Bioelectrical impedance phase angle in sport: a systematic review

Innovations in the Assessment of Skeletal Muscle Health: A Glimpse into the Future

Skeletal muscle is the largest organ system in the human body and plays critical roles in athletic performance, mobility, and disease pathogenesis. Despite growing recognition of its importance by major health organizations, significant knowledge gaps remain regarding skeletal muscle health and its crosstalk with nearly every physiological system. Relevant public health challenges like pain, injury, obesity, and sarcopenia underscore the need to accurately assess skeletal muscle health and function. Feasible, non-invasive techniques that reliably evaluate metrics including muscle pain, dynamic structure, contractility, circulatory function, body composition, and emerging biomarkers are imperative to unraveling the complexities of skeletal muscle. Our concise review highlights innovative or overlooked approaches for comprehensively assessing skeletal muscle in vivo. We summarize recent advances in leveraging dynamic ultrasound imaging, muscle echogenicity, tensiomyography, blood flow restriction protocols, molecular techniques, body composition, and pain assessments to gain novel insight into muscle physiology from cellular to whole-body perspectives. Continued development of precise, non-invasive tools to investigate skeletal muscle are critical in informing impactful discoveries in exercise and rehabilitation science.

Phase Angle and Body Composition as Predictors of Fitness and Athletic Performance in Adolescent Boxers

BACKGROUND

Phase angle (PhA) is an indicator of cellular health, function, and integrity. PhA has been considered an indicator of nutritional and health status, but it is uncertain whether it could be used as a fitness or athletic performance indicator.

OBJECTIVE

To analyze the relationship between PhA and the fitness and athletic performance of adolescent boxers and to know whether this association is independent of body composition.

METHODS

Thirty-seven trained youth boxers (15-18 y old) participated in the study. Participants underwent anthropometry and bioelectrical impedance assessments. The following tests were conducted: Fitness-Gram battery; speed, agility, and quickness; ball throws; punch impact force; bench press maximal strength; and vertical and horizontal jumps. Linear regression models were estimated and adjusted by covariates.

RESULTS

The PhA was related to upper-limb strength. Nevertheless, in linear regression models, after adjusting models by body composition, only PhA remained as a predictor of relative maximal strength. The PhA was not a predictor of speed, agility, and quickness; cardiorespiratory fitness; or lower-limb power, in which adiposity was the main predictor of fitness.

CONCLUSIONS

In adolescent boxers, PhA can predict upper-limb maximal strength independently of bioelectrical impedance analysis premises. However, compared with mucle mass, PhA is not a better predictor of upper-limb maximal strength.

Preoperative body composition measured by bioelectrical impedance analysis can predict pancreatic fistula after pancreatic surgery

BACKGROUND

Postoperative pancreatic fistula (POPF) remains one of the most severe complications after pancreatic surgery. The methods for predicting pancreatic fistula are limited. We aimed to investigate the predictive value of body composition parameters measured by preoperative bioelectrical impedance analysis (BIA) on the development of POPF.

METHODS

A total of 168 consecutive patients undergoing pancreatic surgery from March 2022 to December 2022 at our institution were included in the study and randomly assigned at a 3:2 ratio to the training group and the validation group. All data, including previously reported risk factors for POPF and parameters measured by BIA, were collected. Risk factors were analyzed by univariable and multivariable logistic regression analysis. A prediction model was established to predict the development of POPF based on these parameters.

RESULTS

POPF occurred in 41 of 168 (24.4%) patients. In the training group of 101 enrolled patients, visceral fat area (VFA) (odds ratio [OR] = 1.077, P = 0.001) and fat mass index (FMI) (OR = 0.628, P = 0.027) were found to be independently associated with POPF according to multivariable analysis. A prediction model including VFA and FMI was established to predict the development of POPF with an area under the receiver operating characteristic curve (AUC) of 0.753. The efficacy of the prediction model was also confirmed in the internal validation group (AUC 0.785, 95% CI 0.659-0.911).

CONCLUSIONS

Preoperative assessment of body fat distribution by BIA can predict the risk of POPF after pancreatic surgery.

Bioimpedance analysis for identifying new indicators of exercise-induced muscle damage

A noninvasive, immediate, and convenient method for assessing muscle tissue status during exercise-induced muscle damage (EIMD) has not been established. This study was designed to assess and determine parameters suitable for measuring EIMD after eccentric exercise, using multi-frequency bioimpedance analysis (BIA). Thirty-five young male participants performed dumbbell exercises with their left arm, and their BIA parameters were measured at various time points up to 168 h post exercise using a multi-frequency BIA device. At all-time points, intra and extracellular water content was greater in the left arm than in the right arm, whereas the impedance, reactance, resistance, and phase angle were lower in the left arm than in the right arm. Established EIMD indices, such as maximal isometric voluntary contraction, were measured and used in correlational analyses. Only reactance was correlated with biomarkers, indicating muscle damage (r =  - 0.56 to - 0.49). Furthermore, reactance was found to correlate well with indirect indicators of EIMD, suggesting that it may be a suitable marker for evaluating EIMD. However, the relationship with the limited evaluation indices employed in this study is constrained. Future studies should investigate the correlation between reactance and direct damage indicators, such as structural damage, observed in biopsies.

One-Year Changes in Bioelectrical Impedance Data in Adolescent Athletes

Raw bioelectrical impedance (BI) data and vector analysis (BIVA) have been used to evaluate fat-free mass (FFM) cross-sectionally in adolescent athletes; however, there have been no longitudinal studies about it. This study aimed to assess the magnitude of changes in raw BI data (resistance [R], reactance [Xc], and phase angle [PhA]), BIVA, and FFM in adolescent athletes (n = 137, 40% female). BI data were collected using a single-frequency device at baseline and after one year of sports practice. Baseline chronological age categorized the participants (11, 12, or 13 years [y]). In females, Xc/H increased (13 to 14 y, p = 0.04) while R/H decreased in all age groups (p = 0.001). PhA (11 to 12 y, p = 0.048) and FFM (11 to 12 y and 12 to 13 y groups p = 0.001) increased and showed the lowest magnitude of changes in the 13 to 14 y group (p = 0.05). In males, Xc/H decreased (11 to 12 and 12 to 13 y groups, p = 0.001) with a higher magnitude of changes in the 13 to 14 y group (p = 0.004); R/H decreased (p = 0.001); FFM increased in all groups (p = 0.001); however, no magnitude of changes was observed. PhA increased in the 13 to 14 y group (p = 0.004). BIVA showed no differences among ellipse distances in females. In males, a high distance was observed in the 11 to 12 y group. "Time interval" influenced PhA and Xc/H in the female group and R/H and Xc/H in the male group. "Initial age" and "time interval" influenced the increase in PhA in the male group. Raw BI data and BIVA patterns can detect the magnitude of the changes in a sex-dependent manner.

Validation of bioimpedance phase angle in lower extremity of male patients with chronic spinal cord injury

[Purpose] This study aimed to evaluate the relationship between lower extremity phase angle and muscle thickness/echo intensity in males with chronic spinal cord injury. It also compared bioelectrical impedance analysis measurements to investigate skeletal muscle degeneration between individuals with spinal cord injury and healthy controls. [Participants and Methods] This cross-sectional study included 12 male patients with chronic spinal cord injury and 14 healthy male controls. We used bioelectrical impedance analysis and ultrasonography to measure the lower extremity phase angle and muscle thickness/echo intensity of the rectus femoris muscle, respectively. We also compared the bioelectrical impedance analysis measurements between individuals with spinal cord injury and healthy controls. [Results] Lower extremity phase angle was strongly correlated with muscle thickness and echo intensity of the rectus femoris muscle in individuals with spinal cord injury. All measures differed significantly between individuals with spinal cord injury and healthy controls. [Conclusion] These findings suggest that lower extremity phase angle is a valuable skeletal muscle indicator in spinal cord injury. Furthermore, bioelectrical impedance analysis revealed degeneration of the lower extremity skeletal muscles in individuals with chronic spinal cord injury.

Skeletal muscle quality, measured via phase angle, and cardiorespiratory fitness in patients with obesity and heart failure with preserved ejection fraction

OBJECTIVES

Cardiorespiratory fitness (CRF) is influenced by body composition quantity and quality in heart failure with preserved ejection fraction (HFpEF) and obesity. Bioelectrical impedance analysis (BIA) provides a noninvasive quantitative and qualitative body composition assessment. The aim of this study was to determine the role of phase angle (PhA), a BIA-measure of skeletal muscle quality and body cell mass, on CRF in patients with obesity and HFpEF.

METHODS

Fifty-nine consecutive outpatients with HFpEF underwent cardiopulmonary exercise testing to measure CRF. Single-frequency segmental BIA was used to measure PhA and body composition quantity. Resting Doppler echocardiography and biomarkers were measured to assess cardiac function and systemic inflammation.

RESULTS

Compared with patients with lower PhA, patients with higher PhA (above mean 5.8°) presented a greater absolute peak oxygen consumption (VO2; 1.83 [1.3-2.1] versus 1.39 [1.1-1.6] L/min, P = 0.003), VO2 peak adjusted for body weight (17.5 [12.3-18.1] versus 13.3 [12.7-15.2] mL/kg/min, P = 0.040), and a lower edema index (48.7 [2.9] versus 51.4% [2.7], P < 0.001) and N-terminal pro-B-type natriuretic peptide (NT-proBNP; 64 [50-121] versus 183 [68-343.5] pg/dL, P < 0.001). In the overall sample, PhA was correlated with absolute VO2 peak (r = 0.468, P < 0.001), VO2 peak adjusted for body weight (r = 0.368, P = 0.004), VO2 peak adjusted for fat-free mass (r = 0.315, P = 0.015), edema index (r = -0.508, P < 0.001), and NT-proBNP (r = -0.579, P < 0.001). PhA remained a significant predictor for CRF even after adjustment for potential confounders and HFpEF severity.

CONCLUSION

In patients with obesity and HFpEF, a greater PhA is an independent predictor for favorable CRF.

Influence of limb dominance on body and jump asymmetries in elite female handball

Handball is a team sport subjected to asymmetric actions that require high physical capacity demands on players. The development of large asymmetries could negatively affect sports performance. However, few studies have analyzed body composition and the force asymmetries in elite female handball players. The aim of this study was to analyze the presence of asymmetries based on limb dominance in body composition parameters and lower limb power in jumping performances in an elite women's handball team. An entire elite women's handball team, comprised by of 14 players, was analyzed. Dual X-ray Absorptiometry (DXA) and bioimpedance were used to analyze body composition. Force plates were used to evaluate jump performance. Results show the presence of differences between all the players in the different parameters of the CMJ jump. In addition, an asymmetry between the power of the dominant and non-dominant lower limb was observed between the players. The results show differences in muscle mass between the upper limbs, but not in the lower limbs in terms of both muscle and fat mass. However, there were no crossed asymmetries or significant differences between members based on dominance. The results suggest that the presence of asymmetries does not have to be one of the main parameters to be taken into account by coaches in elite athletes and to highlight the importance of including specific analyzes of body composition and sports performance in an individualized way.

Phase angle and body composition: A scoping review

The aim of the study was to map evidence on the association between phase angle (PhA) and body composition in populations healthy and clinical populations). A systematic search for information regarding the topic was conducted in nine electronic databases (CINAHL, LILACS, PubMed, SciELO, Scopus, SPORTDiscus, Science Direct, MEDLINE and Web of Science) between October and November 2021. Studies with different designs, which allowed extracting information about the relationship between PhA and body composition (body cell mass [BCM], muscle tissue, bone mineral content, lean mass, total fat mass, visceral fat, and lean soft tissue mass [LSTM]) were included. Of the total of 11,913 initially identified studies, 59 were included after reading titles, abstracts, full texts and references. Most studies (40.67%; n = 24) presented data from Brazilian samples. With regard to the design of studies, 15 (25.42%) had longitudinal design. The age group of studies was wide, with studies involved 3-year-old children and 88-year-old adults. Body fat mass was evaluated by 31 studies (52.54%) in which 11 observed inverse relationships, nine studies showed direct relationships and 11 observed no relationship. Regarding lean mass, muscle mass, and fat-free mass components, most studies observed direct relationship with PhA (n = 37; 86.04%). It could be concluded that the phase angle was directly associated with lean mass and muscle mass in different age groups (children, adolescents, adults and older adults) and in people with different health diagnoses (HIV, cancer, hemodialysis, sarcopenia and without the diagnosis of diseases). Regarding body fat and the other investigated components, there is not enough evidence to establish the direction of associations.

Regional phase angle, not whole-body, is augmented in response to pre-season in professional soccer players

The objective of this article was to assess the effects of six-week pre-season training on whole-body and regional bioelectrical impedance analysis (BIA)-derived parameters, body composition, power, and aerobic performance in professional soccer players. Ten professional soccer athletes participated in the present study. Whole-body and regional hamstrings BIA-derived parameters [resistance, reactance, impedance, phase angle (PhA)], body composition, total body water (TBW), intracellular (ICW), and extracellular (ECW) were measured before, at mid-point, and after sixth week of the pre-season. Power (countermovement jump and squat jump) and aerobic capacity (Yo-Yo test) were measured before and after pre-season. There was a significant increase in the regional PhA (+13.9%) but not in the whole-body. There was a reduction in fat mass (-4.1%), an increase in fat-free mass (+1.7%), TBW (+8.3%), ICW (+8.8%), and ECW (+7.6%), as well as an increase in jump height (+11.0%) and distance covered in the Yo-Yo test (+34.7%). From our results, it is possible to suggest that pre-season training can induce an increase in hamstring PhA as well as body recomposition and improvement of physical fitness in professional soccer players.

Reduction of Excessive Dietary Sodium Consumption: Effectiveness of a Prevention Intervention among Health Workers in a Large Italian Hospital

Excessive salt consumption is one of the leading causes of high blood pressure. Worldwide salt intake largely exceeds the WHO recommended amount. This study aimed to evaluate the prevalence of high salt consumers and the effectiveness of a short-term workplace educational intervention among health workers. An online survey, assessing daily salt consumption through the MINISAL-SIIA questionnaire, was sent to the 4911 health workers employed by the University Hospital of Verona, Italy. Health workers who had a high (total score ≥ 10) or moderate (total score = 8/9) salt consumption associated with obesity or arterial hypertension were invited to undergo a medical examination and a short individual counselling session. A total of 1665 health workers (34.0%) completed the online questionnaire; 40.9% and 12.6% had moderate and high salt intake, respectively. High salt intake was more prevalent in men, current and past smokers, and obese and overweight subjects. In 95 participants completing the clinical phase, median daily salt consumption decreased from 10 (p25-p75 8-11) to 7 g (6-8) (p < 0.001), systolic blood pressure from 130 (120-140) to 120 (120-130) mmHg and weight from 78 (62-87) to 75 (62-86) kg. More than half of health workers had an excessive salt intake. However, a brief educational intervention in the healthcare working setting can substantially reduce unhealthy dietary habits, fostering weight loss and blood pressure control. Studies with a longer follow-up are needed to evaluate the persistence over time of these effects.

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.

Elite young soccer players have smaller inter-limb asymmetry and better body composition than non-elite players

Body composition (BC) and inter-limb anthropometric asymmetries (LA) may influence the physical performance of soccer players. This study aimed to determine differences in BC and LA among soccer across four performance levels. The study involved 110 male soccer players participating in Czech senior teams who were grouped into four different performance levels (i.e. G1: national team, G2: 1^st division, G3: 2^nd division, G4: 3^rd division). The following BC and LA parameters were compared among groups: body height, body mass, absolute fat-free mass, relative fat-free mass (FFMrel), percentage of fat mass (FM), total body water (TBW), intracellular water (ICW), extracellular water (ECW), phase angle, and bilateral muscle mass differences in the upper and lower extremities. Significant differences were observed in BC parameters among all groups (λ = 0.06, F75,246 = 5.38, p = 0.01, η_p ² = 0.62). High-performance players (i.e. G1, G2) had significantly (p < 0.01) lower FM than lower performance players (i.e. G3, G4). The lowest values of FFMrel, relative TBW, relative ICW and ECW were detected in the lowest-performance players (i.e. G4). Significantly lower bilateral muscle mass differences were detected in G1 players (2.71 ± 1.26%; p < 0.01) compared with G4 players (3.95 ± 1.17%). G1 and G2 players had a higher proportion of muscle mass in the torso (p < 0.01) and upper limbs than G3 and G4 (p < 0.01). Elite and high-performance players have better BC and lower inter-limb anthropometric asymmetries compared with low-performance level players.

Development and Validation of a Nomogram for Prediction of the Risk of MAFLD in an Overweight and Obese Population

BACKGROUND AND AIMS

Metabolic associated fatty liver disease (MAFLD) is a serious condition, and a simple method is needed for practitioners to identify patients with the disease and have a high risk of disease progression.

METHODS

We developed and validated a nomogram for fatty liver disease and reclassified the risk factors for MAFLD. The development cohort had 335 patients who received bioelectrical impedance analysis and liver ultrasound attenuation measurements at Shenzhen People's Hospital between September 2020 and June 2021. The validation cohort had 200 patients from other hospitals who received the same evaluation. A random forest procedure and binary logistic analysis were used to screen for risk factors, establish a fatty liver disease predictive model, and forecast the risk of MAFLD. The performance of the nomogram was evaluated by measurement of discrimination, calibration, and clinical usefulness.

RESULTS

The nomogram provided good predictions in a model that included body mass index (BMI) and waist circumference. The areas under the curve of the nomogram were 0.793 in the development cohort and 0.774 in the validation cohort. The nomogram performed well for calibration, category-free net reclassification improvement, and integrated discrimination improvement. Decision curve analysis indicated the nomogram performed better than BMI for predicting net outcome.

CONCLUSIONS

The nomogram was an effective screening tool for fatty liver disease, and for those overweight individuals, may help physicians make appropriate decisions regarding treatment of MAFLD.

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.

Phase angle (PhA) in overweight and obesity: evidence of applicability from diagnosis to weight changes in obesity treatment

Phase angle (PhA) is a recently proposed marker of nutritional status in many clinical conditions. Its use in patients with obesity presents different critical concerns due to the higher variability of the two measured parameters (resistance, R, and reactance, Xc) that contribute to the determination of PhA. Controversial is the relation between PhA and BMI that might vary with graded levels of obesity due to the variation in fat and free fat mass. Obesity is frequently associated with metabolic, hepatic, cardiovascular and kidney diseases that introduce variations in PhA values, in relation to multimorbidity and severity degree of these diseases. It is reported that the improvement of clinical condition is associated with a positive change in PhA. Also, the treatment of obesity with weight loss might confirm this effect, but with different responses in relation to the type and duration of the intervention applied. In fact, the effect appears not only related to the percentage of weight loss but also the possible loss of free fat mass and the nutritional, metabolic and structural modifications that might follow each therapeutic approach to decrease body weight. We can conclude that the PhA could be used as marker of health status in patients with obesity supporting an appropriate weight loss intervention to monitor efficacy and fat free mass preservation.

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.

Phase Angle as a Predictor for Physical Function in Institutionalized Independent Older Adults

The aim of this study was to investigate the relationship between phase angle (PhA) and physical function in institutionalized, independent older adults. Physical function was evaluated using the Senior Fitness Test Battery. PhA was measured by electrical bioimpedance at 50 khz, and body composition parameters were also registered. Results showed that PhA significantly correlated with all physical fitness tests, except for arm curls. Regarding the results of the multivariate analysis, three models were created: Model 1, formed by a dependent variable "PhA" and two predictor variables "8 ft up-and-go" and "6 min walk"; Model 2, formed by a dependent variable "PhA" and three predictor variables "8 ft up-and-go", "6 min walk" and "30-s chair stand"; and Model 3, formed by a dependent variable "PhA" and four predictor variables "8 ft up-and-go", "6 min walk", "30-s chair stand" and "arm curl". Results showed that predictor variables had a significant influence on the PhA for all three models (Model 1: p = 0.001, 12.5%; Model 2: p = 0.002, 12.9%; and Model 3: p = 0.005, 13.1%). For women, Model 1 showed a significant influence of predictor variables on the PhA (p = 0.030, 9.3%). The results for men in Models 1, 2 and 3 showed significant influences on the PhA (p = 0.002, 31.2%; p = 0.006, 31.6%; and p = 0.016, 31.6%; respectively). This study confirmed previous studies regarding to the relationship between PhA and physical function. It also indicates that PhA could be an excellent predictor of physical function.

Exercise-Based Cancer Rehabilitation Program Improves Phase Angle in Breast Cancer Survivors

Phase angle (PhA) is an index of cell membrane integrity and prognostic indicator of survival and quality of life in cancer survivors. The efficacy of exercise-based cancer rehabilitation programs (ExCR) on PhA is unknown. To assess the effect of ExCR on PhA in breast cancer survivors. Fifty-nine female breast cancer survivors (61 ± 9 years) were referred to the ExCR by their oncologist and participated in one-on-one exercise-based training for 90 minutes, 3 times a week, for 12 weeks. Training sessions included 45 minutes of resistance training at intensities between 40-85% of 1-repetition maximum with a rate of perceived exertion (RPE) between 3-8, 30 minutes of cardiorespiratory training at intensities between 40-85% of heart rate reserve with an RPE between 3-8, and 15 minutes of flexibility training. Participants completed pre- and post-measurements of body composition, cardiorespiratory endurance, flexibility, muscular endurance, muscular strength, and PhA (Inbody 770). PhA significantly increased (p < 0.05) after ExCR (PhA_pre = 4.56; PhA_post = 4.64; Δ = 1.8%). Changes in measures of muscular strength have a weak but significant positive relationship (r = 0.20-0.39; p < 0.05) with changes in PhA. There was no relationship between changes in PhA and changes in cardiorespiratory endurance or muscular endurance. A 12-week ExCR significantly improves PhA in breast cancer survivors. Training muscular strength may be an integral component of ExCR with the objective of improving PhA.

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.

Montmorency tart cherry supplementation does not impact sleep, body composition, cellular health, or blood pressure in healthy adults

Background: Sleep disturbances are linked with cardiovascular and metabolic disease as well as poor body composition. Aim: To investigate the use of tart cherry supplements, which are high in antioxidants and may contain melatonin, on parameters of health such as sleep, body composition, cellular health, and blood pressure (BP). Methods: Forty-four participants had completed sleep record data and were included in this analysis. Participants consumed either two 240 ml bottles per day of Montmorency tart cherry (MTC) juice or placebo or two capsules per day of powdered MTC or placebo for 30 days. Participants tracked their sleep daily via questionnaire and completed body composition and BP assessments at baseline, 14 days, and 30 days after supplementation. Results: There were no significant differences in sleep time or quality between groups, though both increased over 30 days. The capsule groups had significantly lower body mass (BM) 14 days versus baseline for placebo group (p = 0.01, mean difference: 0.70 kg) and at 30 days versus 14 days in MTC group (p = 0.02, mean difference: 0.75 kg). No other differences in body composition or cellular health were found. BP was unaffected by MTC supplementation over 30 days. Despite the potential benefits of antioxidants and melatonin, we did not find improvements in sleep time or quality, cellular health or BP in participants consuming MTC for 30 days, though BM decreased in capsule groups. Conclusion: These results conflict with previous data on MTC and sleep and BP, therefore further investigation is warranted.

Assessment of changes in muscle mass, strength, and quality and activities of daily living in elderly stroke patients

Whether poststroke rehabilitation improves muscle mass and quality along with the recovery of muscle strength is not clear. In this study, we examined the changes in muscle strength, muscle mass, and muscle quality in patients undergoing poststroke rehabilitation and assessed the relationship of these variables with improvement in activities of daily living (ADL). This prospective study was conducted at stroke rehabilitation unit in Japan. Muscle mass and quality were assessed using bioelectrical impedance analysis (BIA). ADLs were assessed using the functional independence measure (FIM). Grip strength of the nonaffected and affected sides was measured using hand dynamometer. All measurements were performed at admission to the stroke rehabilitation unit and at 4 weeks thereafter. We assessed changes in motor FIM items and examined the relationships among the measured variables. This study included 179 patients. Patients received stroke rehabilitation 7 days a week individually. Muscle strength and quality significantly increased after 4 weeks on both the sides. Muscle mass decreased after 4 weeks; however, there was no significant difference between the two time points. Changes in muscle strength and quality showed a significant correlation with improvement in ADLs [r = 0.66 (male), 0.45 (female) and 0.55 (male), 0.31 (female), respectively]; however, muscle mass showed no correlation with improvement in ADLs. Poststroke rehabilitation improves muscle strength and quality, as well as ADLs. Muscle mass is not an appropriate measure to assess the effects of stroke rehabilitation; it is desirable to instead use muscle strength and quality to assess stroke rehabilitation.

Relationship between Nutritional Status, Body Composition, Muscle Strength, and Functional Recovery in Patients with Proximal Femur Fracture

Sarcopenia is a major issue among the elderly. However, the effects of nutritional status and body composition on functional recovery in patients with proximal femur fractures (PFF) remain unclear. Hence, this study aimed to investigate the effects of nutritional status, body composition (skeletal muscle mass and muscle quality measured by phase angle [PhA] values), and muscle strength on the improvement in activities of daily living (ADL) in patients with PFF. We enrolled patients with PFF admitted to a rehabilitation unit. Nutritional status, body composition, grip strength, and motor Functional Independence Measure (FIM) score were assessed on admission day and at 4 weeks thereafter. Of 148 patients, 84 had femoral neck fractures, and 64 had trochanteric fractures. The mean motor FIM score was 49.2 points at admission and 64.9 points after 4 weeks. In multivariate analysis, higher geriatric nutritional risk index and PhA measured by anthropometry were associated with a significantly higher FIM score after 4 weeks. Muscle strength and quality changes significantly correlated with ADL improvement. Poor nutritional status and decreased muscle strength and quality interfered with ADL recovery. Nutritional management before injury and from the acute phase, and rehabilitation to maintain skeletal muscle status, are important for ADL recovery.

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.

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.

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.

Reference Data of Phase Angle Using Bioelectrical Impedance Analysis in Overweight and Obese Chinese

INTRODUCTION

Phase angle (PhA) is a ratio of reactance and resistance {arctangent (reactance (Xc)/resistance (R)) × (180°/π)}, which can be obtained by bioelectrical impedance analysis (BIA). PhA indicates cellular health and integrity, and it is also considered as a prognostic tool in medical disorders and an indicator of nutritional status (especially of muscle quality) in patients with obesity. However, PhA has limited usefulness in clinical practice because of a lackness of reference values for Chinese overweight and obese populations. The main aim of this study was to show PhA reference data in different age and BMI groups by sex. In addition, we also study the association of age, sex, and BMI on PhA.

METHODS

A total of 1729 overweight and obese participants were included in this study. PhA and body composition were measured using segmental multifrequency BIA. Differences in mean values for variables were tested by one-way analysis of variance. Multiple regression analysis was used to assess the associations of PhA with age, sex and BMI.

RESULTS

Multiple regression analysis showed that age, sex and BMI were significant (P < 0.05) independent influence factors of PhA in Chinese overweight and obese adults when age and BMI were continues variables. The mean PhA value for all participants was 5.5°. Mean BMI, age, weight, height and 50kHz-PhA were significantly higher (P < 0.001) in male participants than female ones. In age groups and BMI groups, mean 50kHz-PhA was significantly higher (P < 0.005) in male participants than female ones. When age groups and BMI groups were categorical variables, multiple regression analysis showed that different age groups (46-55 years and ≥ 56 years) had a significantly lower (P < 0.005) PhA as compared with the baseline group (18-25 years) and different BMI groups (≥ 28 kg/m²) had a significantly higher (P < 0.05) PhA as compared with the baseline group (24-27.9 kg/m²).

CONCLUSION

PhA differed according to age, sex and BMI. Reference data in this study can be taken into consideration when deriving the reference values for overweight and obese Chinese populations.

Bioimpedance-based Authentication of Defrosted Versus Fresh Pork at the End of Refrigerated Shelf Life

Correct food labeling is a legal requirement and helps consumers to make informed purchasing choices. Mislabeling defrosted meat as fresh is illegal in the EU. However, there are no standardized technologies to authenticate fresh versus defrosted meat. We address this by testing if bioimpedance-based measurements can separate defrosted meat from refrigerated-only meat at the end of shelf life, i.e., when also fresh meat shows deterioration. Pork sirloin samples from 20 pigs were first tested at 12 days postmortem ('fresh group'). This time point was chosen to represent a typical use-by date for refrigerated storage of fresh pork. Then, all samples were transferred to a -24°C freezer for 3 days and thawed for 2 days before final testing ('frozen-thawed group'). Bioimpedance analyses (BIA) were done in a frequency range of [10²-10⁶ Hz]. Weight, pH and electrode positioning were assessed to test for potential confounding effects. Statistics for treatment dependent differences were based on the established P_y parameter and phase angle, which were extracted from the BI spectra. We found that using bioimpedance testing with tetrapolar electrodes, P_y and phase angle allowed almost complete separation of fresh and previously frozen samples. However, within the whole sample population, there was some overlap between the spectra of fresh and frozen samples. Yet, based on P_y, only one fresh sample (5% of N_total=20) fell in the lowest P_y class with all the frozen samples. We used a multifactorial design that allowed to test the effects of potential confounding factors, such as electrode positioning and meat quality parameters. We found a relatively low explained variance for the P_y parameter, indicating that confounding effects from other factors or quality defects in fresh pork may affect the detection capacity of bioimpedance-based authentication of fresh pork. Our data, therefore, suggest that reliable fresh-label authentication with bioimpedance testing should be based on testing a small number of samples to represent a specific lot of pork that is to be inspected.

Relationships between Body Composition Parameters and Phase Angle as Related to Lifestyle among Young People

The aim of the study was to indicate which body composition parameters and which lifestyle components affect the phase angle (PA) value in young adults. Two-hundred-and-eighty-one students at Wroclaw Medical University participated in the study. A survey on respondent lifestyles was followed by anthropometric measurements, body composition analysis, and basal metabolic rate (BMR) calculation. The differences in the body composition of men and women corresponded to their sexual anatomy and physiology. Sex-dependent differences in lifestyle were also reported. The study revealed a relationship between PA and height, weight, BMR, BMI (body mass index), FFM (fat-free body mass), bone mass, water mass, muscle mass (r~0.4–0.7), ECW/ICW (extracellular water/intracellular water) and fat mass (r~−(0.4–0.6)) for the entire studied group. The relationship between PA values and lifestyle components concerned consumption of energy drinks, cola, alcohol, water, vegetables and fruits, meat, and also intervals between meals, time for physical exercises, and screen time (r~±0.2). The research shows that the PA value increases with an increase in positive body composition parameters. Following the principles of proper nutrition and physical activity increases PA values in most cases.

Bioelectrical Impedance Vector Analysis of Young Elite Team Handball Players

Team handball is a highly dynamic sport where physical demands differ between categories and roles. Thus, physical characteristics are fundamental for the final performance. This study aims to (a) characterize a sample of young male and female elite team handball players with a non-athletic reference population; (b) to generate their 50%, 75%, and 95% percentiles of the bioelectrical variables. The study included 55 young elite team handball players (Males, n = 37, age = 17.0 ± 1.2 yrs, height = 185.8 ± 7.3 cm, weight = 82.0 ± 11.0 kg, body mass index (BMI) = 23.7 ± 2.5; Females, n = 18, age = 17.8 ± 0.9 yrs, height = 171.2 ± 6.4 cm, weight = 67.4 ± 7.2 kg, BMI = 23.0 ± 2.0). Height and bioelectrical variables were assessed in a state of euhydration and standard conditions. Bioelectrical impedance vector analysis (BIVA) was used to characterize the bioelectrical vector (BIA vector) distribution pattern for each group. Compared to the reference values, BIA vector showed statistically significant differences in males U17 (n = 19, T2 = 51.0, p < 0.0001), males U19 (n = 18, T2 = 82.0, p < 0.0001) and females U19 (n = 18, T2 = 85.8, p < 0.0001). Male groups were also bioelectrically different (T2 = 13.7, p = 0.0036). BIVA showed specific bioelectrical characteristics in young male and female elite handball players. This study provides an original data set of bioelectrical impedance reference values of young male and female elite team handball players. Our result might help to interpret individual bioimpedance vectors and define target regions for young handball players.

Extracellular water to total body water ratio may mediate the association between phase angle and mortality in patients with cancer cachexia: A single-center, retrospective study

BACKGROUND & AIMS

Recently, prognostic factors for cancer cachexia patients have been reported. We hypothesized that phase angle (PhA), which is measured by bioelectrical impedance analysis (BIA), might be a promising marker for assessing the nutritional status and prognosis of cancer patients. This study aimed to evaluate the predictive utility of PhA, which is mediated by several BIA factors and other anthropometric parameters, such as calf circumference, for the prognosis of cancer cachexia patients.

METHODS

Consecutive patients (114, both outpatients and inpatients) with an unselected stage of cancer cachexia were recruited between July 2018 and December 2019 in Fujita Health University Hospital for this retrospective cohort study. Their mean age was 74.0 years (standard deviation, 8.5); among the total, 70 were men and 44 women. A time-dependent Cox proportional-hazards regression analysis (adjusted for age and sex) was performed to assess the following: 1) the association between potential mediators and mortality; 2) the association between five PhAs and statistically significant mediators from 1); and 3) the association between the five PhAs and mortality. Finally, Kaplan-Meier survival curves were constructed and compared between the two groups based on the patients' median baseline ratio of extracellular water (ECW) to total body water (TBW) using a log-rank test.

RESULTS

The ECW/TBW ratio (hazard ratio [HR] per 1-interquartile range [IQR] increase: 2.87; 95% confidence interval [CI]: 1.46, 5.46; p < 0.001) and skeletal muscle mass index (HR per 1-IQR increase: 0.67; 95% CI: 0.51, 0.89; p = 0.001) were associated with mortality. All five PhAs were associated with the ECW/TBW ratio (p < 0.001). Before adjustment for the ECW/TBW ratio, all five PhAs were associated with mortality (p < 0.001); only the association of the PhAs of the left arm and the trunk retained the statistical significance after adjusting for confounders (p < 0.05). The median survival times in the low (370 days; 95% CI: 168, not calculated) and high ECW/TBW groups (101 days; 95% CI: 61, 219) differed significantly (p < 0.001).

CONCLUSIONS

The association between PhA and mortality in cancer cachexia patients was largely mediated by the ECW/TBW ratio. We believe that adjusting PhA for the ECW/TBW ratio may improve the prognostication of cancer patients with cachexia, ultimately improving their palliative care.

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.

Resting energy expenditure in elite athletes: development of new predictive equations based on anthropometric variables and bioelectrical impedance analysis derived phase angle

Background

An accurate estimation of athletes’ energy needs is crucial in diet planning to improve sport performance and to maintain an appropriate body composition. This study aimed to develop and validate in elite athletes new equations for estimating resting energy expenditure (REE) based on anthropometric parameters as well as bioimpedance analysis (BIA)-derived raw variables and to validate the accuracy of selected predictive equations.

Methods

Adult elite athletes aged 18–40 yrs were studied. Anthropometry, indirect calorimetry and BIA were performed in all subjects. The new predictive equations were generated using different regression models. The accuracy of the new equations was assessed at the group level (bias) and at the individual level (precision accuracy), and then compared with the one of five equations used in the general population or three athletes-specific formulas.

Results

One-hundred and twenty-six male athletes (age 26.9 ± 9.1 yrs; weight 71.3 ± 10.9 kg; BMI 22.8 ± 2.7 kg/m²) from different sport specialties were randomly assigned to the calibration (n = 75) or validation group (n = 51). REE was directly correlated with individual characteristics, except for age, and raw BIA variables. Most of the equations from the literature were reasonably accurate at the population level (bias within ±5%). The new equations showed a mean bias −0.3% (Eq. A based on anthropometric parameters) and −0.6% (Eq. B based on BIA-derived raw variables). Precision accuracy (individual predicted-measured differences within ±5%) was ~75% in six out of eight of the selected equations and even higher for Eq. A (82.4%) and Eq. B (92.2%).

Conclusion

In elite athletes, BIA-derived phase angle is a significant predictor of REE. The new equations have a very good prediction accuracy at both group and individual levels. The use of phase angle as predictor of REE requires further research with respect to different sport specialties, training programs and training level.

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.

Feasibility of Using Bioelectrical Impedance Analysis for Assessing Youth Weight and Health Status: Preliminary Findings

Background. This study assessed the accuracy of bioimpedance analysis (BIA) for measuring body composition and resting metabolic rate (RMR) in fasted and non-fasted state and the prospect of using phase angle (PA) to indicate cellular health in youth. Methods. BIA body composition, RMR, and hydration measures were compared to dual-energy x-ray absorptiometry (DXA), MedGem metabolic analyzer, and urine specific gravity, respectively, at baseline in a fasted state using one-way ANOVAs. Repeated BIAs at 0, 30, 60, 90, and 120 min post-prandial were compared to baseline using repeated-measures ANOVA. Correlations were used to assess the relationship among PA and health (blood lipids and glucose, resting BP) and fitness (grip strength and a 3 min step test) measures. Results. BIA scans (N = 58; 11.4 ± 2.9 y) measured lower body fat % (BF%) in healthy weight youth (BMI < 85th percentile; 16.4 ± 1.1 vs. 25.1 ± 1.0%) and lower visceral adipose tissue (VAT) in males (44.5 ± 2.9 vs. 34.1 ± 6.0 cm2) than DXA and higher RMR in all youth (1244 ± 41 vs. 1104 ± 39 kcals/day), healthy weight (1231 ± 48 vs. 1049 ± 44 kcals/day), and teens (1541 ± 62 vs. 1234 ± 72 kcals/day) than MedGem. Compared to baseline, immediate post-prandial values were significantly higher for BF% (21.4 ± 1.4 vs. 22.0 ± 1.4%) and VAT (45.4 ± 6.1 vs. 46.2 ± 6.2 cm2). PA was significantly correlated with BF% (r = -0.33; p = 0.01), fat-free mass (r = 0.59; p < 0.001), grip strength (r = 0.56; p < 0.001). Conclusions. While more data are needed to confirm these preliminary findings, the results suggest caution is necessary in using BIA to assess aspects of youth health and weight status, especially in males, healthy weight, and teens. However, these preliminary findings do indicate that phase angle maybe be a valuable, non-invasive tool for identifying youth who are heading towards obesity and/or obesity-related health consequences.

Bioelectrical impedance (BIA)-derived phase angle in adults with obesity: A systematic review

BACKGROUND & AIMS

Bioimpedance analysis-derived phase angle (PhA), as marker of body cell mass and cell integrity, might be altered in obesity, a condition which is characterized by alterations in muscle structure and function. The aim of this systematic review was to evaluate whether and to which extent PhA varies in individuals/patients with excess body weight focusing on: a) changes in PhA due to obesity; b) changes in PhA after bariatric interventions or training programs.

METHODS

According to PRISMA criteria, a systematic literature search until February 2021 using PubMed, Embase, Scopus, and Web of Science was performed. Selection criteria included studies on patients with obesity without comorbidities other than metabolic diseases.

RESULTS

A total of 278 articles were first identified. After removing duplicates and excluding studies that did not fulfil the inclusion criteria, the full text of the remaining 80 potentially relevant studies was examined to finally retrieve 11 cross-sectional and 10 longitudinal studies. Few studies have shown that PhA is lower in individuals/patients with obesity than in controls. The only study on the matter showed a decrease with age after the fourth decade of life. Four out of five studies reported consistently greater mean values in men than in women. In two studies PhA was lower in patients with severe obesity; in addition, Patients with low PhA had higher BMI and PhA was inversely correlated with fat mass. Longitudinal studies showed that PhA markedly decreased after bariatric surgery and slightly increased after training programs.

CONCLUSIONS

Thus, a relatively low number of studies have evaluated PhA in individuals/patients with obesity with sometimes contradictory and preliminary results. PhA might be useful to evaluate muscle quality in individuals/patients with obesity but further studies are needed to more accurately associate this variable with changes in muscle structure and strength, as well as in metabolic functions.

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.

Sarcopenia measurement in research and clinical practice

Sarcopenia is a disease related to accelerated loss of skeletal muscle and subsequent decline in functional capacity. It affects approximately 13% of the world's population aged over 60 years. Sarcopenia is primarily managed and prevented through a combination of exercise prescription combined with appropriate nutritional strategies. This review outlines diagnostic and case finding/screening tools for age-related (primary) sarcopenia used in research and clinical practice. Diagnostic tools critically reviewed include those of the: European Workgroup for Sarcopenia (EWGSOP) versions 1 and 2; Asian Working Group for Sarcopenia (AWGS) versions 1 and 2; Foundation for the National Institutes of Health (FNIH); and the Sarcopenia Definition and Outcomes Consortium (SDOC). Criteria used by diagnostic tools (muscle mass, muscle strength and physical functioning/performance) are also detailed. Case-finding tools include the SARC-F questionnaire, Ishii's formula and Goodman's screening grid. Additionally, this review discusses the strengths and weaknesses of each diagnostic and case-finding tool, and examines their ability to reliably predict adverse clinical outcomes and patient responses to potential therapies.

Impedance Measurement System for Assessing the Barrier Integrity of Three-Dimensional Human Intestinal Organoids

Human pluripotent stem cell (hPSC)-derived intestinal organoids (HIOs) hold unprecedented promise for basic biology and translational applications. However, developing a quantitative method to evaluate the epithelial cell membrane integrity of HIOs as an in vitro intestinal barrier model is a major challenge because of their complex three-dimensional (3D) structure. In this study, we developed an impedance system to measure the change in electrical resistance of 3D HIOs depending on the integrity of the intestinal epithelial cell membrane, which can reflect functionality and maturity. The expression of intestinal maturation- and tight junction-related markers was significantly higher in HIOs matured in vitro by treatment with IL-2 than in control HIOs. Analysis of gap junction size indicated that mature HIOs have greater integrity, with approximately 30% more compact gaps than immature HIOs. We designed a multi-microchannel system controlled by the inhalation pressure where the HIO is loaded, which enhances the stability and sensitivity of the impedance signal. We demonstrated the applicability of the impedance system by showing the difference in resistance between control and mature HIOs, reflecting the expression of tight junction proteins and their maturation status. We also validated the impedance system by monitoring its resistance in real time during junctional damage to HIOs induced by a digestive agent. In summary, we suggest a quantitative method to directly quantify the physiological changes in complex 3D organoid structures based on impedance spectroscopy, which can be applied to noninvasively monitor live cells and therefore enable their use in subsequent experiments.

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.

The relevance of whole or segmental body bioelectrical impedance phase angle and physical performance in adolescent athletes

Objective. The physical condition of athletes can be assessed easily and quantitatively using objective indicators. Bioelectrical impedance measures the phase angle (PA), representing hydration and cell function, and is a potential clinical indicator of physical condition. This study aimed to investigate the association between PA and physical performance in adolescent athletes.Approach. Overall, 170 adolescent athletes underwent a sports medical check-up, including body composition measurements and physical performance tests. Whole-body and segmental PAs (arm and leg) were determined based on body composition values. Isometric grip power and knee isokinetic muscle strength were measured as parameters of muscle strength. Counter movement jump height and squat jump height were measured as jump parameters. Associations between PA and each muscle strength or jump parameters were analysed using Pearson product-moment correlation coefficient or Spearman's rank correlation coefficient.Main results. Whole-body and upper limb PAs were highly correlated with grip power (r= 0.70-0.80). Whole-body and lower limb PAs were correlated with knee isokinetic muscle strength (r= 0.43-0.59). Whole and all segmental PAs were correlated with counter movement jump height (r= 0.46-0.57) and squat jump height (r= 0.42-0.52).Significance. PA can be used to monitor physical condition and sports performance in adolescent athletes. Segmental PAs can help assess the condition of the corresponding body part.

Cell integrity indicators in university athletes: comparison among playing positions in indoor football

BACKGROUND

The aim of this study was to compare cell integrity indicators according to the playing position in university indoor football athletes.

METHODS

The sample consisted of 34 university athletes (20 female and 14 male). Dependent variables were cell integrity indicators: total body water (TBW), intracellular water (ICW), extracellular water (ECW), ECW/ICW ratio, body cell mass (BCM), ECW/BCM ratio, phase angle (PhA), resistance (R), Xc (reactance) and impedance (Z), evaluated by the electrical bioimpedance method. Independent variable was the playing position: goalkeeper (a), defender (a), winger (left and right) and pivot collected through questionnaire. Control variables were age, time of sport practice, participation in competitions per year and training load obtained by applying the anamnesis form, and body fat and fat and bone-free mass were obtained through dual emission X-ray absorptiometry (DXA). Covariance analysis (ANCOVA) was used, with post-roc Tukey's test, to identify difference between groups, with p <0.05.

RESULTS

In the adjusted analysis, female athletes in the defense position had BCM values (31.1 ±2.1) higher than those in the wing position (25.8 ±1.1) (p <0.01). In males, pivots showed higher ICW values (31.47 ±0.77) when compared to defenders (25.7 ±0.8) (p = 0.02). In addition, goalkeepers had higher TBW values (52.7 ±2.5) compared to wingers (42.3 ±1.2) (p = 0.03).

CONCLUSIONS

Cell integrity indicators may vary according to the playing position in indoor football.

Whole body and regional phase angle as indicators of muscular performance in athletes

Bioelectrical impedance analysis (BIA)-derived phase angle (PhA) has been used to assess cellular health in various populations, but its usefulness as a tool for measuring muscular performance in adult athletes has not been extensively investigated. Our investigation examined the association of whole-body (WB) PhA with muscular performance in 117 adult athletes from different sports and additionally assessed whether regional PhA was a better indicator of muscular performance compared to WB, while accounting for lean soft tissue (LST). Muscular performance was assessed with handgrip strength and countermovement jump power. WB and regional PhA and LST were obtained by BIA and dual-energy x-ray absorptiometry, respectively. Multiple linear regression was used to model outcomes, while adjusting for LST. WB PhA was positively associated with relative power and relative and absolute strength (p < 0.05), irrespective of LST. Regional PhA measures explained similar amounts of variance in absolute and relative power and strength as that of WB PhA after accounting for age, sex, height, and sport type (lower limb adj R² = 0.42, 0.60 for power; upper limb adj R² = 0.38, 0.74 for strength; WB adj R² = 0.44, 0.63 and 0.38, 0.75 for power and strength, respectively). Only upper limb PhA was related with strength (p < 0.05) after accounting for upper limb LST. PhA may have the potential to be used as a marker of functional muscle mass, which is important when it comes to assessing muscular performance of athletes. Regional measures of PhA do not provide a better indicator of regional strength or power when compared to WB PhA.

Test-retest reliability of electrical impedance myography in hamstrings of healthy young men

Several techniques are available to assess muscle tissue status, including electrical impedance myography (EIM). Despite being used in the assessment of neuromuscular status in injury and response to exercise, reliability data for hamstrings muscles are limited. Therefore, this study aimed to determine the test-retest reliability of EIM components on hamstrings. Twenty-one healthy males (25.3 ± 3.4 years; 173 ± 6.7 cm; and 79.7 ± 15.9 kg) volunteered for this study. Subjects completed two visits, separated by seven days to collect EIM components (resistance, reactance, impedance, and phase angle) in the longitudinal and transversal axis of hamstrings in both thighs, using a bioimpedance device and Ag/AgCL adhesive contact electrodes. The electrode arrangement was in the muscular belly, half the distance between origin and insertion of the hamstrings. Reliability was determined by the intraclass correlation coefficient (ICC), minimal detectable change (MDC), and Bland-Altman plots. We observed high to excellent reliability (ICC > 0.85) between all EIM components, except for reactance with MDC ranged from 2.0 to 10.8 and the mean bias in Bland-Altman plots ranged from -0.02 to 2.48 (95% limits of agreement from -9.98 to 11.20). From our findings, the hamstrings assessment using EIM technique is reliable to assess muscle tissue; therefore, it enables the evaluation of changes/adaptations in clinical and applied contexts.

Bioimpedance to Assess the Body Composition of High-performance Karate Athletes: Applications, Advantages and Perspectives

Karate, a millennial martial art, was recently inserted among traditional Olympic combat sports for the Olympic Games in Japan. The aim of the present study is to determine, through bioimpedance analysis, the body composition of high-performance athletes participating in the São Paulo Olympic Karate Project. Participants were 22 athletes of both sexes, average age of 23.6 (6.0) years old, body mass of 66.6 (13.5) kg and fat percentage of 16.6 (5.5)%. Bioimpedance test indicated significant differences between sexes related to sexual dysmorphia, which had an impact on bioelectrical variables. Through comparative evaluation between male and female athletes, this study contributes to body composition analysis, indicating that, in the future, related bioimpedance tests should be used beyond their classical application, including phase angle, muscle function and other attributes.

Bioimpedance phase angle in elite male athletes: a segmental approach

OBJECTIVE

Phase angle (PA), a bioelectrical impedance analysis (BIA) parameter, has proven to be a proxy of body cell mass in athletes, but very few data are available on its segmental evaluation (upper and lower limbs). Therefore, we aimed to assess whether whole-body and segmental PA varied among elite male athletes of different sports and compared these to control groups. Additionally, we investigated its relationship with anthropometric and body composition parameters.

APPROACH

Elite athletes practicing cycling, water polo and ballet dance aged 18-40 years underwent anthropometric and BIA measurements. PA (whole-body and upper and lower limbs) was considered as raw BIA variable. Data were also compared with healthy subjects with similar characteristics who served as control groups.

MAIN RESULTS

Participants included three groups of male athletes: 18 cyclists (age 28.6 ± 3.4 years; weight 70.6 ± 5.4 kg; BMI 21.5 ± 1.4 kg m²), 20 water polo players (age 23.9 ± 4 years; weight 89.0 ± 5.2 kg; BMI 25.9 ± 1.9 kg m²) and 18 ballet dancers (age 19.2 ± 1.3 years; weight 63.3 ± 5.8 kg; BMI 20.8 ± 1.0 kg m²) and three groups of healthy control subjects each of which similar for general characteristics (one to one) to the previous ones. Both whole-body and limb PAs were significantly higher in athletes compared to their respective controls, whereas no differences were found among sport groups. PA was positively correlated with BMI and fat-free mass (FFM) more in athletes than in controls and FFM was the main determinant.

SIGNIFICANCE

PA may represent a useful proxy parameter of soft tissue mass quality, directly related to physical activity level. Furthermore, the direct evaluation of segmental PA among athletes practicing different sports may be useful for assessing and monitoring the differences among athletes and changes due to training.

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.

Bioelectrical impedance analysis (BIA) -derived phase angle in sarcopenia: A systematic review

BACKGROUND & AIMS

Bioelectrical impedance analysis-derived phase angle (PhA) has been gaining attention in the clinical evaluation of nutritional status because it is thought to be a proxy of water distribution and body cell mass; it is also associated to muscle strength and is an effective predictor of different clinical outcomes. Since an association may be expected between PhA and sarcopenia (defined by low skeletal muscle mass and impaired muscle function), the aim of this systematic review was to evaluate: a) changes in PhA due to sarcopenia; b) prevalence of sarcopenia according to PhA values; c) derivation of phase angle cut-offs for detecting sarcopenia; d) sarcopenia and PhA as predictors of clinical outcomes.

METHODS

A systematic research on electronic databases (PubMed, Embase, Scopus and Web of Science) from inception to January 31st, 2020 was performed according to PRISMA checklist. Using PICOS strategy, "P" corresponded to participants of any age, gender or ethnicity, "I" designated diagnosis of sarcopenia, "C" indicated subjects without sarcopenia, "O" corresponded to PhA, and "S" selected all study types. Methodological quality was assessed using the National Institute of Health (NIH) quality assessment tool.

RESULTS

Through the initial literature search and after removing duplicates and excluding papers by screening titles and abstracts, 79 potentially relevant studies were examined. Thirteen studies (7668 subjects) met the inclusion criteria. The overall risk of bias was low. Sarcopenia was associated with a significant lower PhA in seven studies out of eight, while five studies out of six reported a high prevalence of sarcopenia was in patients with low PhA. Different cut-off point values from 4.05 to 5.05° have been derived for the identification of sarcopenia. PhA and sarcopenia were independent predictors of survival in cancer patients and geriatric hospitalized patients.

CONCLUSIONS

Data from the selected papers demonstrate that PhA is decreased in sarcopenic subjects and the prevalence of sarcopenia is higher in subjects with low PhA. Further studies are needed to determine to what extent PhA may be valuable in detecting low muscle quality and/or identifying sarcopenia.

Acute Effects of Supervised Making Weight on Health Markers, Hormones and Body Composition in Muay Thai Fighters

Making weight is a practice often used in combat sports. This consists of a rapid weight loss (RWL) and a subsequent rapid weight gain (RWG) in the days preceding competition. However, this practice is often carried out based on anecdotal information provided by ex-athletes or non-professionals, which has led to several adverse events. This study aimed to assess the acute effects of a supervised nutritional period of RWL/RWG on health markers, hormone concentrations, and body composition. We performed a single-arm repeated-measures (baseline, after RWL and after RWG) clinical trial with twenty-one (8F:16M) Italian Muay Thai fighters. Body mass was significantly lower after the RWL (-4.1%) while there was a significantly higher glucose availability after RWL and RWG. Blood urea nitrogen, lipid profile, and creatinine were within the normal range after RWL/RWG. Testosterone decrease significantly after RWL and RWG in the men group. Male fighters had a significant reduction in thyroid-stimulating hormone concentration after the RWL and RWG intervention, but no change was found in women at pre-competition. Bioelectrical parameters were almost fully restored after RWG. An evidence-based and individualized nutrition methodology reduces the adverse events after an RWL and RWG practice, although the impact on the hormonal profile is inevitable.