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

Impedance-derived phase angle as an indicator of physical function in maintenance hemodialysis patients

OBJECTIVES

Maintenance hemodialysis (MHD) patients often impairs physical function, leading to reduced quality of life and increased mortality. Phase angle (PhA), derived by bioelectrical impedance analysis, has been proposed as a predictor of sarcopenia, holds promise as a potential indicator of physical function. The aim of this study was to identify the association between PhA and physical function in MHD patients.

METHODS

This was a multicenter, cross-sectional study included MHD patients from seven dialysis centers from 2020 to 2021. Physical function was measured by handgrip strength (HGS), Short Physical Performance Battery (SPPB), 4-meter gait speed, and timed up and go test (TUGT). Nutritional status was assessed by malnutrition inflammation score (MIS). Body composition, including PhA at 50kHz, was measured by bioelectrical impedance analysis. Sarcopenia was diagnosed according to the 2019 update version of the Asian Working Group for Sarcopenia. Multivariable linear regression models were performed to determine the association between PhA and physical function.

RESULTS

A total of 864 patients (61% male, median age 63 years) were analyzed. The median PhA was 4.5 (interquartile range: 3.9-5.2)°. PhA was negatively associated with age, MIS, Charlson comorbidity index, extracellular water/total body water, visceral fat area, and TUGT, and positively associated with hemoglobin, serum albumin, body mass index, height, weight, skeletal muscle mass index (SMI), SPPB, 4-meter gait speed, and HGS. These associations were consistent across PhA values of whole body and five body segments-right arm, left arm, trunk, right leg, and left leg. Multivariable linear regression analyses indicated that PhA was independently associated with higher SPPB scores (β = 0.33, P < 0.001), faster gait speed (β = 0.29, P < 0.001), greater HGS (β = 0.28, P < 0.001) and shorter TUGT time (β = -0.20, P < 0.001) after fully adjusted for age, sex, spKt/V, dialysis vintage, Charlson comorbidity index, MIS and skeletal muscle index. Subgroup analyses confirmed the robust association of PhA with physical function across different patient characteristics including sarcopenia, malnutrition, age, sex, and diabetes.

CONCLUSIONS

Higher PhA was independently associated with better physical function in MHD patients. Our study suggested that PhA may serve as a non-invasive, reliable clinical indicator for assessing functional status in this population.

Relationship between age and various muscle quality indices in Japanese individuals via bioelectrical impedance analysis (BIA)

BACKGROUND

Bioelectrical impedance analysis (BIA) is widely used as a convenient method of measuring body composition. The validity of the phase angle (PhA), impedance rate (IR), and resistance rate (RR) as indices of muscle quality using BIA has been suggested. This study aimed to investigate the relationship between these muscle quality indices and age, and to clarify their characteristics.

METHODS

The appendicular muscle mass (AMM), AMM corrected for body mass index (AMM/BMI), PhA, IR, and RR were determined using BIA in 1376 Japanese individuals (532 males and 844 females) aged 15-95 years. The PhA was determined from a 50-kHz current, and the IR and RR were determined from the impedance and resistance ratios between the 250- and 5-kHz currents.

RESULTS

AMM/BMI showed greater age-related changes than the other indices of muscle mass. Significant differences in PhA, IR, and RR were found for the whole body at age ≥ 50 years and for the lower limbs at age ≥ 30 years, compared to those in their 20 s. For the arms, age-related changes were small, and significant differences in PhA of females were only observed at aged ≥ 85 years, whereas significant differences in IR and RR were observed at aged ≥ 75 years, compared to those in their 20s.

CONCLUSION

These results suggest that although PhA, IR, and RR in the whole body and lower limbs showed age-related changes, the change in PhA in the upper body was small, especially in females. However, IR and RR in the upper limbs of females reflected age-related changes more than PhA.

Effects of Resistance Training on Muscular Adaptations and Inflammatory Markers in Overweight and Obese Men

PURPOSE

Obesity may blunt exercise responsiveness to improve muscular adaptations. The effect of resistance training (RT) targeting different body regions on muscle and inflammatory markers is unclear. This study aimed to investigate the impact of upper (upper body exercises), lower (lower body exercises), or combined (upper body + lower body exercises) RT on muscle and inflammatory markers, body composition, and performance in overweight and obese men.

METHODS

Sixty overweight and obese men (age, 31 ± 4 yr) were randomly assigned to one of four groups: upper-body RT (UB; n = 15), lower-body RT (LB; n = 15), combined RT (UB + LB; n = 15), or control (C; n = 15). The training protocol consisted of three exercise sessions per week for 12 wk. Blood samples for measuring serum markers (follistatin, myostatin, C-reactive protein (CRP), adiponectin, tumor necrosis factor α (TNF-α), and irisin) were obtained at baseline and 48 h after the final training session. Fat mass (FM), body fat percentage, skeletal muscle mass (SMM), and fat-free mass were measured using bioelectrical impedance analysis (InBody 720).

RESULTS

SMM, fat-free mass, UB and LB strength and power, follistatin, follistatin/myostatin ratio, adiponectin, and irisin significantly increased, whereas FM, body fat percentage, myostatin, CRP, and TNF-α significantly reduced from pre- to post-training in all training groups ( P < 0.05). Changes in LB muscle power ( r = 0.558), both UB ( r = 0.518) and LB ( r = 0.419) muscle strength, and follistatin ( r = 0.545) had moderate positive relationships with ΔSMM, whereas changes in myostatin ( r = -0.585) had a moderate negative relationship with ΔSMM. Also, changes in myostatin ( r = 0.825) and CRP ( r = 0.715) had a strong positive relationship with ΔFM, whereas TNF-α ( r = 0.467) had a moderate positive relationship with ΔFM. Follistatin ( r = -0.789) and adiponectin ( r = -0.713) had a strong negative relationship with ΔFM, whereas irisin ( r = -0.426) had a moderate negative relationship with ΔFM.

CONCLUSIONS

Combined RT elicits the greatest increases in follistatin, follistatin/myostatin ratio, and adiponectin, and decreases in myostatin and CRP compared with other training groups in overweight and obese men. However, systemic improvements may be achieved through performing UB or LB RT alone.

Decreased Lower Limb Phase Angle in Older People Is an Indicator of Standing and Gait Function, Regardless of Age

Background/Objectives: The phase angle (PhA), as measured using bioelectrical impedance analysis (BIA), indicates muscle mass and quality. However, its relationship with age-related muscle changes and motor function and effective BIA assessment/intervention sites remains unclear. Herein, we evaluated age-related changes in PhA, explored the relationship between PhA and muscle mass, and identified effective sites for BIA. Methods: We included 131 healthy community-dwelling adults divided into older (≥65 years) and control (≤65 years) groups. PhA and muscle mass were measured using BIA with a device determining electrical resistance by transmitting a weak alternating current <90 μA. Motor function was measured using ground reaction force index, gait function, and grip strength. The relationships between muscle mass, PhA, and motor function were analyzed. Results: All values, excluding upper limb muscle mass, were lower in the older group, as were the rates of change in muscle mass and PhA in the lower limbs vs. the upper limbs. Lower limb PhA showed negative and positive correlations with the Timed Up and Go test and standing function, respectively; it was significantly associated with all motor functions. Conclusions: Regardless of age, muscle mass and PhA measured by BIA were high and low in the lower limbs, respectively, and lower limb PhA was related to walking and standing function. The decrease in lower limb muscle mass and PhA may accelerate with age. Given global population aging, easy-to-assess lower limb PhA linked to the movements necessary for independent living may be an effective site for assessment and intervention in clinical practice.

Longitudinal trends of body composition in Anorexia Nervosa: Cardiac functioning impacts the restoration of fat-free mass at three-months follow-up

BACKGROUND AND AIMS

Predictors of outcomes are needed in order to improve the clinical management of patients with Anorexia Nervosa (AN). The present study evaluated whether cardiac dysfunction might be associated with different longitudinal outcomes of AN.

METHODS AND RESULTS

A sample of 35 patients with AN (11 restricting, 24 binge-purging- age range 16-28 years old) and 42 healthy controls (18-29 years old) were evaluated in terms of psychometric variables, Body Mass Index (BMI), body composition (by bioimpedance analysis, namely: Fat-Free Mass - FFM, Fat Mass - FM, Body Cell Mass - BCM, Phase Angle - PhA) and cardiac functioning (left ventricular ejection fraction - LVEF; global longitudinal strain - LVGLS). FM was significantly and negatively associated with eating psychopathology (weight and shape concerns, b -0.523, p 0.029; and shape concerns b -0.578, p0.015), while cardiac dysfunction (LVGLS > -18%) was positively associated with dietary restraints (b 1.253, p 0.043). LVEF, in turn, was positively associated with BCM (b 0.721, p 0.008) and FFM (b 0.779, p 0.039). Cardiac dysfunction negatively impacted the effect of nutritional rehabilitation, as those patients reporting reduced LVGLS showed lower FFM (b -4.410, p 0.011), FM (b -1.495, p 0.003) and BCM (b -2.205, p 0.015) at follow-up after three months.

CONCLUSION

These preliminary results showed that cardiac functioning might represent an early predictor of cachexia and chronicity, while body composition seems to be a more accurate measure for evaluating the recovery process of patients with AN.

The Impact of Photobiomodulation Therapy on Swelling Reduction and Recovery Enhancement in Total Knee Arthroplasty: A Randomized Clinical Trial

Background: Total knee arthroplasty (TKA) is commonly performed for severe osteoarthritis but often results in significant postoperative swelling and discomfort, impacting early rehabilitation. Photobiomodulation therapy (PBMT), utilizing low-level laser therapy (LLLT), has emerged as a potential adjunctive treatment to alleviate these symptoms. Methods: In this single-center, nonblinded prospective randomized clinical trial, conducted from May to July 2024, 30 patients undergoing primary TKA were enrolled and divided into two groups. Fifteen patients formed the control group receiving standard postoperative care, while the intervention group consisted of another 15 patients who received additional PBMT from the first to the fifth postoperative day (POD). The swelling was assessed using bioimpedance analysis, which offers a noninvasive, safe, and efficient method for assessing postoperative swelling by measuring tissue impedance, and functional outcomes were measured using the 2-min walk test (2MWT) and active range of motion (aROM). The study was registered with ClinicalTrials.gov (NCT06426251). Results: The PBMT group demonstrated significantly lower impedance, reactance, and phase angle ratios by POD6, suggesting reduced swelling compared to the control group. In the 2MWT, the PBMT group achieved a longer walking distance of 27 m, compared to 16 m in the control group. However, there were no significant differences in aROM or Visual Analogue Scale (VAS) pain scores between the groups. Conclusions: The findings indicate that PBMT effectively reduces postoperative swelling and enhances early mobility post-TKA. These benefits suggest that PBMT can be a valuable addition to conventional postoperative care, potentially accelerating functional recovery, and reducing rehabilitation time.

Six-month trajectory of phase angle after cardiovascular surgery and associated factors of the recovery during cardiac rehabilitation: A retrospective cohort study

BACKGROUND AND AIMS

Although the phase angle (PhA), a measure of frailty and sarcopenia, determined by bioelectrical impedance analysis has been reported as a prognostic factor after cardiovascular surgery, few studies have reported the trajectory of the PhA after discharge. In this study, we examined the trajectory of the PhA along with conventional physical function measures and explored the factors associated with recovery for 6 months after hospital discharge in patients who had undergone cardiovascular surgery.

METHODS

We included 116 patients who underwent elective cardiovascular surgery and cardiac rehabilitation after discharge. The PhA, physical function measures (grip strength, knee extension isometric muscle strength [KEIS], and usual gait speed), and Geriatric Nutritional Risk Index (GNRI) were assessed preoperatively, at discharge, and 3 and 6 months. Correlations between the PhA recovery rates and physical function and nutritional indices were assessed using Spearman's correlation analysis. Multivariate linear regression analysis was performed to examine the factors associated with recoveries of PhA and physical function indices (grip strength, KEIS, gait speed) after discharge.

RESULTS

Mean values of the PhA and physical function measurements and the GNRI score at discharge were lower than the preoperative values (PhA, -8.0 %; grip strength, -8.7 %; KEIS, -6.9 %; usual gait speed, -8.3 %; GNRI, -11 %). The grip strength, KEIS, and gait speed recovered to almost preoperative values 3 months after discharge. Values for the PhA and GNRI were still lower than preoperative values 3 months after discharge but had recovered to preoperative values at 6 months. The PhA was not significantly correlated with the recovery rates of the other indicators. Older age was negatively associated with PhA recovery rate, however, recovery rates decreased significantly with post-discharge physical activity.

CONCLUSIONS

In patients undergoing cardiovascular surgery, the PhA takes longer to recover than muscle strength or gait speed, requiring up to 6 months to recover to preoperative levels. Post-discharge interventions to increase daily physical activity may be an important method of speeding PhA recovery.

Analysis of Body Fluid Distribution, Phase Angle and Its Association With Maximal Oxygen Consumption in Facioscapulohumeral Dystrophy: An Observational Study

Background and Aims

Body composition parameters associated with aerobic fitness, mirrored by maximal oxygen consumption (V̇O2max), have recently gained interest as indicators of physical efficiency in facioscapulohumeral dystrophy (FSHD). Bioimpedance analysis (BIA) allows a noninvasive and repeatable estimate of body composition but is based on the use of predictive equations which, if used in cohorts with different characteristics from those for which the equation was originally formulated, could give biased results. Instead, the phase angle (PhA), a BIA raw bioelectrical parameter reflecting body fluids distribution, could provide reliable data for such analysis.

Methods

33 clinically and genetically characterized FSHD patients (mean age 35.7; 10 females) and 27 sex and age-matched healthy controls (HC) were included in the analysis. BIA was used to evaluate body fluids distribution (intracellular water [ICW], extracellular water [ECW], and total body water [TBW]), and PhA, while cardiopulmonary exercise test was used to estimate V̇O2max.

Results

The groups were comparable for ECW and TBW. Instead, patients showed lower values of ICW (p = 0.020), ICW/ECW ratio (p < 0.001), and PhA (p < 0.001). Moreover, patients reported lower V̇O2max (p = 0.001 for absolute values; p = 0.002 for values expressed in relation to body weight) which, unlike HC, was not associated to PhA.

Conclusion

Based on our results, PhA of FSHD patients is lower than HC. Since PhA mirrors the ICW/ECW ratio, the lower share of ICW seems to be the basis of such difference. Given the lack of association with V̇O2max, PhA cannot be considered a reliable indicator of aerobic fitness in FSHD.

Effects of Far-Infrared Rays Emitted from Loess Bio-Balls on Lymphatic Circulation and Reduction of Inflammatory Fluids

Background: FIR therapy is used in various medical settings to treat diseases associated with inflammation and edema. Unlike conventional FIR lamp therapy, this study investigated how body fluids change depending on the intensity and duration of FIR irradiation to the whole body. Method: Subjects in group A (n = 27) were exposed to FIR emitted from a loess bio-ball mat set at 40 °C for 30 min, and subjects in group B (n = 27) were exposed to FIR emitted from a loess bio-ball mat set at 30 °C for 7 h during sleep. Changes in bioimpedance parameters and fluid-related values were measured using a body fluid analyzer before and after exposure to FIR. Results: Changes in bioimpedance parameters associated with inflammatory fluids were quantitatively confirmed. In group A, there was a minimal change in fluid-related measurements. However, significant changes in bioimpedance parameters associated with inflammatory fluids were observed in group B exposure to FIR for 7 h during sleep. Conclusions: FIR emitted from loess bio-balls activates biological tissues and lymphatic circulation, gradually reducing the levels of inflammatory fluids over time.

Bioelectrical Impedance Analysis Demonstrates Reliable Agreement with Dual-Energy X-ray Absorptiometry in Identifying Reduced Skeletal Muscle Mass in Patients with Metabolic Dysfunction-Associated Steatotic Liver Disease and Hypertension

Background/Objectives: Body composition (BC) affects the risk of developing metabolic dysfunction-associated steatotic liver disease (MASLD) and hypertension (HTN). Currently, dual-energy X-ray absorptiometry (DEXA) is considered the gold standard for assessing BC, even though it has some limitations, including immobility, ionizing radiation, and patient weight restrictions. The aim of the study was to evaluate the correlations of BC parameters measured by bioelectrical impedance analysis (BIA) with those measured by DEXA in patients with MASLD and HTN. Methods: Overall, 78 patients with MASLD and HTN underwent the following study procedures: compilation of an anamnesis, physical examination of a patient, laboratory tests, abdominal ultrasound, BIA, DEXA, and anthropometric measurements. Results: The agreement between BIA and DEXA in diagnosing reduced skeletal muscle mass (SMM) in patients with MASLD and HTN was moderate (kappa values were 0.440 and 0.404 in males and females, respectively). Significant strong direct correlations were found between fat mass (FM) and body fat percentage measured by BIA with corresponding measurements by DEXA (p < 0.001 for both). The area under the receiver operating characteristic curves (AUC) of SMM to body weight ratios calculated using BIA data were 0.834 and 0.929 for reduced appendicular SMM determined by DEXA in males and females with MASLD and HTN, respectively. Conclusions: In conclusion, BIA is an easy-to-use and widely available tool for assessing SMM and FM in patients with MASLD and HTN, demonstrating reliable agreement with DEXA measurement results and completely free of its limitations.

Longitudinal association of objectively measured physical activity and bioimpedance phase angle in older adults

BACKGROUND & AIMS

The benefits of physical activity, including exercise and daily and household chores, on the bioimpedance phase angle remain unclear. We aimed to examine the longitudinal association between objectively measured physical activity and bioimpedance phase angle among community-dwelling older adults.

METHODS

This community-based cohort study enrolled individuals aged 65 years or older without any disability in the basic activities of daily living. The exposure was physical activity level measured objectively using a tri-axial accelerometer at baseline. The outcome was a whole body phase angle at 50 kHz obtained from a bioelectrical impedance analyzer at a one-year follow-up. The linear regression model was fitted to estimate the continuous associations of physical activity level and phase angle with adjustment of confounders, including age, sex, body mass index, physical performance, and phase angle at baseline.

RESULTS

The primary analysis included 229 individuals (mean age = 72.6 years [standard deviation = 4.9], 62.9% females). In the multivariable linear regression model, physical activity level at baseline is associated with a greater phase angle at follow-up (mean difference per 1 increase, 0.53° [95%CI, 0.23-0.83]). Subgroup analysis by sex showed similar trends. Restricted cubic spline analysis indicated a linear association between phase angle at follow-up and physical activity level at baseline (p = 0.66 for non-linearity).

CONCLUSIONS

Higher physical activity level was associated with greater phase angle at one-year follow-up in a linear dose-response manner, independent of demographics, physical performance, and phase angle at baseline, in community-dwelling older adults.

Association between preoperative phase angle and all-cause mortality after cardiovascular surgery: A retrospective cohort study

BACKGROUND

The importance of preoperative physical function assessment for post-operative intervention has been reported in older patients undergoing cardiovascular surgery. Phase angle (PhA), measured using bioelectrical impedance analysis, is an indicator of cellular health and integrity and is reported as a prognostic factor in several chronic diseases; however, its association with the long-term prognosis of cardiovascular surgery remains unclear. This study aimed to investigate the prognostic value of PhA for long-term mortality in patients undergoing cardiovascular surgery.

METHODS

This retrospective cohort study included consecutive patients who underwent elective cardiovascular surgery between October 2016 and March 2021 at Nagoya Heart Center, Japan. PhA was assessed using bioelectrical impedance analysis before surgery, and physical function measures (gait speed, grip strength and short physical performance battery [SPPB]) were measured synchronously. The association between PhA and all-cause mortality after discharge was assessed using Kaplan-Meier and multivariate Cox regression analyses. The incremental prognostic value of PhA was compared with other physical function measures using net reclassification improvement (NRI) and integrated discrimination improvement (IDI).

RESULTS

A total of 858 patients were included in the present analysis (mean age = 68.4 ± 11.9 years, 67.6% male). PhA positively correlated with body mass index (ρ = 0.38, P < 0.001), skeletal muscle mass index (ρ = 0.58, P < 0.001), usual gait speed (ρ = 0.44, P < 0.001), grip strength (ρ = 0.73, P < 0.001) and SPPB (ρ = 0.51, P < 0.001). The mean follow-up period, within which 44 (4.7%) died, was 908.9 ± 499.9 days for the entire cohort. Kaplan-Meier survival curves based on the PhA tertiles showed that higher PhA was associated with better survival (log-rank test, P < 0.001). The Cox regression analysis showed the independent association of PhA with mortality risk (hazard ratio: 0.91 per 0.1° increment; 95% confidence interval [CI]: 0.87-0.95; P < 0.001). The NRI and IDI showed significant improvements in predicting mortality after adding PhA to the clinical model consisting of age, sex and cardiac and renal function (NRI: 0.426, 95% CI: 0.124-0.729, P = 0.006; IDI: 0.037, 95% CI: 0.012-0.062, P = 0.003). The predictive model consisting of the clinical model and PhA was superior to the model consisting of the clinical model and each of the other physical function indicators (P < 0.05).

CONCLUSIONS

PhA correlated with physical function and independently predicted long-term mortality after cardiovascular surgery. The additive prognostic value of PhA compared with the other physical function measures suggests the clinical usefulness of preoperative PhA for risk stratification in planning post-operative treatment and rehabilitation.

Phase Angle as Surrogate Marker of Muscle Weakness in Kidney Transplant Candidates Referred to Prehabilitation

Phase angle (PhA), a marker of nutritional status obtained by bioelectrical impedance analysis (BIA), is associated with the integrity of cell membranes. Damage to muscle fiber membranes can impact muscle strength, which is related to adverse outcomes in adults with advanced chronic kidney disease (CKD). The main objective of this study was to determine the usefulness of the PhA in identifying muscle weakness in candidates for kidney transplants (KTs). Secondly, it aimed to examine the associations of PhA with other parameters of body composition, exercise performance, and muscle structure. Sensitivity, specificity, and area under the receiver operating characteristics curve were used to evaluate the PhA (index test) as a biomarker of muscle weakness. Muscle strength was estimated with maximal voluntary isometric contraction of the quadriceps (MVCI-Q) of the dominant side. Muscle weakness was defined as MVIC-Q < 40% of body weight. A total of 119 patients were evaluated (mean age 63.7 years, 75.6% men). A phase angle cut-off of 5.1° was identified to classify men with a higher likelihood of having low muscle strength in upper limbs (MVIC-Q 40% of their body weight). Male KT candidates with PhA < 5.1° had poorer exercise capacity, lower muscle strength, less muscle mass, and smaller muscle size. A PhA < 5.1° was significantly associated with an eight-fold higher muscle weakness risk (OR = 8.2, 95%CI 2.3-29.2) in a binary regression model adjusted by age, frailty, and hydration status. Remarkably, PhA is an easily obtainable objective parameter in CKD patients, requiring no volitional effort from the individual. The associations of PhA with aerobic capacity, physical activity, muscle mass, and muscle size underscore its clinical relevance and potential utility in the comprehensive evaluation of these patients.

Association between Physical Activity and Phase Angle Obtained via Bioelectrical Impedance Analysis in South Korean Adults Stratified by Sex

This cross-sectional study aimed to examine the association of various aspects of physical activity, including intensity, duration, type, and purpose, with the phase angle (PhA), an objective indicator of health, in Korean adults after stratification by sex. Data from the 2022 Korean National Health and Nutrition Examination Survey, a nationwide, representative, population-based survey, were used. In total, 3996 participants were included in the study. Participants self-reported their weekly intensity, frequency, duration of engagement in physical activity. PhA was categorized into two groups on the basis of sex-specific averages. Multiple logistic regression analysis was used to investigate the relationship between physical activity and PhA, and proportional odds logistic regression analysis was performed to determine the association between physical activity and different subclasses of PhA. A positive association was found between sufficiently active aerobic physical activity and PhA compared with inactive physical activity (sufficiently active, male: odds ratio = 1.952, 95% confidence interval = 1.373-2.776; female: odds ratio = 1.333, 95% confidence interval = 1.019-1.745). This association was further strengthened when aerobic physical activity was accompanied by muscle-strengthening activity (sufficiently active with muscle-strengthening activity, male: aOR = 2.318, 95% CI = 1.512-3.554; female: aOR = 1.762, 95% CI = 1.215-2.556) and vigorous-intensity activities (sufficiently active with sufficient vigorous-intensity activity, male: aOR = 2.785, 95% CI = 1.647-4.709; female: aOR = 2.505, 95% CI = 1.441-4.356) and when there was more leisure-time physical activity than occupational physical activity (sufficiently active with more leisure-time physical activity, male: aOR = 2.158, 95% CI = 1.483-3.140; female: aOR = 1.457, 95% CI = 1.078-1.969). Furthermore, the inclusion of muscle-strengthening activity made a significant difference in the values of PhA for males with insufficiently active physical activity (aOR = 2.679, 95% CI = 1.560-4.602). For females with highly active physical activity (aOR = 1.521, 95% CI = 1.068-2.166), the inclusion of muscle-strengthening and vigorous-intensity activities were significantly associated with higher values for PhA. This study can be utilized to provide specific suggestions for better health programs and can change perception that only occupational physical activity is enough. This study also indicated that PhA can be used for personalized health assessments.

Association between Physical Activity Level, Body Composition, and Phase Angle in University Students from Bioelectrical Impedance Analysis (BIA)

Background: The aim of this study is to determine the relationship between selected components of body composition and the phase angle specified by bioelectrical impedance analysis, depending on the level of physical activity among students. Materials and Methods: The study group consisted of 484 university students from Krosno. The diagnostic survey method (IPAQ-SF), measurements of highs, and analysis of body composition components (BIA) were used. The relationship between variables was determined using the χ2 test, the V-Kramer coefficient, and Spearman's rho coefficient. Results: University students in physical education demonstrated the highest level of physical activity and the lowest incidence of excessive body mass. Among the participants, 28.1% did not engage in any physical activity, or their level was insufficient. The PhA level was correlated with lean body mass and muscle mass. The correlation between higher levels of PA and PhA values was statistically significant, as was the relationship between self-assessment of physical fitness and the level of PA determined by IPAQ-SF. Conclusions: Preventive actions and educational programs, especially about spending leisure time in active ways, should be particularly targeted at students of disciplines with a significant amount of sedentary classes.

Phase angle as an indicator of physical activity in patients with stable chronic obstructive pulmonary disease

OBJECTIVES

Phase angle (PhA) reflects cell membrane integrity and vitality and is an indicator of sarcopenia. PhA is associated with physical function in patients with stable chronic obstructive pulmonary disease (COPD). To our knowledge, the association between PhA and physical activity (PA) has not been investigated. Therefore, the aim of this study was to investigate whether PhA reflects PA in patients with COPD.

METHODS

This single-center, cross-sectional, observational study included 103 patients with stable COPD (87 men; mean age, 74.7 ± 8.1 y; mean forced expiratory volume in 1s %predicted value, 58.9 ± 20.4%). PhA was measured by bioelectrical impedance analysis. Patients were stratified into low (n = 54) and high (n = 49) PhA groups based on median values (4.3° ± 0.6° and 5.4° ± 0.5°, respectively). PA was calculated as the average daily duration of high-intensity light PA (HLPA; 2.0-2.9 metabolic equivalents [METs] of PA) and moderate- to vigorous-intensity PA (MVPA; >3 METs). Correlation and multivariate analyses using multiple regression analysis were performed to confirm the association between PhA and PA.

RESULTS

The high-PhA group demonstrated greater HLPA (104.4 [16.5-332.5] versus 131.3 [61.1-328.7] min, P = 0.005) and MVPA (19.5 [4.7-96.0] versus 46.6 [8.9-139.3] min, P < 0.001) than the low-PhA group. PhA was positively correlated with HLPA (r = 0.32, P < 0.001) and MVPA (r = 0.49, P < 0.001). MVPA (β = 0.178, P = 0.029) and HLPA (β = 0.158, P = 0.026) were associated with PhA independent of age, sex, body mass index, respiratory function, muscle strength, skeletal muscle mass index, and 6-min walking distance.

CONCLUSION

In patients with COPD, PhA may reflect PA as well as muscle function.

Association of resting energy expenditure with phase angle in hospitalized older patients: a cross-sectional analysis

BACKGROUND/OBJECTIVES

Resting energy expenditure (REE) constitutes the largest component of total energy expenditure and undergoes an age-related decline that is unexplained by decreased fat-free mass. Phase angle (PhA) is a cellular health indicator that is possibly associated with REE. We investigated the association of REE and PhA in hospitalized older adults.

SUBJECTS/METHODS

This single-center, cross-sectional analysis utilized the baseline data from a prospective longitudinal study and included 131 eligible patients aged ≥70 years. The REE was measured using indirect calorimetry, and PhA and body composition were assessed using bioelectrical impedance. The association between REE, PhA, and body composition was examined, and REE was compared using previously reported PhA cutoff values.

RESULTS

In this cohort with a mean (±standard deviation) age of 87.4 (±7.0) years, 34.4% of the participants were men. REE and PhA correlated strongly (r: 0.562, p < 0.001) and significantly after adjusting for age and sex (r: 0.433, p < 0.001). Multivariate analysis showed a significant independent association between REE and PhA and skeletal muscle mass (standardized β [95% CI]; 28.072 [2.188-53.956], p = 0.035) without any significant interaction between PhA and age on REE. The low PhA group had a significantly lower REE (kcal/day; 890 [856-925] vs. 1077 [1033-1122], p < 0.001), and this remained significant after adjusting for age, sex, and skeletal muscle mass index.

CONCLUSIONS

PhA is associated with REE in older adults. Adjusting REE calculation algorithms based on PhA values and correcting predicted REE according to PhA may aid in determining more accurate energy requirements.

Feasibility of Mobile Health App-Based Home Aerobic Exercise for Physical Performance in Healthy Young Adults

OBJECTIVE

To investigate the feasibility and effects of a mobile app-based home cycling exercise program compared to home cycling exercise without additional monitoring system. Compared with fitness facilities or outdoor exercise, home-based exercise programs effectively improve physical performance in an indwelling community. However, a flexible, informal environment may decrease motivation and impair adherence to physical exercise. Mobile devices for aerobic exercise and mobile applications provide real-time monitoring, immediate feedback, and encouragement to increase motivation and promote physical performance. We investigated the feasibility and effects of a mobile app-based home exercise program on body composition, muscular strength, and cardiopulmonary function.

METHODS

Between February and May 2023, 20 participants were randomly allocated to the intervention (mobile application with a tablet) and control groups, and they performed aerobic exercise using a stationary bicycle for ≥150 minutes per week for 6 weeks (≤30-minute exercise session, with 3-minute warm-up and 3-minute cool-down). Karvonen formula-based heartrate defined the weekly increase in exercise intensity. Outcome measures included body-composition parameters, isokinetic knee flexor and extensor strength tests, cardiopulmonary exercise test results, and rate of target heart rate (HR) achievement. Participants were assessed at baseline and after the intervention.

RESULTS

Unrelated personal events led two participants to drop out. The intervention and control groups had similar baseline characteristics. Compared with the control group, in the post-intervention isokinetic strength test, bilateral knee flexor and extensor power, and time to target HR achievement significantly increased each week in the intervention group.

CONCLUSION

Home-based exercise to achieve long-term cardiovascular fitness with portable electronic/mobile devices facilitates individualized exercise using real-time feedback to improve motivation and adherence.

Association between fat-free mass and survival in critically ill patients with COVID-19: A prospective cohort study

BACKGROUND

Most critically ill patients with COVID-19 experience malnutrition and weight loss associated with negative clinical outcomes. Our primary aim was to assess body composition during acute and late phase of illness in these patients in relation to clinical outcome and secondary to tailored nutrition support.

METHODS

This prospective cohort study included adult critically ill patients with COVID-19. Body composition (fat-free mass [FFM] [exposure of interest], fat mass [FM], skeletal muscle mass [SMM], and phase angle [PA]) was determined with multifrequency bioelectrical impedance analyses in the acute and late phase. Nutrition support data were collected simultaneously. Clinical outcome was defined as intensive care unit (ICU) survival (primary outcome) and 30-90 days thereafter, duration of mechanical ventilation, and length of ICU stay and length of hospital stay (LOS). Nonparametric tests and regression analyses were performed.

RESULTS

We included 70 patients (73% male, median age 60 years). Upon admission, median BMI was 30 kg/m2 , 54% had obesity (BMI > 30 kg/m2 ). Median weight change during ICU stay was -3 kg: +3 kg FM and -6 kg FFM (-4 kg SMM). Body composition changed significantly (P < 0.001). Regarding clinical outcome, only low PA was associated with prolonged LOS (odds ratio = 0.83, 95% CI = 0.72-0.96; P = 0.015). Patients with optimal protein intake (>80%) during acute phase maintained significantly more FFM (2.7 kg, P = 0.047) in the late phase compared with patients who received <80%.

CONCLUSION

FFM decreased significantly during acute and late phase of illness, but we observed no association with ICU survival. Only low PA was associated with prolonged LOS. FFM wasting likely occurred because of disease severity and immobility.

Relationship between Phase Angle and Physical Activity Intensity among Community-Dwelling Older Adults in Japan: A Cross-Sectional Study

This cross-sectional study aimed to determine the association between phase angle (PhA) and physical activity intensity in community-dwelling older Japanese adults. The intensity and time of physical activity for predicting high PhA were also examined. This study involved 67 community-dwelling older adults (mean age: 78.3 ± 5.5; female: 83.6%). We measured the physical activity and body composition of the participants. Physical activity was measured using a triaxial accelerometer, and light-intensity physical activity (LPA) and moderate-to-vigorous intensity physical activity (MVPA) hours per day were calculated from the results. Body composition was measured using Inbody S10, and the PhA was calculated from the measurements of the right side of the body. Bayesian statistical modeling revealed an association between PhA and MVPA (β = 0.256; p = 0.022; 95% Bayesian confidence interval [CI] = 0.001, 0.012), but not LPA (β = -0.113; p = 0.341; 95% Bayesian CI = -0.002, 0.001), even after adjustment for confounders. The cutoff value of MVPA predicting high PhA, calculated by the receiver operator characteristic curve, was 19.7 min/d (sensitivity = 0.906; specificity = 0.429). These results can be used to develop strategies to increase PhA in older adults and suggest that MVPA is important in this population.

Association of skeletal muscle function, quantity, and quality with gut microbiota in Japanese adults: A cross-sectional study

AIM

The gut microbiota has emerged as a new intervention target for sarcopenia. Prior studies in humans have focused on the association between gut microbiota and skeletal muscle quantity, while the evidence on muscle function and quality is lacking. This study aimed to identify gut microbiota genera associated with skeletal muscle function, quantity, and quality in a general population of Japanese adults.

METHODS

This cross-sectional study included 164 participants aged 35-80 years, women and men recruited from urban areas of Japan. Fecal samples were collected and analyzed using 16S rRNA gene amplicon sequencing. Skeletal muscle function was measured using handgrip strength and leg extension power (LEP), while skeletal muscle mass was estimated using bioelectrical impedance analysis. Phase angle was used as a measure of skeletal muscle quality. Multivariate linear regression analysis stratified by age group was used to examine the association between the dominant genera of the gut microbiota and skeletal muscle variables.

RESULTS

A significant association was found between Bacteroides and Prevotella 9 with LEP only in the ≥60 years group. When both Bacteroides and Prevotella 9 were included in the same regression model, only Bacteroides remained consistently and significantly associated with LEP. No significant associations were observed between skeletal muscle mass, handgrip strength, and phase angle and major gut microbiota genera.

CONCLUSIONS

In this study, we observed a significant positive association between Bacteroides and leg muscle function in older adults. Further studies are required to elucidate the underlying mechanisms linking Bacteroides to lower-extremity muscle function. Geriatr Gerontol Int 2024; 24: 53-60.

Sedentary Behavior and Phase Angle: An Objective Assessment in Physically Active and Inactive Older Adults

The purpose of the present study was to investigate the associations of the objectively assessed total sedentary behavior (SB) amount and SB patterns with phase angle (PhA) in older populations and to conduct a comparison analysis for those who are physically active (meet 150 min/week) and inactive (less than 150 min/week). During May to August 2023, a convenience sampling was used to recruit older adults (aged ≥ 65 years) living in a community in Taiwan. The total SB amount (minutes/day), SB patterns (including SB bouts and breaks), and physical activity were assessed by a triaxial accelerometer. A multifrequency bioelectrical impedance analyzer (BIA) was used to measure PhA. Multiple linear regression analysis was employed to examine the associations between SB and PhA in the total number of participants and stratified in the physically active and inactive groups. For the whole sample (n = 166; mean age: 72.1 ± 5.5 years), the total SB amount and patterns of SB were not associated with PhA. For those physically active, the total SB amount and SB patterns were not associated with PhA. Among those physically inactive, the total SB amount was negatively related to PhA (B: -0.059, 95% CI: -0.118, 0.000). This study underscores the importance of minimizing the total SB amount in physically inactive older adults, providing evidence for future interventions targeting SB and PhA in this population.

Phase angle is related to physical function and quality of life in preoperative patients with lumbar spinal stenosis

Lumbar spinal stenosis (LSS) can interfere with daily life and quality of life (QOL). Evaluating physical function and QOL and helping patients to improve is the focus of rehabilitation. Phase angle (PhA) assessment is widely used to measure body composition and is considered an indicator of physical function and QOL. This study investigated the relationship between PhA and physical function, physical activity, and QOL in patients with LSS. PhA, handgrip strength, walking speed, Timed Up and Go test (TUG), Life Space Assessment (LSA), Prognostic Nutritional Index (PNI), Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), and EQ-5D were assessed and statistically analyzed. The study included 133 patients with LSS. Multiple regression analysis of PhA adjusted for age, sex, and body mass index (Model 1) and for Model 1 + PNI (Model 2) showed significant correlations (P < 0.05) with handgrip strength, walking speed, TUG, and LSA. Regarding QOL, PhA was significantly correlated (P < 0.05) with lumbar function in JOABPEQ. PhA was associated with physical function and QOL in patients with LSS and might be a new clinical indicator in this population.

Association of 24-h movement behaviors with phase angle in community-dwelling older adults: a compositional data analysis

BACKGROUND

Phase angle (PhA) is an indicator of cellular conditions. Recent studies have suggested that PhA supports healthy aging. Identifying modifiable lifestyle factors for PhA is important. The associations of PhA in 24-h movement behaviors, including physical activity (PA), sedentary behavior (SB), and sleep, have not been studied in older adults.

OBJECTIVES

We investigated the cross-sectional associations between 24-h movement behaviors and PhA in community-dwelling older adults while appropriately considering the co-dependent nature of daily time use using compositional data analysis.

METHODS

The participants were 113 healthy older adults. PhA was measured using a bioelectrical impedance device. Time spent in light-intensity PA (LPA), moderate- to vigorous-intensity PA (MVPA), and SB was measured using a tri-axial accelerometer. Sleep duration information was self-reported in a questionnaire. Compositional multiple linear regression and compositional isotemporal substitution were performed to examine the associations of 24-h movement behaviors with PhA and hypothetical time reallocation in movement behaviors with PhA, respectively.

RESULTS

Even after adjusting for potential confounders, relative to other behaviors more time spent in MVPA was significantly associated with higher PhA (p < 0.001). The 30 min/day of time reallocation from the other behaviors (SB, LPA, and sleep) to MVPA was predicted to be 0.12 higher PhA (corresponding to 2.3% increase; 95% CI 0.01, 0.24).

CONCLUSIONS

Our results suggest that increasing or maintaining the daily time spent in MVPA is important for managing PhA in older adults, regardless of the other behaviors time consumed instead.

Molecular, Metabolic, and Nutritional Changes after Metabolic Surgery in Obese Diabetic Patients (MoMen): A Protocol for a Multicenter Prospective Cohort Study

Metabolic surgery is an essential option in the treatment of obese patients with type 2 diabetes (T2D). Despite its known advantages, this surgery still needs to be introduced in Malaysia. In this prospective study, the pathophysiological mechanisms at the molecular level will be studied and the metabolomics pathways of diabetes remission will be explored. The present study aims to evaluate the changes in the anthropometric measurements, body composition, phase angle, diet intake, biochemistry parameters, adipokines, microRNA, and metabolomics, both pre- and post-surgery, among obese diabetic patients in Malaysia. This is a multicenter prospective cohort study that will involve obese patients (n = 102) with a body mass index (BMI) of ≥25 kg/m2 (Asian BMI categories: WHO/IASO/IOTF, 2000) who will undergo metabolic surgery. They will be categorized into three groups: non-diabetes, prediabetes, and diabetes. Their body composition will be measured using a bioimpedance analyzer (BIA). The phase angle (PhA) data will be analyzed. Venous blood will be collected from each patient for glycated hemoglobin (HbA1c), lipids, liver, renal profile, hormones, adipokines, and molecular and metabolomics analyses. The serum microRNA will be measured. A gene expression study of the adipose tissue of different groups will be conducted to compare the groups. The relationship between the 1HNMR-metabolic fingerprint and the patients’ lifestyles and dietary practices will be determined. The factors responsible for the excellent remission of T2D will be explored in this study.

Phase angle, muscle tissue, and resistance training

The biophysical response of the human body to electric current is widely appreciated as a barometer of fluid distribution and cell function. From distinct raw bioelectrical impedance (BIA) variables assessed in the field of body composition, phase angle (PhA) has been repeatedly indicated as a functional marker of the cell's health and mass. Although resistance training (RT) programs have demonstrated to be effective to improve PhA, with varying degrees of change depending on other raw BIA variables, there is still limited research explaining the biological mechanisms behind these changes. Here, we aim to provide the rationale for the responsiveness of PhA determinants to RT, as well as to summarize all available evidence addressing the effect of varied RT programs on PhA of different age groups. Available data led us to conclude that RT modulates the cell volume by increasing the levels of intracellular glycogen and water, thus triggering structural and functional changes in different cell organelles. These alterations lead, respectively, to shifts in the resistive path of the electric current (resistance, R) and capacitive properties of the human body (reactance, Xc), which ultimately impact PhA, considering that it is the angular transformation of the ratio between Xc and R. Evidence drawn from experimental research suggests that RT is highly effective for enhancing PhA, especially when adopting high-intensity, volume, and duration RT programs combining other types of exercise. Still, additional research exploring the effects of RT on whole-body and regional BIA variables of alternative population groups is recommended for further knowledge development.

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

OBJECTIVES

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

DESIGN

Cluster randomised control trial.

SETTING AND INTERVENTION

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

MEASUREMENTS

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

RESULTS

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

CONCLUSION

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