Estimation Of Muscle Mass Research Articles

Validity of anthropometric measurements to assess body composition, including muscle mass, in 3‐year‐old children from the SKOT cohort

Nutritional status of children is commonly assessed by anthropometry both in under and overnutrition. The link between anthropometry and body fat, the body compartment most affected by overnutrition, is well known, but the link with muscle mass, the body compartment most depleted in undernutrition, associated with infections, remains unknown. In this study, we examined the relationship between common anthropometric indices and body composition measured by dual-energy X-ray absorptiometry (DEXA) in a sample of 121 healthy 3-year-old Danish children. Appendicular (arms and legs) lean mass was used to estimate muscle mass. Overall, anthropometric measures were more effective to measure absolute size of fat, lean and muscle mass than their relative sizes. Proportion of the variance explained by anthropometry was 79% for lean mass, 76% for fat mass and 74% for muscle mass. For fat mass and lean mass expressed as percentage of total body mass, this proportion was 51% and 66%, respectively; and for muscle mass as percentage of lean mass it was 34%. All the best reduced multivariate models included weight, skinfold and gender except the model estimating the proportion of muscle mass in lean body mass, which included only mid-upper arm circumference and subscapular skinfold. The power of height in the weight-to-height ratio to determine fat mass proportion was 1.71 with a 95% confidence interval (0.83-2.60) including the value of 2 used in body mass index (BMI). Limitations of anthropometry to assess body composition, and especially for muscle mass as a proportion of lean mass, should be acknowledged.

Sarcopenia prevalence: reply to comment by Perez-Zepeda et al

Dear Editor, As we discussed in our paper [1], our study population consisted of 70to 80-year-old home-dwelling women who voluntarily participated in the DEX randomized controlled trial [2], and it is likely that the prevalence of sarcopenia in the unselected Finnish population of elderly women would have been higher than that reported by us. We estimated muscle mass with dual-energy X-ray absorptiometry, which is the preferred method for research and clinical use [3]. In the study by ArangoLopera and colleagues, muscle mass was determined by calf circumference [4]. Diagnostic criteria (including those used in the European Working Group on Sarcopenia in Older People algorithm) need to be standardized and consistently applied before they can be deemed worthy of comparison. Unless this is done, diagnosis and prevalence rates of sarcopenia are difficult to compare and do not hold credibility. We also explored the rationale behind measuring muscle mass to predict the onset of disability in older adults. The result was that muscle mass and derived indices of sarcopenia were not related to measures of physical function. It seemed that an appropriate and standardized functional ability test battery might be better suited to detect changes in physical function and, consequently, reveal the onset of disability.

Regression Equation from Dual Energy X Ray Absorptiometry (DEXA) for Estimating Muscle Mass Segment

Metodos antropometricos eran usados para estimar la masa muscular (MM) no especificando valores para segmentos de cuerpo, un hecho critico para individuos que practican actividades fisicas o el diagnostico clinico. En este estudio, 60 atletas recreacionales son evaluados antropometricalmente y por absorciometria de energia dual de Rayos X. La estadistica de regresion lineal posteriormente es usada para establecer el constante el permiso de la obtencion del mm de segmento. Tres ecuaciones fueron obtenidas, un para los miembros superiores: MMUL = (0.533*FAP) - (0.176*RAP) + (0.42*WP) + (0.282*SRL) - 19,985; una segunda ecuacion para la masa muscular de los miembros superiores: MMLL = (0.186*H) - (0.158*LTTL) - (0.024*LTL) + (0451*LP) ­ 24.535; y una tercera para la masa muscular del tronco: TrMM = (0.026*W) + (0.046*H) + (0.154*TTD) + (0.025*NP) ­ (0.025*AP) ­ 5.839. Estas ecuaciones permiten la adquisicion de la informacion detallada sobre la distribucion de MM por una tecnica de acceso facil y rapido, como la antropometria, de un Metodo de Gold Estandar como DEXA.

Positive associations between serum levels of IGF-I and subcutaneous fat depots in young men. The Odense Androgen Study

IntroductionSerum levels of IGF-I are of growing interest due to the associations with morbidity and mortality. Despite markedly suppressed GH secretion, total IGF-I levels are often within normal range in obese adults. AimTo study associations between IGF-I and estimated muscle mass in the Odense Androgen Study population and secondly to investigate associations between serum IGF-I and regional fat depots. MethodThe Odense Androgen Study is a population-based, cross-sectional study of 776 randomly selected men aged 20–29years. Regional lean and fat mass were measured by dual-energy X-ray absorptiometry, whereas regional muscle and fat areas were assessed by magnetic resonance imaging. ResultsAge-adjusted IGF-I levels correlated significantly with different estimates of muscle mass (r‐values between 0.15 and 0.19; p<0.001). Using multiple linear regression, serum IGF-I correlated positively with subcutaneous adipose tissue on the abdomen (SAT) after controlling for visceral adipose tissue (VAT) in the whole group and in the subgroup of men with normal waist circumference (r-values between 0.13 and 0.15; p<0.03). In addition, IGF-I correlated positively with subcutaneous thigh fat area (TFA) after controlling for intramyocellular lipid (imcl) r=0.18; p<0.004) and IGF-I correlated negatively with TFAimcl in the whole group and in the subgroup of men with normal waist circumference. ConclusionSAT and subcutaneous TFAs were positively associated with IGF-I in regression analyses. Conversely, imcl of the thigh was inversely associated with IGF-I levels. These findings emphasize the differential associations between IGF-I and regional fat deposits. Future studies may provide further insight regarding the interplay between circulating IGF-I levels and regional muscle and fat mass.

Estimation of appendicular muscle mass and fat mass by near infrared spectroscopy in older persons

Near infrared spectroscopy has been reported to have a high reliability and accuracy in assessing the percentage of body fat. However, whether muscle mass can be accurately estimated using this method has not been established. This study examined whether a near infrared spectroscopy method could estimate appendicular muscle mass and fat mass, with dual-energy X-ray absorptiometry as the standard method for comparison. A total of 20 orthopedic inpatients (mean age 73.2 ± 6.8 years) were recruited for this study. Their body composition was assessed using near infrared spectroscopy and dual-energy X-ray absorptiometry. Appendicular muscle mass and fat mass were estimated from height, weight and optical densities. The optical densities for the upper arm (biceps, triceps) and forearm (flexor carpi radialis) were significantly correlated with appendicular muscle mass (r = 0.534 to 0.623) or fat mass (r = -0.483 to -0.827). Estimated appendicular muscle mass and fat mass explained 89% and 80% of the variance in the dual-energy X-ray absorptiometry-derived muscle mass and fat mass estimates using height, weight and optical density values of the proximal flexor carpi radialis. Near infrared spectroscopy is a useful method to assess not only fat mass, but also muscle mass in older adults.

Anthropometric equation for estimation of appendicular skeletal muscle mass in Chinese adults.

The purpose of this study was to develop and cross-validate anthropometric equations for the estimation of appendicular skeletal muscle mass (ASM) in Chinese adults. A total of 763 adults aged 18-69 years (345 men and 418 women) were recruited from residents living in four regions (Jinan, Guangzhou, Xi'an and Chengdu) in China. ASM were measured by fan-beam dual energy x-ray absorptiometry. Participants' body weight, height, limb circumferences (upper arm, thigh, and calf), waist circumference, and skinfold thicknesses (triceps, thigh, and calf) were measured by trained testers. The participants were randomly assigned to two groups: a model-development group (MD group) and a cross-validation group (CV group). Prediction models were established using the data from the MD group, and cross-validated with the data of the CV group. The results suggested that the developed equations had satisfactory prediction qualities, and could be applied as a practical method of quantifying ASM in Chinese adults.

A comparison of fat mass and skeletal muscle mass estimation in male ultra-endurance athletes using bioelectrical impedance analysis and different anthropometric methods.

Two hundred and fifty seven male Caucasian ultra-endurance athletes were recruited, pre-race, before different swimming, cycling, running and triathlon races. Fat mass and skeletal muscle mass were estimated using bioelectrical impedance analysis (BIA) and anthropometric methods in order to investigate whether the use of BIA or anthropometry would be useful under field conditions. Total body fat estimated using BIA was significantly high (P < 0.001) compared with anthropometry. When the results between BIA and anthropometry were compared, moderate to low levels of agreement were found. These results were in accordance with the differences found in the Bland-Altman analysis, indicating that the anthropometric equation of Ball et al. had the highest level of agreement (Bias = -3.0 ± 5.8 kg) with BIA, using Stewart et al. (Bias = -6.4 ± 6.3 kg), Faulkner (Bias = -4.7 ± 5.8 kg) and Wilmore-Siri (Bias = -4.8 ± 6.2 kg). The estimation of skeletal muscle mass using BIA was significantly (P < 0.001) above compared with anthropometry. The results of the ICC and Bland-Altman method showed that the anthropometric equation from Lee et al. (Bias = -5.4 ± 5.3 kg) produced the highest level of agreement. The combined method of Janssen et al. between anthropometry and BIA showed a lower level of agreement (Bias = -12.5 ± 5.7 kg). There was a statistically significant difference between the results derived from the equation of Lee et al. and Janssen et al. (P < 0.001). To summarise, the determination of body composition in ultra-endurance athletes using BIA reported significantly high values of fat and skeletal muscle mass when compared with anthropometric equations.

Commentaries on Viewpoint: Can muscle size fully account for strength differences between children and adults?

# {#article-title-2} to the editor: As comprehensively explained in their Viewpoint article ([1][1]), the answer to the question posed in the title has received conflicting answers. Since the contractile machinery in children is the same as that in adults, there is no reason to believe that

Albumin:Creatinine Ratio – A Flawed Measure? The Merits of Estimated Albuminuria Reporting

Current guidelines illogically recommend that a different approach is taken to the correction for creatinine generation rate when estimating glomerular filtration rate (GFR) and when interpreting urine albumin:creatinine ratio (ACR). Age, gender and race are routinely used to adjust for predicted muscle mass in GFR estimation, even though estimated GFR is expressed per unit body surface area. Conversely, ACR is at most adjusted with the use of gender-specific classification thresholds. This difference is surprising since the proportional effect of muscle mass on serum and urine creatinine is identical. Failure to adjust for creatinine generation rate compromises ACR, potentially adversely affecting management decisions and mislabelling individuals as having/not having CKD. A greater ACR is also a marker of low muscle mass, which has confounding prognostic effects. Determination of the optimal method to adjust ACR for estimated muscle mass should improve its performance. Routine reporting of the resulting ‘estimated albumin excretion rate’, as for routine eGFR reporting, would remove the need for gender-specific thresholds.

Effects of gestation and transition diets, piglet birth weight, and fasting time on depletion of glycogen pools in liver and 3 muscles of newborn piglets1

The experiment was conducted to assess the effects of maternal nutrition in late gestation on glycogen pools of newborn piglets of different birth weights and to assess how rapidly the glycogen pools in the liver and 3 muscles are mobilized during fasting. Until d 108 of gestation, 48 sows were fed a gestation standard diet (GSD) with low dietary fiber (DF, 17.1%), or 1 of 3 diets with high DF (32.3 to 40.4%) consisting of pectin residue (GPR), potato pulp (GPP), or sugar-beet pulp (GSP). From d 108 until farrowing, sows were fed 1 of 6 transition diets with low or high dietary fat: one group received a standard diet (TSD; control) containing 3% animal fat, another group received the TSD diet + 2.5 g/d of hydroxy-methyl butyrate as topdressing (THB), and 4 other groups received diets with 8% added fat from coconut oil (TCO), sunflower oil (TSO), fish oil (TFO), or 4% octanoic acid + 4% fish oil (TOA). Two piglets per litter (the second and fifth born) were blood sampled, and 1 was killed immediately after birth, whereas the other, depending on the litter, was killed after 12, 24, or 28.5 to 36 h (mean 32.5 h) of fasting. Samples of liver, LM, M. semimembranousus (SM), and M. diaphragm (DP) were collected and analyzed for glycogen concentration. No dietary effects (P > 0.20) on glycogen concentrations in liver, LM, SM, or DP were observed. The weight of the liver was affected by gestation diet (P < 0.05) and was greater in GSD and GSP piglets (36.7 and 36.3 g) than in GPR piglets (32.6 g), and intermediate (33.6 g) in GPP piglets. Liver weight, estimated muscle mass, and glycogen pools (P < 0.001) were affected by birth weight, whereas glycogen concentrations in liver and LM, SM, and DP muscles were not (P > 0.05). Liver weight; glycogen concentrations in liver, LM, SM, and DP; and glycogen pools in liver and muscles decreased (P < 0.001) with increasing duration of fasting, and at 32.5 h of fasting, glycogen concentration was reduced by 80% in liver, 64% in DP, 46% in SM, and 36% in LM. Based on a broken-line model, labile glycogen in SM, a locomotory muscle, was estimated to be depleted after 16.4 h of fasting. In conclusion, piglet size had a major impact on estimated glycogen pools, whereas sow nutrition in late gestation had a minor impact, if any. Furthermore, varying proportions of pools of glycogen present in liver and selected muscles were mobilized, and data indicate that newborn piglets are fatally depleted of energy after 16 h of fasting.

Cancer Fatigue: Does Forearm Muscle Mass and Handgrip Correlate with Fatigue Severity? (714)

1.Discuss the concept of “catastrophic” fatigue and “central governor” fatigue theory.2.Recognize that by comparing forearm muscle mass, hand grip, and fatigue that there are relationships between variables which are altered by fatigue. Background. A “catastrophe” fatigue theory has muscle exhaustion and ATP depletion as the main mechanism which would correlate with muscle mass and composition. It is also hypothesized that a brain “central governor” controls muscle activity and that the human body functions as a complex system during exercise until a central brake prevents loss of homeostasis. A “central governor” fatigue theory places the fatigue mechanism in the subconscious brain which ensures homeostasis and protects muscle from damage. The governor “set point” may be altered by illness. Bioelectrical impedance (BIA) estimates of muscle mass are validated against MRI measured muscle mass. The main electron conductor with BIA is muscle. Muscle mass is inversely related to impedance (Z) and directly related to the muscle area (L2). Research objectives. We hypothesized that the relationship between maximum handgrip strength, segmental forearm muscle mass (L2/Z) and fatigue is altered in cancer-related fatigue (CRF) if fatigue is central in origin. Methods. Twenty individuals, ten healthy controls, and ten with CRF were studied. Data collected was: BFI, handgrip x 4 (dominant arm), and forearm BIA impedance. Results. The median total BFI score was 18 for controls and 45 for CRF. In those with CRF relative to healthy controls, there was a poor correlation between BFI and forearm muscle mass, between handgrip strength and BFI, and handgrip strength and muscle mass (Figures1-3, red, healthy controls; blue, CRF). Conclusion. This pilot study demonstrated in those with CRF a poor correlation between handgrip strength, forearm muscle mass and fatigue severity which differed from healthy controls. This suggests that the “central governor” which controls muscle activation is altered in CRF and that fatigue is unlikely to be arising from reduced muscle mass (peripheral fatigue). Implications for research, policy, or practice. Fatigue severity in CRF is unrelated to muscle mass and handgrip strength. Interventions to increase muscle are unlikely to relieve fatigue.

A DXA-Based Mathematical Model Predicts Midthigh Muscle Mass from Magnetic Resonance Imaging in Typically Developing Children but Not in Those with Quadriplegic Cerebral Palsy ,

Valid methods for assessing regional muscle mass in children are needed. The aim of this study was to determine whether dual-energy X-ray absorptiometry (DXA) can accurately estimate midthigh muscle mass from MRI (muscleMRI) in typically developing children and children with quadriplegic cerebral palsy (CP). A mathematical model predicting muscleMRI from midthigh, fat-free soft tissue mass from DXA (FFSTDXA) was developed using 48 typically developing children (6–13 y) and was validated using the leave-one-out method. The model was also tested in children with quadriplegic CP (n = 10). The model produced valid estimates of midthigh muscle mass (muscleDXA) in typically developing children, as indicated by a very strong relationship between muscleDXA and muscleMRI (r2 = 0.95; SEE = 68 g; P < 0.001), no difference in muscleDXA and muscleMRI (P = 0.951), and visual examination using a Bland-Altman plot. MuscleDXA was very strongly related to muscleMRI in children with CP (r2 = 0.96; SEE = 54 g; P < 0.001); however, muscleDXA overestimated muscleMRI by 15% (P = 0.006). The overestimation of muscleMRI by muscleDXA was strongly related to the lower ratio of muscleMRI to FFSTDXA (muscleMRI/FFSTDXA) in children with CP (r2 = 0.75; P = 0.001). The findings suggest that the DXA-based mathematical model developed in the current study can accurately estimate midthigh muscle mass in typically developing children. However, a population-specific model that takes into account the lower muscleMRI/FFSTDXA is needed to estimate midthigh muscle mass in children with quadriplegic CP.

Body composition in older orthopaedic rehabilitation inpatients: Are field methods valid?

AbstractAim: The assessment of body composition is an important aspect of the determination of nutritional health. This cross‐sectional measurement study aimed to assess the relative validity of a range of field techniques for the measurement of body composition in a sample of older orthopaedic inpatients participating in rehabilitation.Methods: Assessment of percent fat‐free mass of 31 adults, aged 65 years and over, was conducted under fasting conditions by two types of bioelectrical impedance analysis (multi‐frequency and single frequency—using manufacturer's pre‐programmed prediction equation) and compared with percent fat‐free mass estimated by dual energy X‐ray absorptiometry, a reference technique. Data from multi‐frequency bioelectrical impedance analysis were also used to calculate percent fat‐free mass from the prediction equation of Dey et al. for comparison. Skeletal muscle mass was derived from assessment of corrected arm muscle area and compared with skeletal muscle mass from dual energy X‐ray absorptiometry analysis. Bland‐Altman analysis was performed to determine the level of agreement between each field technique and dual energy X‐ray absorptiometry.Results: Mean bias and limits of agreement between single frequency bioelectrical impedance analysis and dual energy X‐ray absorptiometry were −5.7% (−24.0, 12.6), between multi‐frequency bioelectrical impedance analysis (manufacturer's pre‐programmed prediction equation) and dual energy X‐ray absorptiometry were 1.4% (−13.4, 16.1), between multi‐frequency bioelectrical impedance analysis (Dey et al. prediction equation) and dual energy X‐ray absorptiometry were −5.0% (−16.6, 6.6) and between skeletal muscle mass as derived from assessment of corrected arm muscle area and skeletal muscle mass from dual energy X‐ray absorptiometry analysis −0.97 kg (−8.37, 6.43).Conclusion: None of the methods assessed are clinically acceptable for assessment of body composition in older orthopaedic rehabilitation patients; however, estimation of skeletal muscle mass, as derived from corrected arm muscle area, is likely to be of more use in the clinical setting as there is no requirement for patients to be fasted.

Protein Needs in Adolescent Sprint Athletes: a Longitudinal Study

Nutrition plays a key role in health, performance, growth and development, especially in adolescent athletes. Adequate protein intake is important for optimal lean tissue repair and acquisition. Nitrogen balance studies are usually used to determine the specific protein needs for different types of athletes. Data regarding protein intake recommendations for adolescent sprint athletes are scarce. PURPOSE: To estimate protein needs for sprint athletes during adolescence. METHODS: A 7-day diet diary, during which period 2 × 24hour urine samples were collected, was administered 5 times with a 6 month interval to 32 female and 33 male adolescent sprint athletes (age at start respectively 14.8±1.6 and 14.7±1.9yrs). Anthropometric data were collected allowing the estimation of skeletal muscle mass (SMM). Diaries were analyzed for nutrient intakes using the Belgian and Dutch food data banks. A cut-off value of 1.1 x basal metabolic rate was used to check for underreporting. During the 24hour urine collections, athletes ingested 3 x 180mg para-amino benzoate. Urine collections containing a minimum of 85% para-amino benzoate were analyzed for their nitrogen content using the Kjeldahl method. All data were normally distributed. ANOVA procedures and Pearson correlations were applied at the 5% confidence level. RESULTS: Mean daily protein intakes remained within a narrow range of 1.4±0.3 and 1.5±0.3g/kg in girls (p=.49) and 1.5±0.3 and 1.6±0.3g/kg in boys (p=.15). For both genders, a protein intake around 1.4g/kg was required to be in a positive nitrogen balance. This remained stable throughout the experimental period. Girls became 2.8±3.6cm taller, 4.7±3.0kg heavier and acquired 1.6±1.7kg SMM between the 1st and 5th measurement. Boys gained 5.5±6.0cm in height, 8.0±4.6kg in weight and 3.6±2.3kg in SMM. Height and weight evolution was comparable to that of their Belgian peers. A gain in body height, weight or SMM did not alter nitrogen balance in both genders. There was no significant relation between protein intake and a gain in height, weight or SMM. CONCLUSIONS: A daily protein intake between 1.3-1.5g/kg appears adequate to sustain a positive nitrogen balance in sprint adolescent male and female athletes. Sufficient protein was provided through the diet in most of the athletes studied.

Estimativa da massa muscular esquelética em mulheres idosas: validade da impedância bioelétrica

O presente estudo tem como objetivos: a) verificar a concordância entre os métodos da impedância bioelétrica (BIA) e da absortometria radiológica de dupla energia (DXA) para a estimativa da massa muscular esquelética (MME); e b) analisar o poder preditivo de variáveis antropométricas e da BIA para a predição da MME em idosas. Foram avaliadas 120 mulheres (60 a 81 anos), residentes na região Sul do Brasil. Mensuraram-se as variáveis antropométricas (massa corporal e estatura); a resistência e hidratação dos tecidos livres de gordura foram medidas pela técnica da BIA tetrapolar (Biodinamics - BF-310), e pela DXA de corpo inteiro (Lunar Prodigy DF + 14319 Radiation e software 7.52.002 DPX-L). A diferença entre os métodos foi verificada pelo teste t pareado, análise dos resíduos e o coeficiente de correlação. O valor preditivo das variáveis antropométricas e de BIA foi verificado pela regressão linear múltipla, adotando nível de significância de p &lt; 0,05. Não houve diferença estatística entre os métodos para a estimativa da MME (p &gt; 0,01). Observou-se que a BIA subestimou em média 0,8kg (IC95%: -3,7; 2,0kg) a MME, quando comparada com a DXA. Foi observada alta correlação entre os métodos (r² = 0,75; p &lt; 0,01). A análise de regressão demonstrou que a variável da razão entre a estatura ao quadrado e a resistência (EST²/R) explica 80% da variação da MME, quando ajustada para massa corporal e idade, e essa relação é independente das variáveis de gordura corporal, hidratação dos tecidos magros e índice de massa corporal. Assim, nota-se que a equação da BIA, aqui testada, é válida para a estimativa da MME em mulheres idosas e seu valor pode ser mais bem predito pelo modelo de regressão proposto a partir da medida de EST²/R ajustada para a massa corporal e idade.

The K153R variant in the myostatin gene and sarcopenia at the end of the human lifespan

We studied the A55T, E164K, I225T, K153R and P198A variants in the myostatin (GDF8) gene, muscle strength and mass, and physical function during daily living in 41 nonagenarians [33 women, age range, 90, 97]. No participant carried a mutant allele of the aforementioned variants, except three participants (all women), who carried the R allele of the K153R polymorphism, with one of them (woman aged 96 years) being homozygous. Overall, in KR women muscle phenotype values (1RM leg press and estimated muscle mass) were low-to-normal compared to the whole group (approximately 25th-50th percentile), and their functional capacity (Barthel and Tinetti tests) was normal. In the woman bearing the RR genotype, values of muscle mass and functional capacity were below the 25th percentile. She is the first RR Caucasian whose phenotype has been characterised specifically. In summary, heterozygosity for the GDF8 K153R polymorphism does not seem to exert a negative influence on the muscle phenotypes of women who are at the end of the human lifespan, yet homozygosity might do so. More research on larger cohorts of nonagenarians is needed to corroborate the present findings.

Greater lean tissue and skeletal muscle mass are associated with higher bone mineral content in children

BackgroundTo compare the relationship of skeletal muscle mass with bone mineral content in an ethnically diverse group of 6 to 18 year old boys and girls.Methods175 healthy children (103 boys; 72 girls) had assessments of body mass, height, and Tanner stage. Whole body bone mineral content, non-bone lean body mass (nbLBM), skeletal muscle mass, and fat mass were assessed using dual-energy X-ray absorptiometry (DXA). Muscle mass was estimated from an equation using appendicular lean soft tissue measured by DXA, weight and height. Estimates of skeletal muscle mass and adipose tissue were also assessed by whole body multi-slice magnetic resonance imaging (MRI). Linear regression was used to determine whether skeletal muscle mass assessed by DXA or by MRI were better predictors of bone mineral content compared with nbLBM after adjusting for sex, age, race or ethnicity, and Tanner stage.ResultsGreater skeletal muscle mass was associated with greater bone mineral content (p < 0.001). The skeletal muscle mass assessed by MRI provided a better fitting regression model (determined by R2 statistic) compared with assessment by DXA for predicting bone mineral content. The proportion of skeletal muscle mass in nbLBM was significantly associated with greater bone mineral content adjusted for total nbLBM.ConclusionsThis study is among the first to describe and compare the relationship of skeletal muscle to bone using both MRI and DXA estimates. The results demonstrate that the use of MRI provides a modestly better fitting model for the relationship of skeletal muscle to bone compared with DXA. Skeletal muscle had an impact on bone mineral content independent of total non-bone lean body mass. In addition, Hispanics had greater bone mineral content compared to other race and ethnic groups after adjusting for sex, age, adipose tissue, skeletal muscle mass, and height.

Estimation of whole-body skeletal muscle mass by bioelectrical impedance analysis in the standing position

Summary Objective To develop a clinical method for evaluating skeletal muscle (SM) mass using whole-body bioelectrical impedance (BI) analysis in the standing position. Subjects Two hundred and forty-four volunteers (men=106 and women=138) participated in this study. The subjects were randomly separated into validation and cross-validation groups. Methods The whole-body impedance ( Z ) between the hands and feet was measured in the standing position. A stepwise multiple regression analysis was used to develop the prediction equation for SM mass. Whole-body SM mass, measured by magnetic resonance imaging (MRI), was used as a reference. Results BI index (height 2 / Z ), body surface area (BSA), gender, and age were selected as significant contributors to predict SM in the validation group. There was no significant difference between the measured and estimated SM mass and no systematic error in BI analysis in the cross-validation group. All data were pooled to generate the final regression equation: SM mass \( kg \) = \( 0.126 × BI index \) + \( 1.937 × BSA \) + \( − 0.062 × age \) + \( − 2.186 × gender \) − 2.881 , where age is in years. Gender for men=1 and women=2. Analysis revealed that the slope and intercept were not significantly different from one and zero, respectively. The r 2 and SEE values of the regression equation were 0.893 and 1.65kg, respectively. Conclusions Using our developed prediction equation, the BIA system can be used to accurately evaluate whole-body skeletal muscle mass with the subject in the standing position.

Comment on “Higher Serum Creatinine Concentrations in Black Patients with Chronic Kidney Disease

The article “Higher Serum Creatinine Concentrations in Black Patients with Chronic Kidney Disease: Beyond Nutritional Status and Body Composition” by Hsu et al . (1) suggests that a greater creatinine generation rate on the basis of larger muscle mass does not explain the higher serum creatinine levels observed in black prevalent hemodialysis patients. In our opinion, this conclusion is not tenable given the limitations of the study design and method. The most critical methodologic shortcoming of Hsu's approach is the choice of 50-kHz single-frequency bioimpedance analysis (BIA) and the way it was used to correct for, as the authors stated, “body composition.” Creatinine is predominantly derived from skeletal muscle creatine (endogenous) and, to a lesser extent, from the diet (exogenous); therefore, when attempting to correct for creatinine generation rate by adjusting for body composition, the appropriate body compartment to adjust for is skeletal muscle. 50-kHz single-frequency BIA is not a valid method for delineating body fluid compartments in individuals with altered hydration (2); however, accurate delineation of intracellular volume is essential for estimation of muscle mass by BIA, although even the most accurate BIA-derived measure of intracellular volume will never be a perfect reflection of muscle volume, because BIA cannot distinguish between intracellular water from muscle cells and intracellular water from other tissues, such as the viscera, skin, and adipose tissue. Notwithstanding this, BIA can be a valid tool for estimation of body composition, including in patients with chronic kidney disease (3), and population-specific bioimpedance-based regression models can provide valid muscle mass estimates (4). Of note, though, in individuals with an altered intracellular-to-extracellular volume ratio ( e.g ., patients with chronic kidney disease), the 0/∞-kHz parallel Cole-Cole model is the method of choice for determining body water compartmentalization, as has been comprehensively shown by Gudivaka et al . (2). An adjustment …

Assessment of Body Composition in Dialysis Patients by Arm Bioimpedance Compared to MRI and 40K Measurements

This study used multi-frequency bioimpedance spectroscopy (BIS) of the arm and whole body to estimate muscle mass (MM) and subcutaneous adipose tissue (SAT) in 31 hemodialysis (HD) patients comparing these results with magnetic resonance imaging (MRI) and body potassium (⁴⁰K) as gold standards. Total body and arm MM (MM_MRI) and SAT (SAT_MRI) were measured by MRI. All measurements were made before dialysis treatment. Regression models with the arm (aBIS) and whole body (wBIS) resistances were established. Correlations between gold standards and the BIS model were high for the arm SAT (r² = 0.93, standard error of estimate (SEE) = 3.6 kg), and whole body SAT (r² = 0.92, SEE = 3.5 kg), and for arm MM (r² = 0.84, SEE = 2.28 kg) and whole body MM (r² = 0.86, SEE = 2.28 kg). Total body MM and SAT can be accurately predicted by arm BIS models with advantages of convenience and portability, and it should be useful to assess nutritional status in HD patients.