Article

The prevalence of sarcopenia before and after correction for DXA-derived fat-free adipose tissue

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Abstract

The literature suggests that the estimate of lean mass may be overestimated in the obese using dual-energy X-ray absorptiometry (DXA), as ~15% of adipose tissue is composed of fat-free tissue. The purpose of this study was to investigate how the DXA-derived fat-free adipose influences appendicular lean mass and prevalence of sarcopenia across a range of body fat % in both men and women using a national sample (n=1946). The appendicular lean mass/m(2) went from 7.0 kg/m(2) (confidence interval (CI): 6.9, 7.2) to 5.9 kg/m(2) (CI: 5.8, 6.1) following correction in those with ⩾35% body fat, whereas it only went from 7.5 kg/m(2) (CI: 7.2, 7.8) to 7.1 kg/m(2) (CI: 6.8, 7.4) following correction in those with <25% body fat. Fat-free adipose tissue may need to be accounted for when estimating appendicular lean mass and failure to account for fat-free adipose tissue may underestimate the prevalence of sarcopenia.European Journal of Clinical Nutrition advance online publication, 10 August 2016; doi:10.1038/ejcn.2016.138.

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... [11] Recently, Loenneke and colleagues investigated the prevalence of low muscle mass before and after correction for DXA-derived appendicular FFAT in a sample from the National Health and Nutrition Examination Survey (NHANES). [12] The authors found that the prevalence of low muscle mass increased following the correction for appendicular FFAT. [12] However, the previous study used traditional definitions (cutoff values without correction for FFAT). ...
... [12] The authors found that the prevalence of low muscle mass increased following the correction for appendicular FFAT. [12] However, the previous study used traditional definitions (cutoff values without correction for FFAT). Therefore, it is unknown whether the prevalence of low muscle mass differs between cutoff values for DXAderived aLM that have been corrected for FFAT from those that have not been. ...
... Recently, Loenneke and colleagues [12] investigated the prevalence of low muscle mass before and after correction for DXA-derived aFFAT in a sample from the National Health and Nutrition Examination Survey (NHANES 1999(NHANES -2000. The authors reported that the prevalence of low muscle mass increased following the correction for FFAT in men and women. ...
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Background/objectives: To investigate the impact of eliminating fat-free adipose tissue (aFFAT) on the prevalence of low muscle mass in older adults. Subjects/methods: Three hundred and forty-three (153 men and 190 women) well-functioning Japanese older adults (aged 65-79) had their appendicular lean mass (aLM) and appendicular fat mass (aFM) measured using dual-energy X-ray absorptiometry (DXA). aFFAT was then estimated from DXA-derived aFM (aFM = (FM/0.15)*0.85). Both traditional cutoffs and those corrected for aFFAT were used for diagnosing low muscle mass. Results: With traditional cutoff values, the prevalence of low muscle mass using the unadjusted aLM index was 20.1%. After adjusting the aLM index for aFFAT, the prevalence increased to 49.0% (p < 0.001). However, when the cutoff values were also adjusted for aFFAT, the prevalence of low muscle mass only increased to 23.0% (p < 0.001). Further, ~5% of the participants (7 men and 8 women) were newly classified as having low muscle mass after correction for aFFAT. However, several women (n = 5) were not classified as having low muscle mass using the corrected cutoff value, although they would have been when using the non-corrected cutoff. Conclusions: Adjusting for the effect of aFFAT on DXA-derived aLM significantly increases the prevalence of low muscle mass in older adults. For clinical research and practice, the influence of aFFAT on DXA-derived aLM may need to be taken into consideration when diagnosing low muscle mass.
... For instance, a study reported that the difference in appendicular FFAT between the low ( < 25% body fat) and high ( 35% body fat) body fat groups is 2.0 kg in middleaged and older women. 10 Recently, Loenneke et al (2016) investigated the prevalence of sarcopenia before and after correction for DXA-derived appendicular FFAT in a sample from the 1999-2000 National Health and Nutrition Examination Survey (n 5 1946). 11 The authors found that the prevalence of sarcopenia increases following the correction for FFAT, and the percent change in prevalence is much greater in the highest percent body fat group. ...
... 10 Recently, Loenneke et al (2016) investigated the prevalence of sarcopenia before and after correction for DXA-derived appendicular FFAT in a sample from the 1999-2000 National Health and Nutrition Examination Survey (n 5 1946). 11 The authors found that the prevalence of sarcopenia increases following the correction for FFAT, and the percent change in prevalence is much greater in the highest percent body fat group. 11 Therefore, FFAT may need to be accounted for when measuring or estimating aLM to evaluate "true" muscle mass loss with age, especially for individuals with high body fat content. ...
... 11 The authors found that the prevalence of sarcopenia increases following the correction for FFAT, and the percent change in prevalence is much greater in the highest percent body fat group. 11 Therefore, FFAT may need to be accounted for when measuring or estimating aLM to evaluate "true" muscle mass loss with age, especially for individuals with high body fat content. ...
Article
Objectives: To develop regression-based equations for estimating dual-energy x-ray absorptiometry (DXA) derived appendicular fat-free adipose tissue (FFAT) using a single ultrasound image in the forearm, and to investigate the validity of those equations to calculate FFAT-free appendicular lean mass (aLM-minus-FFATappendicular ) in 311 Japanese adults aged 60 to 79 years. Methods: Subjects were randomly separated into two groups: 215 in the model-development group (91 men and 124 women) and 96 in the cross-validation group (42 men and 54 women). Appendicular fat mass and aLM were measured by the DXA, and subcutaneous adipose tissue (AT-forearm) and muscle (MT-ulna) thicknesses were measured by ultrasound. Appendicular FFAT was calculated based on the results of a previous study (appendicular FFAT = appendicular fat mass/0.85 x 0.15). The aLM was estimated from MT-ulna using a previously published equation (aLM = 4.89 x MT-ulna x body height - 9.15). Stepwise linear regression analysis was used to determine predictive models for DXA-derived appendicular FFAT from AT-forearm, sex, age, and anthropometrical variables. The best ultrasound prediction equation for estimation of appendicular FFAT was developed and then cross-validated in a subsample of older adults. Results: There was no significant difference between the DXA-derived and ultrasound-predicted aLM-minus-FFATappendicular . A strong correlation was observed between the DXA-derived and ultrasound-predicted aLM-minus-FFATappendicular (r = 0.935, P < .001). Bland-Altman analysis did not indicate a bias in the prediction of the aLM-minus-FFATappendicular for the validation group. Conclusions: Our results indicated that a single ultrasound forearm measurement can be used to accurately estimate DXA-derived aLM-minus-FFATappendicular in Japanese older adults, which may be advantageous for community-based physical examinations.
... Approximately 85% of adipose tissue is fat, and approximately 15% consists of FFAT. Adipose-free adipose tissue may need to be taken into account when measuring lean body mass in the extremities using DXA, and uncorrected DXA-derived FFAT may underestimate the true prevalence of sarcopenia (46,47). Although our results did not show a benefit of exercise combined with HMB supplementation on body composition in patients with sarcopenia, the combination of HMB supplementation and resistance exercise may still be a potential strategy to improve sarcopenia and obesity based on the aforementioned studies (12). ...
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Objectives This systematic review and meta-analysis aimed to assess the effects of exercise with/without β-hydroxy-β-methylbutyrate (HMB) supplementation on muscle mass, muscle strength, physical performance, and body composition in patients with sarcopenia. Methods A literature search for randomized controlled trials (RCTs) on the effects of exercise with or without HMB supplementation on muscle mass, muscle strength, physical performance, and body composition in patients with sarcopenia was conducted using PubMed, Web of Science, EBSCO, The Cochrane Library, EMBASE, Scopus, Science Direct, China Knowledge Resource Integrated Database (CNKI), and Wan Fang database. The search was limited to studies published up to April 2024 for each database. The outcome measures included muscle mass, muscle strength, physical performance, and body composition. The Cochrane Risk of Bias Assessment Tool was used to evaluate the quality of the included literature, and RevMan 5.4 software was employed to perform a meta-analysis of the outcome indicators. Results Five RCTs involving 257 elderly patients with sarcopenia were included in this study. Meta-analysis showed that in terms of physical performance, exercise with HMB supplementation significantly increased gait speed in sarcopenic patients compared to the exercise combined with the placebo group (SMD = 0.48, 95% CI: 0.15 to 0.82, p = 0.005), but exercise combined with HMB supplementation did not have significant effects on SMI (SMD = 0.06, 95% CI: −0.20 to 0.32, p = 0.66), grip strength (SMD = 0.23, 95% CI: −0.05 to 0.52, p = 0.11), five-time chair stand test (SMD = –0.83, 95% CI: −1.88 to 0.21, p = 0.12), fat-free mass (SMD = 0.04, 95% CI: –0.26 to 0.35, p = 0.78), BMI (SMD = –0.09, 95% CI: –0.43 to 0.25, p = 0.60), and fat mass (SMD = 0.01, 95% CI: –0.25 to 0.27, p = 0.94). Conclusion The current evidence indicates that exercise with HMB supplementation may enhance physical performance in patients with sarcopenia compared to exercise with the placebo group. However, the effects on muscle mass, muscle strength, and body composition are likely minimal. The above findings are limited by the number of included studies and require further validation through high-quality studies. Systematic Review Registration Prospero (CRD42024500135).
... In addition, we also performed computations to adjust for the presence of FFAT (fat free adipose tissue), as outlined in this seminal paper by Takashe Abe et al. [31]. Presence or absence of sarcopenia is determined by the extent of FFAT [32]. ...
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This study addresses the pressing need for improved methods to predict lean mass in adults, and in particular lean body mass (LBM), appendicular lean mass (ALM), and appendicular skeletal muscle mass (ASMM) for the early detection and management of sarcopenia, a condition characterized by muscle loss and dysfunction. Sarcopenia presents significant health risks, especially in populations with chronic diseases like cancer and the elderly. Current assessment methods, primarily relying on Dual-energy X-ray absorptiometry (DXA) scans, lack widespread applicability, hindering timely intervention. Leveraging machine learning techniques, this research aimed to develop and validate predictive models using data from the National Health and Nutrition Examination Survey (NHANES) and the Action for Health in Diabetes (Look AHEAD) study. The models were trained on anthropometric data, demographic factors, and DXA-derived metrics to accurately estimate LBM, ALM, and ASMM normalized to weight. Results demonstrated consistent performance across various machine learning algorithms, with LassoNet, a non-linear extension of the popular LASSO method, exhibiting superior predictive accuracy. Notably, the integration of bone mineral density measurements into the models had minimal impact on predictive accuracy, suggesting potential alternatives to DXA scans for lean mass assessment in the general population. Despite the robustness of the models, limitations include the absence of outcome measures and cohorts highly vulnerable to muscle mass loss. Nonetheless, these findings hold promise for revolutionizing lean mass assessment paradigms, offering implications for chronic disease management and personalized health interventions. Future research endeavors should focus on validating these models in diverse populations and addressing clinical complexities to enhance prediction accuracy and clinical utility in managing sarcopenia.
... These discussions mainly involve the criterion for determining sarcopenia, which can vary widely. It is worth noting that the fat-free mass corrected for fat-free adipose tissue (estimated from DXA measurements) should be considered since the latter may have a potential confounding effect when assessing the prevalence of sarcopenia (77). Therefore, reaching a consensus on the definition of sarcopenia is crucial to advance research in the field, and more importantly, to determine the prognostic value of a sarcopenia diagnosis and the appropriate RT strategies for affected older adults (78). ...
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Background Sarcopenic obesity (SO) is a clinical and functional disease characterized by the coexistence of obesity and sarcopenia. Resistance training (RT) characteristics for older adults with sarcopenia or obesity are already well established in the scientific literature. Nonetheless, we still do not know how detailed the RT protocols are described for older adults with SO. Therefore, we aimed to analyze the characteristics of RT programs, including each of their variables, recommended for older adults with SO. Methods This is a scoping review study that was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis for Scoping Reviews. The search was carried out until November 2022 in PubMed/MEDLINE, EMBASE, Cochrane Library, Web of Science, Scopus, LILACS, Google Scholar, and medRxiv databases. The studies included SO diagnosis and RT as an intervention strategy. The RT variables analyzed were as follows: exercise selection, the volume of sets, the intensity of load, repetition cadence, rest interval between sets, and weekly frequency. Results A total of 1,693 studies were identified. After applying the exclusion criteria, 15 studies were included in the final analysis. The duration of the RT intervention ranged from 8 to 24 weeks. All studies included full-body routines, with single/multi-joint exercises. Regarding the volume of sets, some studies fixed it in three sets, whereas others varied between one and three sets. The load was reported by repetition range and the weight lifted, elastic-band color/resistance, percentage of one repetition maximum, or perceived exertion scale. Repetition cadence was fixed in some studies, while it was self-selected between concentric and eccentric phases in others. The interval between sets of rest varied from 30 to 180 s. All studies reported progression overload during the interventions. Not all studies reported how the exercise selection, repetition cadence, and rest interval were made. Conclusion The characteristics of RT protocols and their variables prescribed in the literature for older adults with SO were mapped. The lack of detail on some training variables (i.e., exercise selection, repetition cadence, and rest interval) was identified. RT protocols are heterogeneous and described only partially among studies. The recommendations for RT prescription details in older adults with SO are provided for future studies. Systematic review registration https://osf.io/wzk3d/.
... Measuring the skeletal muscle mass is the most crucial element for the diagnosis of sarcopenia. These measurements can be taken using several technologies, including dual energy X-ray absorption (DXA) (9), ultrasound (US) (10), computed tomography (CT) (11,12), and magnetic resonance imaging (MRI) (13). DXA is currently the most widely used technology, its standardized approach in diagnosis of sarcopenia was proposed by European Working Group on Sarcopenia in Older People in 2010 (1). ...
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Rationale and Objectives Skeletal muscle mass measurement is the most important element for diagnosing sarcopenia. MRI has an excellent soft-tissue contrast, which can non-invasively assess abdominal skeletal muscle area (SMA) as well as CT. This study aimed to assess the validity and reliability of abdominal SMA measurement by comparing CT and MRI based on the fat image of IDEAL-IQ sequence at the lumbar level mid-L3. Materials and Methods CT and MRI images of 32 patients diagnosed with various kidney diseases were used to analyze intra-observer variability among abdominal SMA measurements. This was done to evaluate the correlation of SMA between CT and fat images of MRI. SMA images were segmented using Materialise Mimics software before quantification. Interobserver reliability and validation of measurements was evaluated by two independent investigators. Abdominal SMA reproducibility and correlation between CT and MRI were then assessed using the intraclass correlation coefficient (ICC), coefficient of variation (CV), Bland-Altman plot, and Pearson's correlation coefficient respectively. Results The interobserver reliability of MRI was excellent. The CV value was 2.82% while the ICC values ranged between 0.996 and 0.999. Validity was high (CV was 1.7% and ICC ranged between 0.986 and 0.996) for measurements by MRI and CT. Bland Altman analysis revealed an average difference of 2.2% between MRI and CT. The Pearson's correlation coefficient was 0.995 (p < 0.0001). This result revealed that there was a strong correlation between the two technologies. Conclusion MRI exhibited good interobserver reliability and excellent agreement with CT for quantification of abdominal SMA.
... This is also in line with previous work reporting a positive intercept and a slope steeper than 1 [15]. It has been suggested that protein or other material in adipose tissue may contribute to this over estimation of muscle mass by DXA [31,32]. However, adjustments to account for connective tissue, fat infiltration and none bone mineral content of bones [7,33] did not remove this bias. ...
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Magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry (DXA) were used to assess changes in thigh lean mass in septuagenarian men and women during a 5-year longitudinal study. Twenty-four older individuals participated in the study (10 men: 71.6 ± 4.1 years; 14 women: 71.3 ± 3.2 years at baseline). Thigh MRI and whole-body DXA scans were used to estimate changes in thigh lean mass. Both MRI and DXA showed that thigh lean mass was reduced by approximately 5% (P = 0.001) over the 5-year period in both men and women. The percentage loss of muscle mass determined with MRI and DXA showed moderate correlation (R² = 0.466; P < 0.001). Bland–Altman analysis showed that the average change over 5 years of follow-up measured by DXA was only 0.18% greater than MRI, where the limits of agreement between DXA and MRI were ± 10.4%. Baseline thigh lean mass did not predict the percentage loss of thigh lean mass over the 5-year period (R² = 0.003; P = 0.397), but a higher baseline body fat percentage was associated with a larger loss of thigh muscle mass in men (R² = 0.677; P < 0.003) but not in women (R² = 0.073; P < 0.176). In conclusion, (1) DXA and MRI showed a similar percentage loss of muscle mass over a 5-year period in septuagenarian men and women that (2) was independent of baseline muscle mass, but (3) increased with higher baseline body fat percentage in men.
... [25][26][27] For such reasons, when available, an assessment of FM may help identifying those individuals with excess adiposity that may impair health. A FM25% in men and 35% in women has been suggested to be used for defining obesity, 28,29 however, sex, age, and race/ethnicity-specific cut-off have been proposed in the literature. 30 Importantly, sarcopenic obesity may develop following 2 different scenarios: 1 associated with weight gain, with a disproportional increase in FM compared to LM, and 1 associated with weight loss in individuals with obesity and severe obesity in which weight loss and FM loss may be paralleled with a significant amount of LM loss (Fig 3). ...
Article
The role of body composition in patients with heart failure (HF)has been receiving much attention in the last few years. Particularly, reduced lean mass (LM), the best surrogate for skeletal muscle mass, is independently associated with abnormal cardiorespiratory fitness (CRF)and muscle strength, ultimately leading to reduced quality of life and worse prognosis. While in the past, reduced CRF in patients with HF was thought to result exclusively from cardiac dysfunction leading to reduced cardiac output at peak exercise, current evidence supports the concept that abnormalities in LM may also play a critical role. Abnormalities in the LM body composition compartment are associated with the development of sarcopenia, sarcopenic obesity, and cachexia. Such conditions have been implicated in the pathophysiology and progression of HF. However, identification of such conditions remains challenging, as universal definitions for sarcopenia, sarcopenic obesity, and cachexia are lacking. In this review article, we describe the most common body composition abnormalities related to the LM compartment, including skeletal and respiratory muscle mass abnormalities, and the consequences of such anomalies on CRF and muscle strength in patients with HF. Finally, we discuss the potential nonpharmacologic therapeutic strategies such as exercise training (ie, aerobic exercise and resistance exercise)and dietary interventions (ie, dietary supplementation and dietary patterns)that have been implemented to target body composition, with a focus on HF.
... This methodology may provide a noninvasive and radiation-free assessment for human study. If this method is impractical or unavailable, there is also a method to indirectly estimate the fat-free adipose tissue mass (FFAT) using the constant ratio of FFAT to fat found in adipose tissue fat cells (7)(8)(9)(10). Aclassical study investigating the chemical composition of adipose tissue using 61 biopsy specimens reported that adipose tissue contains roughly 61%-94% fat in humans ranging in age from 14 to 93years (11). ...
... [6,7] That increase in lean mass with higher fat mass is age-, sex-, and race/ethnicity-dependent; to what degree it is accounted for by differences in physical activity is unknown. [5,23,33] Failure to account for adiposity in sarcopenia definitions may lead to misclassification of patients with a relative deficit in lean for their amount of adiposity. Our analysis suggests that this misclassification may be particularly relevant in CKD as only low ALMI FMI for age was significantly associated with CKD while low ALMI for age was not. ...
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Aims Conventional definitions of sarcopenia based on lean mass fail to capture low lean mass relative to fat mass, i.e., relative sarcopenia. Unlike percent body fat (%BF) and Quételet's (body mass) index (BMI, kg/m ² ), definitions of obesity based on fat mass index (FMI, kg/m ² ) are not confounded by lean mass. The objective is to determine the prevalence of sarcopenia, relative sarcopenia, and obesity in CKD, and determine if CKD is associated with relative sarcopenia and obesity, independent of demographics and comorbidities. Methods and Results DXA‐derived appendicular lean mass index (ALMI, kg/m ² ) and FMI were assessed in 13,980 NHANES participants. ALMI, FMI, and ALMI relative to FMI (ALMI FMI ) were expressed as sex‐ and race/ethnicity‐specific standard deviation scores compared with young adults (T‐scores) and by age (Z‐scores). Sarcopenia was defined as ALMI T‐score < −2, relative sarcopenia as ALMI FMI T‐score < −2, and low lean mass relative to fat mass for age as ALMI FMI Z‐score < −1. Obesity was defined using conventional BMI and %BF cutpoints and as sex‐ and race/ethnicity‐specific FMI cutpoints. Glomerular filtration rate (GFR) was estimated using creatinine‐ (eGFR Cr ) and cystatin C‐ (eGFR Cys ). The prevalence of relative sarcopenia was higher than the prevalence of sarcopenia, especially in CKD stages 3b and 4 using eGFR Cr ; these CKD stages were associated with the highest FMI. CKD stage was independently associated with low ALMI FMI for age using eGFR Cys . BMI underestimated and %BF overestimated the prevalence of obesity compared with FMI. CKD was not independently associated with obesity by FMI. Conclusions In CKD, conventional definitions of sarcopenia underestimate muscle deficits and %BF overestimates the prevalence of obesity. CKD is independently associated with relative sarcopenia, but not excess adiposity.
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We recently reported the fat fraction percentage of white adipose tissue in adolescents and adults measured by the water-fat separation method, but there was limited discussion about the change in adipose tissue fat fraction with growth. The purpose of this updated review was to examine the fat content of white (subcutaneous) adipose tissue during the process from birth to adulthood by adding the latest available data. A relevant database was searched through November 2020. Nineteen studies were included. We found that calculated mean values of fat fraction percentage in white adipose tissue were 72.2% in neonates, 87.2% in children, and 87.4% in adults. In contrast, fat fraction percentage of truncal white adipose tissue in the fetuses was from 10% to 24% (29 and 34 weeks of gestational age, respectively). Our results suggest that the fat fraction percentage of white adipose tissue may not undergo large changes during the process from birth to adulthood (neonates = 72.2%, children = 87.2%, adults = 87.4%), which was different from the results of a study utilizing a biopsy. The mean value and range of fat fraction percentages for children over 7 years old were especially similar to adults. Further, the fat fraction percentage for neonates was relatively close to the results of children and adults. At the moment, the characteristics of the changes in fat fraction percentage of adipose tissue from birth to preschool children are unclear and future research is needed to clarify this issue.
Chapter
Muscle and bone are tightly coupled in both form and function across the lifespan. A better understanding of how muscle and bone interact is needed to optimize preventive and therapeutic strategies that can reduce the burden of musculoskeletal diseases, such as sarcopenia and osteoporosis. In this chapter, we begin by examining the interactions between muscle and bone from mechanical to biological levels. We then discuss the clinical significance of age-associated muscle and bone loss and provide a brief overview of techniques used to assess sarcopenia in clinical and research settings. We conclude by summarizing the pharmacologic and lifestyle-based interventions currently available, with a focus on how obesity affects sarcopenia and osteoporosis.
Article
Background & aims: B-mode ultrasound accurately measures both muscle mass, body density and percent body fat (% BF) in younger adults, but how well it can estimate % BF in middle-aged and older adults using DXA-derived %BF as the criterion is unclear. We sought to develop % BF prediction equations for middle-aged and older adults using ultrasound subcutaneous fat thickness (SFT). Methods: A cross-sectional study of Japanese adults (n = 414, 50-79 years) where 276 subjects were randomly assigned to a model development group and the other 138 subjects were assigned to a cross-validation group. B-mode ultrasound measured SFT at nine sites. Dual energy X-ray absorptiometry (DXA) measured % BF, arm fat mass (FM) and leg FM. Stepwise multiple linear regression developed prediction equations from anthropometric data (body mass, height, waist and hip circumference) and ultrasound SFT sites. Bland-Altman plots assessed validity of the prediction equations to measure % BF in the cross-validation group. Results: The best prediction equation for % BF was the following: [% BF = 15.709 + (1.753*anterior trunk SFT) + (5.626*Sex) + (3.635*posterior upper arm SFT) - (4.428*anterior lower leg SFT) - (0.170*height) + (0.264*waist) + (anterior thigh SFT*2.241); r2 = 0.809, standard error of the estimate (SEE) = 3.3 kg]. Arm FM and leg FM prediction equations had r2 values ranging from 0.690 to 0.812 and SEEs of 0.29 and 0.75 kg. A small mean bias was noted for estimating % BF (-0.14%), but large limits of agreement were found (-8.0-7.7%) and systematic error was noted in all of the equations (r = 0.275 to 0.515, p < 0.05). Conclusions: Despite high r2 values and a small mean bias found between predicted and DXA % BF, wide limits of agreement were found with some systematic error present. Therefore, these prediction equations for middle-aged and older adults may not be sufficiently accurate to use in a clinical setting.
Article
Objective Dual-energy X-ray absorptiometry (DXA)-derived appendicular lean soft tissue mass (aLM) is used to diagnose sarcopenia. However, DXA-derived aLM includes non-skeletal muscle components, such as fat-free component of adipose tissue fat cell. These components, if not accounted for, could falsely inflate the aLM in individuals with a high amount of adipose tissue mass. B-mode ultrasound accurately measures muscle size in older adults. We sought to develop regression-based prediction equations for estimating DXA-rectified appendicular lean tissue mass (i.e. DXA-derived aLM minus appendicular fat-free adipose tissue (aFFAT); abbreviated as aLM minus aFFAT) using B-mode ultrasound. Design Cross-sectional study. Measurements Three hundred and eighty-nine Japanese older adults (aged 60 to 79 years) volunteered in the study. aLM was measured using a DXA, and muscle thickness (MT) was measured using ultrasound at nine sites. An ordinary least-squares multiple linear regression model was used to predict aLM minus aFFAT from sex, age and varying muscle thicknesses multiplied by height. Based on previous studies, we chose to use 4 MT sites at the upper and lower extremities (4-site MT model) and a single site (1-site MT model) at the upper extremity to develop prediction models. Results The linear prediction models (4 site MT model; R² = 0.902, adjusted R² = 0.899, and 1-site MT model; R² = 0.868, adjusted R² = 0.866) were found to be stable and accurate for estimating aLM minus aFFAT. Bootstrapping (n=1000) resulted in optimism values of 0.0062 (4-site MT model) and 0.0036 (1-site MT model). Conclusion The results indicated that ultrasound MT combined with height, age and sex can be used to accurately estimate aLM minus aFFAT in older Japanese adults. Newly developed ultrasound prediction equations to estimate aLM minus aFFAT may be a valuable tool in population-based studies to assess age-related rectified lean tissue mass loss.
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The purpose of this study was to examine the association between daily movement patterns and dual energy X-ray absorptiometry-determined body fat percent (DXA-BF%) among children and adolescents while applying both traditional and novel analytical procedures. Using data from the cross-sectional 2003-2006 National Health and Nutrition Examination Survey (n = 5607), physical activity was assessed via accelerometry, with the following movement patterns assessed: 1) meeting moderate-to-vigorous physical activity (MVPA) guidelines and engaging in more light-intensity physical activity (LIPA) than sedentary behavior (SB); 2) meeting MVPA guidelines, but engaging in less LIPA than SB; 3) not meeting MVPA guidelines, but engaging in more LIPA than SB; and 4) not meeting MVPA guidelines and engaging in less LIPA than SB. Various markers of adiposity (e.g., DXA-BF%) were assessed. Children in movement pattern 1 (52 %), compared to those in movement pattern 4, had significantly lower levels of BMI (∆ 2.2 kg/m(2)), waist circumference (∆ 6.5 cm), tricep skinfold (∆ 4.2 mm), subscapularis skinfold (∆ 2.6 mm), android BF% (∆ 7.6 %), gynoid BF% (∆ 5.1 %), and total BF% (∆ 5.2 %). Substituting 60 min/day of SB with MVPA resulted in a 4.6 % decreased estimate of total DXA-BF%. No findings were significant for adolescents. The low proportion of children engaging in ≥ 60 min/day of MVPA and accumulating relatively more LIPA than SB had the lowest DXA-BF%.
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Objectives: Magnetic resonance imaging (MRI) and dual-energy x-ray absorptiometry (DXA) were used to examine the thigh lean mass in young and old men and women. Methods: A whole-body DXA scan was used to estimate thigh lean mass in young (20 men; 22.4±3.1y; 18 women; 22.1±2.0y) and older adults (25 men; 72.3±4.9y; 28 women; 72.0±4.5y). Thigh lean mass determined with a thigh scan on the DXA or full thigh MRI scans were compared. Results: Although the thigh lean mass quantified by DXA and MRI in young and older participants were correlated (R(2)=0.88; p<0.001) the magnitude of the differences in thigh lean mass between young and old was smaller with DXA than MRI (old vs. young men 79.5±13.1% and 73.4±11.2%; old vs. young women 88.6±11.8% and 79.4±12.3%, respectively). Detailed analysis of MRI revealed 30% smaller quadriceps muscles in the older than young individuals, while the other thigh muscles were only 18% smaller. Conclusions: DXA underestimates the age-related loss of thigh muscle mass in comparison to MRI. The quadriceps muscles were more susceptible to age-related atrophy compared with other thigh muscles.
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The European Working Group on Sarcopenia in Older People (EWGSOP) developed a practical clinical definition and consensus diagnostic criteria for age-related sarcopenia. EWGSOP included representatives from four participant organisations, i.e. the European Geriatric Medicine Society, the European Society for Clinical Nutrition and Metabolism, the International Association of Gerontology and Geriatrics—European Region and the International Association of Nutrition and Aging. These organisations endorsed the findings in the final document. The group met and addressed the following questions, using the medical literature to build evidence-based answers: (i) What is sarcopenia? (ii) What parameters define sarcopenia? (iii) What variables reflect these parameters, and what measurement tools and cut-off points can be used? (iv) How does sarcopenia relate to cachexia, frailty and sarcopenic obesity? For the diagnosis of sarcopenia, EWGSOP recommends using the presence of both low muscle mass + low muscle function (strength or performance). EWGSOP variously applies these characteristics to further define conceptual stages as ‘presarcopenia’, ‘sarcopenia’ and ‘severe sarcopenia’. EWGSOP reviewed a wide range of tools that can be used to measure the specific variables of muscle mass, muscle strength and physical performance. Our paper summarises currently available data defining sarcopenia cut-off points by age and gender; suggests an algorithm for sarcopenia case finding in older individuals based on measurements of gait speed, grip strength and muscle mass; and presents a list of suggested primary and secondary outcome domains for research. Once an operational definition of sarcopenia is adopted and included in the mainstream of comprehensive geriatric assessment, the next steps are to define the natural course of sarcopenia and to develop and define effective treatment.
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Muscle mass decreases with age, leading to “sarcopenia, ” or low relative muscle mass, in elderly people. Sarcopenia is believed to be associated with metabolic, physiologic, and functional impairments and disability. Methods of estimating the prevalence of sarcopenia and its associated risks in elderly populations are lacking. Data from a population-based survey of 883 elderly Hispanic and non-Hispanic white men and women living in New Mexico (the New Mexico Elder Health Survey, 1993–1995) were analyzed to develop a method for estimating the prevalence of sarcopenia. An anthropometric equation for predicting appendicular skeletal muscle mass was developed from a random subsample(n = 199) of participants and was extended to the total sample. Sarcopenia was defined as appendicular skeletal muscle mass (kg)/height2 (m2) being less than two standard deviations below the mean of a young reference group. Prevalences increased from 13–24% in persons under 70 years of age to >50% in persons over 80 years of age, and were slightly greater in Hispanics than in non-Hispanic whites. Sarcopenia was significantly associated with self-reported physical disability in both men and women, independent of ethnicity, age, morbidity, obesity, income, and health behaviors. This study provides some of the first estimates of the extent of the public health problem posed by sarcopenia. Am J Epidemiol 1998; 147: 755–63.
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To compare two methods for classifying an individual as sarcopenic for predicting decline in physical function in the Health, Aging and Body Composition Study. Observational cohort study with 5 years of follow-up. Communities in Memphis, Tennessee, and Pittsburgh, Pennsylvania. Men and women aged 70 to 79 (N=2,976, 52% women, 41% black). Appendicular lean mass (aLM) was measured using dual energy x-ray absorptiometry, and participants were classified as sarcopenic first using aLM divided by height squared and then using aLM adjusted for height and body fat mass (residuals). Incidence of persistent lower extremity limitation (PLL) was measured according to self-report, and change in objective lower extremity performance (LEP) measures were observed using the Short Physical Performance Battery. There was a greater risk of incident PLL in women who were sarcopenic using the residuals sarcopenia method than in women who were not sarcopenic (hazard ratio (HR)=1.34, 95% confidence interval (CI)=1.11-1.61) but not in men. Those defined as sarcopenic using the aLM/ht(2) method had lower incident PLL than nonsarcopenic men (HR=0.76, 95% CI=0.60-0.96) and women (HR=0.75, 95% CI=0.60-0.93), but these were no longer significant with adjustment for body fat mass. Using the residuals method, there were significantly poorer LEP scores in sarcopenic men and women at baseline and Year 6 and greater 5-year decline, whereas sarcopenic men defined using the aLM/ht(2) method had lower 5-year decline. Additional adjustment for fat mass attenuated this protective effect. These findings suggest that sarcopenia defined using the residuals method, a method that considers height and fat mass together, is better for predicting disability in an individual than the aLM/ht(2) method, because it considers fat as part of the definition.
Sarcopenia: European consensus on definition and diagnosis: Report of the European Working Group on Sarcopenia in Older People
  • Aj Cruz-Jentoft
  • Jp Baeyens
  • Jm Bauer
  • Y Boirie
  • T Cederholm
  • F Landi