Validation of rapid 4-component body composition assessment with the use of dual-energy X-ray absorptiometry and bioelectrical impedance analysis

Rapid Four-Compartment Models in Athletes Using Alternative Solutions for Body Volume and Water

The criterion four-compartment (4C) model combines dual-energy x-ray absorptiometry (DXA), deuterium dilution, and air displacement plethysmography (ADP), but its complexity limits practicality. This study aimed to externally validate a DXA-derived body volume (BV) equation (DXA-BVSilva) and assess the accuracy of a rapid 4C model replacing deuterium dilution total body water (TBW) with bioelectrical impedance spectroscopy (BIS) alongside DXA-derived BV in athletes. A total of 143 athletes (27.3% females) validated DXA-BV, with 115 (33.9% females) assessed for FM. Criterion 4C used DXA for bone mineral content, ADP for BV, and deuterium dilution for TBW. Several rapid 4C models were tested. DXA-BVSilva and DXA-BVHeymsfield reliably estimated BV, showing minimal mean differences and narrow 95% limits of agreement (LOA) compared to ADP. Among rapid 4C models, 4CTBWBIS, 4C BVSilvaTBWBIS, and 4C BVHeymsfieldTBWBIS provided the most accurate FM estimates with small, nonsignificant differences to the criterion (MD [SD]: -0.18 [1.25] kg; -0.23 [1.82] kg; 0.18 [1.87] kg, respectively) and narrow 95% LOA (-2.62 to 2.27, -3.79 to 3.33 and - 3.48 to 3.83 kg, respectively) with no proportional bias. This research supports the implementation of rapid 4C models in settings where the criterion 4C model is impractical. By improving accuracy in body composition assessment, our findings have implications for sports nutrition, sports science, and academic research, offering a viable alternative to traditional 2C and 3C models (DXA).

Association of body composition measures to muscle strength using DXA, D3Cr, and BIA in collegiate athletes

Muscle mass and strength are crucial for physiological function and performance in athletes, playing a significant role in maintaining health and optimal athletic performance. Skeletal muscle, which constitutes the majority of lean soft tissue (LST) and appendicular lean soft tissue (ALST) when measured by dual-energy X-ray absorptiometry (DXA), represents a commonly used surrogate for strength. Research has investigated alternative measures of body composition, such as the assessment of ALST through bioelectrical impedance analysis (BIA) and the determination of whole-body muscle mass from creatine pool size using the deuterated creatine (D3Cr) dilution method, for their associations to strength. While the relationship between body composition measures and strength has been studied in older adults, this relationship remains unexplored in athletic populations. This study examined muscle body composition measures using DXA, D3Cr, and BIA and their association with strength in a sample of collegiate athletes. The study enrolled 80 collegiate athletes (40 females) of differing sports disciplines who consumed a 60 mg dose of D3Cr and completed DXA and BIA measures in addition to trunk and leg strength tests. Analysis was sex-stratified using Pearson's correlations, linear regression, and quartile p trend significance. With an average participant age of 21.8 years, whole-body DXA correlations to muscle strength surpassed height- or mass-normalized values. This trend was especially pronounced in trunk strength's relationship with body composition over leg strength, across measurement methods. While DXA LST values were higher than BIA and D3Cr in predicting strength, the values did not differ significantly. Adjustments for age, BMI, and BIA variables didn't enhance this association. A significant trend between DXA LST and all strength measures underscored the equal relevance of DXA and D3Cr muscle mass to strength, favoring whole-body over regional assessments. This calls for future research on muscle mass's effects on LST and functional outcomes in broader groups, highlighting the importance of comprehensive body composition analysis in athletic performance studies.

The SARC-F score may indirectly reflect the extracellular water-to-total body water ratio

BACKGROUND & AIMS

In the Asian Working Group for Sarcopenia 2019 guidelines, SARC-F is used to screen for sarcopenia. SARC-F is measured based on five components: strength, assistance with walking, rising from a chair, climbing stairs, and falling. However, it has been reported that SARC-F has high specificity but low sensitivity for sarcopenia screening. Considering that SARC-F is currently recommended for sarcopenia screening, indicating the utility of SARC-F not only in sarcopenia screening but also in other aspects is pivotal. This cross-sectional study aimed to clarify the relationship between the SARC-F score and the extracellular water-to-total body water ratio (ECW/TBW) in community-dwelling older people.

METHODS

This study included 167 community-dwelling older people (aged ≥65) who were able to walk independently and used the SARC-F as a screening test for sarcopenia diagnosis. ECW/TBW and the skeletal muscle mass index (SMI) were measured using bioelectrical impedance analysis. The associations among the SARC-F score, ECW/TBW, and SMI were assessed using Spearman's correlation coefficient. Multiple linear regression analyses of the SARC-F score were conducted. Age, sex, number of medications, pain, medical history, ECW/TBW, and SMI were considered independent variables in multiple linear regression analysis.

RESULTS

The analyses revealed a significant positive correlation between the SARC-F score and ECW/TBW (ρ = 0.473, p < 0.001). SMI was significantly and negatively correlated with the SARC-F score (ρ = -0.233, p = 0.002). In the multiple linear regression analysis, ECW/TBW (β = 0.311, p < 0.001) and prevalence of pain (β = 0.169, p = 0.023) were significantly and independently associated with the SARC-F score (R2 = 0.260). SMI was not significantly associated with the SARC-F score (β = 0.002, p = 0.986).

CONCLUSION

This study revealed a positive correlation between SARC-F score and ECW/TBW in community-dwelling older people, and this relationship persisted even after adjusting for confounding factors. However, there was no correlation between the SARC-F score and SMI. Our study indicated that the SARC-F score may be considered an indirect indicator of ECW/TBW. The score might also be useful for discriminating high and low ECW/TBW. These findings highlight a new use for SARC-F.

Relative validity of bioelectrical impedance analysis in estimating body composition in women with overweight and obesity 2 weeks and 6 months postpartum

Objective

To investigate the relative validity of bioelectrical impedance analysis (BIA) in estimating fat mass (FM) and fat free mass (FFM) with dual-energy X-ray absorptiometry (DXA) as reference method in women with overweight and obesity 2 weeks and 6 months postpartum (pp).

Methods

Body composition of 94 women with overweight and obesity was assessed using Seca mBCA 515 and GE Healthcare Lunar iDXA. Agreement between the two methods for FM and FFM at 2 weeks and 6 months pp, as well as the changes in FM and FFM between the two timepoints, were tested using paired t-test, Bland-Altman plots and regression analyses.

Results

The mean (standard deviation [SD]) body mass index (BMI) at 2 weeks pp was 30.6 (2.6) kg/m2 and mean (SD) weight loss at 6 months pp was 4.7 (4.8) kg. BIA underestimated FM at both 2 weeks pp and 6 months pp by mean (SD) 0.7 (1.4) kg and 0.3 (1.3) kg and overestimated FFM at both timepoints by 1.2 (1.5) kg and 0.7 (1.4) kg, with proportional bias for FFM. BIA underestimated changes in FM by mean (SD) 0.5 (1.1) kg and overestimated changes in FFM by 0.5 (1.0) kg, with proportional bias for change in extracellular water by total body water. Agreement was generally high for both cross-sectional and longitudinal comparisons.

Conclusions

At group level, BIA was a valid tool for assessment of FM and FFM in women with overweight and obesity at 2 weeks and 6 months pp when compared to DXA. We also consider it valid for following changes in FM and FFM over time when fluid distribution is stable.

Comparison of hemodialysis urea clearance using spent dialysate and Kt/Vurea equations

INTRODUCTION

Dialysis adequacy is traditionally calculated from pre- and post-hemodialysis session serum urea concentrations and expressed as the urea reduction ratio, or Kt/Vurea. However, with increasing hemodiafiltration usage, we wished to determine whether there were any differences between standard Kt/Vurea equations and directly measured spent dialysate urea clearance.

METHODS

Urea clearance was measured from collected effluent dialysate and compared with various other methods of Kt/Vurea calculation, including change in total body urea from measuring pre- and post-total body water with bioimpedance and the Watson equation, by standard Kt/V equations, and online clearance measurements using effective ionic dialysance (OLC).

RESULTS

We compared urea clearance in 41 patients, 56.1% male, mean age 69.3 ± 12.6 years with 87.8% treated by hemodiafiltration. Reduction in total body urea was greater when estimating changes in total body urea, compared to measured dialysate losses of 58.4% (48.5-67.6) vs 71.6% (62.1-78), p < 0.01. Sessional urea clearance (Kt/Vurea) was greater using the online Solute-Solver program compared to OLC, median 1.45(1.13-1.75) vs 1.2 (0.93-1.4), and 2nd generation Kt/V equations 1.3 (1.02-1.66), p < 0.01, but not different from estimated total body urea clearance 1.36 (1.15-1.73) and dialysate clearance 1.36 (1.07-1.76). The mean bias compared to the Solute-Solver program was greatest with OLC (-0.25), compared to second-generation equations (-0.02), estimated total body clearance (-0.02) and measured dialysate clearance (-0.01).

CONCLUSION

This study demonstrated that the result from equations estimating urea clearance indirectly from pre- and postblood samples from hemo- and hemodiafiltration treatments was highly correlated with direct measurements of dialysate urea clearance.

Whole-Body and Segmental Phase Angles and Cognitive Function in the Older Korean Population: Cross-Sectional Analysis

Background

Recently, the phase angle (PhA) has emerged as an essential indicator of cellular health. Most studies have examined its association with physiological conditions, such as sarcopenia, frailty, and physical function, in older populations. Simultaneously, growing attention is being paid to the clinical relevance of segmental PhAs for future applications. However, few studies have explored the relationship between PhAs, especially segmental PhAs, and the psychological aspects of health, particularly cognitive function.

Objective

We aimed to investigate the association between whole-body and segmental PhAs and cognitive function in older adults.

Methods

Individuals aged 65 years and above were recruited from adult community groups residing in Busan, South Korea, through the 2022 Bus-based Screening and Assessment Network (BUSAN) study of Pusan National University Hospital. Participants' whole-body and segmental PhAs were measured using a bioelectrical impedance analyzer (BWA 2.0 Body Water Analyzer, InBody), and cognitive functions (overall and subdomains, including memory, orientation, attention and calculation, and language) were self-reported using the Korean version of the Mini-Mental State Examination. Multiple linear regression analyses were performed to examine these associations.

Results

This study included 625 older adults aged 65-96 years (women: n=444, 71%; men: n=191, 29%). A positive association was observed between whole-body PhA and cognitive function (b=0.62, 95% CI 0.16-1.08; P<.01). We observed significant positive associations between the PhA of the lower limbs (b=0.72, 95% CI 0.38-1.06; P<.001) and cognitive function. Analysis of the Mini-Mental State Examination subdomains revealed that whole-body PhA was significantly related to memory (b=0.11, 95% CI 0.00-0.22; P=.04); the PhA of the upper limbs was significantly related to orientation (b=0.29, 95% CI 0.09-0.49; P=.01); and the PhA of the lower limbs was significantly related to orientation (b=0.24, 95% CI 0.10-0.38; P<.001), attention and calculation (b=0.21, 95% CI 0.06-0.37; P=.01), memory (b=0.14, 95% CI 0.05-0.22; P=.001), and language functions (b=0.07, 95% CI 0.01-0.12; P=.01). However, trunk PhA showed no significant association.

Conclusions

Our findings bolster the emerging evidence of a significant positive correlation between whole-body PhA and cognitive function in our sample, with nuanced relationships observed across different segmental PhAs and cognitive subdomains. Therefore, this study revealed that PhAs could be a useful tool for screening or preventing cognitive decline in the general older population, offering substantial evidence for future interventional studies. Further research should delve into the mechanisms and assess targeted interventions that enhance regional physical function to support cognitive health in older adults. Further long-term investigation on these associations is warranted.

Trunk-to-leg volume and appendicular lean mass from a commercial 3-dimensional optical body scanner for disease risk identification

BACKGROUND & AIMS

Body shape expressed as the trunk-to-leg volume ratio is associated with diabetes and mortality due to the associations between higher adiposity and lower lean mass with Metabolic Syndrome (MetS) risk. Reduced appendicular muscle mass is associated with malnutrition risk and age-related frailty, and is a risk factor for poor treatment outcomes related to MetS and other clinical conditions (e.g.; cancer). These measures are traditionally assessed by dual-energy X-ray absorptiometry (DXA), which can be difficult to access in clinical settings. The Shape Up! Adults trial (SUA) demonstrated the accuracy and precision of 3-dimensional optical imaging (3DO) for body composition as compared to DXA and other criterion measures. Here we assessed whether trunk-to-leg volume estimates derived from 3DO are associated with MetS risk in a similar way as when measured by DXA. We further explored if estimations of appendicular lean mass (ALM) could be made using 3DO to further improve the accessibility of measuring this important frailty and disease risk factor.

METHODS

SUA recruited participants across sex, age (18-40, 40-60, >60 years), BMI (under, normal, overweight, obese), and race/ethnicity (non-Hispanic [NH] Black, NH White, Hispanic, Asian, Native Hawaiian/Pacific Islander) categories. Each participant had whole-body DXA and 3DO scans, and measures of cardiovascular health. The 3DO measures of trunk and leg volumes were calibrated to DXA to express equivalent trunk-to-leg volume ratios. We expressed each blood measure and overall MetS risk in quartile gradations of trunk-to-leg volume previously defined by National Health and Nutrition Examination Survey (NHANES). Finally, we utilized 3DO measures to estimate DXA ALM using ten-fold cross-validation of the entire dataset.

RESULTS

Participants were 502 (273 female) adults, mean age = 46.0 ± 16.5y, BMI = 27.6 ± 7.1 kg/m2 and a mean DXA trunk-to-leg volume ratio of 1.47 ± 0.22 (females: 1.43 ± 0.23; males: 1.52 ± 0.20). After adjustments for age and sex, each standard deviation increase in trunk-to-leg volume by 3DO was associated with a 3.3 (95% odds ratio [OR] = 2.4-4.2) times greater risk of MetS, with individuals in the highest quartile of trunk-to-leg at 27.4 (95% CI: 9.0-53.1) times greater risk of MetS compared to the lowest quartile. Risks of elevated blood biomarkers as related to high 3DO trunk-to-leg volume ratios were similar to previously published comparisons using DXA trunk-to-leg volume ratios. Estimated ALM by 3DO was correlated to DXA (r2 = 0.96, root mean square error = 1.5 kg) using ten-fold cross-validation.

CONCLUSION

Using thresholds of trunk-to-leg associated with MetS developed on a sample of US-representative adults, trunk-to-leg ratio by 3DO after adjustments for offsets showed significant associations to blood parameters and MetS risk. 3DO scans provide a precise and accurate estimation of ALM across the range of body sizes included in the study sample. The development of these additional measures improves the clinical utility of 3DO for the assessment of MetS risk as well as the identification of low muscle mass associated with poor cardiometabolic and functional health.

Advancing body composition assessment in patients with cancer: First comparisons of traditional versus multicompartment models

BACKGROUND AND AIMS

Measurement of body composition using computed tomography (CT) scans may be a viable clinical tool for low muscle mass assessment in oncology. However, longitudinal assessments are often infeasible with CT. Clinically accessible body composition technologies can be used to track changes in fat-free mass (FFM) or muscle, though their accuracy may be impacted by cancer-related physiological changes. The purpose of this study was to examine the agreement among accessible body composition method with criterion methods for measures of whole-body FFM measurements and, when possible, muscle mass for the classification of low muscle in patients with cancer.

METHODS

Patients with colorectal cancer were recruited to complete measures of whole-body DXA, air displacement plethysmography (ADP), and bioelectrical impedance analysis (BIA). These measures were used alone, or in combination to construct the criterion multicompartment (4C) mode for estimating FFM. Patients also underwent abdominal CT scans as part of routine clinical assessment. Agreement of each method with 4C model was analyzed using mean constant error (CE = criterion - alternative), linear regression including root mean square error (RMSE), Bland-Altman limits of agreement (LoA) and mean percentage difference (MPD). Additionally, appendicular lean soft tissue index (ALSTI) measured by DXA and predicted by CT were compared for the absolute agreement, while the ALSTI values and skeletal muscle index by CT were assessed for agreement on the classification of low muscle mass.

RESULTS

Forty-five patients received all measures for the 4C model and 25 had measures within proximity of clinical CT measures. Compared to 4C, DXA outperformed ADP and BIA by showing the strongest overall agreement (CE = 1.96 kg, RMSE = 2.45 kg, MPD = 98.15 ± 2.38%), supporting its use for body composition assessment in patients with cancer. However, CT cutoffs for skeletal muscle index or CT-estimated ALSTI were lower than DXA ALSTI (average 1.0 ± 1.2 kg/m2) with 24.0% to 32.0% of patients having a different low muscle classification by CT when compared to DXA.

CONCLUSIONS

Despite discrepancies between clinical body composition assessment and the criterion multicompartment model, DXA demonstrates the strongest agreement with 4C. Disagreement between DXA and CT for low muscle mass classification prompts further evaluation of the measures and cutoffs used with each technique. Multicompartment models may enhance our understanding of body composition variations at the individual patient level and improve the applicability of clinically accessible technologies for classification and monitoring change over time.

Body Size Measurements Grouped Independently of Common Clinical Measures of Metabolic Health: An Exploratory Factor Analysis

BACKGROUND

Obesity is commonly aggregated with indices of metabolic health. Proponents of body positivity approaches question whether body size is a determinant of health and well-being. Our objective was to conduct an exploratory factor analysis (EFA) to determine if body size measurements factor load with or independent of metabolic health measures.

METHODS

The EFA was conducted on n= 249 adults using baseline data from four weight loss trials (Sample 1: n = 40; Sample 2: n = 52; Sample 3: n = 53; Sample 4: n = 104). An EFA of nine items (systolic blood pressure [SBP], diastolic blood pressure [DBP], hemoglobin A1c [HbA1c], HDL-cholesterol [HDL], LDL-cholesterol [LDL], total cholesterol [TC], body mass index [BMI], body fat percent BF%], and waist circumference [WC]) was conducted with oblique rotation.

RESULTS

Three factors were retained, which produced a model explaining 87.5% of the variance. Six items loaded strongly (>0.8) under three components and were selected for retention (Factor 1: LDL and TC; Factor 2: BMI and WC; Factor 3: SBP and DBP).

CONCLUSION

Body size measures loaded separately from measures of metabolic health and metabolic health were further split into lipid- and blood pressure-focused factors. These results support weight-neutral interventions to improve overall health and well-being.

Differences in patient-reported and clinical characteristics by age group in adults with type 2 diabetes

BACKGROUND

The global burden of type 2 diabetes (T2D) is growing, and the age of onset is widening, resulting in increasing numbers of young adults and elderly patients with T2D. Age-specific diabetes care needs have yet to be fully explored.

AIMS

This study examined (1) differences in patient-reported and clinical characteristics by age group and (2) the effect of age on two proxy measures assessing psychological health and self-care adherence after adjusting for potential mediators.

METHODS

A cross-sectional, correlational design was used. Adults with type 2 diabetes (T2D) were recruited from a university hospital in Korea between 2019 and 2020. Participants were divided into four groups based on years of age (40s and younger group [n = 27]; 50s group [n = 47]; 60s group [n = 54]; and 70s and older group [n = 48]) to compare patient-reported and clinical characteristics. Chi-square tests, ANOVA, Kruskal-Wallis tests, and logistic regression analysis were performed to assess group differences and effect of age on psychological health and self-care adherence.

RESULTS

Of 178 participants, two-thirds were men (n = 114; 64.41%). The mean ages in the 40s and younger, 50s, 60s, and 70s and older groups were 39.4, 54.7, 63.9, and 76.0 years, respectively. There were significant differences in patient-reported and clinical characteristics by age group. The youngest group reported the poorest psychological health and self-care behaviors. Although the oldest group showed the poorest physical functioning, this group also showed the highest self-care adherence and the best psychological health. Regarding clinical characteristics, traditional diabetes-related blood test results showed no significant group differences.

LINKING EVIDENCE TO ACTION

Age-specific diabetes care needs were identified in adults with T2D. Interventions to improve psychological health and priming effects of behavioral adherence need to be developed. Furthermore, meticulous investigation to detect potential complications early is essential in adults with T2D.

Differences in anthropometric and vertical jump force-time characteristics between U16 and U18 female basketball players

Considering the importance of body composition and lower-body strength and power for basketball players' on-court performance, as well as a lack of sports science research focused on female athletes, the purpose of the present investigation was to record the anthropometric and countermovement vertical jump (CMJ) characteristics of top-tier U16 and U18 female basketball players and examine between-group differences in the aforementioned tests. Thirty-two athletes who were a part of the national basketball academy volunteered to participate in the present investigation. Following the body composition assessment conducted via a segmental multifrequency bioimpedance analyzer, athletes performed three CMJs while standing on a force plate system sampling at 1000 Hz. Independent t-test and Mann-Whitney U-test were used to examine between-group differences. The findings reveal significant differences in body composition and lower-body neuromuscular performance characteristics between female basketball players ages 16 and 18. Although no differences were observed in muscle and body fat percentages, the U18 group had significantly greater height, overall body mass (both muscle and fat mass), as well as greater segmental fat-free mass (trunk, both legs and arms), intracellular and extracellular water, and body mass index when compared to their U16 counterparts. On the other hand, the U18 group demonstrated longer eccentric, concentric, and braking phase duration, as well as overall contraction time when compared to the U16 players. In addition, the U18 athletes exhibited higher eccentric mean force and power, concentric impulse, peak power, and mean and peak force.

Advantages and Limitations of the Body Mass Index (BMI) to Assess Adult Obesity

Obesity reflects excessive fat deposits. At-risk individuals are guided by healthcare professionals to eat fewer calories and exercise more, often using body mass index (BMI; weight/height2) thresholds for screening and to guide progress and prognosis. By conducting a mini-narrative review of original articles, websites, editorials, commentaries, and guidelines, we sought to place BMI in the context of its appropriate use in population health, clinical screening, and monitoring in clinical care. The review covers studies and publications through 2023, encompassing consensus reviews and relevant literature. Recent consensus reviews suggest that BMI is a valuable tool for population surveys and primary healthcare screening but has limitations in predicting the risk of chronic diseases and assessing excess fat. BMI can guide nutritional and exercise counseling, even if it is inadequate for reliable individual risk prediction. BMI cut-offs must be reconsidered in populations of varying body build, age, and/or ethnicity. Since BMI-diagnosed overweight persons are sometimes physically and physiologically fit by other indicators, persons who are overweight on BMI should be more fully evaluated, diagnosed, and monitored with combined anthropometric and performance metrics to better clarify risks. The use of combined anthropometric and performance metrics involves integrating measurements of body composition with assessments of physical function and fitness to provide a more comprehensive evaluation of an individual's health and fitness status. Eligibility for bariatric surgery or semaglutide satiety/appetite-reduction medications should not be determined by BMI alone. Awareness of the advantages and limitations of using BMI as a tool to assess adult obesity can maximize its appropriate use in the context of population health and in rapid clinical screening and evaluation.

Influence of aging on extracellular water-to-total body water ratio in community-dwelling females

BACKGROUND & AIMS

The European Working Group of Sarcopenia in Older People 2 has emphasized the significance of evaluating not only muscle mass but also muscle quality as a diagnostic criterion for sarcopenia. The extracellular water-to-total body water ratio (ECW/TBW), measured using bioelectrical impedance analysis (BIA), has recently received attention as an indicator of muscle quality. However, the influence of aging on the ECW/TBW remains unclear. If ECW/TBW increases with age, it is important to know whether the timing of the decrease in SMI and the increase in ECW/TBW are the same or different. This study aimed to investigate the influence of aging on ECW/TBW in community-dwelling females.

METHODS

This cross-sectional study included 237 community-dwelling females aged 20-89 years who could perform activities of daily living independently. ECW/TBW and SMI were measured using BIA. Multiple linear regression analyses of ECW/TBW and SMI were conducted. Age, body mass index (BMI), number of medications, pain, and medical history were considered independent variables in the multiple linear regression. The participants were divided into three (20-39, 40-64, and 65-89 years) or four (20-39, 40-64, 65-74, and 75-89 years) groups based on age. Analysis of covariance adjusted for the BMI, number of medications, pain, and medical history was conducted to determine the differences in ECW/TBW and SMI among the three or four groups.

RESULTS

In the multiple linear regression analysis, age was significantly and independently associated with ECW/TBW and SMI. When the participants were divided into three groups based on age, an increase in ECW/TBW and a decrease in SMI in the 65-89-year group were confirmed compared with the 20-39 and 40-64-year groups. When the participants were divided into four groups based on age, an increase in ECW/TBW in the 75-89-year group was confirmed compared with the 65-74-year group. However, there were no significant differences in SMI among the four groups.

CONCLUSIONS

This study revealed that ECW/TBW increases with aging in community-dwelling females. Moreover, the negative influences of aging were confirmed earlier in ECW/TBW than in SMI. Assessing muscle mass alone may not be adequate to capture the influences of aging on muscle composition, and evaluating ECW/TBW may be crucial for diagnosing sarcopenia.

Fat and fat-free mass measurement agreement by dual-energy X-ray absorptiometry versus bioelectrical impedance analysis: Effects of posture and waist circumference

Background

Bioelectrical impedance analysis (BIA) operates under the assumption that the conductor has a uniform cylindrical shape. However, this assumption may be violated if measures are taken in the seated position, especially in people with a high waist circumference (WC).

Aims

The aims of this research were to determine whether posture (supine, standing, and seated) and WC affect agreement between BIA and dual-energy X-ray absorptiometry (DXA) measures of fat mass (FM) and fat-free mass (FFM).

Materials & Methods

Baseline data were collected from 28 adults (mean = 61.4 ± 6.9 years, 64.3% female) with obesity (BMI 38.6 ± 5.0 kg/m2). Body composition was measured using BIA in the supine, standing, and seated positions and by DXA while supine. Intraclass correlation coefficient (ICC) analyses with two-way mixed effects and absolute agreement were performed to determine agreement.

Results

Point estimates were excellent for FM and FFM while supine, excellent for FM and good for FFM while standing, and moderate for FM and good for FFM while seated. BIA measures in the supine position resulted in the narrowest 95% confidence intervals compared with other positions. Better agreement was observed across all positions in participants with a WC below the median (118.3 cm).

Discussion

Despite the potential pragmatic value of measuring with BIA in a seated position, the results of this analysis demonstrate the poorest agreement between DXA and BIA methods, especially in individuals with high WC.

Conclusion

Findings from this study demonstrate that BIA, particularly when measured in a supine position, can serve as a viable alternative to DXA for measuring body composition in people with obesity.

Development and validation of a rapid multicompartment body composition model using 3-dimensional optical imaging and bioelectrical impedance analysis

BACKGROUND & AIMS

The multicompartment approach to body composition modeling provides a more precise quantification of body compartments in healthy and clinical populations. We sought to develop and validate a simplified and accessible multicompartment body composition model using 3-dimensional optical (3DO) imaging and bioelectrical impedance analysis (BIA).

METHODS

Samples of adults and collegiate-aged student-athletes were recruited for model calibration. For the criterion multicompartment model (Wang-5C), participants received measures of scale weight, body volume (BV) via air displacement, total body water (TBW) via deuterium dilution, and bone mineral content (BMC) via dual energy x-ray absorptiometry. The candidate model (3DO-5C) used stepwise linear regression to derive surrogate measures of BV using 3DO, TBW using BIA, and BMC using demographics. Test-retest precision of the candidate model was assessed via root mean square error (RMSE). The 3DO-5C model was compared to criterion via mean difference, concordance correlation coefficient (CCC), and Bland-Altman analysis. This model was then validated using a separate dataset of 20 adults.

RESULTS

67 (31 female) participants were used to build the 3DO-5C model. Fat-free mass (FFM) estimates from Wang-5C (60.1 ± 13.4 kg) and 3DO-5C (60.3 ± 13.4 kg) showed no significant mean difference (-0.2 ± 2.0 kg; 95 % limits of agreement [LOA] -4.3 to +3.8) and the CCC was 0.99 with a similar effect in fat mass that reflected the difference in FFM measures. In the validation dataset, the 3DO-5C model showed no significant mean difference (0.0 ± 2.5 kg; 95 % LOA -3.6 to +3.7) for FFM with almost perfect equivalence (CCC = 0.99) compared to the criterion Wang-5C. Test-retest precision (RMSE = 0.73 kg FFM) supports the use of this model for more frequent testing in order to monitor body composition change over time.

CONCLUSIONS

Body composition estimates provided by the 3DO-5C model are precise and accurate to criterion methods when correcting for field calibrations. The 3DO-5C approach offers a rapid, cost-effective, and accessible method of body composition assessment that can be used broadly to guide nutrition and exercise recommendations in athletic settings and clinical practice.

Correlations between Mental Health, Physical Activity, and Body Composition in American College Students after the COVID-19 Pandemic Lockdown

Restrictions associated with the COVID-19 pandemic had forced American college students to significantly reduce their daily energy expenditure and increase their sedentary behaviors, thus presumably increasing mental health symptoms, decreasing physical activity levels, and enhancing the promotion of unhealthy eating habits. This study aimed to explore the correlations between mental health symptoms, physical activity levels, and body composition in college students in the years following the pandemic, focusing on the lingering effects of lockdown measures. American college students completed pre-existing, well-validated surveys for both mental health (Hospital Anxiety and Depression Scale) and physical activity (International Physical Activity Questionnaire-Long Form). Body composition was assessed in person with the use of an Inbody 570 device. Of the 90 American college students (M age = 22.52 ± 4.54, 50 females) who participated in this study, depressive and anxious symptom scores consistent with heightened symptomatology were reported by 58% of the participants (N = 52), moderate borderline symptomatology by 17% (N = 15), and asymptomatology by 25% (N = 23). In regard to physical activity, 79% (N = 71) of the students were highly physically active, 18% (N = 16) were moderately active, and 3% (N = 3) reported low levels of physical activity. Additionally, 46% (N = 41) of the students maintained an unhealthy body fat percentage based on the World Health Organization recommendations. Strong, significant relationships were found between anxiety and depression symptomatology and body fat percentage (positive correlation, p = 0.003) and between anxiety and depression symptomatology and skeletal muscle mass (negative correlation, p = 0.015), with said symptomatology increasing with added body fat and decreasing with added skeletal muscle mass. The COVID-19 pandemic lockdown restrictions affected American college students through an increase in mental health symptomatology and a deterioration in overall body composition.

Comparisons of Psycho-Behavioral Factors, Body Composition, and Clinical Outcomes in Adults With Type 2 Diabetes by Perceived Hypoglycemia

PURPOSE

The purpose of the study was to examine the associations between perceived hypoglycemia and psycho-behavioral and clinical factors in persons with type 2 diabetes (T2D).

METHODS

Adults with T2D were recruited from outpatient clinics in a university hospital in Korea. Sociodemographics, psycho-behavioral and clinical factors, and body composition were assessed. The participants were divided into 2 groups reporting perceived hypoglycemia or not in the previous month based on an item of the Control Problem Scale. Group differences were compared at α = .05 using SPSS (version 26.0).

RESULTS

Of 177 participants, approximately one-third (n = 67) perceived hypoglycemia. The hypoglycemia group reported poor health-related quality of life, frequent blood monitoring and foot care, and sleep difficulties. However, no differences between groups were identified for diet, exercise, or glycosylated hemoglobin. The hypoglycemia group had a lower body mass index and a trend toward a lower skeletal muscle mass and fat free mass.

CONCLUSIONS

Perceived hypoglycemia was associated with psycho-behavioral factors and body composition. Importantly, some persons on oral antidiabetic medications that do not cause hypoglycemia still perceived hypoglycemia. Further investigation is warranted to examine the efficacy of strategies to minimize hypoglycemia and inappropriate fear of hypoglycemia. In addition, clinicians should be aware of the potential risk of hypoglycemia in persons with lower muscle mass.

Relationships between longitudinal changes in body composition and bone mineral density in middle-to-older aged Australians

There are limited longitudinal data regarding relationships between changes in body composition and bone mineral density (BMD). In 3671 participants aged 46-70 years at baseline, ∆lean mass was a stronger determinant than ∆fat mass of ∆BMD over 6 years. Maintained or increased lean mass may slow down age-related bone loss.

PURPOSE

There are limited longitudinal data regarding relationships between changes in body composition and bone mineral density (BMD) with ageing. We examined these in the Busselton Healthy Ageing Study.

METHODS

We studied 3671 participants (2019 females) aged 46-70 years at baseline with body composition and BMD assessments by dual-energy x-ray absorptiometry at baseline and after ~6 years. Relationships between changes in total body mass (∆TM), lean mass (∆LM) and fat mass (∆FM) with ∆BMD at total hip, femoral neck and lumbar spine were evaluated using restricted cubic spline modelling (accounting for baseline covariates) and mid-quartile least square means were compared.

RESULTS

∆TM was positively associated with ∆BMD of total hip and femoral neck in both sexes, and spine in females; in females but not males, associations plateaued at ∆TM above ~5kg for all sites. In females, ∆LM was positively associated with ∆BMD of all three sites with plateauing of the relationship at ∆LM above ~1kg. Women in the highest quartile of ∆LM (Q4, mid-quartile value +1.6 kg) had 0.019-0.028 g/cm2 less reduction in BMD than those in the lowest quartile (Q1, -2.1 kg). In males, ∆LM was positively associated with ∆BMD of total hip and femoral neck; men in Q4 (+1.6 kg) had 0.015 and 0.011 g/cm2 less bone loss, respectively, compared with Q1 (-2.7 kg). ∆FM was positively associated with ∆BMD of total hip only in both sexes.

CONCLUSION

∆LM is a stronger determinant than ∆FM of ∆BMD. Maintained or increased LM is associated with less age-related bone loss.

Accuracy and Precision of 3-dimensional Optical Imaging for Body Composition by Age, BMI, and Ethnicity

BACKGROUND

The obesity epidemic brought a need for accessible methods to monitor body composition, as excess adiposity has been associated with cardiovascular disease, metabolic disorders, and some cancers. Recent 3-dimensional optical (3DO) imaging advancements have provided opportunities for assessing body composition. However, the accuracy and precision of an overall 3DO body composition model in specific subgroups are unknown.

OBJECTIVES

This study aimed to evaluate 3DO's accuracy and precision by subgroups of age, body mass index, and ethnicity.

METHODS

A cross-sectional analysis was performed using data from the Shape Up! Adults study. Each participant received duplicate 3DO and dual-energy X-ray absorptiometry (DXA) scans. 3DO meshes were digitally registered and reposed using Meshcapade. Principal component analysis was performed on 3DO meshes. The resulting principal components estimated DXA whole-body and regional body composition using stepwise forward linear regression with 5-fold cross-validation. Duplicate 3DO and DXA scans were used for test-retest precision. Student's t tests were performed between 3DO and DXA by subgroup to determine significant differences.

RESULTS

Six hundred thirty-four participants (females = 346) had completed the study at the time of the analysis. 3DO total fat mass in the entire sample achieved R2 of 0.94 with root mean squared error (RMSE) of 2.91 kg compared to DXA in females and similarly in males. 3DO total fat mass achieved a % coefficient of variation (RMSE) of 1.76% (0.44 kg), whereas DXA was 0.98% (0.24 kg) in females and similarly in males. There were no mean differences for total fat, fat-free, percent fat, or visceral adipose tissue by age group (P > 0.068). However, there were mean differences for underweight, Asian, and Black females as well as Native Hawaiian or other Pacific Islanders (P < 0.038).

CONCLUSIONS

A single 3DO body composition model produced accurate and precise body composition estimates that can be used on diverse populations. However, adjustments to specific subgroups may be warranted to improve the accuracy in those that had significant differences. This trial was registered at clinicaltrials.gov as NCT03637855 (Shape Up! Adults).

Automated body composition estimation from device-agnostic 3D optical scans in pediatric populations

BACKGROUND

Excess adiposity in children is strongly correlated with obesity-related metabolic disease in adulthood, including diabetes, cardiovascular disease, and 13 types of cancer. Despite the many long-term health risks of childhood obesity, body mass index (BMI) Z-score is typically the only adiposity marker used in pediatric studies and clinical applications. The effects of regional adiposity are not captured in a single scalar measurement, and their effects on short- and long-term metabolic health are largely unknown. However, clinicians and researchers rarely deploy gold-standard methods for measuring compartmental fat such as magnetic resonance imaging (MRI) and dual X-ray absorptiometry (DXA) on children and adolescents due to cost or radiation concerns. Three-dimensional optical (3DO) scans are relatively inexpensive to obtain and use non-invasive and radiation-free imaging techniques to capture the external surface geometry of a patient's body. This 3D shape contains cues about the body composition that can be learned from a structured correlation between 3D body shape parameters and reference DXA scans obtained on a sample population.

STUDY AIM

This study seeks to introduce a radiation-free, automated 3D optical imaging solution for monitoring body shape and composition in children aged 5-17.

METHODS

We introduce an automated, linear learning method to predict total and regional body composition of children aged 5-17 from 3DO scans. We collected 145 male and 206 female 3DO scans on children between the ages of 5 and 17 with three scanners from independent manufacturers. We used an automated shape templating method first introduced on an adult population to fit a topologically consistent 60,000 vertex (60 k) mesh to 3DO scans of arbitrary scanning source and mesh topology. We constructed a parameterized body shape space using principal component analysis (PCA) and estimated a regression matrix between the shape parameters and their associated DXA measurements. We automatically fit scans of 30 male and 38 female participants from a held-out test set and predicted 12 body composition measurements.

RESULTS

The coefficient of determination (R2) between 3DO predicted body composition and DXA measurements was at least 0.85 for all measurements with the exception of visceral fat on 3D scan predictions. Precision error was 1-4 times larger than that of DXA. No predicted variable was significantly different from DXA measurement except for male trunk lean mass.

CONCLUSION

Optical imaging can quickly, safely, and inexpensively estimate regional body composition in children aged 5-17. Frequent repeat measurements can be taken to chart changes in body adiposity over time without risk of radiation overexposure.

Evaluation of a Rapid Four-Compartment Model and Stand-Alone Methods in Hispanic Adults

BACKGROUND

A rapid 4-compartment (4C) model integrates dual-energy x-ray absorptiometry (DXA) and multi-frequency bioimpedance analysis (MFBIA), which may be useful for clinical and research settings seeking to employ a multi-compartment model.

OBJECTIVES

This study aimed to determine the added benefit of a rapid 4C model over stand-alone DXA and MFBIA when estimating body composition.

METHODS

One hundred and thirty participants (n = 60 male; n = 70 female) of Hispanic descent were included in the present analysis. A criterion 4C model that employed air displacement plethysmography (body volume), deuterium oxide (total body water), and DXA (bone mineral) was used to measure fat mass (FM), fat-free mass (FFM), and body fat percent (%BF). A rapid 4C model (DXA-derived body volume and bone mineral; MFBIA-derived total body water) and stand-alone DXA (GE Lunar Prodigy) and MFBIA (InBody 570) assessments were compared against the criterion 4C model.

RESULTS

Lin's concordance correlation coefficient values were >0.90 for all comparisons. The standard error of the estimates ranged from 1.3 to 2.0 kg, 1.6 to 2.2 kg, and 2.1 to 2.7% for FM, FFM, and %BF, respectively. The 95% limits of agreement ranged from ±3.0 to 4.2 kg, ±3.1 to 4.2 kg, and ±4.9 to 5.2% for FM, FFM, and %BF, respectively.

CONCLUSIONS

Results revealed that all 3 methods provided acceptable body composition results. The MFBIA device used in the current study may be a more economically friendly option than DXA or when there is a need to minimize radiation exposure. Nonetheless, clinics and laboratories that already have a DXA device in place or that value having the lowest individual error when conducting a test may consider continuing to use the machine. Lastly, a rapid 4C model may be useful for assessing body composition measures observed in the current study and those provided by a multi-compartment model (e.g., protein).

Body water percentage from childhood to old age

BACKGROUND

Total body water (TBW) increases with growth, but the body water percentage (TBW%) decreases with aging. The objective of our study was to delineate TBW% in males and females by bioelectrical impedance analysis (BIA) from early childhood to old age.

METHODS

We enrolled 545 participants aged 3 to 98 years (258 male, 287 female). Among the participants, 256 had a normal weight and 289 were overweight. The TBW was measured by BIA, and TBW% was derived by dividing the TBW (L) value by body weight (kg). For analysis, we divided participants into the four age groups of 3-10, 11-20, 21-60, and ≥61 years.

RESULTS

In normal-weight subjects, the TBW% was similar at 62% between males and females in the 3-10-year group. It remained unchanged in males until and through adult life, then decreased to 57% in the ≥61-year group. In normal-weight female subjects, the TBW% decreased to 55% in the 11-20-year group, remained relatively unaltered in the 21-60-year group, then decreased to 50% in the ≥61-year group. In overweight subjects, the TBW% values in males, as well as females, were significantly lower as compared to those with normal weight.

CONCLUSION

Our study showed that the TBW% in normal-weight males changes very little from early childhood to adult life compared to that of females, who showed a decrease in TBW% during the pubertal years. In normal-weight subjects of both sexes, the TBW% decreased after the age of 60 years. Overweight subjects had significantly lower TBW% as compared to those with normal weight.

Phase Angle as a Prognostic Indicator of Survival in Institutionalized Psychogeriatric Patients

Phase angle (PhA) has been evidenced to be a useful survival indicator and predictor of morbi-mortality in different pathologies, but not in psychogeriatric patients. The aim of this study was to evaluate the clinical utility of PhA as a prognostic indicator of survival in a group of institutionalized psychogeriatric patients. A survival study was conducted on 157 patients (46.5% dementia, 43.9% schizophrenia). Functional impairment stage, frailty, dependence, malnutrition (MNA), comorbidity, polypharmacy, BMI, and waist circumference were registered. Body composition was analyzed using a 50-kHz whole-body BIA; PhA was recorded. The association between mortality and standardized-PhA was evaluated through univariate and multivariate Cox regression models and ROC-curve. The risk of death decreased when Z-PhA, BMI, and MNA were higher. Mortality increases with age, frailty, and dependence. The risk of death was statistically significantly lower (56.5%) in patients with schizophrenia vs. dementia (89%). The Z-PhA cut-off point was -0.81 (Sensitivity:0.75; Specificity:0.60). Mortality risk was multiplied by 1.09 in subjects with a Z-PhA < -0.81, regardless of age, presence of dementia, and BMI. PhA presented a remarkable clinical utility as an independent indicator of survival in psychogeriatric patients. Moreover, it could be useful to detect disease-related malnutrition and to identify subjects eligible for an early clinical approach.

Monitoring body composition change for intervention studies with advancing 3D optical imaging technology in comparison to dual-energy X-ray absorptiometry

BACKGROUND

Recent 3-dimensional optical (3DO) imaging advancements have provided more accessible, affordable, and self-operating opportunities for assessing body composition. 3DO is accurate and precise in clinical measures made by DXA. However, the sensitivity for monitoring body composition change over time with 3DO body shape imaging is unknown.

OBJECTIVES

This study aimed to evaluate the ability of 3DO in monitoring body composition changes across multiple intervention studies.

METHODS

A retrospective analysis was performed using intervention studies on healthy adults that were complimentary to the cross-sectional study, Shape Up! Adults. Each participant received a DXA (Hologic Discovery/A system) and 3DO (Fit3D ProScanner) scan at the baseline and follow-up. 3DO meshes were digitally registered and reposed using Meshcapade to standardize the vertices and pose. Using an established statistical shape model, each 3DO mesh was transformed into principal components, which were used to predict whole-body and regional body composition values using published equations. Body composition changes (follow-up minus the baseline) were compared with those of DXA using a linear regression analysis.

RESULTS

The analysis included 133 participants (45 females) in 6 studies. The mean (SD) length of follow-up was 13 (5) wk (range: 3-23 wk). Agreement between 3DO and DXA (R2) for changes in total FM, total FFM, and appendicular lean mass were 0.86, 0.73, and 0.70, with root mean squared errors (RMSEs) of 1.98 kg, 1.58 kg, and 0.37 kg, in females and 0.75, 0.75, and 0.52 with RMSEs of 2.31 kg, 1.77 kg, and 0.52 kg, in males, respectively. Further adjustment with demographic descriptors improved the 3DO change agreement to changes observed with DXA.

CONCLUSIONS

Compared with DXA, 3DO was highly sensitive in detecting body shape changes over time. The 3DO method was sensitive enough to detect even small changes in body composition during intervention studies. The safety and accessibility of 3DO allows users to self-monitor on a frequent basis throughout interventions. This trial was registered at clinicaltrials.gov as NCT03637855 (Shape Up! Adults; https://clinicaltrials.gov/ct2/show/NCT03637855); NCT03394664 (Macronutrients and Body Fat Accumulation: A Mechanistic Feeding Study; https://clinicaltrials.gov/ct2/show/NCT03394664); NCT03771417 (Resistance Exercise and Low-Intensity Physical Activity Breaks in Sedentary Time to Improve Muscle and Cardiometabolic Health; https://clinicaltrials.gov/ct2/show/NCT03771417); NCT03393195 (Time Restricted Eating on Weight Loss; https://clinicaltrials.gov/ct2/show/NCT03393195), and NCT04120363 (Trial of Testosterone Undecanoate for Optimizing Performance During Military Operations; https://clinicaltrials.gov/ct2/show/NCT04120363).

Dual X-ray absorptiometry-derived total and regional body volume

BACKGROUND & AIMS

Although dual X-ray absorptiometry (DXA) has been used to determine total body volume, using DXA to determine regional (i.e., arm and leg) volumes needs further assessment. Thus, the aim of the present study is to evaluate the validity of total and regional DXA-derived body volume compared to a traditional method for measuring body volume.

METHODS

A total of 30 males and females (Age: 25.9 ± 4.0 yrs; Height: 1.75 ± 0.10 m; Weight: 70.98 ± 14.02 kg) underwent one whole body DXA scan, underwater weighing, and regional measures of volume via water displacement. Manually created DXA region of interest boxes were used to determine regional DXA body composition. Total body volume was calculated by taking the participant's dry weight and dividing it by the average density from underwater weighing. Linear regression models with body volume from underwater weighing for total body volume and water displacement for regional volume as the dependent variable and DXA lean mass, fat mass, and bone mass as independent variables created total and regional DXA-derived body volume. T-tests assessed DXA-derived body volume to the traditional method of body volume assessment. Regression models were cross-validated using the Repeated k-fold Cross Validation method.

RESULTS

DXA-derived total body volume was not significantly (p = 0.999) different from total body volume measured via total body water displacement. In addition, both arm and leg regional DXA-derived volume was not significantly different (p = 0.999) compared to regional volume measured by regional water displacement. Cross-validation of each model produced R² values of 0.992, 0.923, and 0.932 for total body, arm, and leg, respectively.

CONCLUSIONS

The DXA may be used as valid method for estimating total and regional body volume. Thus, these results expand the DXA's capabilities and potentially allow for a convenient regional four-compartment model with DXA-derived regional volume.

The inverse relationship between fatness and bone mineral content is mediated by the adolescent appendicular skeletal muscle mass index: The Cogni-Action Project

Background

Excess adipose tissue negatively influences bone health during childhood, affecting future bone fragility diseases such as osteoporosis. However, little is known about how adolescent appendicular skeletal muscle mass index (ASMI) may mediate the relation between fatness and bone mineral content (BMC).

Methods

The sample comprised 1,296 adolescents (50% girls) aged 10-14. A principal component analysis was performed to obtain a factor made up of four fatness indicators (a) neck circumference, (b) kilograms of fat, (c) visceral fat area, and (d) waist-to-height ratio. BMC, kilograms of fat, visceral fat area, and appendicular skeletal muscle mass were obtained by a multi-frequency bioelectrical impedance analyzer. ASMI was calculated as the appendicular skeletal muscle mass divided by height squared (kg/m2). A mediation analysis was performed adjusting by age, sex, maturation, socioeconomic status, physical activity, and adolescents' body weight. We also explore differences by sex and nutritional status.

Results

The fatness factor explained 71.5% of the proportion variance. Fatness was inversely associated with the ASMI and BMC, while the ASMI was positively related to BMC. Overall, the inverse relationship between fatness and BMC was partially mediated by the adolescents' ASMI (29.7%, indirect effect: B= -0.048, 95%CI -0.077 to -0.022), being higher in girls than in boys (32.9 vs. 29.2%). Besides, the mediation effect was higher in adolescents with normal body weight than with overweight-obese (37.6 vs 23.9%, respectively).

Conclusions

This finding highlighted the relevance of promoting healthy habits to reduce fatness and improve muscle mass in adolescents. Moreover, this highlights the central role of ASMI mediating the inverse association between fatness and BMC in female and male adolescents. Public health strategies should promote bone health in childhood, reducing the incidence of early osteopenia and osteoporosis.

Associations between body composition and physical fitness among Chinese medical students: a cross-sectional study

Background

This study examined associations between body composition and physical fitness scores among medical students in Shenyang, China.

Methods

A total of 2291 medical students aged 18–20 (815 male and 1476 female) in Shenyang of China were recruited to participate in the research in May 2019. With the use of the BCA-1B body composition analyzer and standard method of physical fitness assessment, the body composition and seven measures of physical fitness (body mass index, vital capacity, sit and reach, standing long jump, pull-ups/crunches, 50-m sprint, and 800/1000-m run) of college students were measured, respectively. The associations between body composition and physical fitness scores were assessed using multiple linear regression analysis.

Results

The height, weight, total body water, protein mass, mineral content, body mass index, vital capacity, and body function scores of male students were significantly higher than those of female students. However, fat mass (FM), body shape score, physical quality score, and total physical fitness score of female students were significantly higher than those of male students. The results of the multiple linear regression analysis indicated that in male students, only FM was negatively associated with body shape score, body function score, physical quality score, and total physical fitness score. In female students, FM was associated with lower body shape scores, physical quality scores, and total physical fitness scores. Furthermore, the ratio of overweight to obesity in male students was significantly higher than that in female students.

Conclusions

In Chinese medical colleges, the physical fitness level of female students is better than that of male students, and a higher FM was significantly associated with worse physical fitness of medical students. Moreover, male students with a higher rate of overweight and obesity are an important group that needs weight control.

Next-generation smart watches to estimate whole-body composition using bioimpedance analysis: accuracy and precision in a diverse, multiethnic sample

BACKGROUND

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

OBJECTIVES

This study evaluated smart watches with integrated bioelectrical impedance analysis (BIA) sensors for their ability to measure and monitor changes in body composition.

METHODS

Participants recruited across BMIs received duplicate body composition measures using 2 wearable bioelectrical impedance analysis (W-BIA) model smart watches in sitting and standing positions, and multiple versions of each watch were used to evaluate inter- and intramodel precision. Duplicate laboratory-grade octapolar bioelectrical impedance analysis (8-BIA) and criterion DXA scans were acquired to compare estimates between the watches and laboratory methods. Test-retest precision and least significant changes assessed the ability to monitor changes in body composition.

RESULTS

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

CONCLUSIONS

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

Equations based on anthropometric measurements for adipose tissue, body fat, or body density prediction in children and adolescents: a scoping review

PURPOSE

Assessing the body composition of children and adolescents is important to monitor their health status. Anthropometric measurements are feasible and less-expensive than other techniques for body composition assessment. This study aimed to systematically map anthropometric equations to predict adipose tissue, body fat, or density in children and adolescents, and to analyze methodological aspects of the development of anthropometric equations using skinfolds.

METHODS

A scoping review was carried out following the PRISMA-ScR criteria. The search was carried out in eight databases. The methodological structure protocol of this scoping review was retrospectively registered in the Open Science Framework ( https://osf.io/35uhc/ ).

RESULTS

We included 78 reports and 593 anthropometric equations. The samples consisted of healthy individuals, people with different diseases or disabilities, and athletes from different sports. Dual-energy X-ray absorptiometry (DXA) was the reference method most commonly used in developing equations. Triceps and subscapular skinfolds were the anthropometric measurements most frequently used as predictors in the equations. Age, stage of sexual maturation, and peak height velocity were used as complementary variables in the equations.

CONCLUSION

Our scoping review identified equations proposed for children and adolescents with a great diversity of characteristics. In many of the reports, important methodological aspects were not addressed, a factor that may be associated with equation bias.

LEVEL IV

Evidence obtained from multiple time series analysis such as case studies. (NB: dramatic results in uncontrolled trials might also be regarded as this type of evidence).

Agreement and Precision of Deuterium Dilution for Total Body Water and Multicompartment Body Composition Assessment in Collegiate Athletes

BACKGROUND

Deuterium oxide (D2O) dilution is the criterion method for total body water (TBW) measurement, but results may vary depending on the specimen type, analysis method, and analyzing laboratory. Bioelectrical impedance (BIA) estimates TBW, but results may vary by device make and model.

OBJECTIVES

We investigated the accuracy and precision of TBW estimates and how measurement conditions affected the accuracy of body composition using multicompartment body composition models.

METHODS

Eighty collegiate athletes received duplicate TBW measures acquired from 3 BIA devices (S10, SFB7, and SOZO) and from unique D2O combinations of specimen type (saliva, urine), analysis methodology [Fourier transform infrared spectrophotometry (FTIR), isotope-ratio mass spectrometry (IRMS)], and 3 different laboratories. TBW measures were substituted into 2-compartment (2C) and 5-compartment (5C) body composition models. Criterion measures were compared using Lin's concordance correlation coefficient cutoff of poor (<0.90), moderate (0.90-0.95), substantial (0.95-0.99), and almost perfect (>0.99).

RESULTS

Fifty-one participants (26 female) completed the protocol. Using IRMS saliva as the criterion TBW, all other measures produced a substantial or almost perfect agreement, except for SFB7 (poor) and SOZO (moderate). The 2C body composition measures using D2O and BIA produced poor agreement except for moderate agreement for lab 3 FTIR saliva. The 5C body composition measures using D2O produced a substantial agreement, whereas the BIA device S10 and SOZO had a moderate agreement, while the SFB7 had a poor agreement to the criterion. Test-retest precision varied between techniques from 0.3% to 1.2% for TBW.

CONCLUSIONS

Small differences in TBW measurement led to significant differences in 2C models. The 5C models partially mitigate differences seen in 2C models when different TBW measures are used. Interchanging TBW measures in multicompartment models can be problematic and should be performed with these considerations.

Extracellular water-to-total body water ratio is an essential confounding factor in bioelectrical impedance analysis for sarcopenia diagnosis in women

PURPOSE

The extracellular water-to-total body water ratio (ECW/TBW) is used in bioelectrical impedance analysis (BIA) for measuring muscle mass; however, ECW/TBW may be affected by several factors common in older individuals. Here, we assessed the relationships of ECW/TBW with handgrip strength, gait speed, and skeletal muscle mass index (SMI) in older women.

METHODS

In this cross-sectional study, 73 community-dwelling women aged ≥ 65 years who could independently perform activities of daily living were included. ECW/TBW was measured using direct segmental multifrequency BIA. The participants were divided into ECW/TBW < 0.40 (n = 54) and ECW/TBW ≥ 0.40 (n = 19) groups, with the latter indicating overhydration. SMI was calculated as appendicular skeletal muscle mass/(height)² (kg/m²). The relationships of SMI with handgrip strength and gait speed were assessed using partial correlation coefficients. Age, number of medications, pain, and medical history were treated as control variables.

RESULTS

The average age of participants was 77.6 ± 6.0 years. The SMI was significantly related to handgrip strength (partial correlation coefficient = 0.293, P = 0.016) but not to gait speed (partial correlation coefficient = - 0.183, P = 0.138). Similarly, the SMI of the ECW/TBW < 0.40 group was significantly related to handgrip strength (partial correlation coefficient = 0.372, P = 0.009) but not gait speed (partial correlation coefficient = - 0.267, P = 0.066); however, the SMI of the ECW/TBW ≥ 0.40 group was not related to either variable.

CONCLUSION

ECW/TBW represents a confounding factor, which should be considered when using BIA for sarcopenia diagnosis.

Impact of a school-based health intervention program on body composition among South African primary schoolchildren: results from the KaziAfya cluster-randomized controlled trial

BACKGROUND

The prevalence of overweight and obesity is increasing among African children potentially predisposing them to greater obesity and non-communicable diseases (NCDs) in adulthood. This risk may be higher among growth-impaired children who may have greater fat mass. Therefore, we examined the effects of school-based physical activity (PA) promotion and multi-micronutrient supplementation (MMNS) on body composition among South African children enrolled in a longitudinal school-based randomized controlled trial.

METHODS

Children were cluster-randomized by class to one of four groups: (a) a physical activity group (PA), (b) a multi-micronutrient supplementation group (MMNS), (c) a physical activity + multi-micronutrient supplementation group (PA + MMNS), and (d) control group, and were being followed for 3 years. Linear random effects regression models with random intercepts for school classes tested the associations of each intervention arm with overall fat mass (FM), fat-free mass (FFM), truncal fat mass (TrFM), and truncal fat-free mass (TrFFM) at 9 months (T2) for boys and girls. These differences were then explored among children who differed in height velocity (HV).

RESULTS

A total of 1304 children (614 girls, 667 boys) in twelve clusters were assessed at baseline and after 9 months follow-up (T2). At baseline, approximately 15% of children were classified as overweight or obese while approximately 38% of children were classified as mildly stunted or moderately/severely stunted. Among girls, promotion of PA was associated with reduced FM and TrFM at T2 while MMNS was associated with increased FFM. Children with reduced HV in the PA arm had reduced FM while children in the MMNS arm with lower HV had increased FM compared to children in the control arm. Similarly, children with lower HV in the MM and PA groups had reduced TrFM compared to children in the control arm.

CONCLUSIONS

Our study suggests that the promotion of school-based physical activity programs and micronutrient supplementation can reduce childhood adiposity and so reduce the risk of obesity and chronic diseases later in adulthood.

TRIAL REGISTRATION

ISRCTN, ISRCTN29534081 . Registered on August 9, 2018. The trial was designed, analyzed, and interpreted based on the CONSORT protocol (Additional file 1: CONSORT checklist for randomized trial).

Assessment of clinical measures of total and regional body composition from a commercial 3-dimensional optical body scanner

BACKGROUND

The accurate assessment of total body and regional body circumferences, volumes, and compositions are critical to monitor physical activity and dietary interventions, as well as accurate disease classifications including obesity, metabolic syndrome, sarcopenia, and lymphedema. We assessed body composition and anthropometry estimates provided by a commercial 3-dimensional optical (3DO) imaging system compared to criterion measures.

METHODS

Participants of the Shape Up! Adults study were recruited for similar sized stratifications by sex, age (18-40, 40-60, >60 years), BMI (under, normal, overweight, obese), and across five ethnicities (non-Hispanic [NH] Black, NH White, Hispanic, Asian, Native Hawaiian/Pacific Islander). All participants received manual anthropometry assessments, duplicate whole-body 3DO (Styku S100), and dual-energy X-ray absorptiometry (DXA) scans. 3DO estimates provided by the manufacturer for anthropometry and body composition were compared to the criterion measures using concordance correlation coefficient (CCC) and Bland-Altman analysis. Test-retest precision was assessed by root mean square error (RMSE) and coefficient of variation.

RESULTS

A total of 188 (102 female) participants were included. The overall fat free mass (FFM) as measured by DXA (54.1 ± 15.2 kg) and 3DO (55.3 ± 15.0 kg) showed a small mean difference of 1.2 ± 3.4 kg (95% limits of agreement -7.0 to +5.6) and the CCC was 0.97 (95% CI: 0.96-0.98). The CCC for FM was 0.95 (95% CI: 0.94-0.97) and the mean difference of 1.3 ± 3.4 kg (95% CI: -5.5 to +8.1) reflected the difference in FFM measures. 3DO anthropometry and body composition measurements showed high test-retest precision for whole body volume (1.1 L), fat mass (0.41 kg), percent fat (0.60%), arm and leg volumes, (0.11 and 0.21 L, respectively), and waist and hip circumferences (all <0.60 cm). No group differences were observed when stratified by body mass index, sex, or race/ethnicity.

CONCLUSIONS

The anthropometric and body composition estimates provided by the 3DO scanner are precise and accurate to criterion methods if offsets are considered. This method offers a rapid, broadly available, and automated method of body composition assessment regardless of body size. Further studies are recommended to examine the relationship between measurements obtained by 3DO scans and metabolic health in healthy and clinical populations.

Validity of body fat percentage through different methods of body composition assessment in elite soccer referees

abstract The arbitration exercise in a soccer game requires high physical fitness and all federations apply physical tests to referees, including anthropometric tests, classifying them as fit or not for the role. The aim of this study was to assess the validity of the total body fat percentage (%BF) through different evaluation methods of body composition referenced in a four-compartment (4C) model. Cross-sectional study performed in 2018 with 21 elite male referees. %BF was estimated by 4 methods: anthropometry; bioelectrical impedance analysis (BIA); Dual X-ray absorptiometry (DXA) and air displacement plethysmography (ADP). Moreover, three and four-compartment (3 and 4C) models were calculated. Bland–Altman and intraclass correlations (ICC) analysis were performed to determine validity of all methods compared to a 4C reference. The results of one-way ANOVA revealed that there was no significant difference (F=1.541; p=0.182) between %BF analyzed by 4C model (15.98 ± 6.20), anthropometry (mean ± SD, 18.46 ± 7.03), ADP (16.19 ± 6.24), BIA (16.67 ± 5.30), DXA (20.33 ± 6.56) and 3C (16.92 ± 5.53). The Bland–Altman analysis showed that all methods analyzed overestimate %BF compared to the 4C model. The best agreement was obtained from the ADP evaluation (bias=-0.2), followed by BIA (bias=-0.6), 3C (bias=-0.9), anthropometry (bias=-2.4) and DXA (bias=-4.3). Validation assessed by ICC was excellent (ICC≥0.90) in most methods, except for anthropometry (ICC=0.80) and DXA (ICC=0.71). Overall, the results suggest that ADP, BIA and 3C were the best method to %BF evaluation. Nevertheless, anthropometry remains as a feasible method to monitor %BF of elite soccer referees.

DXA-Derived Adiposity and Lean Indices for Management of Cardiometabolic and Musculoskeletal Frailty: Data Interpretation Tricks and Reporting Tips

The proper assessment and follow-up of obesity and sarcopenia are relevant for the proper management of the complications of cardiometabolic and musculoskeletal frailty. A total body dual-energy X-ray absorptiometry (DXA) scan should be systematically incorporated in the rehabilitative routine management of patients with obesity and sarcopenia. In the former patients, the total body DXA can be used to assess the fat tissue amount and distribution, while in the latter patients, it can be used to quantify the reduction of appendicular lean mass and to investigate the inter-limb lean mass asymmetry. This tutorial article provides an overview of different DXA-derived fat and lean indices and describes a step-by-step procedure on how to produce a complete DXA report. We suggest that the systematic incorporation of these indices into routine examinations of the patients with obesity and sarcopenia can be useful for identifying the patients at risk for cardiometabolic and neuromuscular impairment-related comorbidities and for evaluating the effectiveness of pharmacological and rehabilitative interventions.

Cardiorespiratory Fitness of Firefighters: Initial Results of a Multi-Phased Study

OBJECTIVE

To address which body composition (BC) measures best correlate with cardiorespiratory fitness (CRF) in firefighters and develop a model for accurate CRF estimation compared with traditional methods.

METHODS

Career firefighters had body mass index (BMI) and waist circumference (WC) measured in addition to body fat percentage (FM%) by dual-energy x-ray absorptiometry (DXA). CRF as maximum oxygen uptake (VO2max) was estimated by rowing machine and measured by indirect calorimetry in a treadmill exercise test.

RESULTS

Fifty two firefighters participated (92.3% men). Univariate correlations with BMI were best with WC. Univariate correlations with VO2max were best with FM%. Obesity classifications by BC measures agreed weakly at best. Multivariate analysis of several variables yielded an improved VO2max estimate (R2 = 0.70).

CONCLUSIONS

Fire departments may benefit from more sophisticated measures of BC and CRF to evaluate firefighter fitness.

Multicomponent density models for body composition: Review of the dual energy X-ray absorptiometry volume approach

Accurate and precise body composition estimates, notably of total body adiposity, are a vital component of in vivo physiology and metabolic studies. The reference against which other body composition approaches are usually validated or calibrated is the family of methods referred to as multicomponent "body density" models. These models quantify three to six components by combining measurements of body mass, body volume, total body water, and osseous mineral mass. Body mass is measured with calibrated scales, volume with underwater weighing or air-displacement plethysmography, total body water with isotope dilution, and osseous mineral mass by dual-energy X-ray absorptiometry. Body density is then calculated for use in model as body mass/volume. Studies over the past decade introduced a new approach to quantifying body volume that relies on dual-energy X-ray absorptiometry measurements, an advance that simplifies multicomponent density model development by eliminating the need for underwater weighing or air-displacement plethysmography systems when these technologies are unavailable and makes these methods more accessible to research and clinical programs. This review critically examines these new dual-energy X-ray approaches for quantifying body volume and density, explores their shortcomings, suggests alternative derivation approaches, and introduces ideas for potential future research studies.

The Effects of Lifestyle Interventions on the Health-Promoting Behavior, Type D Personality, Cognitive Function and Body Composition of Low-Income Middle-Aged Korean Women

Low-income middle-aged women (LMW) who are vulnerable have various physical and psychosocial problems. They need lifestyle interventions to actively cope with these risk factors. This study used a randomized control group pretest-posttest design. LMW aged from 40 to 60 years were recruited and randomly assigned to an experimental group (n = 31) and a control group (n = 32). The lifestyle interventions for this study, which were implemented for eight weeks, included nutritional management, physical activity, stress management and cognitive function improvement based on King’s goal attainment theory. The measured outcomes were health-promoting behaviors, Type D personality, cognitive function and body composition. The experimental group scored significantly higher than the control group for health-promoting behaviors (effect size (ES) = 0.68~1.27, p < 0.001~0.014) and cognitive function (ES = 0.79~1.31, p < 0.001~0.005). The negative affectivity (ES = 0.70, p = 0.012) and the prevalence of a Type D personality (x² = 4.39, p = 0.047) and the systolic blood pressure (ES = 0.65, p = 0.019) decreased significantly in the experimental group compared with the control group. Lifestyle interventions for LMW were effective in improving health-promoting behavior, Type D personality traits and cognitive function.

Five-component model validation of reference, laboratory and field methods of body composition assessment

This study reports the validity of body fat percentage (BF%) estimates from several commonly employed techniques as compared with a five-component (5C) model criterion. Healthy adults (n 170) were assessed by dual-energy X-ray absorptiometry (DXA), air displacement plethysmography (ADP), multiple bioimpedance techniques and optical scanning. Output was also used to produce a criterion 5C model, multiple variants of three- and four-component models (3C; 4C) and anthropometry-based BF% estimates. Linear regression, Bland-Altman analysis and equivalence testing were performed alongside evaluation of the constant error (CE), total error (TE), se of the estimate (SEE) and coefficient of determination (R2). The major findings were (1) differences between 5C, 4C and 3C models utilising the same body volume (BV) and total body water (TBW) estimates are negligible (CE ≤ 0·2 %; SEE < 0·5 %; TE ≤ 0·5 %; R2 1·00; 95 % limits of agreement (LOA) ≤ 0·9 %); (2) moderate errors from alternate TBW or BV estimates in multi-component models were observed (CE ≤ 1·3 %; SEE ≤ 2·1 %; TE ≤ 2·2 %; R2 ≥ 0·95; 95 % LOA ≤ 4·2 %); (3) small differences between alternate DXA (i.e. tissue v. region) and ADP (i.e. Siri v. Brozek equations) estimates were observed, and both techniques generally performed well (CE < 3·0 %; SEE ≤ 2·3 %; TE ≤ 3·6 %; R2 ≥ 0·88; 95 % LOA ≤ 4·8 %); (4) bioimpedance technologies performed well but exhibited larger individual-level errors (CE < 1·0 %; SEE ≤ 3·1 %; TE ≤ 3·3 %; R2 ≥ 0·94; 95 % LOA ≤ 6·2 %) and (5) anthropometric equations generally performed poorly (CE 0·6- 5·7 %; SEE ≤ 5·1 %; TE ≤ 7·4 %; R2 ≥ 0·67; 95 % LOA ≤ 10·6 %). Collectively, the data presented in this manuscript can aid researchers and clinicians in selecting an appropriate body composition assessment method and understanding the associated errors when compared with a reference multi-component model.

Water Reductive Effect of Lymphaticovenular Anastomosis on Upper-Limb Lymphedema: Bioelectrical Impedance Analysis and Comparison with Lower-Limb Lymphedema

Background We previously examined the water reductive effect of lymphaticovenular anastomosis (LVA) using bioelectrical impedance analysis (BIA) measurement on lower-limb lymphedema and revealed mean water volume reduction and edema reduction rate by leg LVA to be 0.86 L and 45.1%, respectively. This study aimed to clarify the water reductive effect of LVA on arm lymphedema and compare its results with those for leg lymphedema.

Patients and Methods The efficacy of LVA for unilateral arm lymphedema was evaluated using BIA in a retrospective cohort. Limb circumference and arm body water volume (ABW) of the affected and unaffected arms were measured before and after LVA. Mean water volume reduction (ΔABW) and edema reduction rate by arm LVA were compared with values for leg LVA cited from our previous report as a historical control.

Results Nineteen consecutive patients were enrolled. The mean ΔABW and edema reduction rate by BIA were 0.267 L and 46.0%, respectively. The decreasing rate of ABW by BIA was significantly larger than those of the upper extremity lymphedema index and sum of 5 circumferences measurement methods. ΔABW could be predicted by a regression line based on the preoperative water volume difference between affected and unaffected limbs. The mean edema reduction rates for arm and leg LVA were comparable.

Conclusion The water reductive effect of LVA on upper-limb lymphedema was demonstrated by BIA assessment. BIA can reflect the effect of LVA more sensitively than conventional objective measurements and may facilitate the interpretation of LVA results. Although water volume reduction by arm LVA was less than that by leg LVA, the edema reduction rates were comparable.

Evaluation of fat-free mass hydration in athletes and non-athletes

PURPOSE

To evaluate the hydration of fat-free mass (FFM) in athletes and non-athletes.

METHODS

We analyzed the data of 128 healthy young adults (athletes: 61 men, 36 women; non-athletes: 19 men, 12 women) using the two-component (2C), 3C and 4C models. Under-water weighing or air-displacement plethysmography and deuterium dilution methods were used for estimating body density and total body water, respectively. The bone mineral content (BMC) was determined using whole-body scans by dual-energy X-ray absorptiometry.

RESULTS

There was no significant difference in FFM hydration between the athletes (men, 72.3 ± 1.3%; women, 71.8 ± 1.3%) and non-athletes (men, 72.1 ± 1.2%; women, 72.2% ± 1.0%) in the 3C model. The total mean FFM hydration (72.1% ± 1.3%) was similar to the corresponding value in the literature (~ 73%). The estimation error of the percentage fat by the 2C vs the 4C model was significantly and highly correlated with hydration (r = 0.96), BMC (r = - 0.70), and total body protein (r = - 0.86) in the 4C model FFM.

CONCLUSION

Although FFM hydration was similar in athletes and non-athletes, it would be underestimated or overestimated when the 2C model is used for evaluation, and the biological FFM hydration value deviates from the 73% value inter-individually. Despite that this inter-individual variation in FFM hydration is low in terms of between-individual standard deviation (1.3%), the BMC and total body protein differ greatly in athletes, and when it affects FFM hydration, it may also affect the percentage fat measurement in the 2C model. Thus, FFM hydration would not be affected by FFM, percent body fat, or the athletic status.

Digital anthropometry via three-dimensional optical scanning: evaluation of four commercially available systems

BACKGROUND

Digital anthropometry is increasingly accessible due to commercial availability of three-dimensional optical scanners (3DO).

METHODS

One hundred and seventy-nine participants were assessed by four 3DO systems (FIT3D®, Size Stream®, Styku®, and Naked Labs®) in duplicate, air displacement plethysmography (ADP), and dual-energy x-ray absorptiometry (DXA). Test-retest precision was evaluated, and validity of total and regional volumes was established.

RESULTS

All scanners produced precise estimates, with root mean square coefficient of variation (RMS-%CV) of 1.1-1.3% when averaged across circumferences and 1.9-2.3% when averaged across volumes. Precision for circumferences generally decreased in the order of: hip, waist and thigh, chest, neck, and arms. Precision for volumes generally decreased in the order of: total body volume (BV), torso, legs, and arms. Total BV was significantly underestimated by Styku® (constant error [CE]: -10.1 L; root mean square error [RMSE]: 10.5 L) and overestimated by Size Stream® (CE: 8.0 L; RMSE: 8.3 L). Total BV did not differ between ADP and FIT3D® (CE: -3.9 L; RMSE: 4.2 L) or DXA BV equations (CE: 0-1.4 L; RMSE: 0.7-1.5 L). Torso volume was overestimated and leg and arm volumes were underestimated by all 3DO. No total or regional 3DO volume estimates exhibited equivalence with reference methods using 5% equivalence regions, and proportional bias of varying magnitudes was observed.

CONCLUSIONS

All 3DO produced precise anthropometric estimates, although variability in specific precision estimates was observed. 3DO BV estimates did not exhibit equivalence with reference methods. Conversely, DXA-derived total BV exhibited superior validity and equivalence with ADP.

Does a spinal implant alter dual energy X-ray absorptiometry body composition measurements?

Background

Most manufacturer manuals do not verify the use of dual energy X-ray absorptiometry for body composition analysis in subjects with a metal implant. This study aimed to quantify the effects of a spinal implant on body composition, and to determine whether unadjusted lean mass estimates are valid for patients with a spinal implant.

Methods

A total of 30 healthy subjects were recruited. Three consecutive scans were performed for each participant, one with and two without extraneous spinal implant, without repositioning between scans. Lean, fat and bone estimates in the total body, trunk and limb were measured.

Results

Precision errors for all total and regional body compositions were within the recommended ranges. Bone masses in the trunk and total body were significantly increased with spinal implant, and the increases exceeded the least significant change. For total and regional lean and fat estimates, the measurements between subjects with and without metal implants were in substantial to almost perfect agreement and the differences were not significant and did not exceed the least significant change.

Conclusions

Spinal metal artifacts significantly increased the total body and trunk bone mass but the differences in lean- and fat-related estimates at total and regional body levels and all estimates in the extremity remained within the clinical acceptable range. Thus, a spinal implant may not compromise screening of patients for fat and lean masses using dual energy X-ray absorptiometry. Application of image reconstruction or a filtering algorithm may help reduce the effect of metallic artifacts and further study is needed.

Time-restricted feeding plus resistance training in active females: a randomized trial

BACKGROUND

A very limited amount of research has examined intermittent fasting (IF) programs, such as time-restricted feeding (TRF), in active populations.

OBJECTIVE

Our objective was to examine the effects of TRF, with or without β-hydroxy β-methylbutyrate (HMB) supplementation, during resistance training (RT).

METHODS

This study employed a randomized, placebo-controlled, reduced factorial design and was double-blind with respect to supplementation in TRF groups. Resistance-trained females were randomly assigned to a control diet (CD), TRF, or TRF plus 3 g/d HMB (TRFHMB). TRF groups consumed all calories between 1200 h and 2000 h, whereas the CD group ate regularly from breakfast until the end of the day. All groups completed 8 wk of supervised RT and consumed supplemental whey protein. Body composition, muscular performance, dietary intake, physical activity, and physiological variables were assessed. Data were analyzed prior to unblinding using mixed models and both intention-to-treat (ITT) and per protocol (PP) frameworks.

RESULTS

Forty participants were included in ITT, and 24 were included in PP. Energy and protein intake (1.6 g/kg/d) did not differ between groups despite different feeding durations (TRF and TRFHMB: ∼7.5 h/d; CD: ∼13 h/d). Comparable fat-free mass (FFM) accretion (+2% to 3% relative to baseline) and skeletal muscle hypertrophy occurred in all groups. Differential effects on fat mass (CD: +2%; TRF: -2% to -4%; TRFHMB: -4% to -7%) were statistically significant in the PP analysis, but not ITT. Muscular performance improved without differences between groups. No changes in physiological variables occurred in any group, and minimal side effects were reported.

CONCLUSIONS

IF, in the form of TRF, did not attenuate RT adaptations in resistance-trained females. Similar FFM accretion, skeletal muscle hypertrophy, and muscular performance improvements can be achieved with dramatically different feeding programs that contain similar energy and protein content during RT. Supplemental HMB during fasting periods of TRF did not definitively improve outcomes. This study was prospectively registered at clinicaltrials.gov as NCT03404271.

Reliability and validity of various laboratory methods of body composition assessment in young adults

Accurate measures of body composition (BC) are essential for performance and health. In addition to accuracy, BC measures should be practical and be minimally invasive to maximize their utility. The purpose of the present study was to compare the day-to-day variability and validity of four common laboratory-based body composition assessments to a criterion four-compartment model. Dual x-ray absorptiometry (DXA), air displacement plethysmography (BP), multi-frequency bioelectrical impedance (MF-BIA) and underwater weighing (UWW) were performed twice in a sample of 32 young men and women. Participants were assessed in a fasted, euhydrated state 2-7 days apart. All methods were compared to a criterion four-compartment model using BP-derived body volume, DXA-derived bone mineral content and MF-BIA-derived total body water (4C_BP ). Additional four-compartment models using UWW- and DXA-derived body volume were also examined (4C_UWW ) and (4C_DXA ). Validity results were conducted with paired t-tests and Bland-Altman analysis. Reliability was determined using intraclass correlations (ICC), coefficients of variation (CV) and standard error of the measurement (SEM). Validity analysis revealed that all methods overestimated per cent body fat and fat mass, and underestimated fat-free mass when compared with 4C_BP , but only DXA and BP were significantly different (P<0·008). All measures were highly reliable across days (ICCs > 0·9, CVs < 12%). Results of the present study indicate that typical laboratory-based methods of body composition are valid and reliable. However, we caution that results should not be translated between methods and assessments should be performed with the same instrument when the goal is to monitor changes in body composition over time.