The epidemiology of sarcopenia in community living older adults: what role does lifestyle play?

The association between inflammatory cytokines and sarcopenia-related traits: a bi-directional Mendelian randomization study

BACKGROUND

Sarcopenia is among the most common musculoskeletal illnesses, yet its underlying biochemical mechanisms remain incompletely understood. Identifying the relationship of inflammatory cytokines with sarcopenia components would help understand the etiology of sarcopenia. We performed a bi-directional Mendelian randomization study to explore the causal relationship between 41 inflammatory cytokines and sarcopenia-related traits.

METHODS

The study was performed in two stages using bidirectional dual-sample Mendelian randomization. We obtained aggregated statistical data on inflammatory factors, low grip strength, and ALM from genome-wide association studies. To explore the causal association between exposure and outcomes, we primarily utilized the inverse variance weighted strategy. Furthermore, we conducted sensitivity analyses through the use of Mendelian randomization (MR) Egger, weighted median and simple mode methods. To evaluate robustness of the results and to identify and adjust for horizontal pleiotropy, we performed the MR Pleiotropy RESidual Sum and Outlier test, the MR Egger intercept test, and a leave-one-out analysis.

RESULTS

The results displayed a potential association between interleukin-10 (OR: 1.046, 95% CI: 1.002-1.093, p = 0.042) and vascular endothelial growth factor (OR: 1.024, 95% CI: 1.001-1.047, p = 0.038) and the risk of low hand-grip strength. Moreover, interferon gamma-induced protein 10 (OR: 1.010, 95% CI: 1.000-1.019, p = 0.042) and macrophage colony-stimulating factor (OR: 1.010, 95% CI: 1.003-1.017, p = 0.003) were significantly linked to a higher risk of ALM.

CONCLUSION

We identified a causal relationship between multiple inflammatory factors and sarcopenia-related traits. Our study offers valuable insights into innovative methods for the sarcopenia prevention and treatment by regulating inflammatory factors.

Pathophysiology of sarcopenia: Genetic factors and their interplay with environmental factors

Sarcopenia is a geriatric disorder characterized by a progressive decline in muscle mass and function. This disorder has been associated with a range of adverse health outcomes, including fractures, functional deterioration, and increased mortality. The pathophysiology of sarcopenia is highly complex and multifactorial, involving both genetic and environmental factors as key contributors. This review consolidates current knowledge on the genetic factors influencing the pathogenesis of sarcopenia, particularly focusing on the altered gene expression of structural and metabolic proteins, growth factors, hormones, and inflammatory cytokines. While the influence of environmental factors such as physical inactivity, chronic diseases, smoking, alcohol consumption, and sleep disturbances on sarcopenia is relatively well understood, there is a dearth of studies examining their mechanistic roles. Therefore, this review emphasizes the interplay between genetic and environmental factors, elucidating their cumulative role in exacerbating the progression of sarcopenia beyond their individual effects. The unique contribution of this review lies in synthesizing the latest evidence on the genetic factors and their interaction with environmental factors, aiming to inform the development of novel therapeutic or preventive interventions for sarcopenia.

Nutrition Risk Is Associated with 3-Year Strength and Performance Indicators among Older Adults in the Canadian Longitudinal Study on Aging

OBJECTIVES

Determine if nutrition risk, as measured by SCREEN-8 is predictive of 3-year strength and performance indicators among community-living older adults after adjusting for key demographic and health variables. Sex-stratified analyses were also determined.

DESIGN

Cohort study with baseline and 3-year follow-up data from the Canadian Longitudinal Study on Aging (CLSA).

PARTICIPANTS

Participants 55 years and older at baseline were included (n = 22,502); those who reported nasogastric or abdominal tube feeding at either timepoint were excluded (n = 26). The final sample of participants available for analyses slightly varied depending on completion of the three outcome variables. List-wise deletion was used for nutrition risk and covariates to arrive at the sample available for analysis (n = 17,250).

MEASUREMENTS

The valid and reliable SCREEN-8 tool was used to measure nutrition risk. The minimum and maximum score of SCREEN-8 is 0 and 48, respectively, with lower scores indicating greater nutrition risk. Baseline SCREEN-8 score was used in analyses. Grip strength, chair rise test time and gait speed assessed at the 3-year follow-up were the strength and performance outcomes. Criteria outlined by the European Working Group on Sarcopenia in Older People 2 were used to determine low performance for grip strength (<27 kg for males and <16 kg for females), chair rise test time (>15 seconds) and gait speed (≤0.8 m/s).

RESULTS

Half of participants were female (49.4%) and mean age was 66.7 years (SD 7.9). Mean SCREEN-8 score was 39.2 (SD 6.0). Low grip strength, chair rise test performance and gait speed were found in 18.5%, 19.6% and 29.3% of participants, respectively. After adjusting for covariates (e.g., sex, age, education), SCREEN-8 score was significantly associated with grip strength (F = 11.21, p = .001; OR = 0.98, CI [0.97, 0.99]), chair rise time (F = 5.97, p = .015; OR = 0.99, CI [0.97, 0.997]), and gait speed (F = 9.99, p = .002; OR = 0.98, CI [0.97, 0.99]). Similar interpretation was seen in sex-stratified analyses, although chair rise time was not significant. Age, body mass index, Life Space Index Score and self-rated health were consistently associated with all outcome measures.

CONCLUSION

Nutrition risk, as measured by SCREEN-8, significantly predicted 3-year strength and performance measures. Greater nutrition risk is associated with an increased odds of low performance on grip strength, chair rise test, and gait speed. Future research should implement nutrition risk screening in primary care settings with subsequent assessment and treatment for at risk clients to determine if nutrition interventions implemented post screening can delay age-related losses in strength and performance.

Definition of an adapted cut-off for determining low lean tissue mass in older women with obesity: a comparison to current cut-offs

The prevalence of sarcopenia in patients with obesity varies according to the definition used. The purpose of our study was to: (i) determine the prevalence of sarcopenia in terms of lean tissue mass in older women with obesity using the current cut-offs, (ii) redefine a specific cut-off for low lean tissue mass (LLTM), and (iii) re-determine the prevalence of LLTM using this new cut-off. Appendicular lean mass (ALM) and the ALM index [ALM/height²: ALMI(h²)] and ALMI/body mass index [ALMI(BMI)] were determined in 791 women with or without obesity. LLMM prevalence was calculated using the current cut-offs: EWGSOP2: ALM < 15 kg and ALMI(h²) < 5.5 kg/m²; FNIH: ALM < 15.02 kg and ALMI(BMI) < 0.51; and IWGS: ALMI(h²) < 5.67 kg/m² and cut-offs newly determined from data provided from young women with obesity. ALM, ALMI(h²) and ALMI(BMI) were lower in older compared to young obese women. Using the current cut-offs, a wide distribution of LLTM prevalence (0 to 29.2%) was observed. When the newly determined cut-offs were applied – i.e., ALM < 18.51 kg; ALMI(h²) < 7.15 kg/m², ALMI(BMI) < 0.483, and T-score: [(ALMI(h²) measured)-(2.08 + 0.183*BMI)]/0.72] − the LLTM mass prevalence was 17.37%; 8.47, 14.8 and 12.71%. respectively. This study showed that the current cut-offs for LLTM as criteria for sarcopenia diagnosis are not adapted to the obese population. Although the new “static” cut-offs appeared to be more adapted, a “dynamic” cut-off for ALMI(h²) that took into account the BMI and thus the obesity severity appeared even more relevant.

Dietary patterns and sarcopenia in elderly adults: the Tianjin Chronic Low-grade Systemic Inflammation and Health (TCLSIH) study

Sarcopenia is a core contributor to several health consequences, including falls, fractures, physical limitations and disability. The pathophysiological processes of sarcopenia may be counteracted with the proper diet, delaying sarcopenia onset. Dietary pattern analysis is a whole diet approach used to investigate the relationship between diet and sarcopenia. Here, we aimed to investigate this relationship in an elderly Chinese population. A cross-sectional study with 2423 participants aged more than 60 years was performed. Sarcopenia was defined based on the guidelines of the Asian Working Group for Sarcopenia, composed of low muscle mass plus low grip strength and/or low gait speed. Dietary data were collected using a FFQ that included questions on 100 food items along with their specified serving sizes. Three dietary patterns were derived by factor analysis: sweet pattern, vegetable pattern and animal food pattern. The prevalence of sarcopenia was 16·1 %. The higher vegetable pattern score and animal food pattern score were related to lower prevalence of sarcopenia (P_trend = 0·006 and < 0·001, respectively); the multivariate-adjusted OR of the prevalence of sarcopenia in the highest v. lowest quartiles were 0·54 (95 % CI 0·34, 0·86) and 0·50 (95 % CI 0·33, 0·74), separately. The sweet pattern score was not significantly related to the prevalence of sarcopenia. The present study showed that vegetable pattern and animal food pattern were related to a lower prevalence of sarcopenia in Chinese older adults. Further studies are required to clarify these findings.

Lifestyle (Medicine) and Healthy Aging

Healthy aging is a process that occurs over the life cycle. Health habits established early and practiced throughout life impact longevity, the ability to reach old age, and the health with which one experiences older adulthood. The new field of lifestyle medicine addresses root causes of disease by targeting nutrition, physical activity, well-being, stress management, substance use, connectedness, and sleep. As a result, lifestyle medicine can optimize the trajectory of aging, and promote targets that have been recognized in geriatric medicine as essential to well-being and quality of life, resulting in a compression of morbidity.

Prevalence of probable sarcopenia in community-dwelling older Swiss people - a cross-sectional study

BACKGROUND

The European Working Group on Sarcopenia in Older People has recently defined new criteria for identifying "(probable) sarcopenia" (EWGSOP2). However, the prevalence of probable sarcopenia, defined by these guidelines, has not been determined extensively, especially in the oldest old. This study aims to determine the prevalence of probable sarcopenia in older, community-living people and its association with strength-related determinants.

METHODS

Handgrip strength and reported determinants (age, height, weight, osteoarthritis of hands, medications, fall history, physical activity, activities of daily living (ADL) and global cognitive function) were collected in a cross-sectional study of 219 community-living Swiss people (75 years and over). Probable sarcopenia was estimated based on cut-off values for handgrip strength as recommended by EWGSOP2. Spearman correlations, binary-regression analyses and contingency tables were used to explore relationships between variables.

RESULTS

The prevalence of probable sarcopenia in women (n = 137, age 84.1 ± 5.7 years) and men (n = 82, age 82.6 ± 5.2 years) was 26.3 and 28.0%, respectively. In women, probable sarcopenia correlated positively with age and falls (rs range 0.332-0.195, p < .05), and negatively with weight, cognition, physical activity, using stairs regularly, participating in sports activities and ADL performance (rs range = - 0.141 - -0.409, p < .05). The only significant predictor of probable sarcopenia at the multivariate level was ADL performance (Wald(1) = 5.51, p = .019). In men, probable sarcopenia was positively correlated with age (rs = 0.33, p < .05) and negatively with physical activity, participation in sports and ADL performance (rs range - 0.221 - - 0.353, p < .05). ADL performance and age (Wald(1) = 4.46, p = .035 and Wald(1) = 6.30, p = .012) were the only significant predictors at the multivariate level. Men and women with probable sarcopenia were 2.8 times more likely to be dependent in ADL than those without.

CONCLUSION

Probable sarcopenia affected one in every four community-living, oldest old people and was independently associated with impaired ADL performance in both sexes. This highlights the importance of detection of handgrip strength in this age group in clinical practice. Although prospective studies are required, independence in ADL might help to protect against probable sarcopenia.

The mechanisms and treatments for sarcopenia: could exosomes be a perspective research strategy in the future?

The age-related loss of muscle mass and muscle function known as sarcopenia is a primary contributor to the problems faced by the old people. Sarcopenia has been a major public health problem with high prevalence in many countries. The related underlying molecular mechanisms of sarcopenia are not completely understood. This review is focused on the potential mechanisms and current research strategies for sarcopenia with the aim of facilitating the recognition and treatment of age-related sarcopenia. Previous studies suggested that protein synthesis and degradation, autophagy, impaired satellite cell activation, mitochondria dysfunction, and other factors associated with muscle weakness and muscle degeneration may be potential molecular pathophysiology of sarcopenia. Importantly, we also prospectively highlight that exosomes (small vesicles) as carriers can regulate muscle regeneration and protein synthesis according to recent researches. Dietary strategies and exercise represent the interventions that can also alleviate the progression of sarcopenia. At last, building on recent studies pointing to exosomes with the roles in increasing muscle regeneration, mediating the beneficial effects of exercise, and serving as messengers of intercellular communication and as carriers for research strategies of many diseases, we propose that exosomes could be a potential research direction or strategies of sarcopenia in the future.

Late life maintenance and enhancement of functional exercise capacity in low and high responding rats after low intensity treadmill training

Intrinsic exercise capacity is predictive of both lifespan and healthspan but whether adaptive exercise capacity influences the benefits achieved from aerobic training implemented later in life is not known.

AIM

To determine if exercise late in life provides any functional improvements or underlying beneficial biochemical adaptations in rats bred to have a high response to training (HRT rats) or little to no response to training (LRT rats).

METHODS

Adult (11 months) and old (22 months) female LRT and HRT rats either remained sedentary (SED) or were exercised (EXER) on a treadmill 2-3 times/week at 60% of their initial maximum running speed and distance for 4 months. At 26 months of age, exercise capacity was re-evaluated and extensor digitorum longus, gastrocnemius (GTN), and tibialis anterior (TA) muscles were excised for histological and biochemical analysis.

RESULTS

Both SED-HRT and SED-LRT rats showed decreased exercise capacity from 22 to 26 months, but with 4 months of treadmill training, EXER-HRT rats displayed a 50% improvement in exercise capacity while EXER-LRT rats maintained pre-training levels. Protein levels of antioxidant enzymes PRDX3, CuZnSOD, and PRXV were 6-fold greater in TA muscles of aged HRT rats compared to LRT rats. PGC-1α protein levels were ~2-fold greater in GTN and TA muscles of aged HRT than in LRT rats and TFAM protein was similarly elevated in GTN muscles of aged HRT rats compared with LRT rats. BNIP3 protein levels were 5-fold greater in TA muscles of aged HRT than in LRT rats while PINK1 protein content was reduced by 78% in GTN muscles of aged HRT rats compared with LRT rats.

CONCLUSION

HRT rats retained the ability to improve exercise capacity into late life and that ability was associated with inherent and adaptive changes in antioxidant enzyme levels and markers of and mitochondrial quality related to healthspan benefits in aging. Moreover, low intensity exercise prevented the age-associated decline in functional exercise capacity in LRT rats.

Improving the comprehension of sarcopenic state determinants: An multivariate approach involving hormonal, nutritional, lifestyle and genetic variables

It is known that sarcopenia is a multifaceted phenomenon, which involves genetic, nutritional, hormonal and living habits aspects. Then, an integrated analysis, as a multivariate approach, could improve the comprehension about the determinants of sarcopenic state in old adults. The present study aimed to investigate the interaction among serum vitamin D, daily caloric and protein intake, lifestyle habits, ACE I/D gene polymorphism and sarcopenic state in community-dwelling old adults. One hundred one community-dwelling old adults were clinically stratified as sarcopenic or non-sarcopenic. Serum vitamin D, daily caloric and protein intake, lifestyle habits (smoking, physical activity level and sedentary behavior) and ACE I/D gene polymorphism were recorded. A multivariate logistic regression technique was applied to investigate the interaction among the selected independent variables and the sarcopenic state. The independent variables age, smoking, serum Vitamin D and ACE I/D polymorphism achieved the statistical criteria to be inserted in the multivariate analysis. After a stepwise procedure from the multivariate logistic regression, the variables age, serum Vitamin D and ACE I/D polymorphism remained, together, in the final model. Sarcopenic state was significantly associated to older age, II-genotype and low serum Vitamin D in old adults from 60 years old.

A potential strategy for counteracting age-related sarcopenia: preliminary evidence of combined exercise training and leucine supplementation

Previous research has demonstrated the positive effects of concurrent/combined aerobic and resistance exercise or leucine supplementation on skeletal muscle protein synthesis (MPS) and hypertrophy in aging organisms. However, the effects of a multimodal intervention which combines both aerobic and resistance exercise and leucine supplementation has not been fully elucidated. Eighteen month old and 2 month old C57BL/6 mice were assigned to aging control (AC, n = 8), aging and multimodal intervention (AMI, n = 8) and young control (YC, n = 8). Mice in the YC and AC groups were fed an alanine-rich diet (3.4%), and mice in the AMI group received an isonitrogenous leucine-supplemented (5%) diet in combination with combined aerobic (30 minutes swimming) and resistance exercise training (incremental jumping submersed in water with overload corresponding to 40%-50% body weight) for a total of 4 weeks. The gastrocnemius muscles were dissected for western blotting detection (signaling proteins involved in MPS) and the ex vivo determination of protein synthesis and protein content. The muscle strength of the hind limbs was measured pre-experiment and repeated once per week on Sunday for 4 weeks. Mice in the AC and AMI groups showed lower ex vivo protein synthesis, protein content, expression of signaling proteins involved in MPS, maximal grip strength but higher plasma cortisol compared with the YC group post intervention. When compared to AC mice, the multimodal treatment led to lower activity of Sestrin2, higher expression of PI3K III and the phosphorylation of mTOR, p70S6K and 4E-BP1, as well as higher plasma leucine, wet gastrocnemius muscle weight and muscle weight to body weight ratio. Furthermore, the multimodal intervention induced more pronounced anabolic response such as higher ex vivo protein synthesis rate, total protein content, and myofibrillar fractions in gastrocnemius muscle, and greater maximum grip strength. The present research shows that a multimodal intervention including combined both aerobic and resistance exercise training and 5% leucine supplementation has the potential to maintain skeletal muscle protein synthesis and attenuate losses in muscular strength during the aging process.

Isotemporal Substitution of Sedentary Behavior and Physical Activity on Function

The amount of time spent in sedentary behaviors (SB) progressively increases with age, while reducing time spent in light-intensity physical activity (LPA) and moderate- to vigorous-intensity physical activity (MVPA). These trajectories in PA and SB are linked to accelerated reductions in physical functioning.

PURPOSE

This study aimed to examine the association of substituting SB time with LPA and MVPA on physical function in older adults.

METHODS

Ninety-one older adults (mean age, 70.7 ± 10.2 yr) wore a hip-mounted accelerometer to measure SB, LPA, and MVPA time. Measures of physical function included a 400-m walk test (400W), the usual gait speed (UGS), the five times sit-to-stand (5xSTS) test, and the short physical performance battery (SPPB). Isotemporal substitution regression modeling was performed to assess the relationship of replacing the amount of time spent in one activity for another.

RESULTS

Replacing 30 min·d of SB with LPA was associated with a significant improvement in 400W (P = 0.0497), whereas MVPA resulted in a significant improvement (P < 0.01) in 400W, UGS, 5xSTS, and SPPB. Replacing 60 min·d of SB with 10 min·d of MVPA and 50 min·d of LPA was associated with significant improvements in the 400W, UGS, and 5xSTS (P < 0.05). Meanwhile, as little as 5 min·d of MVPA and 55 min·d of LPA were linked to a 78% increased odds of scoring with good function in the SPPB (P = 0.0247).

CONCLUSION

Replacing SB with LPA was linked to a significant improvement in the 400W, but not the other brief functional measures. Mixed doses of LPA and MVPA may add flexibility to interventions targeting reductions of SB in older adults for clinically relevant improvements in physical function.

Combination of alfacalcidol and calcium improved handgrip strength and mobility among Indonesian older women: A randomized controlled trial

AIM

To determine the effect of alfacalcidol on muscle strength and functional mobility in Indonesian older women whose handgrip strength was low.

METHODS

A randomized, double-blind controlled trial was carried out among 95 older women whose handgrip strength was ≤22 kg. Participants were randomized into two groups: 47 participants received alfacalcidol 0.5 μg/day and 48 participants received a placebo. Each participant in both groups was given calcium 500 mg/day. Handgrip strength as well as the Timed-Up and Go test were measured before and after 90 days of intervention. Per protocol analysis after intervention between two groups was carried out.

RESULTS

There was a significant improvement of handgrip strength in the group that received alfacalcidol compared with the placebo group (15.50 vs 13.75; P = 0.003). The median time for the Timed-Up and Go test in the alfacalcidol group also improved significantly compared with the placebo group (9.01 vs 10.07, P = 0.028).

CONCLUSIONS

Alfacalcidol with daily doses of 0.5 μg significantly improved muscle strength and functional mobility in Indonesian older women. Geriatr Gerontol Int 2018; 18: 434-440.

Public Health issues in hospital management of Sarcopenic patients

Sarcopenia is a combination of a progressive and generalized loss of skeletal muscle mass and muscle strength or physical performance, with high risk of adverse outcomes such as physical disability, poor quality of life and death. It mainly affects older people, aged 60-70 years. The development of sarcopenia is multifactor. The first step towards the management of sarcopenia is the proper and professional diagnosis. According to EWGSOP the diagnosis of sarcopenia depends on the presence of low muscle mass (LMM) plus low muscle strength (LMS) or low physical performance (LPP). Although it is difficult to establish its prevalence, the higher prevalence is observed in hospitalized elderly patients. It has direct and indirect impact on public health, which are difficult to be measured due to numerous negative outcomes of sarcopenia.

Mitochondria and ageing: role in heart, skeletal muscle and adipose tissue

Age is the most important risk factor for most diseases. Mitochondria play a central role in bioenergetics and metabolism. In addition, several lines of evidence indicate the impact of mitochondria in lifespan determination and ageing. The best-known hypothesis to explain ageing is the free radical theory, which proposes that cells, organs, and organisms age because they accumulate reactive oxygen species (ROS) damage over time. Mitochondria play a central role as the principle source of intracellular ROS, which are mainly formed at the level of complex I and III of the respiratory chain. Dysfunctional mitochondria generating less ATP have been observed in various aged organs. Mitochondrial dysfunction comprises different features including reduced mitochondrial content, altered mitochondrial morphology, reduced activity of the complexes of the electron transport chain, opening of the mitochondrial permeability transition pore, and increased ROS formation. Furthermore, abnormalities in mitochondrial quality control or defects in mitochondrial dynamics have also been linked to senescence. Among the tissues affected by mitochondrial dysfunction are those with a high-energy demand and thus high mitochondrial content. Therefore, the present review focuses on the impact of mitochondria in the ageing process of heart and skeletal muscle. In this article, we review different aspects of mitochondrial dysfunction and discuss potential therapeutic strategies to improve mitochondrial function. Finally, novel aspects of adipose tissue biology and their involvement in the ageing process are discussed.

The influence of physical fitness on pressure pain threshold of elderly women

Several factors may influence pressure pain threshold (PPT), including physical fitness. However, only a few authors have studied this relationship. The aim of this study was to investigate the relationships between muscle strength, functional capacity (ability to perform physical work and activities of daily living) and PPT in elderly women. This observational cross-sectional study involved 75 healthy women aged between 60 and 75 years. Volunteers underwent an evaluation consisting of anthropometry, functional capacity, muscle strength and PPT assessment by algometry in the following muscles: biceps brachii, flexor carpi ulnaris, flexor carpi radialis, vastus medialis, vastus lateralis and gluteus maximus. Mean age of the 75 volunteers was 66.8 ± 4.6 years old. No significant correlations were found between handgrip or elbow flexion strength and PPT in the upper limb muscles evaluated. The same was observed regarding functional capacity, lower limbs strength and PPT in lower limb muscles. Functional capacity and muscle strength did not correlate with PPT in healthy elderly women.

Physical activity and incidence of sarcopenia: the population-based AGES-Reykjavik Study

BACKGROUND

the prevalence of sarcopenia increases with age. Physical activity might slow the rate of muscle loss and therewith the incidence of sarcopenia.

OBJECTIVE

to examine the association of physical activity with incident sarcopenia over a 5-year period.

DESIGN

data from the population-based Age, Gene/Environment, Susceptibility-Reykjavik Study were used.

SETTING

people residing in the Reykjavik area at the start of the study.

SUBJECTS

the study included people aged 66-93 years (n = 2309).

METHODS

the amount of moderate-vigorous physical activity (MVPA) was assessed by a self-reported questionnaire. Sarcopenia was identified using the European Working Group on Sarcopenia in Older People algorithm, including muscle mass (computed tomography imaging), grip strength (computerised dynamometer) and gait speed (6 m).

RESULTS

mean age of the participants was 74.9 ± 4.7 years. The prevalence of sarcopenia was 7.3% at baseline and 16.8% at follow-up. The incidence proportion of sarcopenia over 5 years was 14.8% in the least-active individuals and 9.0% in the most-active individuals. Compared with the least-active participants, those reporting a moderate-high amount of MVPA had a significantly lower likelihood of incident sarcopenia (OR = 0.64, 95% CI 0.45-0.91). Participants with a high amount of MVPA had higher baseline levels of muscle mass, strength and walking speed, but baseline MVPA was not associated with the rate of muscle loss.

CONCLUSION

a higher amount of MVPA seems to contribute to counteracting the development of sarcopenia. To delay the onset of sarcopenia and its potential adverse outcomes, attention should be paid to increasing physical activity levels in older adults.

Original Research: Central and peripheral quadriceps fatigue in young and middle-aged untrained and endurance-trained men: A comparative study

This study aimed to compare quadriceps function (i.e. strength, endurance, central, and peripheral fatigue) of young (Young-UnTr) and middle-aged (MidAge-UnTr) untrained men and young endurance-trained men (Young-Tr). Twenty-four male subjects (eight Young-UnTr (26 ± 4 yr), eight Young-Tr (29 ± 3 yr), and eight MidAge-UnTr (56 ± 4 yr) performed a maximal cycling test to assess their fitness level. On a separate visit, subjects performed sets of 10 intermittent (5-s on/5-s off) isometric contractions starting at 10% maximum voluntary contraction (MVC), with 10% MVC increments from one set to another until exhaustion. Electrophysiological and mechanical (e.g. twitch) evoked responses elicited with magnetic femoral nerve stimulation in the relaxed muscle and during MVC (i.e. estimation of voluntary activation using the interpolated twitch technique) were measured at baseline and after each set to assess peripheral and central fatigue, respectively. Endurance (= total number of contractions) was also evaluated. Young-UnTr exhibited larger reductions in evoked quadriceps mechanical responses than MidAge-UnTr and Young-Tr after identical standardized muscle loading (e.g. after the 50% MVC set, reduction in single potentiated twitch was -36 ± 9%, -21±16%, and -2 ± 4%, respectively). At both 50% MVC set and exhaustion, MidAge-UnTr exhibited similar reduction in maximal voluntary activation and displayed similar endurance compared to Young-UnTr. Young-Tr exhibited greater endurance than Young-UnTr without significant changes in maximal voluntary activation throughout the test. This study provides robust comparative data regarding the influence of chronic exposure to endurance training and middle-aged on central and peripheral quadriceps fatigability and endurance. Endurance-trained subjects showed smaller level of peripheral fatigue and displayed no significant central fatigue, even at exhaustion and despite greater endurance performance. Our findings also demonstrate that men in the sixth decade exhibit significant alterations in quadriceps function typically observed in much older subjects. These data emphasize the need for developing normative data for both central and peripheral quadriceps fatigability.

Antihypertensive and Statin Medication Use and Motor Function in Community-Dwelling Older Adults

OBJECTIVES

To investigate whether the use of antihypertensive and statin medication in very old adults is associated with the level of motor performance.

DESIGN

Cross-sectional study.

SETTINGS

A community-based study recruited from over 40 residential facilities across the metropolitan Chicago area.

PARTICIPANTS

Community-dwelling very old adults (n = 1520; mean age 80.2; standard deviation 7.7).

MEASUREMENTS

Eleven motor performances were summarized using a composite motor score. All prescription and over the counter medications taken by participants were inspected and coded using the Medi-Span Data Base System. Demographic characteristics and medical history were obtained by means of detailed interview and medical examinations.

RESULTS

In multiple linear regression models, antihypertensive medications were associated with global motor score [β = -0.075, standard error (SE) 0.011, P < .001]. Thus, motor function in an individual with antihypertensive medication, was on average, about 7.5% lower than an age-, sex-, and education-matched individual without antihypertensive medication. The number of antihypertensive medications, which were being used had an additive effect, such that a reduction in the level of motor function was observed with each additional medication, and receiving 3 or more antihypertensive medications was associated with about a 15% reduction in the level of motor function. The association between antihypertensive medications and motor function was robust, and remained unchanged after adjusting for confounding by indication using several potentially confounding variables: smoking, hypertension, diabetes, stroke, congestive heart failure, myocardial infarction, and intermittent claudication (β = -0.05, SE 0.015, P = .001). In contrast, the use of statin medications was not related to motor function (unadjusted: β = 0.003, SE 0.015, P = .826; fully adjusted: β = 0.018, SE 0.014, P = .216).

CONCLUSIONS

The use of antihypertensive medications is associated with a lower level of motor function in very old adults. The nature of this association warrants further investigation.

Handgrip Strength Cutoff Points to Identify Mobility Limitation in Community-dwelling Older People and Associated Factors

BACKGROUND

Sarcopenia is defined as a progressive and generalized loss of skeletal muscle mass and strength. The specific threshold of muscle weakness that leads to mobility limitations has not been identified.

OBJECTIVES

To determine the best cutoff point of handgrip strength for identifying mobility limitation and to investigate the factors associated with muscle weakness and mobility limitation in community-dwelling older people.

DESIGN

Transversal study.

SETTING

Cities of Belo Horizonte, Barueri and Santa Cruz in Brazil.

PARTICIPANTS

1374 community-dwelling older people from the Frailty study in Brazilian older people (FIBRA Study).

MEASUREMENTS

Outcomes included muscle weakness determined according to gender-specific handgrip strength cutoff points generated by Receiver Operating Characteristic curves, mobility limitation defined as a gait speed ≤ 0.8 m/s; and a combination of both muscle weakness and mobility limitation. Associated factors included socio-demographic variables, lifestyle, anthropometrics, health conditions, use of health services and disability.

RESULTS

The cutoff points of handgrip strength with the best balancing between sensitivity and specificity for mobility limitation were 25.8 kgf for men (sensitivity 69%, specificity 73%) and 17.4 kgf (sensitivity 60%, specificity 66%) for women. Age and disability in instrumental activities of daily living were associated with all outcomes. Women had greater odds of mobility limitation than men. Physical inactivity, body fat, diabetes, depression, sleeping disturbances, number of medications and occurrence of falls remained as significant associated factors in the final model.

CONCLUSIONS

Handgrip strength can be a useful tool to identify mobility limitation in clinical practice. Interventions to prevent or minimize impacts of sarcopenia should stimulate physical activity and improvement of body composition in addition to the management of chronic diseases and disabilities.

Prevalence of sarcopenia in older Brazilians: A systematic review and meta-analysis

AIM

Sarcopenia is the age-related loss of muscle mass and function that evolves into disability, loss of independence and death. In Brazil the number of older people is rapidly growing, resulting in an increased prevalence of chronic conditions associated with old age. As prevalence estimates provide essential information to policymakers when developing healthcare strategies, this systematic review and meta-analysis aimed to estimate the prevalence of sarcopenia in older Brazilians.

METHODS

Electronic database searches and hand-searching in relevant journals and reference lists were carried out without language restriction. Studies that reported the prevalence of sarcopenia in Brazilians aged 60 years or older were considered for inclusion. Sarcopenia was defined as low muscle mass, low muscle function or low muscle mass and function. Meta-analysis was carried out using a random-effects model.

RESULTS

A total of 31 studies were included pooling 9416 participants. The overall prevalence of sarcopenia in older Brazilians was 17.0% (95% CI 13.0-22.0). Sensitivity analysis showed rates of 20.0% (95% CI 11.0-32.0) in women and 12.0% (95% CI 9.0-16.0) in men. Prevalence was 16.0% (95% CI 12.0-23.0) based on low muscle mass and function; and 17.0% (95% CI 9.0-31.0) based only on low muscle mass. The difference between these two criteria was not significant (P = 0.96).

CONCLUSIONS

Sarcopenia is an emerging public health issue in Brazil. Attention should be paid to changes in prevalence rates over the next years because of the increase in the older population. Geriatr Gerontol Int 2017; 17: 5-16.

Relation of serum 25-hydroxyvitamin D status with skeletal muscle mass by sex and age group among Korean adults

The objective of this study was to examine whether high serum 25-hydroxyvitamin D (25(OH)D) concentration was associated with high skeletal muscle mass, taking into account the effects of sex and age among the participants of the Korea National Health and Nutrition Examination Survey (KNHANES) aged 40 years or older. This was a cross-sectional study using data from the 2009 to 2010 KNHANES; a total of 8406 subjects (3671 men and 4735 women) were included. The appendicular skeletal muscle mass index (ASMMI, kg/m2) was estimated to measure the skeletal muscle mass. Hypovitaminosis was classified when the level of serum 25(OH)D was <20 ng/ml. The general linear model adjusted for confounding factors was used to determine differences in means of ASMMI by 25(OH)D status. The mean values of ASMMI were higher for men when compared with women. Women had a greater proportion of hypovitaminosis (71·1%) compared with men (53·2%). After adjusting for multiple factors, men were seen to have significant differences in ASMMI based on 25(OH)D status regardless of age, showing a lower mean value of ASSMI in those with hypovitaminosis. However, there was no difference in ASMMI by 25(OH)D status among women in both younger and older age groups. In conclusion, we found that there might be a positive relationship between 25(OH)D and skeletal muscle mass in men, indicating that interventions to improve 25(OH)D levels that are aimed at increasing muscle mass could be beneficial for men with more rapid decreased rate of skeletal muscle mass.

Prevalência de sarcopenia em idosos: resultados de estudos transversais amplos em diferentes países

ResumoA sarcopenia caracteriza-se pela perda generalizada e progressiva da força e massa muscular esquelética com o envelhecimento. Com o aumento da população idosa em ritmo acelerado em todo o mundo, torna-se necessário o maior entendimento dos fenômenos associados ao processo de envelhecimento. Portanto, descrever a frequência e distribuição desses fenômenos, tal como a sarcopenia, é um passo fundamental para se conhecer os componentes atrelados a sua ocorrência e promover a assistência à saúde direcionada ao idoso. O objetivo desta revisão de literatura foi apresentar a síntese dos resultados de estudos epidemiológicos de base populacional sobre a prevalência de sarcopenia em idosos da comunidade, mostrando também as características sociodemográficas das populações estudadas e a diferença dos resultados entre os sexos. Os resultados de seis estudos transversais, entre os anos 2002 e 2014, provenientes dos seguintes países: Estados Unidos, Reino Unido, Brasil, Japão, Coreia do Sul e Taiwan, foram apresentados. Verificou-se neles que a sarcopenia tem alta prevalência na população a partir dos 60 anos de idade, em ambos os sexos, sendo mais alta nas mulheres em cinco dos seis trabalhos. O Japão foi o país que apresentou as maiores taxas de prevalência, seguido pelo Brasil. A sarcopenia aumentou com a idade em todos os estudos e esteve associada com várias adversidades. A dificuldade em se estabelecer uma avaliação padronizada para sarcopenia, sobretudo pelas peculiaridades de cada população, constitui um importante fator a ser analisado na leitura de estudos de prevalência sobre essa síndrome.

Understanding the gastrointestinal tract of the elderly to develop dietary solutions that prevent malnutrition

Although the prevalence of malnutrition in the old age is increasing worldwide a synthetic understanding of the impact of aging on the intake, digestion, and absorption of nutrients is still lacking. This review article aims at filling the gap in knowledge between the functional decline of the aging gastrointestinal tract (GIT) and the consequences of malnutrition on the health status of elderly. Changes in the aging GIT include the mechanical disintegration of food, gastrointestinal motor function, food transit, chemical food digestion, and functionality of the intestinal wall. These alterations progressively decrease the ability of the GIT to provide the aging organism with adequate levels of nutrients, what contributes to the development of malnutrition. Malnutrition, in turn, increases the risks for the development of a range of pathologies associated with most organ systems, in particular the nervous-, muscoskeletal-, cardiovascular-, immune-, and skin systems. In addition to psychological, economics, and societal factors, dietary solutions preventing malnutrition should thus propose dietary guidelines and food products that integrate knowledge on the functionality of the aging GIT and the nutritional status of the elderly. Achieving this goal will request the identification, validation, and correlative analysis of biomarkers of food intake, nutrient bioavailability, and malnutrition.

Sarcopenia and fragility fractures: molecular and clinical evidence of the bone-muscle interaction

➤ Bone and muscle tissues are in close relationship, and the aging process is a factor involved in the loss of the functionality of both bones and muscles.➤ Sarcopenia and osteoporosis are linked from a biological and functional perspective and are related to an increased fracture risk in the elderly.➤ The increased fracture risk in sarcopenic and osteoporotic subjects is due to the decline of muscle mass and strength, the decrease in bone mineral density, and limited mobility.

Molecular and cell-based therapies for muscle degenerations: a road under construction

Despite the advances achieved in understanding the molecular biology of muscle cells in the past decades, there is still need for effective treatments of muscular degeneration caused by muscular dystrophies and for counteracting the muscle wasting caused by cachexia or sarcopenia. The corticosteroid medications currently in use for dystrophic patients merely help to control the inflammatory state and only slightly delay the progression of the disease. Unfortunately, walkers and wheel chairs are the only options for such patients to maintain independence and walking capabilities until the respiratory muscles become weak and the mechanical ventilation is needed. On the other hand, myostatin inhibition, IL-6 antagonism and synthetic ghrelin administration are examples of promising treatments in cachexia animal models. In both dystrophies and cachectic syndrome the muscular degeneration is extremely relevant and the translational therapeutic attempts to find a possible cure are well defined. In particular, molecular-based therapies are common options to be explored in order to exploit beneficial treatments for cachexia, while gene/cell therapies are mostly used in the attempt to induce a substantial improvement of the dystrophic muscular phenotype. This review focuses on the description of the use of molecular administrations and gene/stem cell therapy to treat muscular degenerations. It reviews previous trials using cell delivery protocols in mice and patients starting with the use of donor myoblasts, outlining the likely causes for their poor results and briefly focusing on satellite cell studies that raise new hope. Then it proceeds to describe recently identified stem/progenitor cells, including pluripotent stem cells and in relationship to their ability to home within a dystrophic muscle and to differentiate into skeletal muscle cells. Different known features of various stem cells are compared in this perspective, and the few available examples of their use in animal models of muscular degeneration are reported. Since non coding RNAs, including microRNAs (miRNAs), are emerging as prominent players in the regulation of stem cell fates we also provides an outline of the role of microRNAs in the control of myogenic commitment. Finally, based on our current knowledge and the rapid advance in stem cell biology, a prediction of clinical translation for cell therapy protocols combined with molecular treatments is discussed.

Sarcopenia and cardiovascular risk in physically active adult and elderly women

The purpose of this study was to assess the prevalence of sarcopenia and its association with risk factors for cardiovascular diseases (CVD) in non-sedentary women. Study participants were 124 women (control group (CG) n = 33; 24.5 ± 2.9 years and study group (SG) n = 91; 61.9 ± 8.7 years). Anthropometric measurements, blood parameters, body composition (DXA), anthropometric indices and questionnaire answers were analyzed. Sarcopenia was considered as a standard deviation below mean values for young people, corresponding to 7.3 kg/m2 and classifying 34.1% of SG as sarcopenic. Prevalence of risk for CVD considered low, moderate and high was 21%, 60% and 19%, respectively. Logistic regression showed no relationship between sarcopenia and risk factors for CVD, except for body mass index as a protection factor. There was a tendency for sarcopenia to assume associations as risk factor for variables smoking, triglycerides, obesity, abdominal fat, and Framingham Risk Score and as a protection factor for variable physical activity level.

Biobanking across the phenome - at the center of chronic disease research

Background

Recognized public health relevant risk factors such as obesity, physical inactivity, smoking or air pollution are common to many non-communicable diseases (NCDs). NCDs cluster and co-morbidities increase in parallel to age. Pleiotropic genes and genetic variants have been identified by genome-wide association studies (GWAS) linking NCD entities hitherto thought to be distant in etiology. These different lines of evidence suggest that NCD disease mechanisms are in part shared.

Discussion

Identification of common exogenous and endogenous risk patterns may promote efficient prevention, an urgent need in the light of the global NCD epidemic. The prerequisite to investigate causal risk patterns including biologic, genetic and environmental factors across different NCDs are well characterized cohorts with associated biobanks. Prospectively collected data and biospecimen from subjects of various age, sociodemographic, and cultural groups, both healthy and affected by one or more NCD, are essential for exploring biologic mechanisms and susceptibilities interlinking different environmental and lifestyle exposures, co-morbidities, as well as cellular senescence and aging. A paradigm shift in the research activities can currently be observed, moving from focused investigations on the effect of a single risk factor on an isolated health outcome to a more comprehensive assessment of risk patterns and a broader phenome approach. Though important methodological and analytical challenges need to be resolved, the ongoing international efforts to establish large-scale population-based biobank cohorts are a critical basis for moving NCD disease etiology forward.

Summary

Future epidemiologic and public health research should aim at sustaining a comprehensive systems view on health and disease. The political and public discussions about the utilitarian aspect of investing in and contributing to cohort and biobank research are essential and are indirectly linked to the achievement of public health programs effectively addressing the global NCD epidemic.

Nutritional influences on age-related skeletal muscle loss

Age-related muscle loss impacts on whole-body metabolism and leads to frailty and sarcopenia, which are risk factors for fractures and mortality. Although nutrients are integral to muscle metabolism the relationship between nutrition and muscle loss has only been extensively investigated for protein and amino acids. The objective of the present paper is to describe other aspects of nutrition and their association with skeletal muscle mass. Mechanisms for muscle loss relate to imbalance in protein turnover with a number of anabolic pathways of which the mechanistic TOR pathway and the IGF-1–Akt–FoxO pathways are the most characterised. In terms of catabolism the ubiquitin proteasome system, apoptosis, autophagy, inflammation, oxidation and insulin resistance are among the major mechanisms proposed. The limited research associating vitamin D, alcohol, dietary acid–base load, dietary fat and anti-oxidant nutrients with age-related muscle loss is described. Vitamin D may be protective for muscle loss; a more alkalinogenic diet and diets higher in the anti-oxidant nutrients vitamin C and vitamin E may also prevent muscle loss. Although present recommendations for prevention of sarcopenia focus on protein, and to some extent on vitamin D, other aspects of the diet including fruits and vegetables should be considered. Clearly, more research into other aspects of nutrition and their role in prevention of muscle loss is required.

Obesity in the ageing man

As the population is ageing globally, both ageing and obesity are recognized as major public health challenges. The aim of this narrative review is to present and discuss the current evidence on the changes in body composition, energy balance and endocrine environment that occur in the ageing man. Obesity in the ageing man is related to changes in both body weight and composition due to alterations in energy intake and total energy expenditure. In addition, somatopenia (decreased GH secretion), late-onset hypogonadism (LOH), changes in thyroid and adrenal function, as well as changes in appetite-related peptides (leptin, ghrelin) and, most importantly, insulin action are related to obesity, abnormal energy balance, redistribution of the adipose tissue and sarcopenia (decreased muscle mass). A better understanding of the complex relationship of ageing-related endocrine changes and obesity could lead to more effective interventions for elderly men.

Musculoskeletal ageing and primary prevention

Loss of musculoskeletal mass and function is a natural ageing trait, reinforced by an unhealthy life style. Loss of bone (osteoporosis) and muscle (sarcopaenia) are conditions whose prevalence are increasing because of the change in population distribution in the western world towards an older mean age. Improvements in lifestyle factors, such as diet, smoking and exercise, are the most powerful tools to combat this decline efficiently; however, public health interventions aimed at tackling these problems have shown abysmal success at the population level, mostly due to failure in compliance. With these issues in mind, we believe that the primary prevention modality in coming decades will be pharmacological. We review the basic biology of musculoskeletal ageing and what measures can be taken to prevent ageing-associated loss of musculoskeletal mass and function, with particular emphasis on pharmacological means.

Do statins cause diabetes?

A wealth of evidence has established that cholesterol-lowering statin drugs, widely used for the prevention of cardiovascular disease, do increase the risk of new-onset diabetes, possibly by impairing pancreatic beta cell function and decreasing peripheral insulin sensitivity. Groups at particular risk include the elderly, women, and Asians. The diabetogenic effect of statins appear directly related to statin dose and the degree of attained cholesterol lowering. Statins can cause hyperinsulinemia even in the absence of hyperglycemia and the potential mitogenic effects and implications of prolonged hyperinsulinemia are discussed. Suggestions are made as to how physicians might avert the hyperinsulinemic and diabetogenic effects of statin therapy in clinical practice, and modulate the detrimental effects of these drugs on exercise performance. Finally, long-term studies are needed to determine if the deleterious hyperinsulinemic and diabetogenic effects of statin therapy undermine the beneficial cardiovascular disease risk outcomes in various segments of the population.

Prevalence of sarcopenia and associated factors among Thai population

The purpose of this study was to determine the prevalence of sarcopenia using the skeletal muscle index (SMI) criteria in the Thai population. The secondary objective was to demonstrate factors influencing low SMI in this population. Femoral neck bone mass density (BMD) was measured by dual-energy X-ray absorptiometry (GE Lunar, Madison, WI, USA) in 435 urban and 397 rural subjects (334 men and 498 women) between 20 and 84 years of age. Body mass index (BMI) was calculated from weight and height. The respective prevalence of sarcopenia among men and women was 35.33 % (95 % CI, 29.91, 40.41) and 34.74 % (95 % CI, 30.56, 39.10). Factors associated with sarcopenia using multiple logistic regression analyses in both sexes were (a) living in the city, (b) higher BMI, and (c) older age. Living in an urban area was the strongest factor, with an odds ratio (OR) of 17.26 ± 7.12 (95 % CI, 7.68, 38.76) in men and 8.62 ± 2.74 (95 % CI, 4.62, 16.05) in women (p < 0.05). The prevalence rate ratio for persons living in urban compared to rural areas was 2.01 (95 % CI, 1.14, 3.53) in men and 1.69 (95 % CI, 1.31, 2.17) in women (p < 0.05). Sarcopenia, as based on SMI, occurs frequently in the Thai population and increases with age. The prevalence of sarcopenia is particularly high among pre-retirement women (50-59 years of age) whereas the number of men with sarcopenia gradually rises with age. An urban environment is the most predictive factor for sarcopenia, followed by high BMI and age. Given the aging population, early recognition of this condition can be beneficial for prevention of an epidemic of sarcopenia-related disability.

Highlights of mechanistic and therapeutic cachexia and sarcopenia research 2010 to 2012 and their relevance for cardiology

Sarcopenia and cachexia are significant medical problems with a high disease-related burden in cardiovascular illness. Muscle wasting and weight loss are very frequent particularly in chronic heart failure and they relate to poor prognosis. Although clinically largely underestimated, the fields of cachexia and sarcopenia are of great relevance to cardiologists. In cachexia and sarcopenia a significant number of research publications related to basic science questions of muscle wasting and lipolysis were published between 2010 and 2012. Recently, the two processes of muscle wasting and lipolysis were found to be closely linked. Treatment research in pre-clinical models involves studies on a number of different therapeutic entities, including ghrelin, selective androgen receptor modulators (SARMs), as well as drugs targeting myostatin or melanocortin-4. In the human setting, studies using enobosarm (a SARM) and anamorelin (ghrelin) are in phase III. The last 3 years have seen significant efforts to define the field using consensus statements. In the future, these definitions should also be considered for guidelines and treatment trials in cardiovascular medicine. The current review aims to summarize important information and development in the fields of muscle wasting, sarcopenia and cachexia, focusing on findings in cardiovascular research, in order for cardiologists to have a better understanding of the progress in this still insufficiently known field.

Sarcopenia and its determinants among Iranian elderly (SARIR): study protocol

BACKGROUND

The elderly populations increase in world because of improved health status in communities, so health and independency of seniors has become and will be one of the main priorities of public health systems.Ageing have been associated with changes in body composition, including loss of muscle mass, loss of bone mass and increase fat mass. Involuntary age related loss of muscle mass, sarcopenia,has been linked to functional impairment and physical disability. Several definitions for sarcopenia have been presented based on the method of measuring body composition, but an internationally accepted definition doesn't presently exist yet.In 2010, the European working group on sarcopenia developed a new definition for sarcopenia according to measure muscle mass and muscle function. Several studies have been done about sarcopenia in world, but to our knowledge this study is the first in Iran which is one of the largest countries of the Middle East that faces a fast growing elderly population. The aim of this study is to evaluate sarcopenia and related risk factors in Iran according new definition of sarcopenia.

METHODS

This study will be conducted in two phase among elderly men and women over 55 years in the 6th district of TehranThe first phase will be a population-based cross-sectional study to determine the frequency of sarcopenia in the study population, and to conduct case finding for the second phase. The second phase will be a case-control study to comparison the metabolic and inflammatory factors in sarcopenic and non sarcopenic groups.The association between sarcopenia and major dietary pattern will be evaluated using factor analysis.

CONCLUSION

This study is the first study that evaluates sarcopenia and its risk factor in Iranian elderlies.We discuss details of how we collect the data and appropriate instruments to measure muscle mass, muscle power and muscle strength, and suitable cut- off to define sarcopenia in Iranian elderlies. We believe the result of our study can be useful to health policy makers prepare the necessary infrastructure for elderly health improvements and increase the quality of life in geriatric.

Mass spectrometry-based proteomic analysis of middle-aged vs. aged vastus lateralis reveals increased levels of carbonic anhydrase isoform 3 in senescent human skeletal muscle

The age-related loss of skeletal muscle mass and associated progressive decline in contractile strength is a serious pathophysiological issue in the elderly. In order to investigate global changes in the skeletal muscle proteome after the fifth decade of life, this study analysed total extracts from human vastus lateralis muscle by fluorescence difference in-gel electrophoresis. Tissue specimens were derived from middle-aged (47-62 years) vs. aged (76-82 years) individuals and potential changes in the protein expression profiles were compared between these two age groups by a comprehensive gel electrophoresis-based survey. Age-dependent alterations in the concentration of 19 protein spots were revealed and mass spectrometry identified these components as being involved in the excitation-contraction-relaxation cycle, muscle metabolism, ion handling and the cellular stress response. This indicates a generally perturbed protein expression pattern in senescent human muscle. Increased levels of mitochondrial enzymes and isoform switching of the key contractile protein, actin, support the idea of glycolytic-to-oxidative and fast-to-slow transition processes during muscle aging. Importantly, the carbonic anhydrase (CA)3 isoform displayed an increased abundance during muscle aging, which was independently verified by immunoblotting of differently aged human skeletal muscle samples. Since the CA3 isoform is relatively muscle-specific and exhibits a fibre type-specific expression pattern, this enzyme may represent an interesting new biomarker of sarcopenia. Increased levels of CA are indicative of an increased demand of CO₂-removal in senescent muscle, and also suggest age-related fibre type shifting to slower-contracting muscles during human aging.

The effects of pre-habilitative conditioning on unloading-induced adaptations in young and aged neuromuscular systems

The capacity of pre-habilitative conditioning - exercise performed a priori - to mitigate neuromuscular maladaptations to disuse is unclear. This study evaluated pre-habilitation by examining neuromuscular junctions (NMJs) and the myofibers they innervate in young adult and aged muscles. Within each age category, 40 rats were divided into four treatment groups: 1) control, 2) hindlimb suspended (unloaded), 3) prehabilitative conditioning preceding hindlimb suspension, and 4) pre-habilitative conditioning alone. Cytofluorescent staining was used to visualize NMJs, and histochemical staining to assess myofiber profiles (size and type). Statistical analysis featured 2-way ANOVA with main effects for age and treatment, along with interaction. NMJs consistently revealed significant (P≤0.05) main effects for age, but not treatment, or interaction. Typically, aged NMJs showed elongated nerve terminal branching, and more dispersed post-synaptic clusters of ACh receptors, resulting in reduced post-synaptic area per given length of pre-synaptic branching. Analysis of myofiber profiles showed significant main effects for age, treatment, and their interaction. Aged myofibers were smaller than the young ones and a higher percentage of them were Type I. Aged fibers experienced significantly greater unloading-induced atrophy than the young ones. Pre-habilitative conditioning significantly attenuated unloading-induced atrophy among aged, but not young myofibers. It was also observed that pre-habilitative conditioning alone increased myofiber size among aged, but not young adult muscles. In summary, myofibers were more sensitive than NMJs to the treatment interventions implemented. Although more sensitive to the negative effects of muscle unloading, aged myofibers were also more responsive to the hypertrophic effects of pre-habilitative conditioning.

Sarcopenia and cachexia: the adaptations of negative regulators of skeletal muscle mass

Recent advances in our understanding of the biology of muscle, and how anabolic and catabolic stimuli interact to control muscle mass and function, have led to new interest in the pharmacological treatment of muscle wasting. Loss of muscle occurs as a consequence of several chronic diseases (cachexia) as well as normal aging (sarcopenia). Although many negative regulators [Atrogin-1, muscle ring finger-1, nuclear factor-kappaB (NF-κB), myostatin, etc.] have been proposed to enhance protein degradation during both sarcopenia and cachexia, the adaptation of mediators markedly differs among these conditions. Sarcopenic and cachectic muscles have been demonstrated to be abundant in myostatin- and apoptosis-linked molecules. The ubiquitin-proteasome system (UPS) is activated during many different types of cachexia (cancer cachexia, cardiac heart failure, chronic obstructive pulmonary disease), but not many mediators of the UPS change during sarcopenia. NF-κB signaling is activated in cachectic, but not in sarcopenic, muscle. Some studies have indicated a change of autophagic signaling during both sarcopenia and cachexia, but the adaptation remains to be elucidated. This review provides an overview of the adaptive changes in negative regulators of muscle mass in both sarcopenia and cachexia.

Age, weight and obesity

The western world is facing the consequences of higher standards of medical care and improved living conditions. While people are living longer the prevalence of overweight and obesity is escalating which increases the risk of developing non-communicable diseases. However it must be noted that there is a U shaped relationship between weight and mortality with both under and overweight increasing risk. This review examines possible contributory factors for overweight and obesity in older people: life style, depression, changes in body composition, endocrine alterations, sympathetic tone, oxidative stress and concomitant disease.