Sarcopenia: Definition, Epidemiology, and Pathophysiology
01 May 2013-Journal of Bone Metabolism (Korean Society for Bone and Mineral Research)-Vol. 20, Iss: 1, pp 1-10
TL;DR: The definition and epidemiology of sarcopenia and its underlying pathophysiology are addressed, together with results from Korean sarcopenic obesity study (KSOS) that was performed.
Abstract: The epidemiological trends that characterize our generation are the aging of the population. Aging results in a progressive loss of muscle mass and strength called sarcopenia, which is Greek for 'poverty of flesh'. Sarcopenia could lead to functional impairment, physical disability, and even mortality. Today, sarcopenia is a matter of immense public concern for aging prevention. Its prevalence continues to rise, probably as a result of increasing elderly populations all over the world. This paper addressed the definition and epidemiology of sarcopenia and its underlying pathophysiology. In addition, we summarized the abundant information available in the literature related to sarcopenia, together with results from Korean sarcopenic obesity study (KSOS) that we performed.
Citations
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TL;DR: The positive association between sarcopenia with falls and fractures in older adults strengthens the need to invest in sarc Openia prevention and interventions to evaluate its effect on falls and fracture.
Abstract: Sarcopenia is a potentially modifiable risk factor for falls and fractures in older adults, but the strength of the association between sarcopenia, falls, and fractures is unclear. This study aims to systematically assess the literature and perform a meta-analysis of the association between sarcopenia with falls and fractures among older adults. A literature search was performed using MEDLINE, EMBASE, Cochrane, and CINAHL from inception to May 2018. Inclusion criteria were the following: published in English, mean/median age ≥ 65 years, sarcopenia diagnosis (based on definitions used by the original studies' authors), falls and/or fractures outcomes, and any study population. Pooled analyses were conducted of the associations of sarcopenia with falls and fractures, expressed in odds ratios (OR) and 95% confidence intervals (CIs). Subgroup analyses were performed by study design, population, sex, sarcopenia definition, continent, and study quality. Heterogeneity was assessed using the I2 statistics. The search identified 2771 studies. Thirty-six studies (52 838 individuals, 48.8% females, and mean age of the study populations ranging from 65.0 to 86.7 years) were included in the systematic review. Four studies reported on both falls and fractures. Ten out of 22 studies reported a significantly higher risk of falls in sarcopenic compared with non-sarcopenic individuals; 11 out of 19 studies showed a significant positive association with fractures. Thirty-three studies (45 926 individuals) were included in the meta-analysis. Sarcopenic individuals had a significant higher risk of falls (cross-sectional studies: OR 1.60; 95% CI 1.37-1.86, P < 0.001, I2 = 34%; prospective studies: OR 1.89; 95% CI 1.33-2.68, P < 0.001, I2 = 37%) and fractures (cross-sectional studies: OR 1.84; 95% CI 1.30-2.62, P = 0.001, I2 = 91%; prospective studies: OR 1.71; 95% CI 1.44-2.03, P = 0.011, I2 = 0%) compared with non-sarcopenic individuals. This was independent of study design, population, sex, sarcopenia definition, continent, and study quality. The positive association between sarcopenia with falls and fractures in older adults strengthens the need to invest in sarcopenia prevention and interventions to evaluate its effect on falls and fractures.
421 citations
Cites background from "Sarcopenia: Definition, Epidemiolog..."
...This reflects the complex role of muscle as not only a strength generator but also an important organ performing protein storage, glucose regulation, hormone production, and other cellular mechanisms.(96) A discussion on the use of a single diagnostic criterion or a combination of diagnostic criteria for sarcopenia should take into account which criterion has the strongest predictive value on clinical outcomes....
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TL;DR: The definition of sarcopenia is now defined as a decline in walking speed or grip strength associated with low muscle mass, which leads to loss of mobility and function, falls, and mortality.
Abstract: Sarcopenia is now defined as a decline in walking speed or grip strength associated with low muscle mass Sarcopenia leads to loss of mobility and function, falls, and mortality Sarcopenia is a major cause of frailty, but either condition can occur without the other being present Sarcopenia is present in about 5 to 10 % of persons over 65 years of age It has multiple causes including disease, decreased caloric intake, poor blood flow to muscle, mitochondrial dysfunction, a decline in anabolic hormones, and an increase in proinflammatory cytokines Basic therapy includes resistance exercise and protein and vitamin D supplementation There is now a simple screening test available for sarcopenia—SARC-F All persons 60 years and older should be screened for sarcopenia and treated when appropriate
417 citations
Cites background from "Sarcopenia: Definition, Epidemiolog..."
...Normal aging is associated with approximately a 1 % loss of muscle from 30 years of age, and this loss tends to accelerate after the age of 70 years [15]....
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TL;DR: The molecular mechanisms associated with the pathology of muscle wasting in both sarcopenia and cachexia are discussed, as well as the intracellular effects of exercise training in attenuating the debilitating loss of muscle mass in these specific conditions are highlighted.
Abstract: Skeletal muscle provides a fundamental basis for human function, enabling locomotion and respiration. Transmission of external stimuli to intracellular effector proteins via signalling pathways is a highly regulated and controlled process that determines muscle mass by balancing protein synthesis and protein degradation. An impaired balance between protein synthesis and breakdown leads to the development of specific myopathies. Sarcopenia and cachexia represent two distinct muscle wasting diseases characterized by inflammation and oxidative stress, where specific regulating molecules associated with wasting are either activated (e.g. members of the ubiquitin‐proteasome system and myostatin) or repressed (e.g. insulin‐like growth factor 1 and PGC‐1α). At present, no therapeutic interventions are established to successfully treat muscle wasting in sarcopenia and cachexia. Exercise training, however, represents an intervention that can attenuate or even reverse the process of muscle wasting, by exerting anti‐inflammatory and anti‐oxidative effects that are able to attenuate signalling pathways associated with protein degradation and activate molecules associated with protein synthesis. This review will therefore discuss the molecular mechanisms associated with the pathology of muscle wasting in both sarcopenia and cachexia, as well as highlighting the intracellular effects of exercise training in attenuating the debilitating loss of muscle mass in these specific conditions.
280 citations
TL;DR: Evidence is provided that behavioral paradigms and signaling pathways that are involved in longevity also affect neuromuscular junction stability and sarcopenia, suggesting that the mechanisms involved in neuromUScular junction maintenance might be disturbed during aging.
Abstract: The neuromuscular junction is the chemical synapse between motor neurons and skeletal muscle fibers. It is designed to reliably convert the action potential from the presynaptic motor neuron into the contraction of the postsynaptic muscle fiber. Diseases that affect the neuromuscular junction may cause failure of this conversion and result in loss of ambulation and respiration. The loss of motor input also causes muscle wasting as muscle mass is constantly adapted to contractile needs by the balancing of protein synthesis and protein degradation. Finally, neuromuscular activity and muscle mass have a major impact on metabolic properties of the organisms. This review discusses the mechanisms involved in the development and maintenance of the neuromuscular junction, the consequences of and the mechanisms involved in its dysfunction, and its role in maintaining muscle mass during aging. As life expectancy is increasing, loss of muscle mass during aging, called sarcopenia, has emerged as a field of high medical need. Interestingly, aging is also accompanied by structural changes at the neuromuscular junction, suggesting that the mechanisms involved in neuromuscular junction maintenance might be disturbed during aging. In addition, there is now evidence that behavioral paradigms and signaling pathways that are involved in longevity also affect neuromuscular junction stability and sarcopenia.
274 citations
Cites background from "Sarcopenia: Definition, Epidemiolog..."
..., changes in testosterone, estrogen, growth hormone, IGF1) and muscle-specific changes in the anabolic or catabolic pathways, in mitochondrial function, and in excitation-contraction coupling (105, 229)....
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References
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TL;DR: The European Working Group on Sarcopenia in Older People (EWGSOP) developed a practical clinical definition and consensus diagnostic criteria for age-related sarcopenia as discussed by the authors.
Abstract: 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.
8,440 citations
TL;DR: Some of the first estimates of the extent of the public health problem posed by sarcopenia are provided, independent of ethnicity, age, morbidity, obesity, income, and health behaviors.
Abstract: 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.
3,478 citations
"Sarcopenia: Definition, Epidemiolog..." refers background in this paper
...Baumgartner et al.[12] were the first to develop a definition of sarcopenia with DXA....
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...1-fold higher rates compared with those with greater muscle mass.[12] However, ASM/ height(2) index is highly correlated with BMI as current criterion of obesity....
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...First, when Baumgartner et al.[12] used a cut-off point of two SD for ASM/height(2) in the young reference group to define sarcopenia, the prevalence of sarcopenia ranged from 13 to 24% in persons aged 65 to 70 years and was over 50% for those older than 80 years....
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...First, when Baumgartner et al.[12] used a cut-off point of two SD for ASM/height2 in the young reference group to define sarcopenia, the prevalence of sarcopenia ranged from 13 to 24% in persons aged 65 to 70 years and was over 50% for those older than 80 years....
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...In this study, the prevalence was higher for men over age 75 years (58%) than for women (45%).[12] In a similar study, the prevalence based on total skeletal mass determined by DXA was 10% for men and 8% for women between 60 and 69 years and 40 and 18%, respectively, for men and women over 80 years....
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TL;DR: The prevalence of obesity and diabetes continues to increase among US adults, and interventions are needed to improve physical activity and diet in communities nationwide.
Abstract: ContextRecent reports show that obesity and diabetes have increased in the
United States in the past decade.ObjectiveTo estimate the prevalence of obesity, diabetes, and use of weight control
strategies among US adults in 2000.Design, Setting, and ParticipantsThe Behavioral Risk Factor Surveillance System, a random-digit telephone
survey conducted in all states in 2000, with 184 450 adults aged 18 years
or older.Main Outcome MeasuresBody mass index (BMI), calculated from self-reported weight and height;
self-reported diabetes; prevalence of weight loss or maintenance attempts;
and weight control strategies used.ResultsIn 2000, the prevalence of obesity (BMI ≥30 kg/m2) was
19.8%, the prevalence of diabetes was 7.3%, and the prevalence of both combined
was 2.9%. Mississippi had the highest rates of obesity (24.3%) and of diabetes
(8.8%); Colorado had the lowest rate of obesity (13.8%); and Alaska had the
lowest rate of diabetes (4.4%). Twenty-seven percent of US adults did not
engage in any physical activity, and another 28.2% were not regularly active.
Only 24.4% of US adults consumed fruits and vegetables 5 or more times daily.
Among obese participants who had had a routine checkup during the past year,
42.8% had been advised by a health care professional to lose weight. Among
participants trying to lose or maintain weight, 17.5% were following recommendations
to eat fewer calories and increase physical activity to more than 150 min/wk.ConclusionsThe prevalence of obesity and diabetes continues to increase among US
adults. Interventions are needed to improve physical activity and diet in
communities nationwide.
2,779 citations
"Sarcopenia: Definition, Epidemiolog..." refers background in this paper
...Epidemiology of sarcopenia The epidemiological trends that characterize our generation are an obesity epidemic and the aging of the population.[23] Aging results in sarcopenia, which is Greek for ‘poverty of flesh’....
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TL;DR: To establish the prevalence of sarc Openia in older Americans and to test the hypothesis that sarcopenia is related to functional impairment and physical disability in older persons is established.
Abstract: OBJECTIVES: To establish the prevalence of sarcopenia in older Americans and to test the hypothesis that sarcope- nia is related to functional impairment and physical dis- ability in older persons. DESIGN: Cross-sectional survey. SETTING: Nationally representative cross-sectional sur- vey using data from the Third National Health and Nutri- tion Examination Survey (NHANES III). PARTICIPANTS: Fourteen thousand eight hundred eigh- teen adult NHANES III participants aged 18 and older. MEASUREMENTS: The presence of sarcopenia and the relationship between sarcopenia and functional impairment and disability were examined in 4,504 adults aged 60 and older. Skeletal muscle mass was estimated from bioimped- ance analysis measurements and expressed as skeletal mus- cle mass index (SMIskeletal muscle mass/body mass � 100). Subjects were considered to have a normal SMI if their SMI was greater than -one standard deviation above the sex-specific mean for young adults (aged 18-39). Class I sarcopenia was considered present in subjects whose SMI was within -one to -two standard deviations of young adult values, and class II sarcopenia was present in subjects whose SMI was below -two standard deviations of young adult values. RESULTS: The prevalence of class I and class II sarcope- nia increased from the third to sixth decades but remained relatively constant thereafter. The prevalence of class I (59% vs 45%) and class II (10% vs 7%) sarcopenia was greater in the older ( � 60 years) women than in the older men ( P � .001). The likelihood of functional impairment and disability was approximately two times greater in the older men and three times greater in the older women with class II sarcopenia than in the older men and women with a normal SMI, respectively. Some of the associations be- tween class II sarcopenia and functional impairment re- mained significant after adjustment for age, race, body mass index, health behaviors, and comorbidity. CONCLUSIONS: Reduced relative skeletal muscle mass in older Americans is a common occurrence that is signifi- cantly and independently associated with functional im- pairment and disability, particularly in older women. These observations provide strong support for the prevailing view that sarcopenia may be an important and potentially re- versible cause of morbidity and mortality in older persons. J Am Geriatr Soc 50:889-896, 2002.
2,710 citations
TL;DR: 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.
Abstract: 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.
2,266 citations
"Sarcopenia: Definition, Epidemiolog..." refers background in this paper
...[6] A 10-15% loss of leg strength per decade is seen until 70 years of age, after which a faster loss, ranging from 25% to 40% by decade, occurs.[7,8] It is estimated that a 10....
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...2) Operational definitions of sarcopenia based on SMI and muscle strength and function Muscle strength does not depend solely on muscle mass, and the relationship between strength and mass is not linear.[8,21] Therefore, from the initial definition of ‘age-related loss in skeletal muscle’, sarcopenia subsequently evolved to current operative definitions simultaneously capturing both quantitative (i....
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