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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Sarcopenia: European consensus on definition and diagnosis Report of the European Working Group on Sarcopenia in Older People

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Bioelectrical impedance analysis--part I: review of principles and methods.

We employed a whole body magnetic resonance imaging protocol to examine the influence of age, gender, body weight, and height on skeletal muscle (SM) mass and distribution in a large and heterogene...

Skeletal muscle mass and distribution in 468 men and women aged 18–88 yr

BACKGROUND: The loss of muscle mass is considered to be a major determinant of strength loss in aging. However, large-scale longitudinal studies examining the association between the loss of mass and strength in older adults are lacking. METHODS: Three-year changes in muscle mass and strength were determined in 1880 older adults in the Health, Aging and Body Composition Study. Knee extensor strength was measured by isokinetic dynamometry. Whole body and appendicular lean and fat mass were assessed by dual-energy x-ray absorptiometry and computed tomography. RESULTS: Both men and women lost strength, with men losing almost twice as much strength as women. Blacks lost about 28% more strength than did whites. Annualized rates of leg strength decline (3.4% in white men, 4.1% in black men, 2.6% in white women, and 3.0% in black women) were about three times greater than the rates of loss of leg lean mass ( approximately 1% per year). The loss of lean mass, as well as higher baseline strength, lower baseline leg lean mass, and older age, was independently associated with strength decline in both men and women. However, gain of lean mass was not accompanied by strength maintenance or gain (ss coefficients; men, -0.48 +/- 4.61, p =.92, women, -1.68 +/- 3.57, p =.64). CONCLUSIONS: Although the loss of muscle mass is associated with the decline in strength in older adults, this strength decline is much more rapid than the concomitant loss of muscle mass, suggesting a decline in muscle quality. Moreover, maintaining or gaining muscle mass does not prevent aging-associated declines in muscle strength.

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The Loss of Skeletal Muscle Strength, Mass, and Quality in Older Adults: The Health, Aging and Body Composition Study

Chronic diseases are major killers in the modern era. Physical inactivity is a primary cause of most chronic diseases. The initial third of the article considers: activity and prevention definitions; historical evidence showing physical inactivity is detrimental to health and normal organ functional capacities; cause vs. treatment; physical activity and inactivity mechanisms differ; gene-environment interaction [including aerobic training adaptations, personalized medicine, and co-twin physical activity]; and specificity of adaptations to type of training. Next, physical activity/exercise is examined as primary prevention against 35 chronic conditions [Accelerated biological aging/premature death, low cardiorespiratory fitness (VO2max), sarcopenia, metabolic syndrome, obesity, insulin resistance, prediabetes, type 2 diabetes, non-alcoholic fatty liver disease, coronary heart disease, peripheral artery disease, hypertension, stroke, congestive heart failure, endothelial dysfunction, arterial dyslipidemia, hemostasis, deep vein thrombosis, cognitive dysfunction, depression and anxiety, osteoporosis, osteoarthritis, balance, bone fracture/falls, rheumatoid arthritis, colon cancer, breast cancer, endometrial cancer, gestational diabetes, preeclampsia, polycystic ovary syndrome, erectile dysfunction, pain, diverticulitis, constipation, and gallbladder diseases]. The article ends with consideration of deterioration of risk factors in longer-term sedentary groups; clinical consequences of inactive childhood/adolescence; and public policy. In summary, the body rapidly maladapts to insufficient physical activity, and if continued, results in substantial decreases in both total and quality years of life. Taken together, conclusive evidence exists that physical inactivity is one important cause of most chronic diseases. In addition, physical activity primarily prevents, or delays, chronic diseases, implying that chronic disease need not be an inevitable outcome during life.

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Lack of exercise is a major cause of chronic diseases

OBJECTIVE: To compare 16 currently used total body fat methods to a six-compartment criterion model based on in vivo neutron activation analysis. DESIGN: Observational, inter-method comparison study. SUBJECTS: Twenty-three healthy subjects (17 male and 6 female). MEASUREMENTS: Total body water (TBW) was measured by tritium dilution; body volume by underwater weighing (UWW); total body fat and bone mineral by dual-energy X-ray absorptiometry (DXA), total body potassium (TBK) by whole-body 40K counting; total body carbon, nitrogen, calcium, phosphorus, sodium and chlorine by in vivo neutron activation analysis; skinfolds/circumferences by anthropometry (Anth); and resistance by single-frequency bioimpedance analysis (BIA). RESULTS: The average of total body fat mass measurements by the six-compartment neutron activation model was 19.7±10.2 kg (mean±s.d.) and comparable estimates by other methods ranged from 17.4–24.3 kg. Although all 16 methods were highly correlated with the six-compartment criterion model, three groups emerged based on their comparative characteristics (technical error, coefficient of reliability, Bland-Altman analysis) relative to criterion fat estimates, in decreasing order of agreement: 1. multi-compartment model methods of Baumgartner (19.5±9.9 kg), Heymsfield (19.6±9.9 kg), Selinger (19.7±10.2 kg) and Siri-3C (19.6±9.9 kg); 2. DXA (20.0±10.8 kg), Pace-TBW (18.8±10.1 kg), Siri-2C (20.0±9.9 kg), and Brozek-UWW (19.4±9.2 kg) methods; and 3. Segal-BIA (17.4±7.2 kg), Forbes-TBN (21.8±10.5 kg), Durnin-Anth (22.1±9.5 kg), Forbes-TBK (22.9±11.9 kg), and Steinkamp-Anth (24.3±9.5 kg) methods. CONCLUSION: Relative to criterion fat estimates, body composition methods can be organized into three groups based on inter-method comparisons including technical error, coefficient of reliability and Bland-Altman analysis. These initial groupings may prove useful in establishing the clinical and research role of the many available fat estimation methods.

Six-compartment body composition model: inter-method comparisons of total body fat measurement.

Objectives: Air displacement plethysmography (ADP) may provide a partial alternative to body density (Bd) and therefore body composition measurement compared to conventional hydrodensitometry (Hd) in children. As there are no evaluation studies of ADP in children, this study had a two-fold objective: to compare Bd estimates by ADP and Hd; and to compare fat estimates by both ADP and Hd to fat estimates by another reference method, dual energy X-ray absorptiometry (DXA). Setting: Obesity Research Center, St. Luke’s=Roosevelt Hospital, New York, USA. Subjects: One hundred and twenty subjects (66 females=54 males) who ranged in age from 6 ‐ 86 y and in body mass index (BMI, kg=m 2 ) from 14.1 ‐ 40.0 kg=m 2 met study entry criteria. Study Design: Cross-sectional study of healthy children (age 19 y) and adult group for comparison to earlier studies. Each subject completed ADP, Hd, and DXA studies on the same day. Only subjects with subjectivelyjudged successful Hd studies were entered into the study cohort. Results: There was a high correlation between Bd by ADP and Hd (Bd Hda 0.11a 0.8966Bd ADP; ra 0.93, SEEa 0.008 g=cm 3 , P 0.9, P< 0.0001) with %fat by DXA in child and adult subgroups. Bland ‐ Altman analyses revealed no significant %fat bias by either ADP or Hd vs DXA in either children or adults, although a bias trend (Pa 0.11) was detected in the child subgroup. Conclusion: With additional refinements, the air displacement plethysmography system has the potential of providing an accurate and practical method of quantifying body fat in children as it now does in adults. Sponsorship: This study was in-part supported by NIH Grants RR00645, NIDDK 42618 and NIDDK 37352. Descriptors: air displacement plethysmography; body composition; hydrodensitometry; children

Body composition in children and adults by air displacement plethysmography.

Despite skeletal muscle's central role in the pathogenesis of sarcopenia, measurement methods remain underinvestigated and inadequately validated. Our review indicates that skeletal muscle (SM) measurement methods quantify different components and properties of muscle, ranging from the atomic to whole-body levels of body composition. Laboratory methods tend to measure whole body SM (e.g., total muscle protein, muscle cell mass, and adipose tissue-free SM components) while epidemiological methods tend to measure regional muscle (e.g., anatomic SM of an extremity). Advances in computerized axial tomography and magnetic resonance imaging methods now allow accurate estimates of whole body and regional SM and promise to finally permit comprehensive in vivo studies of SM biology and methodology. These imaging methods may help to resolve many of the confusing issues that surround the investigation of this major body composition component.

Measurement of Skeletal Muscle: Laboratory and Epidemiological Methods

Obesity prevalence rates are increasing worldwide and one prevailing hypothesis is that physical activity levels of modern humans are markedly reduced compared to those of our Paleolithic ancestors. We examine this hypothesis by deriving relative activity energy expenditure from available doubly labeled water and indirect calorimetry data in free-ranging non-human mammals. Our results, given the constraints posed by limited data availability, suggest that a low physical activity level, much less than that observed in free-ranging non-human mammals or highly active humans, is present in modern adult humans living within advanced settings. Our observations lend support to the hypothesis that low activity-related energy expenditure levels contribute to the rising worldwide prevalence of obesity.

Low physical activity levels of modern Homo sapiens among free-ranging mammals.

Objective: This overview examines concepts related to a category of body composition methods generally referred to as multi-component models, that is, those models that include three or more components. We summarize the rationale for, applications, and types of multi-component models along with sources of error. Our review presents the strengths and limitations of available models and identifies important future research directions. Sponsorship: National Institutes of Health Grant R01-N1DDK 42618. European Journal of Clinical Nutrition (2001) 55, 69–75

Z. M. Wang

Papers

Six-compartment body composition model: inter-method comparisons of total body fat measurement.

Body composition in children and adults by air displacement plethysmography.

Measurement of Skeletal Muscle: Laboratory and Epidemiological Methods

Low physical activity levels of modern Homo sapiens among free-ranging mammals.

Multi-component body composition models: recent advances and future directions.