelve weeks. A novel finding of this study was that RT is the most used type of exercise by authors when assessing the PhA in older adults.

Phase angle obtained via bioelectrical impedance analysis and objectively measured physical activity or exercise habits

The phase angle (PhA), measured via bioelectrical impedance analysis, is considered an indicator of cellular health, where higher values reflect higher cellularity, cell membrane integrity, and better cell function. This study aimed to examine the relationship between PhA and exercise habits or objectively measured physical activity. We included 115 people aged 32-69 years. The body composition and PhA were measured using a bioelectrical impedance device. Physical activity and sedentary behavior (SB) were assessed using a triaxial accelerometer. Exercise habits were also obtained through structured interviews, and participants were categorized into the no exercise habit (No-Ex), resistance training exercise habit (RT), or aerobic training exercise habit (AT) groups. Objectively measured moderate-to-vigorous physical activity or step count significantly correlated with PhA, independent of age, sex, height, percent body fat, body cell mass, and leg muscle power. In contrast, SB was not significant determinants of PhA. People who exercised regularly (RT or AT) had significantly higher PhA values than did those in the No-Ex group. Furthermore, the PhA was not significantly different between the RT and AT groups. Regularly engaging in exercise with moderate-to-vigorous intensity may improve or maintain muscle cellular health and muscle quality.

Phase angle of bioimpedance at 50 kHz is associated with cardiovascular diseases: systematic review and meta-analysis

The phase angle of bioimpedance is an important prognostic tool in clinical practice. The aim of this study was to investigate the association between phase angle and cardiovascular diseases. Electronic searches were carried out on MEDLINE, EMBASE, Cochrane, SCIELO, LILACS, CINAHL, Scopus, and the Web of Science. The PECO was "P" adults over 18 years of age, "E" the presence of cardiovascular disease, "C" absence of cardiovascular disease, and "O" phase angle values. The phase-angle means difference (MD) was analyzed separately by sex. Subgroup metanalysis with age, body mass index, and heart failure disease and meta-regressions were analyzed with random-effects models. Sensitivity analysis was performed considering only studies with high quality. The heterogeneity among studies was assessed using the Q-Cochran test and I² statistics. Four-hundred-thirty-nine articles were identified, and 22 studies were included in this systematic review, totaling 10.010 participants. Eight studies met the criteria for the meta-analysis, involving 2164 participants. The phase angle (PA) was measured at 50 kHz frequency in all studies. Individuals with cardiovascular disease had a smaller PA compared to the control group, for both males (MD -0.70; 95% CI -1.01 to -0.39) and females (MD -0.76; 95% CI -1.39 to -0.13). In the sensitivity analysis, in men, the quality of studies (P < 0.01), and in women, heart failure (P < 0.01) was significantly different between groups.The values of the phase angle were lower in individuals with cardiovascular disease than in control subjects. This result reinforces the importance of this tool in clinical practice, highlighting its potential to assess health status. Registration: The systematic review protocol was registered in the PROSPERO database as CRD42020164178.

MUSCLE DEPLETED OBESITY IN INDIVIDUALS SCREENED FOR COLORECTAL CÂNCER

BACKGROUND

Colorectal cancer (CRC) is the third most incident cancer in the world and the second leading cause of cancer death. Significant decreases in incidence and mortality can be achieved by reducing risk factors and adhering to healthy lifestyle recommendations, as well as screening for the disease.

OBJECTIVE

To evaluate the clinical nutritional profile of individuals at medium risk screened for CRC residing in the city of Piranhas/Alagoas.

METHODS

Cross-sectional study conducted from September to October 2020, with individuals at medium risk for CRC, of both sexes and aged between 50 and 70 years old. Participants were screened for CRC with fecal immunochemical testing (FIT) and colonoscopy. Personal, socioeconomic, clinical, lifestyle and nutritional assessment data were collected. The latter was performed using anthropometric data (weight, height, arm circumference and triceps skinfold thickness), body composition (bioimpedance) and physical examination. Descriptive analysis of data frequencies and dichotomization according to the presence or absence of overweight was performed, followed by comparison of means and medians and frequencies by chi-square or Fisher's exact test.

RESULTS

In total, 82 people agreed to undergo the clinical nutritional assessment, most of them female (56.1%; n=46), adults (56.1%; n=46), with a mean age of 59.02 years (±6.30 SD). Pre-cancerous lesions were identified in 54.5% (n=42) of those screened, 52.4% (n=43) were smokers or former smokers, and 65.9% (n=54) did not practice scheduled physical activity. Nutritional assessment showed that 64.6% (n=53) were overweight according to body mass index. On the other hand, the muscle mass, % arm muscle circumference adequacy and body muscle mass (kg) markers showed that 32.9% (n=27) and 47.6% (n=39) of the subjects were muscle depleted, respectively. Above all, overweight participants had, in parallel, lower muscle mass (P<0.05), suggesting sarcopenic obesity in this population.

CONCLUSION

Obesity is one of the main risk factors for CRC; when concomitant with sarcopenia, it favors worse health outcomes. In this context, evidence shows the need to assess muscle composition in people with obesity, especially through other methods of assessing body composition. Our results add to the evidence on the importance of the population being guided about screening and adherence to healthy lifestyle recommendations, especially strategies aimed at weight control and the practice of physical activity.

Association between phase angle and adverse clinical outcomes in hospitalized patients with COVID-19: A systematic review

Phase angle, obtained by bioelectrical impedance, is an indicator of cellular integrity and has been proposed as a prognostic parameter in patients who are critically ill. This systematic review aimed to evaluate the association between phase angle and adverse clinical outcomes in hospitalized patients with coronavirus disease–2019 (COVID‐19). An extensive literature search was performed in the MEDLINE/PubMed, Embase, and Web of Science databases, with interest in observational studies evaluating the association between phase angle and adverse clinical outcomes in individuals aged ≥18 years hospitalized with COVID‐19. Studies were independently selected by two reviewers, according to eligibility criteria. Subsequently, data were extracted and presented in a qualitative synthesis. The evaluation of the quality of the studies was performed according to the Newcastle‐Ottawa scale. The full methodology was published in PROSPERO (ID CRD42022306177). A total of 392 articles were identified, resulting in seven selected studies, of which six were prospective cohorts and one was retrospective. In the quality assessment, six studies obtained scores equal to or greater than seven, indicating a low risk of bias. A total of 750 participants composed the samples of the selected studies. Five studies reported an independent association between phase angle and adverse clinical outcomes during hospitalization for COVID‐19, with emphasis on prolonged hospitalization and mechanical ventilation and higher mortality in patients with a lower phase angle. Thus, phase angle measurement can be useful in the early identification of risks in patients hospitalized with COVID‐19, for the purpose of adequacy of clinical management.

Proposal of a New Parameter for Evaluating Muscle Mass in Footballers through Bioimpedance Analysis

The evaluation of muscle mass in athletes correlates with sports performance directly. Bioimpedance vector analysis is a growing method of assessing body composition in athletes because it is independent of predictive formulas containing variables such as body weight, ethnicity, age, and sex. The study aims to propose a new parameter (Levi’s Muscle Index, LMI) that evaluates muscle mass through raw bioelectrical data. A total of 664 male footballers underwent bioimpedance assessment during the regular season. LMI was correlated with body cell mass (BCM) and phase angle (PA) to establish efficacy. The footballers were 24.5 ± 5.8 years old, 180.7 ± 5.9 cm tall and weighed 76.3 ± 7.1 kg. The relationships were: LMI-BMI: r = 0.908, r2 = 0.824, p < 0.001; LMI-PA: r = 0.704, r2 = 0.495, p = 0.009 and PA-BCM: r = 0.491, r2 = 0.241, p < 0.001. The results obtained confirm that LMI could be considered a new parameter that provides reliable information to evaluate the muscle mass of athletes. Furthermore, the higher LMI-BCM relationship than PA-BCM demonstrates specificity for muscle mass evaluation in athletes regardless of body weight, ethnicity, age, and sex.

Effect of resistance training on bioelectrical phase angle in older adults: a systematic review with Meta-analysis of randomized controlled trials

Resistance training has been proposed as a valid practice to counteract the aging effect on body mass and its components, which can be easily evaluated though the bioelectrical impedance analysis. This study aimed to achieve a systematic review with meta-analysis on the impact of resistance training on bioelectrical proprieties in older adults.A literature review was done in four electronic databases up to 1 January 2022. The inclusion criteria were: (i) participants aged ≥ 60 years; (ii) resistance training lasted ≥ 8 weeks; (iii) measurement of raw bioelectrical parameters in randomized controlled study designs.The outcomes of the trial had to be bioelectrical phase angle (PhA), resistance (R), and reactance (Xc). The methodological quality was assessed using the Rosendal scale.Overall, seven studies with a total of 344 participants were eligible for the analysis. The quality assessment yielded a score of 71.3%. Bioelectrical PhA (0.52 degree [95%CI 0.32, 0.71], p < 0.001) and Xc (3.58 ohms [95%CI 1.97, 5.19], p < 0.001) increased, whereas R decreased (-28.50 ohms [95%CI -41.39, -15.60], p < 0.001) after the resistance training programs.In this meta-analysis, resistance training promoted increases of PhA, which result from an increase in Xc concomitant with a reduction in R. According to the bioimpedance vector analysis, resistance-trained people experienced a beneficial leftward vector displacement, whilst inactivity induced a rightward vector displacement within the R-Xc graph. In future, more sophisticated and rigorous studies that address specific criteria, methods and targeted designs are required to identify which equipment and protocols allow for an optimization of the resistance training effects.Registration code in PROSPERO: CRD42020168057.

Bioelectrical Impedance Analysis (BIA)- Derived Phase Angle in Children and Adolescents: A Systematic Review

Phase angle (PhA), a directly-measured bioelectrical impedance analysis variable, is suggested to be a proxy of body cell mass as well as extracellular/intracellular water ratio, and is related to cellular integrity and functions. The aim of this systematic review was to evaluate PhA in healthy youths in relation to sex, age, weight status, physical fitness, and sports activities. A systematic literature search (preferred reporting items for systematic reviews and meta-analyses criteria) until January 2022 was performed using PubMed, Embase, Scopus, and Web of Science regarding studies on PhA in healthy children and adolescents 4-18 years of age. Quality was assessed according to the National Institute of Health. After removing duplicates and studies not fulfilling the inclusion criteria, 22 cross-sectional and 1 longitudinal were considered appropriate. As for quality, 14 articles were rated fair and 9 good. Ten studies found that PhA increases with age: the increase was more marked after puberty, whereas changes in younger subjects are by far less defined. A clear sex difference was found in adolescents, likely due to pubertal development. Limited evidence suggests that PhA increases in participants with very high BMI. Limited data were reported on physically active youths without convincing findings. Positive associations of PhA with physical fitness and fat-free mass were found in few studies. In conclusion, partial and limited evidence suggests that changes in PhA over the first 2 decades of life reflect modification in body composition and fat-free mass composition. Further studies are needed for confirming PhA as a relevant marker of nutritional status in youths.

Brazilian Reference Percentiles for Bioimpedance Phase Angle of Healthy Individuals

Objectives

The present study was designed to estimate phase angle percentile curves for a broad age range of healthy individuals.

Methods

This is a cross-sectional study of healthy Brazilian individuals aged five to 80. InBodyS10 was used to assess phase angle. Reference curves were stratified by sex and estimated using Generalized additive models for location, scale, and shape as a continuous function of age. The phase angle determinants analyzed were physical activity, age, BMI, and SES variables.

Results

Data were analyzed from 2,146 individuals, 1,189 (55.2%) of whom were female. In both sexes, the phase angles showed a similar pattern (an increasing trend from childhood to the teenage phase, followed by stabilization during adult ages and a decrease in old adults). In female, the relationship between phase angle and age were associated with BMI and family income. In the male, the relationship between phase angle and age were associated with skin color and family income.

Conclusions

To the best of our knowledge, it is the first attempt to apply the GAMLSS technique to estimate phase angle percentiles in a healthy population covering most of the life cycle. We also showed that there are different phase angle determinants according to sex.

Poor Nutritional Status and Dynapenia Are Highly Prevalent in Post-Acute COVID-19

Poor nutritional status is common (estimated prevalence 5–69%) in acute coronavirus disease-2019 (COVID-19), and has been associated with hospitalization, the need for intensive care, and mortality. Body composition (BC) and muscle function have also been related in such patients to poor disease outcomes.

As the evidence in the literature is limited, a cross-sectional study was carried out to determine the frequency of malnutrition in a cohort of post-acute COVID-19 patients referred to a rehabilitation center after hospital discharge. BC and muscle strength were assessed and the differences between bedridden and not bedridden patients were specifically evaluated.

The study sample was composed of 144 post-acute COVID-19 patients (mean age 64.8 years; males = 95), 37% of whom were bedridden (males = 60%). Nutritional status was evaluated with Mini-Nutritional Assessment (MNA) and Controlling Nutritional status (CONUT). Fat-free mass (FFM) and skeletal muscle mass (SM) were estimated using bioelectrical impedance analysis (BIA). Raw BIA variables (phase angle = PhA and impedance ratios = IRs) were also determined and handgrip strength (HGS) was measured. Dynapenia was identified according to the 2019 EWGSOP criteria.

According to MNA, 18% (n. 26) of patients were malnourished and 62% (n. 89) were at risk of malnutrition. As for CONUT, 21% (n. 31) of cases had moderate–severe malnutrition and 58% (n. 83) had light malnutrition. Abnormalities of raw BIA variables (low PhA and high IRs) and low HGS were more common in bedridden patients, in those who were malnourished, or had low FFM or SM. Dynapenic patients were 65% men and 47% women.

In conclusion, malnutrition, BC alterations, and low HGS occur in post-acute COVID-19 patients and are more common in bedridden patients. Further studies are needed to identify reliable algorithms for assessing nutritional status in post-acute COVID-19 patients undergoing rehabilitation.

Phase Angle as a Comprehensive Tool for Nutritional Monitoring and Management in Patients with Crohn's Disease

Background and Aims: Crohn’s disease (CD) is usually accompanied by malnutrition. CD-related malnutrition can increase morbidity, disability, mortality, and hospitalization costs. The purpose of this study was to find a reliable indicator for evaluating CD patients’ nutritional status. Methods: All data were retrospectively collected from Xiangya Hospital, Central South University between May 2021 and February 2022. All patients were evaluated for nutritional status using the Global Leadership Initiative on Malnutrition (GLIM) criteria. Body composition, resistance, and reactance were recorded by a body analyser, and the phase angle (PhA) was calculated simultaneously. The Mann−Whitney U test, chi-square test, Fisher’s exact test, and univariate and multivariate logistic regression analyses were used. A receiver operating characteristic (ROC) curve was built to evaluate the predictive value of differential variables for diagnosing malnutrition based on the GLIM criteria. Results: A total of 169 CD patients were enrolled, of which 74 (58.3%) males and 32 (76.2%) females were diagnosed with malnutrition; 34 (45.9%) males and 22 (68.8%) females were severely malnourished. Univariate analysis identified that as nutritional status deteriorated, body mass index, PhA, and levels of haemoglobin and albumin decreased, while platelet count, erythrocyte sedimentation rate, and levels of C-reactive protein and fibrinogen increased (p < 0.05). Logistic regression analysis revealed that the PhA was significantly independently associated with malnutrition (p < 0.05). The ROC curve analysis indicated that the optimal PhA cut-off levels of 6.11° and 5.55° could be used to predict malnutrition according to the GLIM criteria in males and females, respectively, with a PhA < 5.53° and < 5.12° indicating severe malnutrition in males and females, respectively. Conclusion: The PhA is a sensitive, noninvasive, portable, inexpensive tool that can be used to monitor and manage the nutritional status of CD patients.

Cancer, Phase Angle and Sarcopenia: The Role of Diet in Connection with Lung Cancer Prognosis

Lung cancer is the most common cause of cancer death and is associated with malnutrition and sarcopenia. The detection of sarcopenia and conduction of simple body composition measurements, such as the phase angle (PhA) deriving from bioelectrical impedance analysis (BIA), can help to early identify, monitor, prevent and treat malnutrition. The present review aims to clarify the relationship between PhA and sarcopenia with the pathophysiology, clinical outcomes, and therapeutic aspects of lung cancer. PhA and sarcopenia are connected to lung cancer prognosis through various mechanisms including inflammation and oxidative stress, although more research is needed to identify the critical thresholds for increased mortality risk. Moreover, emphasis is given on the role of dietary interventions (oral nutritional supplementation, and dietary counseling) to manage sarcopenia and related variables in patients with lung cancer. Oral nutritional supplements and/or those containing n - 3 polyunsaturated fatty acids may have a positive effect on physical strength measures and muscle mass if administered at the beginning of chemotherapy. Data on sole dietary counseling or multimodal interventions are less promising so far. In the future, sophisticated body composition phenotypes deriving from the described methods along with artificial intelligence techniques could be used to design personalized nutrition interventions and timely treat these patients.

The Effects of High-Speed Resistance Training on Health Outcomes in Independent Older Adults: A Systematic Review and Meta-Analysis

Human ageing involves several physiological impairments—in particular, a decrease in sensorimotor function and changes in the nervous system reduce muscle strength, power, balance, and functional capacity performance. Preventive strategies are essential to ensure the quality of life of the elderly. High-speed resistance training (HSRT) may be an effective approach to muscle power development in this population, with significant short-term effects on neural adaptations and muscle power production. Therefore, the present study intends to analyze and systematize the studies focused on HSRT interventions and their effects on health outcomes in independent older adults. Four electronic databases (PubMed, Web of Science, EBSCO, and Scielo) were used for the purposes of searching randomized controlled trials that measured at least one key outcome measure focusing on velocity-based training and health outcomes in older adults on 7 March 2022 and identified 1950 studies. At the end of the process, fourteen studies were included in this systematic review and ten studies were included in the quantitative analysis. The main results showed that HSRT interventions would improve health measures, mostly cognitive function (large effects, p = 0.001, SMD = 0.94), neuromuscular function (moderate effects, p = 0.003, SMD = 0.70), and physical function (moderate effects, p = 0.04, SMD = 0.55 and p = 0.009, SMD = −0.59). Additionally, the results suggested that interventions with ten weeks or more, performed three times a week, provide significant improvements in neuromuscular function. In this sense, HSRT is effective for improving overall health outcomes in older adults. Future studies should include proper follow-ups (e.g., minimum six months) to assess the durability of HSRT intervention effects on all health-related variables.

The Use of the Bioelectrical Impedance Phase Angle to Assess the Risk of Sarcopenia in People Aged 50 and above in Poland

PURPOSE

The increasing aging of many populations requires a continuous evolution of assessment methods in geriatrics, especially methods for identifying sarcopenia. Early diagnosis of unfavorable changes in the condition of skeletal muscles and the implementation of therapeutic methods may reduce the risk of functional limitations in the elderly. The aim of the study was to evaluate the association between the bioelectrical impedance phase angle and the occurrence of pre-sarcopenia in people aged 50 and above.

METHODS

1567 people aged 50-87 were examined. Anthropometric as well as muscle strength and walking speed measurements were performed. Using bioelectrical impedance analysis, the phase angle was measured and the appendicular skeletal muscle mass was estimated. The contribution of the phase angle in explaining the probability of the occurrence of pre-sarcopenia was verified by multivariate logistic regression.

RESULTS

Sarcopenia was diagnosed in 12 people (0.8%) and pre-sarcopenia in 276 people (17.6%). Significantly lower impedance phase angle and muscle functional quality were found in people with confirmed pre-sarcopenia compared to people without sarcopenia. The relative differences for the phase angle were greater than for the indicator of muscle functional quality. Significant logit models were obtained for the probability of occurrence of pre-sarcopenia, in which the strongest predictor was the phase angle, regardless of the type and number of covariates. The cut-off point of the phase angle for identification of pre-sarcopenia was 5.42° in men and 4.76° in women.

CONCLUSION

The strong association between the risk of pre-sarcopenia and the phase angle, which can be easily and quickly assessed by bio-impedance analysis, suggests the necessity to include this parameter in routine geriatric evaluation in order to identify the risk of sarcopenia.

Changes in Intra-to-Extra-Cellular Water Ratio and Bioelectrical Parameters from Day-Before to Day-Of Competition in Bodybuilders: A Pilot Study

The present study analyzed the effects from day-before to day-of bodybuilding competition on intracellular water (ICW), extracellular water (ECW), total body water (TBW), and bioimpedance analysis (BIA) parameters (resistance, R; reactance, Xc; and derived scores) in bodybuilding athletes. We assessed anthropometry and BIA (foot-to-hand; tetrapolar; 50 kHz) in 11 male bodybuilders (29 ± 4 year-old; 81 ± 8 kg; 172 ± 7 cm; 27 ± 2 kg/m²) both on the pre-competition day and on the contest day. Results revealed significant increases in ICW (31.6 ± 2.9 to 33.1 ± 2.8 L), with concomitant decreases in ECW (19.8 ± 1.8 to 17.2 ± 1.4 L) and TBW (51.4 ± 4.6 to 50.3 ± 4.2 L) from the day-before competition to contest day, which resulted in relatively large increases in the ICW/ECW ratio (1.60 ± 0.03 to 1.92 ± 0.01 L). Moreover, significant increases in R (391 ± 34 to 413 ± 33 ohm), Xc (64 ± 7 to 70 ± 6 ohm), and phase angle (9.3 ± 0.6 to 9.6 ± 0.7 degree) were observed between time periods. The phase angle scores reported on show-day of 9.6 and 11.2 appear to be the highest group mean and individual values observed in the literature to date. In conclusion, the strategies carried out on the final day of peak-week bodybuilding preparation lead to changes in BIA parameters and body water, with fluids shifting from the extra- to the intracellular compartment.

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.

Worth the Wait? Time Course of Supine Shifts in Body Water Compartments on Variables of Bioelectrical Impedance Analysis

Bioelectrical impedance analysis (BIA) reference values are based on supine assessments. Little is known regarding the effects of time course shifts in body water compartments after assuming a supine position. The aim of this study was to characterize these effects and provide recommendations regarding the optimal waiting time to perform BIA. Thirty-eight healthy adults underwent BIA via the RJL Quantum Legacy analyzer immediately upon lying down and every 5 minutes for 15 minutes. Differences in resistance (R), reactance (Xc), intracellular (ICW), extracellular (ECW), total body water (TBW), body fat percentage (%BF), and phase angle (PhA) were assessed. There were small but significant increases in R, Xc, and %BF (all p<0.001), as well as small but significant decreases in ICW, ECW, and TBW (all p<0.001) over 15 minutes. No difference was observed for PhA (p=0.065). Average values changed over 15 minutes by +7.14Ω, +1.36Ω, -0.2L, -0.2L, -0.4L, +0.05° and +0.1% for R, Xc, ICW, ECW, TBW, PhA and %BF, respectively. BIA measurements are affected by shifts in body water compartments after assuming a supine position, but these differences lack clinical significance in healthy adults. Technicians working with healthy adults can perform BIA within 15 minutes after participants assume a supine position.

Phase angle as a screening method for sarcopenia in community-dwelling older adults

ABSTRACT Objective We investigated the utility of the phase angle as a screening tool for sarcopenia. Methods We performed a cross-sectional study that included 169 active community-dwelling elderly women. The phase angle was determined using tetrapolar bioelectrical impedance, and sarcopenia was diagnosed based on skeletal muscle mass, muscle strength, and physical performance using bioelectrical impedance analysis, a handheld dynamometer, and the gait speed test, respectively. Receiver operating characteristic curve analysis was performed to investigate the role of the phase angle as a predictor of sarcopenia. Results The prevalence of sarcopenia was 12.4%. The median phase angle was 5.30°; elderly women with sarcopenia had lower phase angles than those without sarcopenia (p=0.006). The phase angle cutoff for the detection of sarcopenia was ?5.15°, with an area under the curve of 0.685, sensitivity 81.0%, specificity 60.8%, and accuracy 63.31%. Elderly women with a low phase angle show a high risk of presenting with reduced muscle mass. Conclusions The phase angle was shown to be a useful screening tool in elderly women with sarcopenia.

The Russian Bioimpedance Database: An Update

Extensive bioelectrical impedance analysis (BIA) data have the potential of health monitoring and the assessment of health risks at the population level. The importance of BIA data lies in their availability and abundance for many countries. In Russia, mass BIA data are generated by the national network of health centers (HCs). Our aim was to describe the structure and capabilities of the updated HCs' BIA database. Upon several requests between 2012 and 2020, 369 HCs representing all Federal districts of Russia and 60 out of 85 Federal subjects in them, submitted raw bioimpedance data which were obtained using the same type of BIA instrument, namely ABC-01 'Medas' (SRC Medas, Russia). After application of strict selection criteria, 2,429,977 BIA measurement records were selected that formed the updated 2010-2019 HCs' database. Various slices of the BIA data are described according to spatiotemporal, demographic and other characteristics. Reference curves of the bioimpedance phase angle according to age and sex are presented. Limitations and prospects for further work are outlined. We believe that, after appropriate sampling, the database can be utilized to study biological, geographical, social and other associations of the bioimpedance and body composition parameters, for generating updated national references, international comparisons and data standardization.

Cardiovascular Diseases Diagnosis by Impedance Cardiography

Cardiovascular disease (CVD) represents the leading cause of mortality worldwide. In order to diagnose CVDs, there are a range of detection methods, among them, the impedance cardiography technique (ICG). It is a non-invasive and low-cost method. In this paper, we highlight recent advances and developments of the CDVs diagnosis mainly by the ICG method. We considered papers published during the last five years (from 2017 until 2022). Based on this study, we expressed the need for an ICG database for the different CDVs.

Bioelectric impedance body composition and phase angle in relation to 90-day adverse outcome in hospitalized COVID-19 ward and ICU patients: The prospective BIAC-19 study

BACKGROUND & AIMS

Gaining insight into readily obtainable baseline characteristics that allow prediction of adverse outcome in COVID-19 aids both treatment and healthcare planning. Bioelectric impedance (BIA) Phase Angle (PhA) is correlated with outcome in a multitude of diseases and may be of added value in predicting adverse outcome of COVID-19. We aimed to associate baseline body composition parameters with 90-day adverse outcome of COVID-19 including ICU-admission and to explore the added predictive value of baseline PhA.

METHODS

We performed a prospective observational study, conducting BIA amongst COVID-19 patients within 24 hours of hospital admission, with a follow-up of 90 days. Data were compared between ward-only and ICU-patients. Regression models were used to assess the associations between baseline characteristics, body composition and 90-day adverse outcome, including a composite outcome score of morbidity, ICU-admission, and mortality. An ROC-curve was used to explore the added predictive value of PhA to other clinical parameters at baseline for the prediction of adverse outcome.

RESULTS

One-hundred-and-fifty patients were included. Mean age was 68 (66-70) years, 67% were male. Forty-one (27%) patients were admitted to ICU and 77 (51%) met the criteria of the composite outcome score. In multiple regression, PhA was independently, inversely correlated with risk of ICU-admission (OR .531, p = .021), complications (OR .579, p = .031), hospital length of stay (OR .875, p = .037) and the composite outcome score (OR .502, p = .012). An ROC-curve showed that the incorporation of PhA in a composite risk-score improved the discriminative power for the composite outcome from poor to fair, compared to individual predictors (AUC 0.79 (95% CI 0.71-0.87)).

CONCLUSION

BIA measurements including Phase Angle are independently correlated with an adverse outcome of COVID-19. Interpretation of Phase Angle can be a valuable addition to risk assessment of adverse outcome of COVID-19 at hospital admission.

CLINICAL TRIAL REGISTRATION

Netherlands Trial Register number NL8562, registered 2020-04-21.

Resistance but not elastic tubes training improves bioimpedance vector patterns and body composition in older women: A randomized trial

The present study aimed to investigate the effects of traditional resistance training compared to elastic tubes training on bioimpedance vector patterns, body composition, and strength in older women. Thirty-eight older women (age 68.7 ± 6.9 years, body mass index 28.8 ± 7.2 kg/m²) were randomly assigned to perform traditional resistance or elastic tubes training three times per week for 12 weeks. Body composition was assessed by dual energy X-ray absorptiometry and bioelectrical impedance vector analysis. In addition, handgrip strength was measured using a dynamometer. Only the participants who followed the 12-week traditional resistance training program significantly (p < 0.05) decreased fat mass (ES: -0.69) and extracellular water (ES: -1.06), and increased total body water (ES: 0.49), intracellular water (ES: 1.11), body cell mass (ES: 0.82), muscle mass (ES: 0.94), and phase angle (ES: 0.99), while no change occurred in the elastic tubes training group. Furthermore, a vector leftward displacement (ES: 1.11) into the resistance-reactance graph was found only after the traditional resistance training program. The handgrip strength increased for both traditional and elastic tubes training groups (ES: 0.64, ES: 0.71, respectively). Traditional resistance training improved body composition and strength in the older women group, while training using elastic tubes was effective only for the latter. The present outcomes encourage the use of systematic resistance training to counteract the effects of aging in older women.

Academy of Nutrition and Dietetics: 2020 Cystic Fibrosis Evidence Analysis Center Evidence-Based Nutrition Practice Guideline

The Academy of Nutrition and Dietetics Evidence Analysis Center conducted a systematic review of the literature to develop an evidence-based practice guideline for primary nutrition issues in cystic fibrosis (CF). This guideline is designed to complement and build upon existing evidence-based CF nutrition guidelines. The objective of this guideline was to provide recommendations for registered dietitian nutritionists in the United States delivering medical nutrition therapy to individuals with CF and their families that fill gaps in current evidence-based guidelines on topics that are crucial in order to improve health and prevent disease progression. This guideline provides 28 nutrition recommendations to guide medical nutrition therapy, including nutrition screening, nutrition assessment, and dietary intake. For topics outside the scope of this guideline, practitioners are referred to external, evidence-based recommendations. The CF landscape is evolving rapidly with breakthroughs in cystic fibrosis transmembrane regulator modulators changing CF at a cellular level. Medical nutrition therapy for individuals with CF from infancy through advanced age requires novel and individualized approaches. The Academy Evidence Analysis Library CF guidelines provide a framework for expanding upon current knowledge to determine effective nutrition strategies for individuals with CF through long and healthy futures.

Phase Angle Is a Marker of Muscle Quantity and Strength in Overweight/Obese Former Athletes

BACKGROUND

An increasing body of evidence indicates that the phase angle (PhA) can be applied as a marker of nutritional status, disease prognosis, and mortality probability. Still, it is not known whether PhA can be used as an indicator of muscular quantity and strength and maximal aerobic capacity in overweight/obese former highly active individuals, an understudied population. This study aimed to analyze the association between PhA with skeletal muscle mass, maximal isometric strength, and maximal aerobic capacity through VO2max, in overweight/obese and inactive former athletes.

METHODS

Cross-sectional information of 94 (62 males) former adult athletes (age: 43.1 ± 9.4 years old; body mass index: 31.4 ± 4.8 kg/m2) taking part in a weight-loss clinical trial was analyzed. Total fat and fat-free mass were determined by dual-energy X-ray absorptiometry, while skeletal muscle mass was predicted from appendicular lean soft tissue. Values for upper- and lower-body maximal isometric strength were assessed by handgrip and leg press dynamometry. VO2max was determined by indirect calorimetry through a graded exercise test performed on a treadmill.

RESULTS

PhA was associated with skeletal muscle mass (r = 0.564, p < 0.001), upper-body strength (r = 0.556, p < 0.001), lower-body strength (r = 0.422, p < 0.001), and VO2max (r = 0.328, p = 0.013). These relationships remained significant for skeletal muscle mass (β = 2.158, p = 0.001), maximal isometric strength (upper-body: β = 2.846, p = 0.012; low-er-body: β = 24.209, p = 0.041) after adjusting for age, sex, and fat mass but not for VO2max (β = -0.163, p = 0.098).

CONCLUSION

Our findings indicated that former athletes with higher values of PhA exhibited greater muscle mass and strength, despite sex, age, and body composition, which suggests that this simple raw BI parameter can be utilized as an indicator of muscle quantity and functionality in overweight/obese former athletes.

Bioimpedance Vector Patterns according to Age and Handgrip Strength in Adolescent Male and Female Athletes

Bioelectric Impedance Vector Analysis (BIVA) can be used to qualitatively compare individuals’ hydration and cell mass independently of predictive equations. This study aimed to analyze the efficiency of BIVA considering chronological age and handgrip strength in adolescent athletes. A total of 273 adolescents (male; 59%) engaged in different sports were evaluated. Bioelectrical impedance (Z), resistance (R), reactance (Xc), and phase angle (PhA) were obtained using a single-frequency bioelectrical impedance analyzer. Fat-free mass (FFM) and total body water were estimated using bioimpedance-based equations specific for adolescents. Female showed higher values of R (5.5%, p = 0.001), R/height (3.8%, p = 0.041), Z (5.3%, p = 0.001), and fat mass (53.9%, p = 0.001) than male adolescents. Male adolescents showed higher values of FFM (5.3%, p = 0.021) and PhA (3.1%, p = 0.033) than female adolescents. In both stratifications, adolescents (older > 13 years or stronger > median value) shifted to the left on the R-Xc graph, showing patterns of higher hydration and cell mass. The discrimination of subjects older than 13 years and having higher median of handgrip strength values was possibly due to maturity differences. This study showed that BIVA identified age and strength influence in vector displacement, assessing qualitative information and offering patterns of vector distribution in adolescent athletes.

Segmental Phase Angle and Body Composition Fluctuation of Elite Ski Jumpers between Summer and Winter FIS Competitions

(1) Background: The purpose of this study was to observe segmental phase angle (PhA) and body composition fluctuation of elite ski jumpers. (2) Methods: In the study, 12 professional ski jumpers took part. Body composition was estimated with segmental multi-frequency bioelectrical impedance analysis. Repeated ANOVA was used to check the parameters' variability in time. The symmetry between the right and left side of the body was verified with the t-test for dependent samples. Pearson's linear correlation coefficient was calculated. (3) Results: The most stable parameter was body weight. An increase in the visceral fat area was noted, the fat-free mass dropped, and significant changes were noted in the internal and external cell water parameters. Parameters connected with water between the right and left side of the body were symmetrical. Significant correlation between PhA values and body parameters with regard to fat tissue and PhA values of the legs was noticed when PhA was measured at 50 kHz. (4) Conclusions: PhA could be considered as a ski jumper body symmetry monitoring tool. The described relationship may be useful for the assessment of body fat change, which, in the case of jumpers, is crucial. Moreover, our data suggest that segmental PhA evaluation could be a good solution for ski jumpers as a confirmation if lowered body mass and low BMI are still healthy and increase the chance for longer jumps and good performance.

Agreement of bioelectrical resistance, reactance, and phase angle values from supine and standing bioimpedance analyzers

OBJECTIVE

Bioimpedance devices are commonly used to assess health parameters and track changes in body composition. However, the cross-sectional agreement between different devices has not been conclusively established. Thus, the objective of this investigation was to examine the agreement between raw bioelectrical variables (resistance, reactance, and phase angle at the 50-kHz frequency) obtained from three bioimpedance analyzers.

APPROACH

Healthy male (n=76, Mean±SD; 33.8±14.5 years; 83.9±15.1 kg; 179.4±6.9 cm) and female (n=103, Mean±SD; 33.4±15.9 years; 65.6±12.1 kg; 164.9±6.4 cm) participants completed assessments using three bioimpedance devices: supine bioimpedance spectroscopy (BIS), supine single-frequency bioelectrical impedance analysis (SFBIA), and standing multi-frequency bioelectrical impedance analysis (MFBIA). Differences in raw bioelectrical variables between the devices were quantified via one-way analysis of variance for the total sample and for each sex. Equivalence testing was used to determine equivalence between methods.

MAIN RESULTS

Significant differences in all bioelectrical variables were observed between the three devices when examining the total sample and males only. The devices appeared to exhibit slightly better agreement when analyzing female participants only. Equivalence testing using the total sample as well as males and females separately revealed that resistance and phase angle were equivalent between the supine devices (BIS, SFBIA), but not with the standing analyzer (MFBIA).

SIGNIFICANCE

The present study demonstrated disagreement between different bioimpedance analyzers for quantifying raw bioelectrical variables, with the poorest agreement between devices that employed different body positions during testing. These results suggest that researchers and clinicians should employ device-specific reference values to classify participants based on raw bioelectrical variables, such as phase angle. If reference values are needed but are unavailable for a particular bioimpedance analyzer, the set of reference values produced using the most similar analyzer and reference population should be selected.

Relationship of Fat Mass Index and Fat Free Mass Index With Body Mass Index and Association With Function, Cognition and Sarcopenia in Pre-Frail Older Adults

BACKGROUND

Body mass index (BMI) is an inadequate marker of obesity, and cannot distinguish between fat mass, fat free mass and distribution of adipose tissue. The purpose of this study was twofold. First, to assess cross-sectional relationship of BMI with fat mass index (FMI), fat free mass index (FFMI) and ratio of fat mass to fat free mass (FM/FFM). Second, to study the association of FMI, FFMI and FM/FFM with physical function including sarcopenia, and cognition in pre-frail older adults.

METHODS

Cross-sectional study of 191 pre-frail participants ≥ 65 years, 57.1% females. Data was collected on demographics, cognition [Montreal Cognitive Assessment (MoCA)], function, frailty, calf circumference, handgrip strength (HGS), short physical performance battery (SPPB) and gait speed. Body composition was measured using InBody S10. FMI, FFMI and FM/FFM were classified into tertiles (T1, T2, T3) with T1 classified as lowest and T3 highest tertile respectively and stratified by BMI.

RESULTS

Higher FFMI and lower FM/FFM in the high BMI group were associated with better functional outcomes. Prevalence of low muscle mass was higher in the normal BMI group. FMI and FM/FFM were significantly higher in females and FFMI in males with significant gender differences except for FFMI in ≥ 80 years old. Small calf circumference was significantly less prevalent in the highest tertile of FMI, FM/FMI and FFMI. Prevalence of sarcopenic obesity and low physical function (HGS, gait speed and SPPB scores) were significantly higher in the highest FMI and FM/FFM tertile. Highest FFMI tertile group had higher physical function, higher MoCA scores, lower prevalence of sarcopenic obesity and sarcopenia, After adjustment, highest tertile of FFMI was associated with lower odds of sarcopenia especially in the high BMI group. Highest tertile of FM/FFM was associated with higher odds of sarcopenia. Higher BMI was associated with lower odds of sarcopenia.

CONCLUSION

FFMI and FM/FFM may be a better predictor of functional outcomes in pre-frail older adults than BMI. Cut-off values for healthy BMI values and role of calf circumference as a screening tool for sarcopenia need to be validated in larger population. Health promotion intervention should focus on FFMI increment.

The Predictive Role of Raw Bioelectrical Impedance Variables in Disordered Eating Attitudes in Female Ballet Dance Students

The present study used receiver operating characteristic (ROC) curve analysis to investigate the accuracy of body composition and raw bioelectrical impedance analysis (BIA) in correctly classifying disordered eating attitudes (DEA) in dance students. Participants were 81 female dancers assigned in two groups: beginner training (BT; age (mean ± SD) = 10.09 ± 1.2 years, n = 32) and advanced training (AT; age = 15.37 ± 2.1 years, n = 49). Fat mass (FM) was estimated by Slaughter's equation and skeletal muscle with Poortman's equation. Impedance (Z), resistance (R), reactance (Xc) and phase angle (PhA) were obtained through multifrequency BIA at a frequency of 50 kHz. Fat-free mass (FFM) was assessed using Sun's equation. For evaluation of DEA, the Eating Attitudes Test-26 (EAT-26) questionnaire was performed. We defined an EAT-26 score ≥ 20 as positive for DEA. Comparisons between groups were performed by a one-way ANOVA test or Kruskall-Wallis test. Spearman's rank correlation coefficients were performed to assess associations between variables. ROC curve analysis was utilized to test the accuracy of body composition and BIA variables in predicting DEA. In the BT group, Xc and PhA demonstrated high accuracy in predicting DEA with an area under the curve (AUC) of 0.976 (95% confidence interval (CI): 0.85-1.00) and 0.957 (95% CI: 0.82-0.99), respectively, (both p < 0.0001). FFM Sun had an AUC of 0.836 (95% CI: 0.66-0.94) (p < 0.0001) in the BT group and FFM Slaughter was 0.797 (95% CI: 0.66-0.90) (p < 0.001) in the AT group. Reactance and Phase angle were excellent and useful predictors of DEA in the BT group.

The Effects of Thermal Water Physical Exercise in Patients with Lower Limb Chronic Venous Insufficiency Monitored by Bioimpedance Analysis

BACKGROUND

Lower limb chronic venous diseases (CVD) lead to possible edema. The aim of the present investigation was to study the effect of thermal aquatic standardize exercise on lower limb edema control in CVD patients assessed by bioimpedance analysis (BIA).

METHODS

Seventeen patients (34 legs) affected by CVD clinical class CEAP C3, 4c, Ep, As, Pr were included. All the cohort performed a standardized exercise protocol in thermal water environment for a total of five sessions. BIA, leg volume, and heart rate at rest were measured.

RESULTS

After the five exercise sessions, BIA showed a significant percentage of extracellular water (ECW) reduction from 42.1 ± 5.8 to 41.24 ± 5.5%; p < 0.001. Moreover, an improvement of resistance (p < 0.0009) and reactance (p < 0.009) was assessed. At the same time, the leg volume reduction rate was 15.7%, p <0.0001. A moderate-strong correlation was found between % ECW and leg volume variation (R = 0.59, p < 0.01). Finally, a significant HR at rest reduction was recorded, p < 0.0001.

CONCLUSION

The investigated exercise protocol significantly affects the lower limb volume, and BIA parameters related to the tissue drainage improvement. The correlation founded between the ECW rate and volume variations suggest the possible use of BIA as a biomarker for monitoring the treatments aimed to reduce edema in CVD.

Association of bioelectric impedance analysis body composition and disease severity in COVID-19 hospital ward and ICU patients: The BIAC-19 study

Background

The current severe acute respiratory syndrome coronavirus 2 pandemic is unprecedented in its impact. It is essential to shed light on patient characteristics that predispose to a more severe disease course. Obesity, defined as a BMI>30 kg/m², is suggested to be one of these characteristics. However, BMI does not differentiate between fat mass and lean body mass, or the distribution of fat tissue. The aim of the present study was to assess the body composition of COVID-19 patients admitted to the ward or the ICU and identify any associations with severity of disease.

Methods

We performed an observational cross-sectional cohort study. Bioelectric impedance analysis was conducted amongst all confirmed COVID-19 patients admitted to the ward or ICU of our hospital in the Netherlands, between April 10 and 17, 2020. Body water measurements and derived values were recalculated to dry weight, using a standard ratio of extracellular water to total body water of 0.38. Data were compared between the ward and ICU patients, and regression models were used to assess the associations between baseline characteristics, body composition, and several indicators of disease severity, including a composite score composed of mortality, morbidity, and ICU admission.

Results

Fifty-four patients were included, of which 30 in the ward and 24 in the ICU. The mean age was 67 years (95%-CI 64–71), and 34 (63%) were male. Mean BMI was 29.7 (95%-CI 28.2–31.1) kg/m² and did not differ between groups. Body composition values were not independently associated with disease severity. In multiple logistic regression analyses, a low phase angle was associated with COVID-19 severity in the composite score (OR 0.299, p = 0.046).

Conclusion

We found no significant associations between body composition, including fat mass, visceral fat area, and fat-free mass, and disease severity in our population of generally overweight COVID-19 patients. A lower phase angle did increase the odds of severe COVID-19. We believe that factors other than body composition play a more critical role in the development of severe COVID-19.

Independent Association of Phase Angle with Fasting Blood Glucose and Hemoglobin A1c in Korean Type 2 Diabetes Patients

The relationship between phase angle (PhA) of bioelectrical impedance analysis (BIA) and glycemic parameters in diabetes mellitus (DM) patients has not been well studied. To evaluate the prognostic value of the PhA from BIA as a glycemic marker, we investigated the relationship of PhA with various variables such as age, body mass index (BMI), and glycemic parameters in Korean patients with type 2 DM (T2DM). We evaluated the anthropometric data, body composition, glycemic parameters, and PhA of 321 T2DM patients aged 30–83 years. The patients were classified by sex into men (n = 133) and women (n = 188). General linear models identified the independent effects of PhA after covarying for age, sex and BMI. The PhA, body cell mass (BCM), extracellular mass (ECM), lean body mass, intracellular water (ICW), extracellular water (ECW), total body water (TBW), fasting blood glucose, and hemoglobin A1c (HbA1c) of T2DM Korean patients were significantly higher in men than in women. However, fat mass, ECM/BCM, ECW/ICW, ECW/TBW, and serum insulin were significantly higher in women than in men. Statistically significant independent associations were observed between PhA and age, BCM, ECM, ECM/BCM, ICW, ECW, ECW/ICW, and ECW/TBW for both sexes. There was no significant association between PhA and BMI the patients. Glycemic parameters, such as HbA1c and fasting blood glucose were independently associated with PhA. These results suggest that PhA could be an indicator for assessing ability to control fasting blood glucose in T2DM patients in Korea.

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.

Mitochondrial DNA methylation and copy number predict body composition in a young female population

Background

Since both genomic and environmental factors are involved in obesity etiology, several studies about the influence of adiposity on both nuclear DNA and mitochondrial DNA methylation patterns have been carried out. Nevertheless, few evidences exploring the usage of buccal swab samples to study mitochondrial DNA epigenetics can be found in literature.

Methods

In this study, mitochondrial DNA from buccal swabs collected from a young Caucasian population (n = 69) have been used to examine potential correlation between mitochondrial DNA copy number and methylation with body composition (BMI, WHtR and bioimpedance measurements).

Results

A negative correlation between mitochondrial DNA copy number and BMI was measured in females (p = 0.028), but not in males. The mean percentage of D-loop methylation is significantly higher in overweight than in lean female subjects (p = 0.003), and a specific CpG located in the D-loop shows per se an association with impaired body composition (p = 0.004). Body composition impairment is predicted by a combined variable including mtDNA copy number and the D-loop methylation (AUC = 0.785; p = 0.009).

Conclusions

This study corroborates the hypothesis that mitochondrial DNA carries relevant information about body composition. However, wider investigations able to validate the usage of mtDNA methylation from buccal swabs as a biomarker are warranted.