The Predictive Role of Raw Bioelectrical Impedance Parameters in Water Compartments and Fluid Distribution Assessed by Dilution Techniques in Athletes

Comparison of series and parallel reactance to identify changes in intracellular water in response to physical training in athletes during a sports season

OBJECTIVE

Cross-sectional evidence has demonstrated that parallel reactance obtained by bioelectrical impedance analysis (BIA) may be an alternative to the regularly used series of measurements to predict intracellular water (ICW) in athletes. However, we are not aware of any studies that have determined the predictive role or compared the effectiveness of both series and parallel reactance for tracking ICW changes during an athletic season. The main aim of this study was to determine the predictive role and compare both series and parallel reactance (Xc) in tracking ICW during an athletic season.

RESEARCH METHODS AND PROCEDURES

This longitudinal study analyzed 108 athletes in the preparatory and competitive periods. Using dilution techniques, total body water (TBW) and extracellular water (ECW) were determined and ICW was calculated. Resistance (R), Xc, and impedance (Z) standardized for height were obtained through BIA spectroscopy using a frequency of 50kHz in a series array and then mathematically transformed in a parallel array.

RESULTS

Multiple regression analyses showed that only changes in parallel Xc and capacitance (CAP) (P < 0.05) were predictors of delta ICW during the sports season. In contracts, this was not the case for Xcs. Both changes in R and Z, series and parallel, predicted similarly the changes in ECW and TBW (P < 0.05) in athletes.

CONCLUSION

Our findings highlight the potential of parallel BIA values to detect changes in body water compartments over a competitive season. These data provide preliminary evidence that changes in parallel Xc/H, and ultimately CAP, represent valid markers of alterations in cell volume during a sports season.

H2OAthletes study protocol: effects of hydration changes on neuromuscular function in athletes

We aim to understand the effects of hydration changes on athletes' neuromuscular performance, on body water compartments, fat-free mass hydration and hydration biomarkers and to test the effects of the intervention on the response of acute dehydration in the hydration indexes. The H2OAthletes study (clinicaltrials.gov ID: NCT05380089) is a randomised controlled trial in thirty-eight national/international athletes of both sexes with low total water intake (WI) (i.e. < 35·0 ml/kg/d). In the intervention, participants will be randomly assigned to the control (CG, n 19) or experimental group (EG, n 19). During the 4-day intervention, WI will be maintained in the CG and increased in the EG (i.e. > 45·0 ml/kg/d). Exercise-induced dehydration protocols with thermal stress will be performed before and after the intervention. Neuromuscular performance (knee extension/flexion with electromyography and handgrip), hydration indexes (serum, urine and saliva osmolality), body water compartments and water flux (dilution techniques, body composition (four-compartment model) and biochemical parameters (vasopressin and Na) will be evaluated. This trial will provide novel evidence about the effects of hydration changes on neuromuscular function and hydration status in athletes with low WI, providing useful information for athletes and sports-related professionals aiming to improve athletic performance.

Glycated hemoglobin (HbA1c) is independently associated with the bioelectrical impedance phase angle in junior sumo wrestlers: A pilot study

The study explores the relationship between phase angle (PhA), an indicator of cellular health, and metabolic health parameters among junior sumo wrestlers in Japan. Given the demanding lifestyle and high-energy diets of sumo wrestlers that predispose them to metabolic syndrome post-retirement, this study focuses on a younger cohort. The primary aim is to evaluate if PhA could serve as an early indicator of metabolic health issues within this unique demographic. A total of 14 sumo wrestlers aged 9-17 years were assessed to determine the relationship between PhA and various metabolic markers, including glycated hemoglobin (HbA1c), using a TANITA MC-780A-N body composition analyzer and standard blood tests. Bivariate regression analysis and Pearson's correlation revealed a negative relationship between PhA and HbA1c even after adjusting for age and weight (ß = -0.496, r2 = 0.776, r = -0.756, p = 0.004). The results indicate a significant negative relationship between PhA and HbA1c levels, suggesting that lower PhA values, which indicate poorer cellular integrity, are associated with higher HbA1c levels, signifying impaired glycemic control. These findings underscore the potential of PhA as a valuable biomarker for monitoring metabolic health in young sumo wrestlers, with implications for early intervention and management strategies.

A meta-analysis on the impact of resistance training on phase angle in middle-aged and older individuals

PURPOSE

To determine the impact of resistance training (RT) on phase angle (PhA) in middle-aged and older individuals via meta-analysis, explore effects in subgroups, and identify optimal RT protocol.

MATERIALS AND METHODS

We searched five databases using predefined criteria, assessed literature quality per Cochrane 5.1 Handbook, and used Revman 5.3 for effect size aggregation, bias assessment, sensitivity analysis, and subgroup analysis.

RESULTS

RT improved PhA in middle-aged and older individuals (d = 0.34, 95 % CI: 0.27-0.40, P < 0.05). Effective subgroups included Suspension (d = 0.62, 95 % CI: 0.33-0.90, P < 0.05), free-weights and machine (d = 0.36, 95 % CI: 0.28-0.45, P < 0.05), equipment training (d = 0.24, 95 % CI: 0.13-0.36, P < 0.05), and moderate-intensity RT (d = 0.34, 95 % CI: 0.27-0.42, P < 0.05). RT was conducted 2-3 times/week (d = 0.20, 95 % CI: 0.01-0.38, P < 0.05) or (d = 0.38, 95 % CI: 0.30-0.47, P < 0.05). PhA improved after 8 weeks (d = 0.37, 95 % CI: 0.23-0.51, P < 0.05), 12 weeks (d = 0.35, 95 % CI: 0.26-0.44, P < 0.05), and ≥ 24 weeks (d = 0.26, 95 % CI: 0.11-0.41, P < 0.05) of RT in aged and older individuals. Low- and high-intensity RT, elastic band training, and weekly exercises did not significantly improve PhA.

CONCLUSIONS

RT enhances PhA in middle-aged and older adults. For optimal results, we recommend 2-3 weekly sessions of free weights and machine training lasting at least 8 weeks.

Bioelectrical impedance analysis as a clinical marker of health status in adult patients with benign gastrointestinal disease: A systematic review

BACKGROUND

Body composition reflects nutritional status, disease status and progression, and treatment responses. Mounting evidence supports the use of bioelectrical impedance analysis (BIA) as a non-invasive tool to assess body composition. Patients with benign gastrointestinal (GI) disease experience disease-related alterations in their body composition, and bioimpedance outcomes in patients with benign GI diseases have not previously been summarized. We aimed to evaluate BIA as a clinical body composition marker for benign GI diseases and describe its association with physical health status.

METHODS

We systematically searched PubMed, Scopus, Web of Science, Embase, and CINAHL from inception to October 2023 (PROSPERO registration: CRD42021265866). Of 971 screened studies, 26 studies were included in the final analysis, comprising a total of 2398 adult patients with benign GI disease. The main outcome was raw impedance data.

RESULTS

The most frequently reported BIA outcome was phase angle (PhA) (reported in 18 of 26 studies), followed by fat-free-mass (FFM) (reported in 13 of 26 studies). The consensus view of the included studies illustrates that BIA can be a useful tool for evaluating body composition in patients with benign GI diseases, and low PhA and FFM were associated with increased nutritional risk, abnormal physical characteristics, and increased mortality risk.

CONCLUSION

To fully utilize BIA as a clinical marker of health in patients with benign GI disease, standardized protocols specific to this population are needed and prospective studies testing cut-offs and ranges, accuracy, and other raw BIA parameters for classifying disease status.

Is muscle localized phase angle an indicator of muscle power and strength in young women?

Objective. This study aimed to investigate the capacity of the bioelectrical muscle localized phase angle (ML-PhA) as an indicator of muscle power and strength compared to whole body PhA (WB-PhA).Approach. This study assessed 30 young women (22.1 ± 3.2 years) for muscle power and strength using the Wingate test and isokinetic dynamometer, respectively. Bioimpedance analysis at 50 kHz was employed to assess WB-PhA and ML-PhA. Lean soft tissue (LST) and fat mass (FM) were quantified using dual x-ray absorptiometry. Performance values were stratified into tertiles for comparisons. Regression and mediation analysis were used to test WB-PhA and ML-PhA as performance predictors.Main results. Women in the second tertile of maximum muscle power demonstrated higher ML-PhA values than those in first tertile (13.6° ± 1.5° versus 11.5° ± 1.5°,p= 0.031). WB-PhA was a predictor of maximum muscle power even after adjusting for LST and FM (β= 0.40,p= 0.039). ML-PhA alone predicted average muscle power (β= 0.47,p= 0.008). FM percentage was negatively related to ML-PhA and average muscle power, and it mediated their relationship (b= 0.14; bias-corrected and accelerated 95% confidence interval: 0.007-0.269).Significance. PhA values among tertiles demonstrated no differences and no correlation for strength variables. The results revealed that both WB and ML-PhA may be markers of muscle power in active young women.

Athletic bioimpedance-based equations underestimate fat free mass components in male elite soccer players: development and validation of new soccer-specific predictive models

BACKGROUND

Bioelectrical impedance analysis (BIA) is a rapid and user-friendly technique for assessing body composition in sports. Currently, no sport-specific predictive equations are available, and the utilization of generalized formulas can introduce systematic bias. The objectives of this study were as follows: (i) to develop and validate new predictive models for estimating fat-free mass (FFM) components in male elite soccer players; (ii) to evaluate the accuracy of existing predictive equations.

METHODS

A total of 102 male elite soccer players (mean age 24.7 ± 5.7 years), participating in the Italian first league, underwent assessments during the first half of the in-season period and were randomly divided into development and validation groups. Bioelectrical resistance (R) and reactance (Xc), representing the bioimpedance components, were measured using a foot-to-hand BIA device at a single frequency of 50 kHz. Dual-energy X-ray absorptiometry was employed to acquire reference data for FFM, lean soft tissue (LST), and appendicular lean soft tissue (ALST). The validation of the newly developed predictive equations was conducted through regression analysis, Bland-Altman tests, and the area under the curves (AUC) of regression receiver operating characteristic (RROC) curves.

RESULTS

Developed models were: FFM = - 7.729 + (body mass × 0.686) + (stature2/R × 0.227) + (Xc × 0.086) + (age × 0.058), R2 = 0.97, Standard error of estimation (SEE) = 1.0 kg; LST = - 8.929 + (body mass × 0.635) + (stature2/R × 0.244) + (Xc × 0.093) + (age × 0.048), R2 = 0.96, SEE = 0.9 kg; ALST = - 24.068 + (body mass × 0.347) + (stature2/R × 0.308) + (Xc × 0.152), R2 = 0.88, SEE = 1.4 kg. Train-test validation, performed on the validation group, revealed that generalized formulas for athletes underestimated all the predicted FFM components (p < 0.01), while the new predictive models showed no mean bias (p > 0.05), with R2 values ranging from 0.83 to 0.91, and no trend (p > 0.05). The AUC scores of the RROC curves indicated an accuracy of 0.92, 0.92, and 0.74 for FFM, LST, and ALST, respectively.

CONCLUSIONS

The utilization of generalized predictive equations leads to an underestimation of FFM and ALST in elite soccer players. The newly developed soccer-specific formulas enable valid estimations of body composition while preserving the portability of a field-based method.

Use of bioimpedance in prevention of sarcopenia in the elderly

OBJECTIVES

Physiological ageing is associated with major and progressive changes in body composition, particularly in the decline of fat-free mass, which puts older individuals at risk of geriatric syndromes such as sarcopenia and sarcopenic obesity. Bioimpedance analysis noninvasively allows the determination of body composition, thus being able to rapidly assess primary risk factors leading to sarcopenia prediction.

METHODS

We conducted a study of 180 probands, 120 females (66.7%) with a mean age of 76.23 (SD = 9.29) years and 60 males (33.3%) with a mean age of 74.01 (SD = 8.99) years in cooperation with facilities for the elderly and with the inpatient department of the clinics of J.A. Reimann Hospital in Prešov. Body height, body weight, hip circumference, and waist circumference were determined by the anthropometric method, from which the values of the body mass index and waist-to-hip ratio were calculated. Active body mass, total body water, extracellular body water, intracellular body water, cell mass, body mass fat, body fat index, fat-free mass index, impedance at frequencies of 50 kHz, resistance, reactance, and phase angle were determined using the Quadscan 4000 Touch bioimpedance instrument. Appendicular skeletal muscle mass (ASMM) and muscle mass (ASMM/Ht2) were calculated. The data obtained from anthropometric and bioimpedance measurements were processed in MS Excel 2000 and STATISTICA ver. 12. The difference of means in the studied groups was tested by the t-test.

RESULTS

Presarcopenia was diagnosed in 12 (6.66%) probands out of 180 probands, of which were 3 (5%) men and 9 women (7.5%). Phase angle, ASMM and ASMM/Ht2 values were significantly lower (p < 0.001) in men and women with presarcopenia.

CONCLUSION

By introducing bioimpedance measurements into practice, it is possible to obtain results in a non-invasive way revealing possible presarcopenia in the elderly.

Prediction of body water compartments by raw bioelectrical impedance parameters in athletes: Comparison between series and parallel measurements

BACKGROUND

The aim of this study was to determine the predictive role of series and parallel bioelectrical impedance-derived parameters in predicting total body (TBW), intracellular (ICW), and extracellular water (ECW) in athletes.

METHODS

This cross-sectional study analyzed 134 male (21.33 ± 5.11 years) and 64 female (20.45 ± 5.46 years) athletes. Using dilution techniques, TBW and ECW were determined while ICW was the difference between both. Raw and standardized for height (/H) bioelectrical resistance (R), reactance (Xc), and impedance (Z) values were obtained using a phase-sensitive device at a single frequency in a series array (s). These were mathematically transformed in a parallel array (p) and capacitance (CAP). Fat-free mass (FFM) was assessed by dual-energy X-ray absorptiometry.

RESULTS

Multiple regressions adjusted for age and FFM show that R/Hs, Z/Hs, R/Hp, and Z/Hp were significant predictors of TBW (p < 0.001 in females and males). While Xc/Hs did not predict ICW, Xc/Hp was a predictor (p < 0.001 in females and Males). In females, R/H and Z/H predicted similarly TBW, ICW, and ECW. In males, R/Hs was considered a better predictor than R/Hp for TBW and ICW, and the Xc/Hp was considered the best predictor for ICW. Another significant predictor of ICW was CAP (p < 0.001 in females and males).

CONCLUSION

This study highlights the potential value of parallel bioelectrical impedance values to identify fluid compartments in athletes as an alternative to the regularly used series measurements. Moreover, this study supports Xc in parallel, and ultimately CAP, as valid indicators of cell volume.

Comparison of Bioelectrical Impedance Indices for Skeletal Muscle Mass and Intracellular Water Measurements of Physically Active Young Men and Athletes

BACKGROUND

Bioelectrical impedance analysis (BIA) is a minimally invasive, safe, easy, and quick technology used to determine body composition.

OBJECTIVES

We compared the relationship among impedance indices obtained using single-frequency BIA, multi-frequency BIA, bioelectrical impedance spectroscopy (BIS), and skeletal muscle mass (SMM) of physically active young men and athletes using the creatine (methyl-d3) dilution method. We also compared the SMM and intracellular water (ICW) of athletes and active young men measured using a reference stable isotope dilution and BIS method, respectively.

METHODS

We analyzed data from 28 men (mean age, 20 ± 2 y) who exercised regularly. Single-frequency BIA at 5 kHz and 50 kHz (R5 and R50), multi-frequency BIA (R250-5), and BIS (RICW) methods of determining the SMM were compared. The deuterium and sodium bromide dilution methods of obtaining the total body water, ICW, and extracellular water measurements were also used, and the results were compared to those acquired using bioimpedance methods.

RESULTS

The correlation coefficients between SMM and L2/R5, L2/R50, L2/R250-5, and L2/RICW were 0.738, 0.762, 0.790, and 0.790, respectively (P < 0.01). The correlation coefficients between ICW and L2/R5, L2/R50, L2/R250-5, and L2/RICW were 0.660, 0.687, 0.758, and 0.730, respectively (P < 0.001). However, the correlation coefficients of L2/R50, L2/R250-5, and L2/RICW for SMM and ICW were not significantly different.

CONCLUSIONS

Our findings suggest that single-frequency BIA at L2/R50, multi-frequency BIA, and BIS are valid for assessing the SMM of athletes and active young men. Additionally, we confirmed that the SMM and ICW were correlated with single-frequency BIA, multi-frequency BIA, and BIS. Bioimpedance technologies may be dependable and practical means for assessing SMM and hydration compartment status of active young adult males; however, cross-validation is needed.

The role of bioelectrical phase angle in patients with heart failure

The most challenging feature of heart failure (HF) still remains the evaluation of congestion. Residual congestion at discharge and the difficulties in perfectly dosing therapies in order to balance the hydration status of the patient are the most worrisome issues when dealing with HF.The use of bioimpedance vector analysis (BIVA) might promote a different approach in the general management of patients with HF. BIVA is a reliable, fast, bedside tool able to assess the congestion status. It proved to be helpful to physicians for diagnosing congestive status, managing therapies, and providing prognostic information in the setting of HF.Bioelectrical Phase Angle (PhA) - as derived from equations related to the parameters of BIVA - recently surged as a possible biomarker for patients with HF. Studies provided data about the application of PhA in the clinical management and in the overall risk stratification of HF patients.Basically, the use of PhA might be considered as a holistic evaluation of patients with HF which includes the need for a multiparametric approach able to effectively depict the clinical status of patients. There is no definite biomarker able to comprehensively describe and identify all the features of HF patient, but scores based on molecules/techniques able to explore the different pathogenetic mechanisms of HF are desirable.The aim of this review was to provide a comprehensive evaluation of literature related to PhA role in HF and the impact of this biomarker on clinical management and risk stratification of HF patients.

Validity of total body water measured by multi-frequency bioelectrical impedance devices in a multi-ethnic sample

BACKGROUND & AIMS

Total body water (TBW) is the largest component of fat free mass and therefore is commonly used in multi-compartment body composition models and as a stand-alone method to assess body composition. Previous literature has not validated bioelectrical impedance spectroscopy device estimates of TBW in racial and ethnic minority populations; previous studies have focused on bioelectrical impedance analysis devices that rely on proprietary algorithms and participant characteristics for accuracy. The purpose of this study was to assess the validity of two bioelectrical impedance spectroscopy devices for measures of TBW compared to a deuterium dilution criterion in a multi-ethnic sample.

METHODS

109 individuals (55% female, Age: 26.6 ± 6.9 yrs, BMI: 25.3 ± 4.0 kg/m²) identifying as Asian, African American/Black, Caucasian/White, Hispanic, and Multi-racial were enrolled. After a 12 h fast, participants provided a saliva sample for the criterion baseline TBW measure and completed two bioelectrical impedance device (BIS, IB) measurements of TBW. Participants then ingested deuterium oxide (D₂O). After an equilibration period, participants provided a second saliva sample for analysis of TBW.

RESULTS

For the total multi-ethnic sample, BIS estimates demonstrated good to fairly good agreement (Total error [TE] = 2.56 L, R² = 0.951) and IB estimates were excellent to very good (TE = 1.95 L, R² = 0.975). Validity results did not vary meaningfully between race and ethnicity.

CONCLUSIONS

The results suggest the BIS and IB devices evaluated can produce valid TBW estimates compared to D₂O in a multi-ethnic sample. TBW estimates from the IB may have better agreement with D₂O compared to the BIS when using the default settings.

Can change in phase angle predict the risk of morbidity and mortality during an 18-year follow-up period? A cohort study among adults

Introduction

Phase angle (PhA, degrees), measured via bioimpedance (BIA, 50 kHz), is an index that has been used as an indicator of nutritional status and mortality in several clinical situations. This study aimed to determine the relationship between 6-year changes in PhA and total mortality as well as the risk of incident morbidity and mortality from cardiovascular disease (CVD) and coronary heart disease (CHD) during 18 years of follow-up among otherwise healthy adults.

Methods

A random subset (n = 1,987) of 35-65 years old men and women was examined at the baseline in 1987/1988 and 6 years later in 1993/1994. Measures included weight, height, and whole-body BIA, from which PhA was calculated. Information on lifestyle was obtained through a questionnaire. The associations between 6-year PhA changes (ΔPhA) and incident CVD and CHD were assessed by Cox proportional hazard models. The median value of ΔPhA was used as the reference value. The hazard ratio (HR) model and confidence intervals (CIs) of incident CVD and CHD were used according to the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles of ΔPhA.

Results

During 18 years of follow-up, 205 women and 289 men died. A higher risk of both total mortality and incident CVD was present below the 50th percentile (Δ = -0.85°). The highest risk was observed below the 5th percentile (ΔPhA = -2.60°) in relation to total mortality (HR: 1.55; 95% CI: 1.10-2.19) and incident CVD (HR: 1.52; 95% CI: 1.16-2.00).

Discussion

The larger the decrease in PhA, the higher the risk of early mortality and incident CVD over the subsequent 18 years. PhA is a reliable and easy measure that may help identify those apparently healthy individuals who may be at increased risk of future CVD or dying prematurely. More studies are needed to confirm our results before it can be definitively concluded that PhA changes can improve clinical risk prediction.

Body Composition, Somatotype and Raw Bioelectrical Impedance Parameters of Adolescent Elite Tennis Players: Age and Sex Differences

Studies analyzing tennis players' body composition and morphological and bioelectrical characteristics are scarce, especially among adolescents. This study aimed to explore sex- and age-based differences in body composition, somatotype, and bioelectrical properties among elite young male and female tennis players aged 13-16 years. Twenty-two male (14.45 ± 1.10 years) and 20 female (14.30 ± 1.03 years) elite tennis players participated in this study and were compared according to sex (males vs. females) and, within each sex, according to age (13-14 years vs. 15-16 years). Female adolescent elite tennis players had higher body fat (BF) percentage and higher endomorphy than males. They also had lower skeletal muscle mass and total body water (TBW) percentages. Older boys had lower resistance and a higher TBW and phase angle (PhA) than younger boys, likely due to maturation and performance. No significant differences were found between younger and older girls, except for the PhA, potentially associated with better cell function and performance. This study provides valuable reference data for coaches of elite youth tennis players. Due to the few differences found in body composition and somatotype in the different age groups, the PhA may be used by practitioners as a reference for cell function and performance.

Higher Body Fat but Similar Phase Angle Values in Patients with the Classical Form of Congenital Adrenal Hyperplasia in Comparison to a Control Group

This study aimed to compare phase angle (PhA) and bioelectrical impedance vector analysis (BIVA) values between adult patients with congenital adrenal hyperplasia caused by 21-hydroxylase deficiency (CAH21OHD) and a control group. A total of 22 patients (15 women, 22.9 ± 3.7 years) were compared with 17 controls (11 women, 27.0 ± 2.5 years). Body composition was determined by dual-energy X-ray absorptiometry. Bioelectrical impedance was used to calculate PhA, and BIVA was performed using specific software. Student’s t-test and analysis of covariance were used to compare groups. Hedges’ G and partial n2 were calculated for the effect estimates. Hotelling’s t2 test was used to compare the mean impedance vectors between the groups. The Mahalanobis test was used to determine the distance between confidence ellipses. Patients with CAH21OHD had a higher fat mass percentage than that of the control group (both sexes). There was no significant difference in PhA values between groups (CAH21OHD vs. control) in females (6.9° vs. 6.3°, p = 0.092) and males (8.2° vs. 8.1°, p = 0.849), after adjusting for covariates (age and height). BIVA analysis showed a significant difference in the mean impedance vectors between the female groups (T2 = 15.9, D = 1.58, p = 0.003) owing to the higher reactance/height (Δ = 8.5; p < 0.001) of the patients. The PhA did not significantly differ between the groups. Female patients had significantly higher reactance values. However, further studies are needed to determine the usefulness of bioimpedance parameters in evaluating the hydration status and cellular integrity of patients with CAH21OHD.

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.

The Use of Compression Stockings to Reduce Water Retention in the Legs During Gaming and Esports: Randomized Controlled Field Study

Background

With the increasing digitalization of daily life, internet-based entertainment such as gaming and streaming has advanced to one of the megatrends of the 21st century. Besides offering a multitude of controversially discussed opportunities for entertainment and social interaction, there is reasonable concern about health issues caused by the absence of physical activity among activities linked to gaming and streaming.

Objective

The aim of this study is to compare the water balance of recreational gamers with and those without compression stockings during a gaming event.

Methods

We measured body composition and water balance with 8-electrode bioelectrical impedance analysis among 46 recreational gamers with an average age of 27.1 (SD 6.5) years (5/46, 11% women and 41/46, 89% men) before and after 24 hours at a gaming event. Of the 46 gamers, 23 (50%) gamers wore compression stockings for the duration of the study.

Results

Our study shows that prolonged gaming and associated behaviors during a 24-hour time frame lead to an increase in total body water (+0.76 L; P<.001) and a decrease of phase angle in the lower extremities (−0.47°; P<.001) but not in the upper extremities (+0.09°; P=.80), when no compression is used. Gamers using compression socks did not show any significant negative effects on their body composition.

Conclusions

Prolonged gaming and streaming are serious risk factors for diseases associated with water retention in the legs, and these risks can be measured by bioelectrical impedance and reduced by wearing compression stockings. We conclude that these findings should be discussed and replicated in larger studies and that there is a considerably large market for compression stockings among gamers and live streamers.

Association between Phase Angle from Bioelectric Impedance and Muscular Strength and Power in Physically Active Adults

This study aimed to compare muscle strength and power indicators according to bioimpedance spectroscopy’s phase angle (PhA) values, in resistance-trained (RT) men, while exploring associations between PhA and performance. Forty-four men aged 18−45 years, engaged in RT, were allocated according to PhA tertiles. Lean soft tissue (LST) and fat mass (%FM) were assessed using dual-energy x-ray absorptiometry; dynamic muscle strength using 1 repetition maximum (1RM) of bench press (BP) and back squat (BS) and muscle power using Wingate test (WT) and countermovement jump (CMJ). For WT and CMJ, the 3rd tertile was significantly higher than the 1st tertile (p = 0.027 and p = 0.018, respectively). Regarding BP 1RM, the 3rd tertile was significantly higher than the 2nd tertile (p = 0.037). LST better explained the variability in the WT, BS and BP (p =< 0.001), while %FM better accounted for jump height in CMJ (p =< 0.001). PhA was a predictor of performance in both CMJ (p = 0.040) and BP (p = 0.012), independently of LST and %FM. Participants with higher PhA also displayed superior muscle strength of the upper limbs and greater muscle power of the lower limbs. PhA displayed significant moderate associations with performance in CMJ and BP, even after controlling for body composition. Still, LST was the most important predictor of muscle strength and power.

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.

Next generation smartwatches to estimate whole body composition using bioimpedance analysis: accuracy and precision in a diverse multiethnic sample

BACKGROUND

Novel advancements in wearable technologies include continuous measurement of body composition via smart watches. The accuracy and stability of devices are unknown.

OBJECTIVES

This study evaluated smart watches with integrated bioimpedance (BIA) sensors for their ability to measure and monitor change in body composition.

DESIGN

Participants recruited across body mass indexes received duplicate body composition measures using two wearable smart watch (W-BIA) models in sitting and standing positions and multiple versions of each watch were used to evaluate inter- and intra-model precision. Duplicate laboratory-grade octapolar bioimpedance (8-BIA) and criterion dual-energy X-ray absorptiometry (DXA) scans were acquired to compare estimates between the watches and laboratory methods. Test-retest precision and least significant changes assessed the ability to monitor change in body composition.

RESULTS

Of 109 participants recruited, 75 subjects completed the full manufacturer-recommended protocol. No significant differences were observed between W-BIA watches in position or between watch models. Significant fat-free mass (FFM) differences (p < 0.05) were observed between both W-BIA and 8-BIA when compared to DXA, though the systematic biases to the criterion were correctable. No significant difference was observed between the W-BIA and the laboratory-grade BIA technology for FFM (55.3 ± 14.5 kg for W-BIA versus 56.0 ± 13.8 kg for 8-BIA, p > 0.05, CCC = 0.97). FFM was less precise on the watches than DXA (CV = 0.7%, RMSE = 0.4 kg versus CV = 1.3%, RMSE = 0.7 kg for W-BIA), requiring more repeat measures to equal the same confidence in body composition change over time as DXA.

CONCLUSIONS

After systematic correction, smart watch BIA devices are capable of stable, reliable and accurate body composition with precision comparable but lower than laboratory measures. These devices allow for measurement in environments not accessible to laboratory systems such as the home, training centers, and geographically remote locations.

Breaking of Sitting Time Prevents Lower Leg Swelling-Comparison among Sit, Stand and Intermittent (Sit-to-Stand Transitions) Conditions

BACKGROUND

Sitting or standing during prolonged periods is related to leg swelling. It is unknown if interrupting sedentary behavior can attenuate lower leg swelling. We aimed to examine if adding sit-to-stand transitions prevents lower leg swelling as compared with uninterrupted motionless standing and sitting, using localized bioelectrical impedance raw parameters.

METHODS

Twenty adults participated in this crossover randomized controlled trial and acted out three conditions: (1) uninterrupted, motionless standing; (2) uninterrupted motionless sitting; (3) sit-to-stand transitions (1 min sitting followed by 1 min standing). Localized resistance (R), reactance (Xc), impedance (Z) and phase angle (PhA) were assessed at baseline, at 10 min and at 20 min for each condition.

RESULTS

For sitting and standing conditions, R and Xc values decreased after 10 and 20 min. Uninterrupted sitting resulted in the highest decrease in R (ΔSit - ΔStand = -9.5 Ω (4.0), p = 0.019; ΔSit - ΔInt = -11.6 Ω (4.0), p = 0.005). For standardized R (R/knee height), sitting was the condition with a greater decrease (ΔSit - ΔStand = -30.5 Ω/m (13.4), p = 0.025; ΔSit - ΔInt = -35.0 Ω/m (13.5), p = 0.011).

CONCLUSIONS

Interrupting sedentary behavior by changing from sit to stand position during short periods may be effective at preventing leg swelling.

Associations between Fat Mass and Fat Free Mass with Physical Fitness in Adolescent Girls: A 3-Year Longitudinal Study

The main purpose of the study was to examine the longitudinal associations between fat mass and fat free mass with health-related physical fitness. Two-hundred and forty 15-year old adolescent girls were measured at the baseline and after a period of 3 years (17 years). Health-related physical fitness included the following tests: (1) explosive power of the lower extremities (standing broad jump); (2) muscle endurance of the trunk (sit-ups in 60 s); (3) flexibility (sit-and-reach test); (4) muscle endurance of the lower extremities (squats in 60 s); (5) aerobic endurance (the 800 m run test); and (6) speed endurance (the 400 m running test). Fat mass and fat free mass were assessed using the bioelectrical impedance method. Longitudinal associations were analyzed with linear mixed model estimates. After adjusting for body mass index, fat mass was negatively associated with standing broad jump (β = −1.13, p < 0.001), sit-ups in 60 s (β = −0.27, p < 0.001), and squats in 60 s (β = −0.27, p < 0001), while positive associations with the 800 m running test (β = 0.02, p < 0.001) and the 400 m running test (β = 0.02, p < 0.001) were observed. On the other hand, fat free mass was positively associated with standing broad jump (β = 1.14, p < 0.001), sit-ups in 60 s (β = 0.28, p < 0.001), and squats in 60 s (β = 0.28, p < 0001), while the 800 m running test (β = −0.02, p < 0.001) and the 400 m running test (β = −0.02, p < 0.001) exhibited negative associations. This study shows that fat mass and fat free mass components are longitudinally, but oppositely associated with health-related physical fitness in adolescent girls.

Body Composition and Cardiovascular Risk Factors in a Paediatric Population

The aim of our study was to evaluate associations between body composition parameters and several clinical parameters. A total of 206 children and adolescents (120 male, 86 female) were prospectively included. Body impedance measurement was performed in all participants. During the hospital work-up, several clinical parameters such as anthropometric measurements and laboratory and ultrasound findings were obtained and correlated to body composition parameters. There was a significant association between body composition parameters and anthropometric measurements, systolic blood pressure, insulin levels, serum creatinine, urate, liver function tests, triglycerides, cholesterols and apolipoproteins, homocysteine, vitamin D and proteins in 24-h urine. Body composition differed by gender, between participants with and without hepatic steatosis and between patients with and without left ventricular hypertrophy. Interestingly, body composition did not correlate with diastolic blood pressure, pulse wave velocity and intima media thickness. This study showed that several clinical parameters are associated with body composition in children. Obesity and body composition play an important role in the development of other cardiovascular risk factors and are not dependent on fat mass alone, and the latter might be used for cardiovascular risk determination.

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.

Bioelectrical Impedance Vector Analysis Discriminates Aerobic Power in Futsal Players: The Role of Body Composition

Aims: The present study aimed to assess the ability of bioelectrical impedance vector analysis (BIVA) in discriminating fitness levels in futsal players, exploring the association of body composition and bioelectrical parameters with aerobic power. Methods: Forty-eight professional futsal players (age 23.8 ± 5.3 years) were involved in a cross-sectional study during their pre-season phase. Fat mass (FM) and muscle mass were determined by dual-energy X-ray absorptiometry. VO2max was obtained by indirect calorimetry through a graded exercise test performed on a treadmill. Bioelectrical resistance (R), reactance (Xc), and phase angle (PhA) were directly measured using a foot-to-hand bioimpedance technology at a 50 kHz frequency. Bioelectric R and Xc were standardized for the participants’ height and used to plot the bioimpedance vector in the R-Xc graph according to the BIVA approach. Results: The participants divided into groups of VO2max limited by tertiles showed significant differences in mean vector position in the R-Xc graph (p < 0.001), where a higher VO2max resulted in a longer vector and upper positioning. FM, muscle mass, and PhA differed (p < 0.01) among the athletes grouped by tertiles of VO2max, where athletes with a greater aerobic power showed a lower percentage of FM and a higher percentage of muscle mass and PhA. FM and PhA were associated with VO2max (FM: r = −0.658, p < 0.001; PhA: r = 0.493, p < 0.001). These relationships remained significant after adjusting for age and body mass (FM: ß = −0.335, p = 0.046; PhA: ß = 0.351, p = 0.003). Conclusions: Bioelectrical impedance vectors positioned on the lower pole of the R-Xc graph identified futsal players with a lower VO2max, while longer vectors corresponded to a greater aerobic power. Additionally, PhA, that describes the vector direction, was positively associated with VO2max, while a higher FM negatively affected VO2max in the futsal players. BIVA and PhA evaluation may represent a valid support for screening the aerobic fitness level in professional futsal players, when more sophisticated assessment methods are not available.

Reference Percentiles for Bioelectrical Phase Angle in Athletes

Simple Summary

The bioelectrical phase angle is a raw parameter that can be utilized as an indicator of performance, muscle quantity and hydration status of cells. However, sex- and sport-specific phase angle reference percentiles are lacking for the athletic population. For the first time, this study provides 5th, 15th, 50th, 85th, and 95th reference percentiles for phase angle in male and female athletes practicing different sports. These reference values can be used to track body composition and performance related-outcomes in sports practice, while leveraging the portability of bioelectric impedance analysis.

Abstract

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.

The Influence of Menstrual Cycle on Bioimpedance Vector Patterns, Performance, and Flexibility in Elite Soccer Players

PURPOSE

To examine whether menstrual cycle affects body composition and bioimpedance vector analysis (BIVA) patterns, jumping and sprinting ability, and flexibility in elite soccer players.

METHODS

A total of 20 elite female soccer players (age: 23.8 [3.4] y, height: 1.63 [0.04] m, body mass: 61.4 [5.9] kg, and body mass index: 22.5 [2.4] kg/m2) were monitored during the early follicular and ovulatory phase across 2 consecutive menstrual cycles. Bioimpedance analysis was performed using foot-to-hand technology, and total body water and fat mass were determined by specific equations developed for athletes. Bioelectrical resistance and reactance were adjusted according to the BIVA procedures and plotted as a vector within the resistance-reactance graph. In addition, countermovement jump, 20-m sprint, and sit and reach were assessed.

RESULTS

A time effect (P < .05) was found for body mass, total body water, bioelectrical resistance and reactance, and flexibility. Specifically, body mass increased (P = .021) along with a gain in total body water (P = .001) from the ovulatory to the early follicular phase, while it decreased from the early follicular to the ovulatory phase during the second menstrual cycle. The BIVA vector shortened during the early follicular phases (P < .001). No change in jumping and sprinting capacity was observed (P > .05). Flexibility was impaired during the early follicular phases (P < .05).

CONCLUSIONS

Specific bioelectrical impedance analysis and BIVA procedures are able to detect menstrual cycle-induced changes in body composition in elite soccer players. The early follicular phase resulted in fluid accumulations and BIVA vector shortening. In addition, while menstrual cycle did not affect performance, a fluctuation in flexibility was observed.

Changes in Factors Regulating Serum Sodium Homeostasis During Two Ultra-Endurance Mountain Races of Different Distances: 69km vs. 121km

Overdrinking and non-osmotic arginine vasopressin release are the main risk factors for exercise-associated hyponatremia (EAH) in ultra-marathon events. However, particularly during ultra-marathon running in mountainous regions, eccentric exercise and hypoxia, which have been shown to modulate inflammation, hormones regulating fluid homeostasis (hypoxia), and oxidative stress, could contribute to serum sodium changes in a dose-dependent manner. To the best of our knowledge, the contribution of these factors, the extent of which depends on the duration and geographical location of the race, has not been well studied. Twelve male participants (11 finishers) of the short (69km, 4,260m elevation-gain) and 15 male participants (seven finishers) of the long (121km, 7,554m elevation-gain) single-stage Südtirol Ultra Sky-Race took part in this observational field study. Venous blood was drawn immediately before and after the race. Analyses included serum sodium concentration, copeptin (a stable marker for vasopressin), markers of inflammation, muscle damage and oxidative stress. Heart rate was measured during the race and race time was obtained from the race office. During the short and the long competition two and one finishers, respectively showed serum sodium concentrations >145mmol/L. During the long competition, one athlete showed serum sodium concentrations <135mmol/L. Only during the short competition percent changes in serum sodium concentrations of the finishers were related to percent changes in body mass (r=-0.812, p=0.002), total time (r=-0.608, p=0.047) and training impulse (TRIMP) (r=-0.653, p=0.030). Data show a curvilinear (quadratic) relationship between percent changes in serum sodium concentration and body mass with race time when including all runners (short, long, finishers and non-finishers). The observed prevalence of hypo- and hypernatremia is comparable to literature reports, as is the relationship between serum sodium changes and race time, race intensity and body mass changes of the finishers of the short race. The curvilinear relationship indicates that there might be a turning point of changes in serum sodium and body mass changes after a race time of approximately 20h. Since the turning point is represented mainly by non-finishers, regardless of race duration slight decrease in body mass and a slight increase in serum sodium concentration should be targeted to complete the race. Drinking to the dictate of thirst seems an adequate approach to achieve this goal.

Body Composition and Bioelectrical-Impedance-Analysis-Derived Raw Variables in Pole Dancers

Few data are available on the body composition of pole dancers. Bioelectrical impedance analysis (BIA) is a method that is used to estimate fat-free mass (FFM) and fat mass (FM), while raw BIA variables, such as the impedance ratio (IR) and phase angle (PhA), are markers of body cell mass and the ratio between extracellular and total body water. The aim of this study was to evaluate the body composition of pole dancers compared to controls, in particular, those raw BIA variables that are considered as markers of muscle composition. Forty female pole dancers and 59 controls participated in the study. BIA was performed on the whole body and upper and lower limbs, separately, at 5, 50, 100 and 250 kHz. The FFM, FFM index, FM and body fat percentage (BF%) were predicted. The bioelectrical impedance indexes IR and PhA were also considered. Pole dancers exhibited higher FFMI and BI indexes and lower BF%. PhA was greater and IRs were smaller in pole dancers than in controls for the whole body and upper limbs. Considering the training level, FFM, whole-body IR and PhA were higher in the professionals than non-professionals. Raw BIA variables significantly differed between the pole dancers and controls, suggesting a higher BCM; furthermore, practicing pole dancing was associated with a greater FFM and lower FM.

Effect of exercise on phase angle in cancer patients: a systematic review

INTRODUCTION

Body composition is one of the main variables of interest in clinical practice in cancer patients. Specific markers from bioelectrical impedance analysis, such as phase angle (PhA), have been assuming increasing relevance in this population. The aim of the present systematic review was to study and systematise the effect of exercise on PhA in cancer survivors, as compared to control conditions, namely usual care, with no exercise. The effect of exercise on PhA in the population of cancer survivors is not yet established. EVIDENCE ACQUISITIONː This systematic review was conducted on October 13, 2021, through PubMed, Web of Science, Wiley Online Library, Directory of Open Access Journals, Science Direct and JSTOR, following PRISMA guidelines and PICOS model that include: cancer survivors with ≥18 years; intervention of any exercise program for the target group; comparison between intervention group and control group that followed control conditions, namely usual care, with no exercise; outcome related to PhA; and studies of randomized control trials.

EVIDENCE SYNTHESIS

We founded a total of 1244 publications, using selected keywords. Eight studies were included in this systematic review, after inclusion/exclusion criteria considered. Compared with the control conditions, exercise training programs seem associated with a positive effect on PhA, both in solid tumours and haematologic cancer types, but only when using resistance exercise alone. According to the best evidence synthesis criteria, we could not conclude the superiority of any exercise program analysed in the value of the PhA.

CONCLUSIONS

There were several exercise details that may have potential to be beneficial for PhA in cancer patients, including an early start of the exercise intervention (during treatment and immediately after discharge from hospital), the use of resistance exercise or/and aerobic exercise, and mainly a long follow-up period (≥ 4 months) to verify the structural effects of exercise on the PhA. However, there were no effects on the PhA value immediately after the intervention, regardless of the type of protocol and the intervention time.

In-Season Body Composition Effects in Professional Women Soccer Players

This study aimed to analyze anthropometric and body composition effects in professional soccer women players across the early and mid-competitive 2019/20 season. Seventeen players (age, height, body mass, and body mass index of 22.7 ± 6.3 years, 167.5 ± 5.6 cm, 60.7 ± 6.6 kg and 21.6 ± 0.2 kg/m2) from a Portuguese BPI League team participated in this study. The participants completed ≥80% of 57 training sessions and 13 matches. They were assessed at three points (before the start of the season (A1), after two months (A2), and after four months (A3)) using the following variables: body fat mass (BFM), soft lean mass (SLM), fat-free mass (FFM), intracellular water (ICW), extracellular water (ECW), total body water (TBW), and phase angle (PhA, 50 Khz), through InBody S10. Nutritional intake was determined through a questionnaire. Repeated measures ANCOVA and effect sizes (ES) were used with p < 0.05. The main results occurred between A1 and A2 for BFM (-21.7%, ES = 1.58), SLM (3.7%, ES = 1.24), FFM (4%, ES = 1.34), ICW (4.2%, ES = 1.41), TBW (3.7%, ES = 1.04). Furthermore, there were significant results between A1 and A3 for FFM (4.8%, ES = 1.51), ICW (5%, ES = 1.68), and PhA (10.4%, ES = 6.64). The results showed that the water parameters improved over time, which led to healthy hydration statuses. The training load structure provided sufficient stimulus for appropriate physical fitness development, without causing negative disturbances in the water compartments.

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.

Raw bioelectrical impedance analysis variables (phase angle and impedance ratio) are significant predictors of hand grip strength in adolescents and young adults

OBJECTIVES

Musculoskeletal fitness and body composition are major components of health-related physical fitness that are expected to be linked to each other. The aim of this study was to explore the association of musculoskeletal fitness (expressed as hand grip strength [HGS]) and raw bioelectrical impedance analysis (BIA) variables and other predictors in the second and third decades of life.

METHODS

Four groups of healthy normal-weight and overweight participants were studied: 130 male adolescents (age 16.0 ± 1.1 y), 143 female adolescents (16.0 ± 0.9 y), 141 young men (25.5 ± 2.0 y), and 141 young women (25.2 ± 1.9 y). Raw BIA variables (impedance [Z] and phase angle [PhA]) for the whole body were measured at four frequencies (5, 50, 100, and 250 kHz), and HGS was measured in both upper limbs.

RESULTS

HGS was higher in males than females and higher in young men than male adolescents. A fairly strong correlation emerged in both genders between HGS and raw BIA variables-that is, bioimpedance index (height²/Z), PhA, and impedance ratios (Z at high frequency/Z at low frequency). In multiple regression analysis, bioimpedance index, PhA, and impedance ratio were more effective predictors of HGS than BIA-derived estimates of body composition or anthropometric variables such as height, weight, and body mass index. In both genders, HGS was significantly higher in young adults than in adolescents for the same PhA or impedance ratio.

CONCLUSIONS

This study provides some insight into the use of raw BIA variables and HGS in the first decades of life, suggesting a new approach for a reliable assessment of muscle quality in terms of both muscle structure and strength.

Association of phase angle with muscle strength and aerobic fitness in different populations: A systematic review

OBJECTIVES

The aim of this study was to summarize the evidence on the association of phase angle (PhA) with muscle strength and aerobic fitness in different populations.

METHODS

A systematic search on this topic was performed in nine electronic databases (CINAHL, LILACS, PubMed, SciELO, Scopus, SPORTDiscus, ScienceDirect, MEDLINE, and Web of Science) in January 2021. Studies with different designs that permitted extraction of information about the relationships between PhA and muscle strength and between PhA and aerobic fitness were included. A total of 4446 studies were initially identified; 34 were included after reading of the title, abstract, full text, and references. Four of the studies included had a longitudinal design, with samples consisting of participants ages 6 to 92 years. Thirty-two of the 34 studies evaluated the relationship between PhA and muscle strength, two cross-sectional studies investigated only PhA and aerobic fitness, and three cross-sectional studies evaluated both components (muscle strength and aerobic fitness).

RESULTS

PhA was directly associated with muscle strength in 30 cross-sectional studies and two longitudinal studies; the two studies that did not find a direct relationship had a cross-sectional design. For aerobic fitness, the five studies identified reported a direct relationship with PhA.

CONCLUSIONS

PhA is directly associated with muscle strength and aerobic fitness in different age groups (children, adolescents, adults, and older adults) and in people with different health conditions (human immunodeficiency virus, Crohn's disease, chronic obstructive pulmonary disease, bariatric surgery, kidney transplant, cancer, hemodialysis, and sarcopenia).

Bioelectrical impedance analysis as a means of quantifying upper and lower limb asymmetry in youth elite tennis players: An explorative study

This study aimed to examine side-to-side differences in phase angle (PhA) in both upper and lower limbs of youth elite tennis players. Among other outcomes, PhA was directly determined using segmental multifrequency bioelectrical impedance analysis (BIA) in 26 tennis players (11.6 ± 1.1 years, 54% boys) and compared against a sex- and age-matched reference population. Significant upper limb asymmetry in PhA (p < 0.001), with a higher value on the dominant side of the body, was observed in the tennis players. At lower limb level, the tennis players showed a tendency towards a significantly higher PhA in the contralateral compared to the ipsilateral limb (p = 0.089). Using vector analysis (BIVA), a significant degree of PhA asymmetry (p = 0.002) was only reflected in the tennis players' upper limb. Additional segmental outcomes also demonstrated a significant degree of upper limb asymmetry in terms of tennis players' lean mass (p < 0.001), total segmental water (p < 0.001), fat mass (p < 0.001), extracellular water (p < 0.001) and extracellular water ratio (p < 0.001), whereas lower limb asymmetry was only observed in tennis players' fat mass (p = 0.037) and extracellular water (p = 0.001). This is the first study to report significantly more pronounced BIA-based side-to-side differences in youth elite tennis players compared to a non-athletic reference population at the upper limb level, whereas no significant between-group differences in the lower limbs were found. This explorative study should trigger future research to further scrutinize the role of BI(V)A as a promising field-method in monitoring bodily asymmetries in youth elite tennis players in view of sport performance and athletic health. HighlightsBioelectrical Impedance Analysis is a promising field-method to monitor side-to-side asymmetry in youth elite tennis players.Youth elite tennis players displayed a more pronounced degree of BIA-based side-to-side differences compared to a non-athletic reference population at the upper limb level, whereas whilst between-group differences appeared to be less evident in the lower limbs.Future research is warranted to scrutinize whether and to what extent these degrees of segmental bodily asymmetry may be related to injury risk (prevention) and athletic development of (pre)adolescent tennis players.

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.

Specific Bioelectrical Impedance Vector Analysis Identifies Body Fat Reduction after a Lifestyle Intervention in Former Elite Athletes

Simple Summary

The ability of specific bioelectrical impedance vector analysis (BIVA) to classify subjects according to the percentage of fat mass has been recognized in different cross-sectional studies, but no longitudinal designs have yet been applied. The results of this investigations showed that specific BIVA can be used as a practical solution for assessing body composition management in former overweight/obese athletes. In particular, reductions in bioelectrical vector length adjusted according to the specific BIVA procedure were found to be associated with reductions in percentage of fat mass.

Abstract

Background: specific bioelectrical impedance vector analysis (BIVA) has been proposed as an alternative bioimpedance method for evaluating body composition. This investigation aimed to verify the ability of specific BIVA in identifying changes in fat mass after a 16-week lifestyle program in former athletes. Methods: The 94 participants included in the Champ4life project (clinicaltrials.gov: NCT03031951) were randomized into intervention (n = 49) and control (n = 45) groups, from which 82 athletes completed the intervention (age 43.9 ± 9.2 y; body mass index 31.1 ± 4.6 kg/m²). Fat mass was estimated by dual-energy X-ray absorptiometry. Bioelectric resistance, reactance, phase angle, and vector length were assessed by bioelectric impedance spectroscopy, and the BIVA procedure was applied. Results: A significant (p < 0.05) group x time interaction for fat mass, specific resistance, reactance, and vector length was found. Fat mass and vector length significantly (p < 0.05) decreased in the intervention group, while no change was measured in the control group. Considering the participants as a whole group, changes in vector length were associated with changes in fat mass percentage (r² = 0.246; β = 0.33; p < 0.001) even after adjusting for age, sex, and group (R² = 0.373; β = 0.23; p = 0.002). Conclusions: The specific BIVA approach is suitable to track fat mass changes during an intervention program aimed to reduce body fat in former athletes.

Phase angle cutoff value as a marker of the health status and functional capacity in breast cancer survivors

Accurate predictive tools are key factors for cancer care. Phase angle (PhA) has been proposed as a marker of cellular health, particularly of cell-membrane integrity. Cutoff values have been proposed, including for cancer survivors. This study aimed to assess the usefulness of the proposed PhA cutoff, as a marker of bioelectrical impedance analysis (BIA) assessed health-status, and functional capacity in breast cancer (BC) survivors. This cross-sectional study included 25 women (50.6 ± 8.6 yrs) survivors of BC, divided into two groups according to the PhA reference value of 5.6° (group 1 [G1]: PhA ≤ 5.6° [n=13]; group 2 [G2]: PhA > 5.6° [n=12]) (Gupta et al. 2008). BIA-assessed health status parameters included: extracellular water (ECW), intracellular water (ICW), total body water (TBW), PhA, body mass, fat-free mass, muscle mass, body cell mass (BCM). Four functional tests were performed: 30 s chair-stand test, timed up and go test, ball throw test and 6-minute walking test. Results showed G2 had lower ECW/ICW ratio (p=0.001; ES=1.2), ECW/BCM ratio (p=0.001; ES=3.2) and ECW/TBW ratio (p=0.001; ES=4.8). There was no difference in functional capacity between groups. The results of the present study show that patients with higher PhA values have a higher ICW values and preservation in the ECW/ICW ratio, suggesting it's a better cell membrane quality and integrity. Relation of both PhA and cell membrane integrity with functional capacity warrants further research.

Bioelectrical Impedance Vector Analysis: A Valuable Tool to Monitor Daily Body Hydration Dynamics at Altitude

Bioelectrical impedance vector analysis (BIVA) is a method used to estimate variation in body hydration. We assessed the potential of BIVA for monitoring daily body hydration fluctuations in nine healthy, normally active males under matching normoxic (NX) and hypobaric hypoxic (HH) experimental conditions. Furthermore, we aimed to investigate whether changes in BIVA may correspond with the development of acute mountain sickness (AMS). Subjects were exposed in a hypobaric chamber to both NX (corresponding to an altitude of 262 m) and HH conditions corresponding to an altitude of 3500 m during two four-day sojourns within which food, water intake and physical activity were controlled. Bioimpedance and body weight measurements were performed three times a day and medical symptoms were assessed every morning using the Lake Louise score (LLS). Total body water (TBW) was also assessed on the last day of both sojourns using the deuterium dilution technique. We detected circadian changes in vector length, indicating circadian body water variations that did not differ between NX and HH conditions (ANOVA effects: time: p = 0.018, eta² = 0.149; interaction: p = 0.214, eta² = 0.083; condition: p = 0.920, eta² = 0.001). Even though none of the subjects developed AMS, four subjects showed clinical symptoms according to the LLS during the first 24 hours of HH conditions. These subjects showed a pronounced (Cohen’s d: 1.09), yet not statistically significant (p = 0.206) decrease in phase angle 6 hours after exposure, which may indicate fluid shift from the intracellular to the extracellular compartment. At the end of each sojourn, vector length correlated with deuterium dilution TBW “gold standard” measurements (linear regression: NX: p = 0.002 and r² = 0.756, HH: p < 0.001 and r² = 0.84). BIVA can be considered a valuable method for monitoring body hydration changes at altitude. Whether such changes are related to the development of clinical symptoms associated with AMS, as indicated in the present investigation, must be confirmed in future studies.

Assessment of Body Composition in Athletes: A Narrative Review of Available Methods with Special Reference to Quantitative and Qualitative Bioimpedance Analysis

Body composition is acknowledged as a determinant of athletic health and performance. Its assessment is crucial in evaluating the efficiency of a diet or aspects related to the nutritional status of the athlete. Despite the methods traditionally used to assess body composition, bioelectric impedance analysis (BIA) and bioelectric impedance vector analysis (BIVA) have recently gained attention in sports, as well as in a research context. Only until recently have specific regression equations and reference tolerance ellipses for athletes become available, while specific recommendations for measurement procedures still remain scarce. Therefore, the present narrative review summarizes the current literature regarding body composition analysis, with a special focus on BIA and BIVA. The use of specific technologies and sampling frequencies is described, and recommendations for the assessment of body composition in athletes are provided. Additionally, the estimation of body composition parameters (i.e., quantitative analysis) and the interpretation of the raw bioelectrical data (i.e., qualitative analysis) are examined, highlighting the innovations now available in athletes. Lastly, it should be noted that, up until 2020, the use of BIA and BIVA in athletes failed to provide accurate results due to unspecific equations and references; however, new perspectives are now unfolding for researchers and practitioners. In light of this, BIA and especially BIVA can be utilized to monitor the nutritional status and the seasonal changes in body composition in athletes, as well as provide accurate within- and between-athlete comparisons.

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.

Body Composition and Physical Health in Sports Practice: An Editorial

The assessment of the health status of athletes, at all ages, is an aspect of fundamental importance, and, in recent years, the analysis of body composition has become a fundamental and essential part in its evaluation, such as in the optimization of sports performance [...].

Phase Angle Is Related to 10 m and 30 m Sprint Time and Repeated-Sprint Ability in Young Male Soccer Players

OBJECTIVE

To examine the association between phase angle (PhA) and bioelectrical impedance vector analysis (BIVA) and components of physical performance in male youth soccer players.

DESIGN

Cross-sectional.

METHODS

Sixty-two players from two professional soccer academies were recruited. Electrical bioimpedance was used to obtain the PhA and BIVA. Body fat (BF) and lean soft tissue mass (LSTM) were measured by dual-energy X-ray absorptiometry. All players completed physical tests including the standing long jump (SLJ), Carminatti's test (peak speed at the end of the test, PST-CAR), 10 m and 30 m straight-line sprints, and repeated-sprint ability (RSA) test (RSAbest and RSAmean times).

RESULTS

Adjusting for chronological age, BF, and LSTM, multiple regression analysis outputs showed that PhA remained inversely related to RSAmean (β = -0.362; p < 0.001), RSAbest (β = -0.239; p = 0.020), 10 m (β = -0.379; p = 0.012), and 30 m (β = -0.438; p < 0.001) sprint times, while the association with PST-CAR and SLJ performance were statistically non-significant. In addition, BIVA showed that differences in confidence ellipses were found between athletes in the reference population and the study sample (p < 0.05). The tolerance ellipses indicated that the athletes in the present study had more total body water (TCW) and lower proportions of intracellular water (ICW) to extracellular water (ECW). The reference population had more TCW and ICW/ECW.

CONCLUSIONS

Our results suggest that young soccer players with higher PhA values, indicating better cell integrity and functionality, have better performance in typical anaerobic running activities, such as sprinting speed and RSA performance, adjusted to age and body composition characteristics.

Validity of water compartments estimated using bioimpedance spectroscopy in athletes differing in hydration status

We aimed to validate bioelectrical impedance spectroscopy (BIS), compared with tracer dilution measurements, for assessing total body water (TBW), intracellular water (ICW), and extracellular water (ECW) in athletes differing in hydration status. A total of 201 athletes participated. Reference TBW and ECW were determined by deuterium and bromide dilution methods, respectively; ICW was calculated as TBW-ECW. Water compartments were estimated by BIS. Urine specific gravity (USG) classified athletes into well-hydrated (WH) (USG < 1.023), euhydrated (EH) (USG:1.024-1.026), and dehydrated (DH) (USG>1.027). No significant differences were found between BIS and the reference methods for WH, EH, and DH athletes for TBW, ICW nor ECW (p>0.05). Concordance of TBW and its compartments by method was significant (p < 0.001) with coefficients of determination ranging by hydration classification [EH:52-96%;DH:56-98%;WH:71-96%]. Bland-Altman analyses showed no trend for TBW and its compartments with the exception of ICW in the WH athletes. The 95% confidence BIS intervals for the WH group ranged from -3.08 to 2.68 kg for TBW, -4.28 to 4.14 kg for ICW, and -3.29 to 3.02 kg for ECW. For the EH athletes, the 95% confidence intervals ranged from -2.78 to 2.24 kg for TBW, -4.10 to 3.94 kg for ICW, and -3.44 to 3.06 kg for ECW. In DH group, TBW ranged between -1.99 and 2.01 kg, ICW between -3.78 and 6.34 kg, and ECW between -6.22 and 3.74 kg. These findings show that BIS is useful at a group level in assessing water compartments in athletes differing in hydration status. However, the usefulness of BIS is limited at an individual level, especially in dehydrated athletes.

Age-Related Decline in Vertical Jumping Performance in Masters Track and Field Athletes: Concomitant Influence of Body Composition

Vertical jumping power declines with advancing age, which is theoretically explicable by loss of muscle mass and increases in body fat. However, the results of previous cross-sectional studies remain inconsistent on these relationships. The present study included 256 masters athletes who competed at the 2018 track and field world championships in Málaga, Spain. We assessed body composition with bioelectrical impedance (Inbody S10) and vertical jumping power with a Leonardo ground reaction force platform. Relationships between age, jumping power, and body composition were analyzed by correlation and regression analyses. Hierarchical multiple regression analysis was used to evaluate effects of each factor on vertical jumping power. Age-related rates of decreases in maximal power and jump height were similar between male and female athletes. Percent fat-free mass and percent body fat were negatively and positively, respectively, associated with age in masters athletes and were comparable to those previously observed in the general population. Moreover, these effects in body composition can, to a great extent, explain the age-related decline in jumping power, an effect that seems at least partly independent of age. Finally, the multiple regression model to determine independent predictors of vertical jump performance yielded an overall R² value of 0.75 with the inclusion of (1) athletic specialization in power events, (2) percent fat-free mass, and (3) phase angle. However, partial regression yielded significant effects of age, but not gender, on peak power, even when adjusting for athletic specialization, percent fat-free mass, and phase angle. We concluded that loss of skeletal muscle mass and changes in bio-impedance phase angle are important contributors to the age-related reduction in anaerobic power, even in adults who maintain high levels of physical activity into old age. However, age per se remains a significant predictor of vertical jump performance, further demonstrating deteriorated muscle quality at old age (sarcosthenia).

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.

Body Water Content and Morphological Characteristics Modify Bioimpedance Vector Patterns in Volleyball, Soccer, and Rugby Players

Background: Bioimpedance vector analysis (BIVA) is a widely used method based on the interpretation of raw bioimpedance parameters to evaluate body composition and cellular health in athletes. However, several variables contribute to influencing BIVA patterns by militating against an optimal interpretation of the data. This study aims to explore the association of morphological characteristics with bioelectrical properties in volleyball, soccer, and rugby players. Methods: 164 athletes belonging to professional teams (age 26.2 ± 4.4 yrs; body mass index (BMI) 25.4 ± 2.4 kg/m²) underwent bioimpedance and anthropometric measurements. Bioelectric resistance (R) and reactance (Xc) were standardized for the athlete's height and used to plot the vector in the R-Xc graph according to the BIVA approach. Total body water (TBW), phase angle (PhA), and somatotype were determined from bioelectrical and anthropometric data. Results: No significant difference (p > 0.05) for age and for age at the start of competition among the athletes was found. Athletes divided into groups of TBW limited by quartiles showed significant differences in the mean vector position in the R-Xc graph (p < 0.001), where a higher content of body fluids resulted in a shorter vector and lower positioning in the graph. Furthermore, six categories of somatotypes were identified, and the results of bivariate and partial correlation analysis highlighted a direct association between PhA and mesomorphy (r = 0.401, p < 0.001) while showing an inverse correlation with ectomorphy (r = -0.416, p < 0.001), even adjusted for age. On the contrary, no association was observed between PhA and endomorphy (r = 0.100, p = 0.471). Conclusions: Body fluid content affects the vector length in the R-Xc graph. In addition, the lateral displacement of the vector, which determines the PhA, can be modified by the morphological characteristics of the athlete. In particular, higher PhA values are observed in subjects with a high mesomorphic component, whereas lower values are found when ectomorphy is dominant.

Phase Angle as a Marker of Muscular Strength in Breast Cancer Survivors

BACKGROUND

accurate prognostic tools are relevant for decision-making in cancer care. Objective measures, such as bioelectrical impedance (BI), have the potential to improve prognostic accuracy for these patients. This cross-sectional study aimed to investigate whether phase angle (PhA) derived from the electrical properties of the body tissues is a predictor of muscular strength in breast cancer survivors (BCS).

METHODS

a total of 41 BCS (age 54.6 ± 9.2 years) were evaluated. PhA, obtained at frequency 50 kHz, was assessed with BI spectroscopy, and muscular strength with a handgrip dynamometer. Moderate-to-vigorous physical activity (MVPA) was assessed using the International Physical Activity Questionnaire (IPAQ). Measurements were performed in the morning after an overnight fast.

RESULTS

linear regression analysis showed that PhA accounted for 22% (r² = 0.22) of muscular strength variance. PhA remained a borderline predictor of muscular strength variance independently of age and MVPA.

CONCLUSIONS

the findings of this study suggest that PhA is a significant predictor of maximal forearm isometric strength and a potential indicator of disease-related functionality in BCS.