Serum concentrations of insulin-like growth factor-1, members of the TGF-beta superfamily and follistatin do not reflect different stages of dynapenia and sarcopenia in elderly women

GDF-15 is associated with sarcopenia and frailty in acutely admitted older medical patients

BACKGROUND

Growth differentiation factor-15 (GDF-15) has been associated with senescence, lower muscle strength, and physical performance in healthy older people. Still, it is not clear whether GDF-15 can be utilized as a biomarker of sarcopenia and frailty in the early stages of hospitalization. We investigated the association of plasma GDF-15 with sarcopenia and frailty in older, acutely admitted medical patients.

METHODS

The present study is based on secondary analyses of cross-sectional data from the Copenhagen PROTECT study, a prospective cohort study including 1071 patients ≥65 years of age admitted to the acute medical ward at Copenhagen University Hospital, Bispebjerg, Denmark. Muscle strength was assessed using handgrip strength, and lean mass was assessed using direct segmental multifrequency bioelectrical impedance analyses and used to clarify the potential presence of sarcopenia defined according to guidelines from the European Working Group on Sarcopenia in Older People. Frailty was evaluated using the Clinical Frailty Scale. Plasma GDF-15 was measured using electrochemiluminescence assays from Meso Scale Discovery (MSD, Rockville, MD, USA).

RESULTS

We included 1036 patients with completed blood samples (mean age 78.9 ± 7.8 years, 53% female). The median concentration of GDF-15 was 2669.3 pg/mL. Systemic GDF-15 was significantly higher in patients with either sarcopenia (P < 0.01) or frailty (P < 0.001) compared with patients without the conditions. Optimum cut-off points of GDF-15 relating to sarcopenia and frailty were 1541 and 2166 pg/mL, respectively.

CONCLUSIONS

Systemic GDF-15 was higher in acutely admitted older medical patients with sarcopenia and frailty compared with patients without. The present study defined the optimum cut-off for GDF-15, related to the presence of sarcopenia and frailty, respectively. When elevated above the derived cutoffs, GDF-15 was strongly associated with frailty and sarcopenia in both crude and fully adjusted models.

Role of irisin and myostatin on sarcopenia in malnourished patients diagnosed with GLIM criteria

OBJECTIVES

Sarcopenia is characterized by the loss of muscle mass. Skeletal muscle can produce and secrete different molecules called myokines. Irisin and myostatin are antagonistic myokines, and to our knowledge, no studies of both myokines have been conducted in patients with disease-related malnutrition (DRM). This study aimed to investigate the role of circulating irisin and myostatin in sarcopenia in patients with DRM.

METHODS

The study included 108 outpatients with DRM according to the Global Leadership Initiative on Malnutrition criteria. Participants had a mean age of 67.4 ± 3.4 y. Anthropometric data, muscle mass by ultrasound at the rectus femoris quadriceps (RFQ) level, impedancemetry (skeletal muscle mass [SMM], appendicular SMM [aSMM], and aSMM index [aSMMI]), dynamometry, biochemical parameters, dietary intake, circulating irisin and myostatin levels were determined in all patients. Confirmed sarcopenia was diagnosed as criteria of probable sarcopenia (low muscle strength) plus abnormal aSMMI.

RESULTS

Of the 108 patients, 44 presented sarcopenia (41%); 64 did not present with the disorder (59%). The following parameters were worse in patients with sarcopenia: Patients without sarcopenia were stronger than those with the disorder (7.9 ±1.3 kg; P = 0.01). Circulating irisin levels were higher in patients without sarcopenia than those with sarcopenia (651.3 ± 221.3 pg/mL; P =0.01). Myostatin levels were similar in both groups. Finally, logistic regression analysis reported a low risk for sarcopenia (odds ratio, 0.39; 95% confidence interval, 0.19-0.92; P = 0.03) in high irisin median levels as a dichotomic parameter after adjusting for body mass index, sex, energy intake, and age.

CONCLUSION

The present study reported that low levels of serum irisin were closely associated with sarcopenia in patients with DRM.

Diabetes Mellitus Should Be Considered While Analysing Sarcopenia-Related Biomarkers

Sarcopenia is a chronic, progressive skeletal muscle disease characterised by low muscle strength and quantity or quality, leading to low physical performance. Patients with type 2 diabetes mellitus (T2DM) are more at risk of sarcopenia than euglycemic individuals. Because of several shared pathways between the two diseases, sarcopenia is also a risk factor for developing T2DM in older patients. Various biomarkers are under investigation as potentially valuable for sarcopenia diagnosis and treatment monitoring. Biomarkers related to sarcopenia can be divided into markers evaluating musculoskeletal status (biomarkers specific to muscle mass, markers of the neuromuscular junction, or myokines) and markers assuming causal factors (adipokines, hormones, and inflammatory markers). This paper reviews the current knowledge about how diabetes and T2DM complications affect potential sarcopenia biomarker concentrations. This review includes markers recently proposed by the expert group of the European Society for the Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) as those that may currently be useful in phase II and III clinical trials of sarcopenia: myostatin (MSTN); follistatin (FST); irisin; brain-derived neurotrophic factor (BDNF); procollagen type III N-terminal peptide (PIIINP; P3NP); sarcopenia index (serum creatinine to serum cystatin C ratio); adiponectin; leptin; insulin-like growth factor-1 (IGF-1); dehydroepiandrosterone sulphate (DHEAS); C-reactive protein (CRP); interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α). A better understanding of factors influencing these biomarkers' levels, including diabetes and diabetic complications, may lead to designing future studies and implementing results in clinical practice.

Identification of molecular mediators of renal sarcopenia risk: a mendelian randomization analysis

BACKGROUND

Observational studies have shown an association between reduced renal function and the risk of sarcopenia. However, the causal relationship and the underlying biological mechanisms remain uncertain. Using a Mendelian randomization (MR) framework, we investigated the causal role of 27 hypothetical risk mediators, including metabolites, hormones, inflammation, and stress traits, on the risk of sarcopenia.

METHODS

Instrumental variables (IVs) to proxy renal function were identified by selecting single nucleotide polymorphisms (SNPs) reliably associated with creatinine and cystatin C-based glomerular filtration rate (GFR) in CKDGen summary data. IVs for putative risk traits and sarcopenia traits were constructed from relevant genome-wide association studies (GWAS). MR estimated effects were obtained using an inverse-variance weighted effects model, and various sensitivity analyses were performed. The mediating role of hypothetical risk factors in the relationship between GFR and sarcopenia was assessed through multivariate MR.

RESULTS

Genetically predicted reduced GFRcrea was associated with higher odds of appendicular lean mass (ALM) (odds ratio (OR): 0.64, 95% confidence interval (CI) 0.37 to 0.68) and grip strength (OR: 0.67; 95% CI 0.58 to 0.78). Likewise, GFRcys highlighted a causal relationship with ALM (OR: 0.52; 95% CI 0.42 to 0.65) and grip strength (OR: 0.66; 95% CI 0.59 to 0.74). Both estimated GFR (eGFR) were negatively associated with IGF-1, IL-16, 25(OH)D, triglycerides (range of effect size per standard deviation: -0.81 to -0.30), and positively correlated with HDL cholesterol (0.62, 0.31). There was a positive correlation between IGF-1, fasting insulin and ALM as well as grip strength (OR range: 1.04-1.67) and a negative correlation between serum CRP and ALM (OR: 0.95) as well as grip strength (OR: 0.98). Additionally, genetically predicted IL-1β (OR: 0.95) and total cholesterol (OR: 0.96) were negatively associated with ALM. We found evidence that IGF-1 mediates the relationship between eGFR and risk for muscle mass and strength.

CONCLUSIONS

This MR study provides insight into the potential causal mechanisms between renal function and the risk of sarcopenia and proposes IGF-1 as a potential target for the prevention of renal sarcopenia.

Biochemical Markers of Musculoskeletal Health and Aging to be Assessed in Clinical Trials of Drugs Aiming at the Treatment of Sarcopenia: Consensus Paper from an Expert Group Meeting Organized by the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) and the Centre Académique de Recherche et d'Expérimentation en Santé (CARES SPRL), Under the Auspices of the World Health Organization Collaborating Center for the Epidemiology of Musculoskeletal Conditions and Aging

In clinical trials, biochemical markers provide useful information on the drug's mode of action, therapeutic response and side effect monitoring and can act as surrogate endpoints. In pharmacological intervention development for sarcopenia management, there is an urgent need to identify biomarkers to measure in clinical trials and that could be used in the future in clinical practice. The objective of the current consensus paper is to provide a clear list of biochemical markers of musculoskeletal health and aging that can be recommended to be measured in Phase II and Phase III clinical trials evaluating new chemical entities for sarcopenia treatment. A working group of the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) proposed classifying biochemical markers into 2 series: biochemical markers evaluating musculoskeletal status and biochemical markers evaluating causal factors. For series 1, the group agreed on 4 biochemical markers that should be assessed in Phase II or Phase III trials (i.e., Myostatin-Follistatin, Brain Derived Neurotrophic Factor, N-terminal Type III Procollagen and Serum Creatinine to Serum Cystatin C Ratio - or the Sarcopenia Index). For series 2, the group agreed on 6 biochemical markers that should be assessed in Phase II trials (i.e., the hormones insulin-like growth factor-1 (IGF-I), dehydroepiandrosterone sulphate, and cortisol, and the inflammatory markers C-reactive protein (CRP), interleukin-6 and tumor necrosis factor-α), and 2 in Phase III trials (i.e., IGF-I and CRP). The group also proposed optional biochemical markers that may provide insights into the mode of action of pharmacological therapies. Further research and development of new methods for biochemical marker assays may lead to the evolution of these recommendations.

Biomarkers associated with lower limb muscle function in individuals with sarcopenia: a systematic review

Lower limb muscle dysfunction is a key driver for impaired physical capacity and frailty status, both characteristics of sarcopenia. Sarcopenia is the key pathway between frailty and disability. Identifying biological markers for early diagnosis, treatment, and prevention may be key to early intervention and prevention of disability particularly mobility issues. To identify biological markers associated with lower limb muscle (dys)function in adults with sarcopenia, a systematic literature search was conducted in AMED, CINAHL, Cochrane Library, EMBASE, Medline, PubMed, Scopus, SPORTDiscus, and Web of Science databases from inception to 17 November 2021. Title, abstract, and full-text screening, data extraction, and methodological quality assessment were performed by two reviewers independently and verified by a third reviewer. Depending on available data, associations are reported as either Pearson's correlations, regression R² or partial R² , P value, and sample size (n). Twenty eligible studies including 3306 participants were included (females: 79%, males: 15%, unreported: 6%; mean age ranged from 53 to 92 years) with 36% in a distinct sarcopenic subgroup (females: 73%, males: 19%, unreported: 8%; mean age range 55-92 years). A total of 119 biomarkers were reported, categorized into: genetic and microRNAs (n = 64), oxidative stress (n = 10), energy metabolism (n = 18), inflammation (n = 7), enzyme (n = 4), hormone (n = 7), bone (n = 3), vitamin (n = 2), and cytokine (n = 4) markers) and seven lower limb muscle measures predominately focused on strength. Seven studies reported associations between lower limb muscle measures including (e.g. power, force, and torque) and biomarkers. In individuals with sarcopenia, muscle strength was positively associated with free testosterone (r = 0.40, P = 0.01; n = 46). In analysis with combined sarcopenic and non-sarcopenic individuals, muscle strength was positively associated with combined genetic and methylation score (partial R²  = 0.122, P = 0.03; n = 48) and negatively associated with sarcopenia-driven methylation score (partial R²  = 0.401, P < 0.01; n = 48). Biomarkers related to genetics (R²  = 0.001-0.014, partial R²  = 0.013-0.122, P > 0.05; n = 48), oxidative stress (r = 0.061, P > 0.05; n ≥ 77), hormone (r = 0.01, ρ = 0.052 p > 0.05, n ≥ 46) and combined protein, oxidative stress, muscle performance, and hormones (R²  = 22.0, P > 0.05; n ≥ 82) did not report significant associations with lower limb muscle strength. Several biomarkers demonstrated associations with lower limb muscle dysfunction. The current literature remains difficult to draw clear conclusions on the relationship between biomarkers and lower limb muscle dysfunction in adults with sarcopenia. Heterogeneity of biomarkers and lower limb muscle function precluded direct comparison. Use of international classification of sarcopenia and a set of core standardized outcome measures should be adopted to aid future investigation and recommendations to be made.

Foreign allometric exponents adequately normalize isokinetic knee extension strength to identify muscle weakness and mobility limitation in Portuguese older adults: a cross-sectional study

Background

Identifying muscle weakness is challenging, because the reduction of strength with aging does not depend only on sarcopenia, but also on sensorimotor deficits. Nevertheless, this identification is improved by adjusting muscle strength allometrically, by removing the influence of body size. However, the effectiveness of foreign models to normalize these (dys)functionalities is not yet tested. This study aimed to compare and apply foreign allometric exponents for normalizing isokinetic knee extension strength in Portuguese older adults to identify muscle weakness/mobility limitation. Additionally, to attest any populational difference, data of these people and Brazilian older adults were compared

Methods

This is a cross-sectional study encompassing 226 Portuguese (n = 132) and Brazilian (n = 94) older adults. Mobility limitation (six-minute walk test, at lowest quartile), lower limb strength (knee extension isokinetic strength at 60º/s), and body dimensions measures were taken. Foreign allometric exponents (^b) were used to normalize Portuguese strength (strength/body-size variables^b). Non-normalized and normalized strength were compared (ROC) to generate the most accurate cut-point for identifying muscle weakness/mobility limitation.

Results

Older Portuguese men and women had better mobility than their Brazilian counterparts. Older Portuguese women had superior muscle strength to Brazilian women. Normalization from 11 foreign models removed the influence of body size on muscle strength, with a negligible correlation (r ≤ 0.30). In contrast to the non-normalized strength, the normalized strength cut-off points were sufficiently accurate (AUC ≥ 0.70) to avoid identifying false-negative cases of weakness/mobility limitation.

Conclusions

Portuguese older women were stronger and had superior functional capacity compared to Brazilian ones. Normalized foreign models improved the accuracy in identifying muscle weakness/mobility limitation in Portuguese older adults. The isokinetic knee extension muscle strength normalized, even using foreign allometric exponents, should be better than no adjustment.

Association between Bone-Related Physiological Substances and Oral Function in Community-Dwelling Older People

BACKGROUND

Oral dysfunction is related to long-term cares including activities of daily living. The objective of this study was to determine the association between oral function and the bone-related physiological substances osteocalcin (OC) and insulin-like growth factor-1 (IGF-1).

METHODS

The study participants were 139 community-dwelling older people in Japan. Evaluation of oral dysfunction was based on subjective judgment by each participant. Blood analysis included OC, IGF-1, and albumin.

RESULTS

Univariate and multiple logistic analyses showed that IGF-1 was significantly associated with a "decline in masticatory function" (p = 0.0074 and p = 0.0308, respectively). Receiver operating characteristic curve analysis of IGF-1 levels revealed a threshold score of 108 ng/mL (p < 0.01) for discriminating a "decline in masticatory function". Logistic regression analysis revealed that participants with an IGF-1 level ≤108 ng/mL had an odds ratio of 4.31 (p < 0.05) for a "decline in masticatory function". No significant association was found between the OC level and oral dysfunction.

CONCLUSIONS

These results suggest a possible relationship between lower serum IGF-1 levels and a decline in masticatory dysfunction in community-dwelling older people.

Myostatin/Activin Receptor Ligands in Muscle and the Development Status of Attenuating Drugs

Muscle wasting disease indications are among the most debilitating and often deadly noncommunicable disease states. As a comorbidity, muscle wasting is associated with different neuromuscular diseases and myopathies, cancer, heart failure, chronic pulmonary and renal diseases, peripheral neuropathies, inflammatory disorders, and, of course, musculoskeletal injuries. Current treatment strategies are relatively ineffective and can at best only limit the rate of muscle degeneration. This includes nutritional supplementation and appetite stimulants as well as immunosuppressants capable of exacerbating muscle loss. Arguably, the most promising treatments in development attempt to disrupt myostatin and activin receptor signaling because these circulating factors are potent inhibitors of muscle growth and regulators of muscle progenitor cell differentiation. Indeed, several studies demonstrated the clinical potential of "inhibiting the inhibitors," increasing muscle cell protein synthesis, decreasing degradation, enhancing mitochondrial biogenesis, and preserving muscle function. Such changes can prevent muscle wasting in various disease animal models yet many drugs targeting this pathway failed during clinical trials, some from serious treatment-related adverse events and off-target interactions. More often, however, failures resulted from the inability to improve muscle function despite preserving muscle mass. Drugs still in development include antibodies and gene therapeutics, all with different targets and thus, safety, efficacy, and proposed use profiles. Each is unique in design and, if successful, could revolutionize the treatment of both acute and chronic muscle wasting. They could also be used in combination with other developing therapeutics for related muscle pathologies or even metabolic diseases.

Associations Between Plasma Growth and Differentiation Factor-15 with Aging Phenotypes in Muscle, Adipose Tissue, and Bone

Growth and differentiation factor 15 (GDF-15) is associated with muscle, fat, and bone metabolism; however, this association has not been well characterized. Plasma GDF-15, appendicular skeletal muscle mass (ASM), fat mass (FM), and bone mineral density (BMD) were measured in 146 postmenopausal women. GDF-15 levels were higher in subjects with low Body Mass Index (BMI)-adjusted ASM than in those without (median [interquartile range] 831.3 [635.4-1011.4] vs. 583.8 [455.8-771.1] pg/mL, p = 0.018). The GDF-15 level was inversely correlated with BMI-adjusted ASM (r =  - 0.377, p < 0.001) and BMD at femur neck (FN-BMD; r =  - 0.201, p = 0.015), and positively correlated with percent FM (pFM; r = 0.328, p < 0.001). After adjusting for confounders, the GDF-15 level was inversely associated with BMI-adjusted ASM (β = -0.250, p = 0.006) and positively associated with pFM (β = 0.272, p = 0.004), and tended to be inversely associated with FN-BMD (β = - 0.176, p = 0.076). The area under the receiver-operating characteristic curve of GDF-15 level > 618.4 pg/mL for sarcopenia was 0.706 (95% confidence interval (CI) 0.625-0.779) with a sensitivity of 83.3% and a specificity of 54.5%. Using a GDF-15 level of 618.4 pg/mL as a cut-off, the GDF-15 level was associated with a significantly greater likelihood of sarcopenia (odds ratio [OR] 2.35; 95% CI 1.00-5.51; p = 0.049), obesity (OR 3.28; 95% CI 1.48-7.27; p = 0.001), osteopenic obesity (OR 3.10; 95% CI 1.31-7.30; p = 0.010), and sarcopenic or osteosarcopenic obesity (OR 4.84; 95% CI 0.88-26.69; p = 0.070). These findings support the potential of GDF-15 as a biomarker for age-related changes in muscle, fat, and bone.

Growth hormone/IGF-I-dependent signaling restores decreased expression of the myokine SPARC in aged skeletal muscle

Skeletal muscle exerts many beneficial effects on the human body including the contraction-dependent secretion of peptides termed myokines. We have recently connected the myokine secreted protein acidic and rich in cysteine (SPARC) to the formation of intramuscular adipose tissue (IMAT) in skeletal muscle from aged mice and humans. Here, we searched for inducers of SPARC in order to uncover novel treatment approaches for IMAT. Endurance exercise in mice as well as forskolin treatment in vitro only modestly activated SPARC levels. However, through pharmacological treatments in vitro, we identified IGF-I as a potent inducer of SPARC expression in muscle cells, likely through a direct activation of its promoter via phosphatidylinositol 4,5-bisphospate 3-kinase (PI3K)-dependent signaling. We employed two different mouse models of growth hormone (GH)/IGF-I deficiency to solidify our understanding of the relationship between IGF-I and SPARC in vivo. GH administration robustly increased intramuscular SPARC levels (3.5-fold) in GH releasing hormone receptor-deficient mice and restored low intramuscular SPARC expression in skeletal muscle from aged mice. Intramuscular glycerol injections induced higher levels of adipocyte markers (adiponectin, perilipin) in aged compared to young mice, which was not prevented by GH treatment. Our study provides a roadmap for the study of myokine regulation during aging and demonstrates that the GH/IGF-I axis is critical for SPARC expression in skeletal muscle. Although GH treatment did not prevent IMAT formation in the glycerol model, targeting SPARC by exercise or by activation of IGF-I signaling might offer a novel therapeutic strategy against IMAT formation during aging. KEY MESSAGES : IGF-I regulates the myokine SPARC in muscle cells directly at the promoter level. GH/IGF-I is able to restore the decreased SPARC levels in aged skeletal muscle. The glycerol model induces higher adipocyte markers in aged compared to young muscle. GH treatment does not prevent IMAT formation in the glycerol model.

Circulating Levels of Apelin, GDF-15 and Sarcopenia: Lack of Association in the MAPT Study

OBJECTIVES

Apelin and GDF-15 have been proposed as biomarkers of age-related sarcopenia but evidence in human models is scarce. This study aimed to explore the associations between blood apelin and GDF-15 with sarcopenia incidence and the evolution of sarcopenia components over two years in older adults >70 years.

DESIGN

Secondary longitudinal analysis of the Multidomain Alzheimer Preventive Trial.

PARTICIPANTS

Older adults (>70 years) attending primary care centers in France and Monaco.

SETTING

Community.

MEASUREMENTS

Serum Apelin (pg/mL) and plasma GDF-15 (pg/mL) were measured. Outcomes included sarcopenia defined by the European Working Group on Sarcopenia in Older People (EWGSOP) and its determinants (appendicular lean mass [ALM] evaluated through a Dual-energy X-ray Absorptiometry (DXA) scan, handgrip strength (HGS) and the 4-meter gait speed) measured over 2 years. Linear mixed models and logistic regression were used to explore the longitudinal associations.

RESULTS

We included 168 subjects from MAPT (median age=76y, IQR=73-79; 78% women). Serum apelin was not significantly associated with sarcopenia incidence (OR=1.001;95%CI=1.000,1.001;p-value>0.05 in full-adjusted models) nor with ALM (β=-5.8E-05;95%CI=-1.0E-04,2.12E-04;p>0.05), HGS (β=-1.1E-04;95%CI=-5.0E-04,2.8E-04;p>0.05), and GS (β=-5.1E-06;95%CI=-1.0E-05,2.0E-05;p>0.05) in fully adjusted models. Similarly, plasma GDF-15 was not associated with both the incidence of sarcopenia (OR=1.001,95%CI=1.000,1.002,p>0.05) and the evolution of its determinants ([ALM, β=2.1E-05;95%CI=-2.6E-04,3.03E-04;p>0.05], HGS [β=-5.9E-04;95%CI=-1.26E-03,8.1E-05; p>0.05] nor GS [β=-2.6E-06;95%CI=-3.0E-05, 2.3E-05;p>0.05]) in fully adjusted models.

CONCLUSIONS

Blood apelin and GDF-15 were not associated with sarcopenia incidence or with the evolution of sarcopenia components over a 2-year follow-up in community-dwelling older adults. Well-powered longitudinal studies are needed to confirm or refute our findings.

Identification of muscle weakness in older adults from normalized upper and lower limbs strength: a cross-sectional study

BACKGROUND

To propose cut-off points for older adults' weakness for upper and lower limbs muscle strength normalized by body size with the ratio standard/muscle quality and allometric scaling.

METHODS

Ninety-four community-dwelling older adults (69.1% women) were assessed for 49 body-size variables (anthropometry, body composition and body indexes), handgrip strength (HGS), one maximum repetition measurement for knee extensors (1RM), isokinetic knee extension peak torque at 60°/s (PT), and six-minute walk test (6MWT). Ratio standard or muscle quality (muscle strength/body size) and allometric scaling (muscle strength/body sizeb; when b is the allometric exponent) were applied for body-size variables significantly correlated with HGS, 1RM and PT. Cut-off points were computed according to sex based on mobility limitation (6MWT < 400 m) with ROC curve and Youden index.

RESULTS

Absolute HGS, 1RM and PT cut-off points were not adequate because they were associated with body size (r > 0.30). But it was corrected with muscle strength normalization according to body size-variables: HGS (n = 1); 1RM (n = 24) and PT (n = 24). The best cut-off points, with the highest area under the curve (AUC), were found after normalization for men: HGS/forearm circumference (1.33 kg/cm, AUC = 0.74), 1RM/triceps skinfold (4.22 kg/mm, AUC = 0.81), and PT/body mass*height0.43 (13.0 Nm/kg*m0.43, AUC = 0.94); and for women: HGS/forearm circumference (1.04 kg/cm, AUC = 0.70), 1RM/body mass (0.54 kg/kg, AUC = 0.76); and PT/body mass0.72 (3.14 Nm/kg0.72; AUC = 0.82).

CONCLUSIONS

Upper and lower limbs muscle weakness cut-off points standardized according to body size were proposed for older adults of both sexes. Normalization removes the effect of extreme body size on muscle strength (both sexes) and improves the accuracy to identify weakness at population level (for women, but not in men), reducing the risk of false-negative/positive cases.

Changes in systemic GDF15 across the adult lifespan and their impact on maximal muscle power: the Copenhagen Sarcopenia Study

BACKGROUND

Although growth differentiation factor 15 (GDF15) is known to increase with disease and is associated with low physical performance, the role of GDF15 in normal ageing is still not fully understood. Specifically, the influence of circulating GDF15 on impairments in maximal muscle power (a major contributor to functional limitations) and the underlying components has not been investigated.

METHODS

Data from 1305 healthy women and men aged 20 to 93 years from The Copenhagen Sarcopenia Study were analysed. Circulating levels of GDF15 and markers of inflammation (tumor necrosis factor-alpha, interleukin-6, and high-sensitivity C-reactive protein) were measured by ELISA (R&D Systems) and multiplex bead-based immunoassays (Bio-Rad). Relative (normalized to body mass), allometric (normalized to height squared), and specific (normalized to leg muscle mass) muscle power were assessed by the Nottingham power rig [leg extension power (LEP)] and the 30 s sit-to-stand (STS) muscle power test. Total body fat, visceral fat, and leg lean mass were assessed by dual energy X-ray absorptiometry. Leg skeletal muscle index was measured as leg lean mass normalized to body height squared.

RESULTS

Systemic levels of GDF15 increased progressively as a function of age in women (1.1 ± 0.4 pg·mL^-1 ·year^-1 ) and men (3.3 ± 0.6 pg·mL^-1 ·year^-1 ) (both P < 0.05). Notably, GDF15 increased at a faster rate from the age of 65 years in women (11.5 ± 1.2 pg·mL^-1 ·year^-1 , P < 0.05) and 70 years in men (19.3 ± 2.3 pg·mL^-1 ·year^-1 , P < 0.05), resulting in higher GDF15 levels in men compared with women above the age of 65 years (P < 0.05). Independently of age and circulatory markers of inflammation, GDF15 was negatively correlated to relative STS power (P < 0.05) but not LEP, in both women and men. These findings were mainly explained by negative associations of GDF15 with specific STS power in women and men (both P < 0.05).

CONCLUSIONS

A J-shaped relationship between age and systemic GDF15 was observed, with men at older age showing steeper increases and elevated GDF15 levels compared with women. Importantly, circulating GDF15 was independently and negatively associated with relative STS power, supporting the potential role of GDF15 as a sensitive biomarker of frailty in older people.

Genetically predicted insulin-like growth factor-I in relation to muscle mass and strength

OBJECTIVE

Insulin-like growth factor I (IGF-I) has been associated with muscle status in animal- and population-based studies. We conducted a Mendelian randomisation study to assess the causality of the associations of IGF-I with muscle strength and mass.

DESIGN AND PATIENTS

Genetic variants associated with serum IGF-I at genome-wide significance in the UK Biobank study (358,072 individuals of European descent) were selected as instrumental variables. Summary-level data on the associations of those variants with muscle weakness (low-grip strength) and muscle mass (fat-free body mass) were available from a meta-analysis of 22 genome-wide association studies including 46,596 cases and 209,927 noncases and genome-wide association analysis in 155,961 individuals from the UK Biobank study, respectively. The univariable and multivariable inverse-variance weighted methods were used.

RESULTS

Higher genetically predicted IGF-I levels were associated with a reduced risk of muscle weakness and increased muscle mass. For one standard deviation increase in genetically predicted IGF-I levels, the odds ratio was 0.92 (95% confidence interval [CI], 0.88, 0.97; p = .001) for muscle weakness and the change was 0.53 (95% CI: 0.28, 0.79; p < .001) kg for muscle mass. In the multivariable model with adjustment for genetically predicted height, the associations were attenuated but persisted for both muscle weakness (odds ratio: 0.95, 95% CI: 0.91, 0.99; p = .015) and muscle mass (change: 0.25, 95% CI: 0.10, 0.40; p = .001).

CONCLUSION

This study suggests that high IGF-I levels may decrease the risk of muscle weakness and loss.

Associations between elevated growth differentiation factor-15 and sarcopenia among community-dwelling older adults

BACKGROUND

Growth differentiation factor 15 (GDF-15) is associated with disease progression, mitochondrial dysfunction, and mortality. Elevated GDF-15 level was recently reported to be associated with poorer physical performance in healthy adults. However, the association between serum GDF-15 level and sarcopenia in community-dwelling older adults has not been well characterized.

METHODS

We conducted cross-sectional (n = 929) and two-year prospective analyses (n = 788) among participants aged 70-84 years enrolled in the Korean Frailty and Aging Cohort Study. Participants with an estimated glomerular filtration rate of <60 mL/min/1.73 m 2 were excluded. Appendicular lean mass was measured using dual-energy X-ray absorptiometry. Sarcopenia status was determined according to the Asian Working Group for Sarcopenia-2019 algorithm.

RESULTS

At baseline, 16.6% of the participants had sarcopenia. Median GDF-15 concentration was higher in the sarcopenic group than in the non-sarcopenic group (1221 pg/mL vs. 1019 pg/mL, p<0.001). In the multivariate analysis adjusted for cardiometabolic risk and biological factors, the highest GDF-15 tertile (≥1245 pg/mL) had an increased likelihood of sarcopenia (odds ratio, 1.96; 95% confidence interval, 1.16-3.33) than the lowest tertile (<885 pg/mL). During the two-year follow-up period, 67 (10.1%) individuals without sarcopenia at baseline developed sarcopenia. There were no significant associations between baseline serum GDF-15 levels and incident sarcopenia or its components (all p>0.05).

CONCLUSIONS

Elevated GDF-15 was associated with prevalent sarcopenia but not able to predict incident sarcopenia in the 2-year follow-up. Further studies are needed to explore the pathophysiological roles of GDF-15 in the development of sarcopenia.

Effects of Exercise Intervention on Mitochondrial Stress Biomarkers in Metabolic Syndrome Patients: A Randomized Controlled Trial

Metabolic syndrome (MetS) pathogenesis involves oxidative stress associated with mitochondrial dysfunction, which triggers integrated stress responses via various compensatory metabolic modulators like mitokines and hepatokines. However, the regulatory mechanisms underlying the exercise-derived benefits with respect to mitokines and hepatokines (potential MetS biomarkers) are unknown. Thus, we investigated the effects of exercise training on MetS biomarkers and their associations with clinical parameters. In this single-center trial, 30 women with MetS were randomly assigned to 12-week supervised exercise or control groups (1:1) and compared with 12 age-matched healthy volunteers. All participants completed the study except one subject in the control group. Expectedly, serum levels of the mitokines, fibroblast growth factor-21 (FGF21), growth differentiation factor-15 (GDF15), and the hepatokine, angiopoietin-like 6 (ANGPTL6), were higher in MetS patients than in healthy volunteers. Moreover, their levels were markedly attenuated in the exercise group. Further, exercise-mediated changes in serum FGF21 and GDF15 correlated with changes in the homeostasis model of assessment of insulin resistance (HOMA-IR) and appendicular lean mass (ALM), respectively. Additionally, changes in serum triglycerides and ANGPTL6 were correlated with changes in leptin. Aberrant mitokine and hepatokine levels can be rectified by relieving metabolic stress burden. Therefore, exercise training may reduce the need for the compensatory upregulation of MetS metabolic modulators by improving gluco-lipid metabolism.

Biomarkers for length of hospital stay, changes in muscle mass, strength and physical function in older medical patients: protocol for the Copenhagen PROTECT study-a prospective cohort study

INTRODUCTION

Sarcopenia is generally used to describe the age-related loss of muscle mass and strength believed to play a major role in the pathogenesis of physical frailty and functional impairment that may occur with old age. The knowledge surrounding the prevalence and determinants of sarcopenia in older medical patients is scarce, and it is unknown whether specific biomarkers can predict physical deconditioning during hospitalisation. We hypothesise that a combination of clinical, functional and circulating biomarkers can serve as a risk stratification tool and can (i) identify older acutely ill medical patients at risk of prolonged hospital stays and (ii) predict changes in muscle mass, muscle strength and function during hospitalisation.

METHOD AND ANALYSIS

The Copenhagen PROTECT study is a prospective cohort study consisting of acutely ill older medical patients admitted to the acute medical ward at Copenhagen University Hospital, Bispebjerg and Frederiksberg, Denmark. Assessments are performed within 24 hours of admission and include blood samples, body composition, muscle strength, physical function and questionnaires. A subgroup of patients transferred to the Geriatric Department are included in a smaller geriatric cohort and have additional assessments at discharge to evaluate the relative change in circulating biomarker concentrations, body composition, muscle strength and physical function during hospitalisation. Enrolment commenced 4 November 2019, and proceeds until August 2021.

ETHICS AND DISSEMINATION

The study protocol has been approved by the local ethics committee of Copenhagen and Frederiksberg (H-19039214) and the Danish Data Protection Agency (P-2019-239) and all experimental procedures were performed in accordance with the Declaration of Helsinki. Findings from the project, regardless of the outcome, will be published in relevant peer-reviewed scientific journals in online (www.clinicaltrials.gov).

TRIAL REGISTRATION NUMBER

NCT04151108.

Sarcopenia and Muscle Aging: A Brief Overview

The world is facing the new challenges of an aging population, and understanding the process of aging has therefore become one of the most important global concerns. Sarcopenia is a condition which is defined by the gradual loss of skeletal muscle mass and function with age. In research and clinical practice, sarcopenia is recognized as a component of geriatric disease and is a current target for drug development. In this review we define this condition and provide an overview of current therapeutic approaches. We further highlight recent findings that describe key pathophysiological phenotypes of this condition, including alterations in muscle fiber types, mitochondrial function, nicotinamide adenine dinucleotide (NAD+) metabolism, myokines, and gut microbiota, in aged muscle compared to young muscle or healthy aged muscle. The last part of this review examines new therapeutic avenues for promising treatment targets. There is still no accepted therapy for sarcopenia in humans. Here we provide a brief review of the current state of research derived from various mouse models or human samples that provide novel routes for the development of effective therapeutics to maintain muscle health during aging.

High Salt Diet Impacts the Risk of Sarcopenia Associated with Reduction of Skeletal Muscle Performance in the Japanese Population

The World Health Organization has recommended 5 g/day as dietary reference intakes for salt. In Japan, the averages for men and women were 11.0 g/day and 9.3 g/day, respectively. Recently, it was reported that amounts of sodium accumulation in skeletal muscles of older people were significantly higher than those in younger people. The purpose of this study was to investigate whether the risk of sarcopenia with decreased muscle mass and strength was related to the amount of salt intake. In addition, we investigated its involvement with renalase. Four groups based on age and salt intake ("younger low-salt," "younger high-salt," "older low-salt," and "older high-salt") were compared. Stratifying by age category, body fat percentage significantly increased in high-salt groups in both younger and older people. Handgrip strength/body weight and chair rise tests of the older high-salt group showed significant reduction compared to the older low-salt group. However, there was no significant difference in renalase concentrations in plasma. The results suggest that high-salt intake may lead to fat accumulation and muscle weakness associated with sarcopenia. Therefore, efforts to reduce salt intake may prevent sarcopenia.

Growth differentiation factor-15 as a biomarker for sarcopenia in aging humans and mice

Sarcopenia is a pathologic status characterized by impaired muscle strength or function accompanying decreased muscle mass. It results in increased vulnerability to chronic diseases. Despite growing clinical concerns about sarcopenia in an aging society, there are few validated biomarkers for age-related sarcopenia. We tested the potential of growth differentiation factor-15 (GDF-15) as a biomarker for sarcopenia in mice and humans across wide age ranges. We used four groups of mice (6, 10, 14, and 18 months old) to explore the association between GDF-15 levels and age, muscle mass, and endurance capacity. Among those four groups, 6- and 18-month-old mice were exposed to 8 weeks of treadmill exercise. The GDF-15 levels were measured in serum and muscle at baseline and after exercise intervention. The body composition was assessed using animal dual-energy X-ray absorptiometry (DXA). GDF-15 levels in tissue and serum increased with age in these mice. The serum levels of GDF-15 had a strong negative correlation with both muscle weight and exercise endurance capacity. Expression of GDF-15 in muscle also had a negative trend with muscle weight and endurance capacity. The muscle expression of GDF-15 was significantly attenuated after 8 weeks of exercise compared with the group without exercise, particularly in older mice. GDF-15 levels were also related to functional capacity and showed responses to therapeutic exercise intervention in this model. We also measured serum GDF-15 levels and muscle mass using DXA in healthy human adults (19 men and 18 women). As in mice, serum levels of GDF-15 were correlated positively with age, but negatively with muscle mass in these subjects. These findings support the potential of GDF-15 as a biomarker for age-related sarcopenia.

The TOR Pathway at the Neuromuscular Junction: More Than a Metabolic Player?

The neuromuscular junction (NMJ) is the chemical synapse connecting motor neurons and skeletal muscle fibers. NMJs allow all voluntary movements, and ensure vital functions like breathing. Changes in the structure and function of NMJs are hallmarks of numerous pathological conditions that affect muscle function including sarcopenia, the age-related loss of muscle mass and function. However, the molecular mechanisms leading to the morphological and functional perturbations in the pre- and post-synaptic compartments of the NMJ remain poorly understood. Here, we discuss the role of the metabolic pathway associated to the kinase TOR (Target of Rapamycin) in the development, maintenance and alterations of the NMJ. This is of particular interest as the TOR pathway has been implicated in aging, but its role at the NMJ is still ill-defined. We highlight the respective functions of the two TOR-associated complexes, TORC1 and TORC2, and discuss the role of localized protein synthesis and autophagy regulation in motor neuron terminals and sub-synaptic regions of muscle fibers and their possible effects on NMJ maintenance.

Myostatin as a Biomarker of Muscle Wasting and other Pathologies-State of the Art and Knowledge Gaps

Sarcopenia is a geriatric syndrome with a significant impact on older patients’ quality of life, morbidity and mortality. Despite the new available criteria, its early diagnosis remains difficult, highlighting the necessity of looking for a valid muscle wasting biomarker. Myostatin, a muscle mass negative regulator, is one of the potential candidates. The aim of this work is to point out various factors affecting the potential of myostatin as a biomarker of muscle wasting. Based on the literature review, we can say that recent studies produced conflicting results and revealed a number of potential confounding factors influencing their use in sarcopenia diagnosing. These factors include physiological variables (such as age, sex and physical activity) as well as a variety of disorders (including heart failure, metabolic syndrome, kidney failure and inflammatory diseases) and differences in laboratory measurement methodology. Our conclusion is that although myostatin alone might not prove to be a feasible biomarker, it could become an important part of a recently proposed panel of muscle wasting biomarkers. However, a thorough understanding of the interrelationship of these markers, as well as establishing a valid measurement methodology for myostatin and revising current research data in the light of new criteria of sarcopenia, is needed.

Vitamin D protects against immobilization-induced muscle atrophy via neural crest-derived cells in mice

Vitamin D deficiency is a recognized risk factor for sarcopenia development, but mechanisms underlying this outcome are unclear. Here, we show that low vitamin D status worsens immobilization-induced muscle atrophy in mice. Mice globally lacking vitamin D receptor (VDR) exhibited more severe muscle atrophy following limb immobilization than controls. Moreover, immobilization-induced muscle atrophy was worse in neural crest-specific than in skeletal muscle-specific VDR-deficient mice. Tnfα expression was significantly higher in immobilized muscle of VDR-deficient relative to control mice, and was significantly elevated in neural crest-specific but not muscle-specific VDR-deficient mice. Furthermore, muscle atrophy induced by limb immobilization in low vitamin D mice was significantly inhibited in Tnfα-deficient mice. We conclude that vitamin D antagonizes immobilization-induced muscle atrophy via VDR expressed in neural crest-derived cells.

Myokines and adipokines in sarcopenia: understanding cross-talk between skeletal muscle and adipose tissue and the role of exercise

Detrimental age-associated changes in skeletal muscle and adipose tissue increase the risk of sarcopenia. Age-related changes in myokines, such as myostatin and irisin, as well as adipokines, such as leptin and adiponectin, contribute to cross-talk between muscle and adipose tissue. These age-related changes in myokines and adipokines have important implications for sarcopenia, however, recent literature highlights discrepancies in these relationships. Exercise may alter serum profiles and muscle receptor expression of these factors, but future work is needed to determine whether these changes in myokines and adipokines relate to improvements in muscle mass and function. Here, we describe myokine-mediated and adipokine-mediated interactions between muscle and adipose tissue, and discuss the fundamental importance of these cytokines to understanding the development of sarcopenia.

Associations Between Serum GDF15 Concentrations, Muscle Mass, and Strength Show Sex-Specific Differences in Older Hospital Patients

Aging is accompanied by a progressive decline of muscle mass and strength and also higher levels of circulating cytokines such as growth differentiation factor 15 (GDF15). Studies evaluating the association of GDF15 with muscle mass and strength are rare. In this analysis, we investigated GDF15 concentrations and their relationship with muscle mass and strength in older men compared with women. GDF15 serum concentrations were measured in 103 (60 years and older) hospital patients and an age-matched control group with an immunosorbent assay. Skeletal muscle mass was determined with the bioelectrical impedance analysis. Grip strength and knee extension strength were assessed and normalized for height. Associations between GDF15 concentrations and muscle mass and strength were evaluated with general linear models. Male patients showed higher levels of GDF15 compared with female patients (p = 0.021). Elevated GDF15 concentrations were associated with lower measures of muscle mass, exclusively in men, after adjustment for age and number of drugs per day. Our results indicate sex differences between associations of GDF15 with muscle mass and strength parameters in a cohort of older hospital patients.

GDF15 Plasma Level Is Inversely Associated With Level of Physical Activity and Correlates With Markers of Inflammation and Muscle Weakness

Growth differentiation factor 15 (GDF15) is a stress molecule produced in response to mitochondrial, metabolic and inflammatory stress with a number of beneficial effects on metabolism. However, at the level of skeletal muscle it is still unclear whether GDF15 is beneficial or detrimental. The aim of the study was to analyse the levels of circulating GDF15 in people of different age, characterized by different level of physical activity and to seek for correlation with hematological parameters related to inflammation. The plasma concentration of GDF15 was determined in a total of 228 subjects in the age range from 18 to 83 years. These subjects were recruited and divided into three different groups based on the level of physical activity: inactive patients with lower limb mobility impairment, active subjects represented by amateur endurance cyclists, and healthy controls taken from the general population. Cyclists were sampled before and after a strenuous physical bout (long distance cycling race). The plasma levels of GDF15 increase with age and are inversely associated with active lifestyle. In particular, at any age, circulating GDF15 is significantly higher in inactive patients and significantly lower in active people, such as cyclists before the race, with respect to control subjects. However, the strenuous physical exercise causes in cyclists a dramatic increase of GDF15 plasma levels, that after the race are similar to that of patients. Moreover, GDF15 plasma levels significantly correlate with quadriceps torque in patients and with the number of total leukocytes, neutrophils and lymphocytes in both cyclists (before and after race) and patients. Taken together, our data indicate that GDF15 is associated with decreased muscle performance and increased inflammation.

Cut-off points of knee extension strength allometrically adjusted to identify sarcopenia risk in older adults: A cross-sectional study

PURPOSE

Handgrip strength used to identify sarcopenia is not representative of overall strength, especially as greater muscle volume and consequent autonomy-mobility are concentrated in the lower limbs. While absolute strength or relative to body mass is used to define sarcopenia, this relationship is not always linear. The aim of this study was to establish allometrically adjusted cut-off points of lower limb (quadriceps) muscle strength to identify sarcopenia risk in older adults.

METHODS

ninety-four physically independent individuals over the age of 60 were measured by DXA and sarcopenia was identified. The one-repetition maximum (1RM) test of knee extension strength was estimated using the extensor chair by the submaximal repetition protocol. The six-minute walk test performance was recorded. 1RM values were scaled by body mass (1RM/body mass) and allometrically adjusted (1RM/body mass^b). Cut-off points for sarcopenia from 1RM were defined with ROC curve and Youden index with functional limitation (walking distance<400 m). Analyzes considered sex (α = 5%).

RESULTS

Sarcopenia was present in 10.6 % of participants. The exponents ^b obtained were 0.70 for women and 0.96 for men. Except for absolute 1RM in women, all areas under the curve were acceptable (>0.70). The cut-off points for women and men were respectively, 38.1 and 56.1 kg for 1RM, 0.53 and 0.85 for 1RM/body mass, 1.48 and 1.00 for 1RM/body mass^b.

CONCLUSIONS

1RM of knee extension scaled by body mass or allometrically adjusted is an effective parameter to identify sarcopenia in older adults. The proposed cut-off points could be used to monitor sarcopenia risk in geriatrics.

Insulin-like growth factor-I is required to maintain muscle volume in adult mice

Insulin-like growth factor-I (IGF-I) is a peptide with diverse functions, among them regulation of embryonic development and bone homeostasis. Serum IGF-I levels decline in the elderly; however, IGF-I function in adults has not been clearly defined. Here, we show that IGF-I is required to maintain muscle mass in adults. We crossed Igf-I flox'd and Mx1 Cre mice to yield Mx1 Cre/Igf-I^flox/flox (IGF-I cKO) mice, and deleted Igf-I in adult mice by polyIpolyC injection. We demonstrate that, although serum IGF-I levels significantly decreased after polyIpolyC injection relative to (Igf-I^flox/flox) controls, serum glucose levels were unchanged. However, muscle mass decreased significantly after IGF-I down-regulation, while bone mass remained the same. In IGF-I cKO muscle, expression of anabolic factors such as Eif4e and p70S6K significantly decreased, while expression of catabolic factors MuRF1 and Atrogin-1 was normal and down-regulated, respectively, suggesting that observed muscle mass reduction was due to perturbed muscle metabolism. Our data demonstrate a specific role for IGF-I in maintaining muscle homeostasis in adults.

Effects of acute resistance exercise on proteolytic and myogenic markers in skeletal muscles of former weightlifters and age-matched sedentary controls

BACKGROUND

Former athletes who continue a regular, performance-oriented training throughout life provide a unique model for studying successful aging. With this in mind, the current study aimed to compare the effects of an acute resistance exercise on proteolytic and myogenic markers in older weightlifters and untrained participants.

METHODS

Sixteen older men (8 former weightlifters, 8 age-matched untrained controls) with an age of 61.2±8.2 years volunteered to participate in the study. Two days after assessing 1-RM, an acute exercise protocol (3 sets, 70-75% of one-repetition maximum until voluntary fatigue) was applied unilaterally on the dominant leg while the other leg served as control. Three hours after termination of the exercise, skeletal muscle tissue was obtained from m. vastus lateralis of both legs.

RESULTS

Acute resistance exercise led to an up-regulation (>1.5-fold) of 14 genes in controls and of 13 genes in weightlifters. The transcription factors FOS and early growth response 1 (EGR1), as well as the E3 protein ligase TRIM63 comprised the most responsive genes to resistance exercise (EGR1:15.7-fold increase, P=0.003, FOS: 36.3-fold increase, P<0.001; TRIM63: 2.9-fold increase, P<0.001). In addition, myostatin levels were decreased in the exercised leg (0.6-fold, P<0.001). FOXO3 gene expression was significantly higher in weightlifters than in untrained controls (1.5-fold, P=0.042).

CONCLUSIONS

Trained and untrained older adults respond to an acute bout of resistance exercise in a very similar way irrespective of training status, although some differences exist in FOXO3, potentially reflecting the superior capacity of trained persons in regulating cellular homeostasis.

Fat Soluble Vitamins in Institutionalized Elderly and the Effect of Exercise, Nutrition and Cognitive Training on Their Status-The Vienna Active Aging Study (VAAS): A Randomized Controlled Trial

BACKGROUND

Institutionalized elderly are at higher risk for micronutrient deficiency. In particular, fat soluble micronutrients, which additionally have antioxidative function, are of interest. The purpose of this secondary investigation of the Vienna Active Ageing Study was to assess and evaluate the plasma status of retinol, alpha- and gamma-tocopherol, alpha- and beta-carotene, lutein, zeaxanthin, beta-cryptoxanthin, and lycopene, as well as vitamin D (25(OH)D) in a cohort of institutionalized elderly. We further determined the effect of six months strength training with or without supplementing (antioxidant) vitamins and protein on the plasma status of these ten micronutrients.

METHODS

Three groups (n = 117, age = 83.1 ± 6.1 years)-resistance training (RT), RT combined with protein and vitamin supplementation (RTS), or cognitive training (CT)-performed two guided training sessions per week for six months. Micronutrients were measured with High Performance Liquid Chromatography (HPLC) at baseline and after 6 months of intervention. Physical fitness was assessed by the 6-min-walking, the 30-s chair rise, isokinetic dynamometry, and the handgrip strength tests.

RESULTS

At baseline, the plasma status of retinol was satisfactory, for alpha-tocopherol, beta-carotene, and 25(OH)D, the percentage of individuals with an insufficient status was 33%, 73% and 61%/81% (when using 50 nmol/L or 75 nmol/L as threshold levels for 25(OH)D), respectively. Plasma analyses were supported by intake data. Six months of elastic band resistance training with or without protein-vitamin supplementation had no biological impact on the status of fat soluble micronutrients. Even for vitamin D, which was part of the nutritional supplement (additional 20 µg/d), the plasma status did not increase significantly, however it contributed to a lower percentage of elderly below the threshold levels of 50/75 nmol/L (49%/74%).

CONCLUSIONS

The findings of the study lead to the strong recommendation for regular physical activity and increased consumption of plant-based foods in institutionalized elderly. When supported by blood analysis, supplementing micronutrients in a moderate range should also be considered.

Association of serum bone- and muscle-derived factors with age, sex, body composition, and physical function in community-dwelling middle-aged and elderly adults: a cross-sectional study

BACKGROUND

Understanding interactions between bone and muscle based on endocrine factors may help elucidate the relationship between osteoporosis and sarcopenia. However, whether the abundance or activity of these endocrine factors is affected by age and sex or whether these factors play a causal role in bone and muscle formation and function is unclear. We aimed to evaluate the association of serum bone- and muscle-derived factors with age, sex, body composition, and physical function in community-dwelling middle-aged and elderly adults.

METHODS

In all, 254 residents (97 men, 157 women) participated in this cross-sectional study conducted in Japan. The calcaneal speed of sound (SOS) was evaluated by quantitative ultrasound examination. Skeletal muscle mass index (SMI) was calculated by bioelectrical impedance analysis. Grip strength was measured using a dynamometer. Gait speed was measured by optical-sensitive gait analysis. Serum sclerostin, osteocalcin (OC), insulin-like growth factor-1 (IGF-1), myostatin, and tartrate-resistant acid phosphatase-5b (TRACP-5b) concentrations were measured simultaneously. The difference by sex was determined using t test. Correlations between serum bone- and muscle-derived factors and age, BMI, SOS, SMI, grip strength, gait speed, and TRACP-5b in men and women were determined based on Pearson's correlation coefficients. Multiple regression analysis was performed using the stepwise method.

RESULTS

There was no significant difference with regard to age between men (75.0 ± 8.9 years) and women (73.6 ± 8.1 years). Sclerostin was significantly higher in men than in women and tended to increase with age in men; it was significantly associated with SOS and TRACP-5b levels. OC was significantly higher in women than in men and was significantly associated with TRACP-5b levels and age. IGF-1 tended to decrease with age in both sexes and was significantly associated with SOS and body mass index. Myostatin did not correlate with any assessed variables.

CONCLUSIONS

Sclerostin was significantly associated with sex, age, and bone metabolism, although there was no discernable relationship between serum sclerostin levels and muscle function. There was no obvious relationship between OC and muscle parameters. This study suggests that IGF-1 is an important modulator of muscle mass and function and bone metabolism in community-dwelling middle-aged and elderly adults.

GH replacement titrated to serum IGF-1 does not reduce concentrations of myostatin in blood or skeletal muscle

OBJECTIVE

Traditional weight-based regimens of GH replacement are more effective at reversing the loss of skeletal muscle in GH-deficient adults than currently recommended regimens, where the dose of GH is increased to restore serum concentrations of IGF-1. While weight-based regimens increase concentrations of IGF-1 and decrease concentrations of myostatin, it is not known whether the reduced effectiveness of individually titrated GH regimens is due to ongoing hypersecretion of myostatin. Consequently, the aims of this study were to determine whether concentrations of myostatin in blood and skeletal muscle are increased in GH-deficient adults, and whether these concentrations are decreased by GH replacement regimens titrated to restore serum IGF-1.

DESIGN

Twenty-six GH deficient adults (18 men and 8 women) were treated with individualised regimens of recombinant human GH aiming to achieve serum concentrations of IGF-1 within one standard deviation of the age- and gender-adjusted mean. Plasma concentrations of myostatin were measured at baseline and after 6 months of treatment were compared to fifteen healthy controls (9 men and 6 women). Skeletal muscle biopsies were performed in 19 of these GH-deficient adults (15 men and 4 women) and 10 of the healthy controls (6 men and 4 women). Expression of IGF-1 and myostatin mRNA was determined by qPCR.

RESULTS

Concentrations of IGF-1 in serum and mRNA in skeletal muscle were reduced, and concentrations of myostatin in plasma and mRNA in skeletal muscle were increased in GH-deficient adults at baseline (P < .05 versus healthy controls). Despite restoring concentrations of IGF-1, GH replacement did not reduce concentrations of myostatin in either blood or skeletal muscle. Concentrations of IGF-1 and myostatin in both blood and skeletal muscle were positively correlated in GH-deficient adults at baseline (P < .05), but not in GH-replete adults.

CONCLUSIONS

Concentrations of myostatin in blood and skeletal muscle are increased in GH-deficient adults. Despite normalising concentrations of IGF-1, individualised regimens of GH replacement do not reduce concentrations of myostatin in blood or skeletal muscle. Ongoing hypersecretion of myostatin may explain why individually titrated GH replacement regimens are less effective than higher weight-based regimens in increasing skeletal muscle mass.

Towards frailty biomarkers: Candidates from genes and pathways regulated in aging and age-related diseases

OBJECTIVE

Use of the frailty index to measure an accumulation of deficits has been proven a valuable method for identifying elderly people at risk for increased vulnerability, disease, injury, and mortality. However, complementary molecular frailty biomarkers or ideally biomarker panels have not yet been identified. We conducted a systematic search to identify biomarker candidates for a frailty biomarker panel.

METHODS

Gene expression databases were searched (http://genomics.senescence.info/genes including GenAge, AnAge, LongevityMap, CellAge, DrugAge, Digital Aging Atlas) to identify genes regulated in aging, longevity, and age-related diseases with a focus on secreted factors or molecules detectable in body fluids as potential frailty biomarkers. Factors broadly expressed, related to several "hallmark of aging" pathways as well as used or predicted as biomarkers in other disease settings, particularly age-related pathologies, were identified. This set of biomarkers was further expanded according to the expertise and experience of the authors. In the next step, biomarkers were assigned to six "hallmark of aging" pathways, namely (1) inflammation, (2) mitochondria and apoptosis, (3) calcium homeostasis, (4) fibrosis, (5) NMJ (neuromuscular junction) and neurons, (6) cytoskeleton and hormones, or (7) other principles and an extensive literature search was performed for each candidate to explore their potential and priority as frailty biomarkers.

RESULTS

A total of 44 markers were evaluated in the seven categories listed above, and 19 were awarded a high priority score, 22 identified as medium priority and three were low priority. In each category high and medium priority markers were identified.

CONCLUSION

Biomarker panels for frailty would be of high value and better than single markers. Based on our search we would propose a core panel of frailty biomarkers consisting of (1) CXCL10 (C-X-C motif chemokine ligand 10), IL-6 (interleukin 6), CX3CL1 (C-X3-C motif chemokine ligand 1), (2) GDF15 (growth differentiation factor 15), FNDC5 (fibronectin type III domain containing 5), vimentin (VIM), (3) regucalcin (RGN/SMP30), calreticulin, (4) PLAU (plasminogen activator, urokinase), AGT (angiotensinogen), (5) BDNF (brain derived neurotrophic factor), progranulin (PGRN), (6) α-klotho (KL), FGF23 (fibroblast growth factor 23), FGF21, leptin (LEP), (7) miRNA (micro Ribonucleic acid) panel (to be further defined), AHCY (adenosylhomocysteinase) and KRT18 (keratin 18). An expanded panel would also include (1) pentraxin (PTX3), sVCAM/ICAM (soluble vascular cell adhesion molecule 1/Intercellular adhesion molecule 1), defensin α, (2) APP (amyloid beta precursor protein), LDH (lactate dehydrogenase), (3) S100B (S100 calcium binding protein B), (4) TGFβ (transforming growth factor beta), PAI-1 (plasminogen activator inhibitor 1), TGM2 (transglutaminase 2), (5) sRAGE (soluble receptor for advanced glycosylation end products), HMGB1 (high mobility group box 1), C3/C1Q (complement factor 3/1Q), ST2 (Interleukin 1 receptor like 1), agrin (AGRN), (6) IGF-1 (insulin-like growth factor 1), resistin (RETN), adiponectin (ADIPOQ), ghrelin (GHRL), growth hormone (GH), (7) microparticle panel (to be further defined), GpnmB (glycoprotein nonmetastatic melanoma protein B) and lactoferrin (LTF). We believe that these predicted panels need to be experimentally explored in animal models and frail cohorts in order to ascertain their diagnostic, prognostic and therapeutic potential.

Relationship of muscle function to circulating myostatin, follistatin and GDF11 in older women and men

Background

Myostatin, its inhibitor follistatin, and growth/differentiation factor 11 (GDF11) have been proposed as factors that could potentially modify biological aging. The study aimed to test whether there is a relationship between these plasma circulating proteins and muscle strength, power and optimal shortening velocity (υ_opt) of older adults.

Methods

The cross-sectional study included 56 women and 45 men aged 60 years and older. Every participant underwent examination which included anthropometric and bioimpedance analysis measurements, functional and cognitive performance tests, muscle strength of upper and lower extremities, muscle power testing with two different methods and blood analyses.

Results

Women had higher plasma levels of myostatin and GDF11 than men. Men had higher plasma level of follistatin than women. In women, plasma level of myostatin was negatively correlated with left handgrip strength and υ_opt. Follistatin was negatively correlated with maximum power output (P_max), power relative to kg of body mass (P_max∙kg^− 1) (friction-loaded cycle ergometer) and power at 70% of the 1-repetition maximum (1RM) strength value (P70%) of leg press (Keiser pneumatic resistance training equipment), and positively correlated with the Timed Up & Go (TUG) test. GDF11 was negatively correlated with body mass, body mass index, waist circumference, fat mass and the percentage of body fat. In men, there were no significant correlations observed between circulating plasma proteins and muscle function measures.

Conclusions

The circulating plasma myostatin and follistatin are negatively associated with muscle function in older women. There is stronger relationship between these proteins and muscle power than muscle strength. GDF11 has a higher association with the body mass and composition than muscle function in older women.

Sarcopenia, nutritional status and functionality in elderly women living in the community

Abstract Objective: to evaluate the relationship between sarcopenia, functional capacity and nutritional status among elderly women living in the community. Method: an observational, cross-sectional study was performed with 100 elderly women aged over 60 years. A questionnaire containing identification and socioeconomic data and information relating to the practice of physical activity was applied, while anthropometric and body composition data were measured through bioimpedance and functionality data was assessed using the six-minute walk test (6MWT). Independent t-tests were performed for the quantitative variables and analysis of variance (ANOVA) was used to compare the means of the variables. Multiple linear regression analyzes were performed to estimate the mean 6MWTfor each of the variables studied. Results: The average age of the elderly women was 67 (± 8.0) years, 41% practiced physical activity, 38% had at least an elementary school education, 48% received up to two minimum wages and 91% were obese according to waist circumference (WC). The prevalence rates for the presence of sarcopenia were: 5% for sarcopenic obesity (SO), 63% for obesity, 14% for sarcopenia and 18% had adequate weight. Elderly women who practiced physical activity, had at least an elementary education and who were non-obese according to WC, performed better in the 6MWT. There were no significant differences in the 6MWTbased on income or Body Mass Index (p>0.05). Non-obese and non-sarcopenic women walked further in the functional test than the other women (p = 0.021). Conclusion: SO was present in 5% of the elderly women and is related to poor physical performance, which was also present in elderly women with sarcopenia and obesity.

Is a decrease of grip strength associated with community mobility restriction in dynapenic older women?

Background: Absolute grip strength (aGS) is  used to detect dynapenia, and is also an  indicator of functional impairments such as mobility limitations. The objective of this study is to investigate whether dynapenia status assessed by absolute grip strength (aGS) is associated with loss of community mobility.Method: The population studied (n=62) was composed of  a dynapenic group of women (aged 66.4 ± 4.8) according to an aGS threshold of ≤ 19.9kg and an age-matched group of nodynapenic women (aged 66.1 ± 5.2). The aGS was measured and body-weigth-related to grip strength (BW/GS) was computed. Fonctionnal laboratory tests were conducted. During 12 days, each participant wore a GPS device to obtain Transit distance in vehicle per day, Transit distance on foot per day and Ellipse area.  The Life space (LS) was assessed using the Life Space Assesment questionnaire (LSA). A Wilcoxon test was used to compare the 2 groups for the community mobility measures. Then, data of the 2 groups were pooled to assess the relationship between BW/GS and community mobility measures. A Spearman correlation was used.Results: The dynapenic group performed worse for fonctionnal capacity tests such as the step test and the walking speed. Howerver, no significant difference was found for GPS measures and LS between the two groups. No significant relationship was found for the BW/GS and community mobility measures with the GPS measures and the LS.  

Comparison of muscle/lean mass measurement methods: correlation with functional and biochemical testing

DXA-measured lean mass is often used to assess muscle mass but has limitations. Thus, we compared DXA lean mass with two novel methods-bioelectric impedance spectroscopy and creatine (methyl-d3) dilution. The examined methodologies did not measure lean mass similarly and the correlation with muscle biomarkers/function varied.

INTRODUCTION

Muscle function tests predict adverse health outcomes better than lean mass measurement. This may reflect limitations of current mass measurement methods. Newer approaches, e.g., bioelectric impedance spectroscopy (BIS) and creatine (methyl-d3) dilution (D3-C), may more accurately assess muscle mass. We hypothesized that BIS and D3-C measured muscle mass would better correlate with function and bone/muscle biomarkers than DXA measured lean mass.

METHODS

Evaluations of muscle/lean mass, function, and serum biomarkers were obtained in older community-dwelling adults. Mass was assessed by DXA, BIS, and orally administered D3-C. Grip strength, timed up and go, and jump power were examined. Potential muscle/bone serum biomarkers were measured. Mass measurements were compared with functional and serum data using regression analyses; differences between techniques were determined by paired t tests.

RESULTS

Mean (SD) age of the 112 (89F/23M) participants was 80.6 (6.0) years. The lean/muscle mass assessments were correlated (.57-.88) but differed (p < 0.0001) from one another with DXA total body less head being highest at 37.8 (7.3) kg, D3-C muscle mass at 21.1 (4.6) kg, and BIS total body intracellular water at 17.4 (3.5) kg. All mass assessment methods correlated with grip strength and jump power (R = 0.35-0.63, p < 0.0002), but not with gait speed or repeat chair rise. Lean mass measures were unrelated to the serum biomarkers measured.

CONCLUSIONS

These three methodologies do not similarly measure muscle/lean mass and should not be viewed as being equivalent. Functional tests assessing maximal muscle strength/power (grip strength and jump power) correlated with all mass measures whereas gait speed was not. None of the selected serum measures correlated with mass. Efforts to optimize muscle mass assessment and identify their relationships with health outcomes are needed.

A targeted proteomic assay for the measurement of plasma proteoforms related to human aging phenotypes

Circulating polypeptides and proteins have been implicated in reversing or accelerating aging phenotypes, including growth/differentiation factor 8 (GDF8), GDF11, eotaxin, and oxytocin. These proteoforms, which are defined as the protein products arising from a single gene due to alternative splicing and PTMs, have been challenging to study. Both GDF8 and GDF11 have known antagonists such as follistatin (FST), and WAP, Kazal, immunoglobulin, Kunitz, and NTR domain-containing proteins 1 and 2 (WFIKKN1, WFIKKN2). We developed a novel multiplexed SRM assay using LC-MS/MS to measure five proteins related to GDF8 and GDF11 signaling, and in addition, eotaxin, and oxytocin. Eighteen peptides consisting of 54 transitions were monitored and validated in pooled human plasma. In 24 adults, the mean (SD) concentrations (ng/mL) were as follows: GDF8 propeptide, 11.0 (2.4); GDF8 mature protein, 25.7 (8.0); GDF11 propeptide, 21.3 (10.9); GDF11 mature protein, 16.5 (12.4); FST, 29.8 (7.1); FST cleavage form FST303, 96.4 (69.2); WFIKKN1, 38.3 (8.3); WFIKKN2, 32.2 (10.5); oxytocin, 1.9 (0.9); and eotaxin, 2.3 (0.5). This novel multiplexed SRM assay should facilitate the study of the relationships of these proteoforms with major aging phenotypes.

The Role of IGF-1 Signaling in Skeletal Muscle Atrophy

Insulin-like growth factor 1 (IGF-1) is a key anabolic growth factor stimulating phosphatidylinositol 3-kinase (PI3K)/Akt signaling which is well known for regulating muscle hypertrophy. However, the role of IGF-1 in muscle atrophy is less clear. This review provides an overview of the mechanisms via which IGF-1 signaling is implicated in several conditions of muscle atrophy and via which mechanisms protein turnover is altered. IGF-1/PI3K/Akt signaling stimulates the rate of protein synthesis via p70S6Kinase and p90 ribosomal S6 kinase and negatively regulates protein degradation, predominantly by its inhibiting effect on proteasomal and lysosomal protein degradation. Caspase-dependent protein degradation is also attenuated by IGF/PI3K/Akt signaling, whereas evidence for an effect on calpain-dependent protein degradation is inconclusive. IGF-1/PI3K/Akt signaling reduces during denervation-, unloading-, and joint immobilization-induced muscle atrophy, whereas IGF-1/PI3K/Akt signaling seems unaltered during aging-associated muscle atrophy. During denervation and aging, IGF-1 overexpression or injection counteracts denervation- and aging-associated muscle atrophy, despite enhanced anabolic resistance with regard to IGF-1 signaling with aging. It remains unclear whether pharmacological stimulation of IGF-1/PI3K/Akt signaling attenuates immobilization- or unloading-induced muscle atrophy. Exploration of the possibilities to interfere with IGF-1/PI3K/Akt signaling reveals that microRNAs targeting IGF-1 signaling components are promising targets to counterbalance muscle atrophy. Overall, the findings summarized in this review show that in disuse conditions, but not with aging, IGF-1/PI3K/Akt signaling is attenuated and that in some conditions stimulation of this pathway may alleviate skeletal muscle atrophy.

The Vicious Cycle of Myostatin Signaling in Sarcopenic Obesity: Myostatin Role in Skeletal Muscle Growth, Insulin Signaling and Implications for Clinical Trials

The age-related loss of skeletal muscle (sarcopenia) is a major health concern as it is associated with physical disability, metabolic impairments, and increased mortality. The coexistence of sarcopenia with obesity, termed 'sarcopenic obesity', contributes to skeletal muscle insulin resistance and the development of type 2 diabetes, a disease prevalent with advancing age. Despite this knowledge, the mechanisms contributing to sarcopenic obesity remain poorly understood, preventing the development of targeted therapeutics. This article will discuss the clinical and physiological consequences of sarcopenic obesity and propose myostatin as a potential candidate contributing to this condition. A special emphasis will be placed on examining the role of myostatin signaling in impairing both skeletal muscle growth and insulin signaling. In addition, the role of myostatin in regulating muscle-to fat cross talk, further exacerbating metabolic dysfunction in the elderly, will be highlighted. Lastly, we discuss how this knowledge has implications for the design of myostatin-inhibitor clinical trials.

Molecular mechanisms and therapeutic interventions in sarcopenia

Sarcopenia is the degenerative loss of muscle mass and function with aging. Recently sarcopenia was recognized as a clinical disease by the International Classification of Disease, 10th revision, Clinical Modification. An imbalance between protein synthesis and degradation causes a gradual loss of muscle mass, resulting in a decline of muscle function as a progress of sarcopenia. Many mechanisms involved in the onset of sarcopenia include age-related factors as well as activity-, disease-, and nutrition-related factors. The stage of sarcopenia reflecting the severity of conditions assists clinical management of sarcopenia. It is important that systemic descriptions of the disease conditions include age, sex, and other environmental risk factors as well as levels of physical function. To develop a new therapeutic intervention needed is the detailed understanding of molecular and cellular mechanisms by which apoptosis, autophagy, atrophy, and hypertrophy occur in the muscle stem cells, myotubes, and/or neuromuscular junction. The new strategy to managing sarcopenia will be signal-modulating small molecules, natural compounds, repurposing of old drugs, and muscle-specific microRNAs.

Inflammatory markers, sarcopenia and its diagnostic criteria among the elderly: a systematic review

Abstract Objective: To identify the relationship between inflammatory markers and sarcopenia, and the diagnostic criteria of the condition among the elderly. Methods: A systematic review was performed based on the consultation of the PubMed and LILACS databases. Eligible original articles were those involving individuals aged 60 years or more, which investigated sarcopenia [low muscle mass (MM) associated with poor muscle strength and/or reduced physical performance, according to the European Working Group on Sarcopenia in Older People consensus (EWGSOP)] or its diagnostic criteria, published in English or Portuguese, between 2010-2015. Results: Four articles were included in the review, the principle results of which were: the growth differentiation factor (GDF-15) exhibited a negative correlation with MM, handgrip strength and gait speed; the insulin-like growth factor-1 (IGF-1) correlated positively with MM; follistatin exhibited a weak correlation with physical performance; activin A and myostatin did not correlate with the diagnostic criteria; the highest tercile of extracellular heat shock protein 72 (eHsp72) was associated with lower median levels of MM, handgrip strength and gait speed; elderly persons with low MM had higher serum ferritin concentrations; women with low MM exhibited lower serum concentration levels of C-reactive protein (CRP). Conclusion: the six investigated inflammatory markers (GDF-15, IGF-1, follistatin, eHsp72, ferritin and CRP) were associated with the diagnostic criteria for sarcopenia, but not with sarcopenia itself. As research in this area is still developing, additional studies are required to broaden knowledge and eventually establish the role of these markers in the diagnosis and management of sarcopenia.

SIDE TO SIDE DIFFERENCES BETWEEN DOMINANT AND NON-DOMINANT ARM'S BONE DENSITY AND ISOMETRIC HANDGRIP STRENGTH IN MALES AND FEMALES AGED 40-65 YEARS OLD

OBJECTIVE

This observational, cross-sectional study, investigates and compares the differences of BMD, T-score, Z-score and isometric strength between dominant (D) versus non-dominant (ND) arms of 162 subjects aged 40-65 in a developing, low income country (Kosova).

MATERIAL AND METHODS

Bone Mineral Density (BMD), T-score and Z-score at distal forearm regions of both arms (measured by DXA scan), together with the Handgrip Isometric Strength (HIS) (by handgrip) were evaluated in a total subjects (53 Males and 109 Females). Additionally, General Healthcare Status Questionnaire together with self-administrated International Physical Activity Questionnaire (IPAQ) were filled.

RESULTS

Significant differences (p<0.05) between arms were found in BMD, T-score, and Z-score in total subjects and in females, whereas not significant differences (p>0.05) were observed in Males BMD comparing to significantly higher results (p<0.05) in T-score and Z-score. Significant differences (p<0.05) were also found in total subjects and in females handgrip, but not (p>0.05) in males. When comparing the total subject's BMD, T-score, Z-score and Handgrip based on the PA levels (1 to 3 according to IPAQ scoring) no significant differences (p>0.05) were found between PA1, as well as PA3 whereas significantly differences (p<0.05) were found in D arms of PA2 level.

CONCLUSION

The study analyses side-to-side differences in bone density and muscular force between D and ND arms amongst a population which is frequently exposed to diagnostic screenings for age related osteomuscular conditions (aged 40-60), and demonstrates that these differences should be in consideration amongst clinicians, but not in the way it is done right now.

Impaired Follistatin Secretion in Cirrhosis

CONTEXT

Follistatin is a liver-derived inhibitor of the muscle-growth inhibitor myostatin. Reduction in acute follistatin release may help explain muscle loss in liver cirrhosis.

OBJECTIVE

The study aimed to investigate the capacity of acute follistatin release in patients with liver cirrhosis compared to healthy control participants.

DESIGN, SETTING, AND PARTICIPANTS

To experimentally increase the glucagon-insulin ratio (mimicking the hormonal effect of exercise), we infused glucagon/somatostatin (to inhibit insulin secretion) and compared the acute follistatin increase in eight male cirrhosis patients with eight healthy control participants. Patients and controls received 1-hour glucagon/somatostatin and saline infusions on 2 separate days.

MAIN OUTCOME MEASURE

Follistatin was measured during and 5 hours after termination of infusions.

RESULTS

The peak follistatin change was significantly decreased in patients with liver cirrhosis compared to healthy control participants (1.9 (interquartile range, 1.4-2.5) versus 3.6 (interquartile range, 3.0-4.0), respectively; P = .003). Patients with liver cirrhosis demonstrated significantly decreased amounts of appendicular lean mass compared to healthy controls (27.6 ± 3.8 vs 34.5 ± 2.9%, respectively; P = .001).

CONCLUSIONS

Patients with cirrhosis show impaired capacity to acutely secrete follistatin. The decrease in acute follistatin release may contribute to the loss of muscle mass in liver cirrhosis.

Effects of elastic band resistance training and nutritional supplementation on muscle quality and circulating muscle growth and degradation factors of institutionalized elderly women: the Vienna Active Ageing Study (VAAS)

PURPOSE

Regular resistance exercise training and a balanced diet may counteract the age-related muscular decline on a molecular level. The aim of this study was to investigate the influence of elastic band resistance training and nutritional supplementation on circulating muscle growth and degradation factors, physical performance and muscle quality (MQ) of institutionalized elderly.

METHODS

Within the Vienna Active Ageing Study, 91 women aged 83.6 (65.0-92.2) years were randomly assigned to one of the three intervention groups (RT, resistance training; RTS, resistance training plus nutritional supplementation; CT, cognitive training). Circulating levels of myostatin, activin A, follistatin, IGF-1 and GDF-15, as well as MQ and functional parameters were tested at baseline as well as after 3 and 6 months of intervention.

RESULTS

MQ of lower extremities significantly increased in the RT group (+14 %) and RTS group (+12 %) after 6 months. Performance improved in the RT and RTS groups for chair stand test (RT: +18 %; RTS: +15 %). Follistatin increased only in the RT group (+18 %) in the latter phase of the intervention, accompanied by a decrease in the activin A-to-follistatin ratio (-7 %). IGF-1, myostatin and GDF-15 levels were not affected by the intervention.

CONCLUSION

Our data confirm that strength training improves physical performance and MQ even in very old institutionalized women. This amelioration appears to be mediated by blocking muscle degradation pathways via follistatin rather than inducing muscle growth through the IGF-1 pathway. As plasma levels of biomarkers reflect an overall status of various organ systems, future studies of tissue levels are suggested.

Sex-specific differences in risk factors for sarcopenia amongst community-dwelling older adults

With considerable variation including potential sex-specific differential rate of skeletal muscle loss, identifying modifiable factors for sarcopenia will be pivotal to guide targeted interventions. This study seeks to identify clinical and biological correlates of sarcopenia in community-dwelling older adults, with emphasis on the role of anabolic and catabolic stimuli, and special reference to gender specificity. In this cross-sectional study involving 200 community-dwelling and functionally independent older adults aged ≥50 years, sarcopenia was defined using the Asian Working Group for Sarcopenia criteria. Comorbidities, cognitive and functional performance, physical activity and nutritional status were routinely assessed. Biochemical parameters included haematological indices, lipid panel, vitamin D level, anabolic hormones [insulin-like growth factor-1 (IGF-1), free testosterone (males only)] and catabolic markers [inflammatory markers (interleukin-6, C-reactive protein) and myostatin]. Multiple logistic regression was performed to identify independent predictors for sarcopenia. Age was associated with sarcopenia in both genders. Malnutrition conferred significantly higher odds for sarcopenia in women (OR = 5.71, 95% CI 1.13-28.84.44, p = 0.035) while higher but acceptable range serum triglyceride was protective in men (OR = 0.05, 95% CI 0.00-0.52, p = 0.012). Higher serum myostatin independently associated with higher odds for sarcopenia in men (OR = 1.11, 95% CI 1.00-1.24, p = 0.041). Serum IGF-1 was significantly lower amongst female sarcopenic subjects, with demonstrable trend for protective effect against sarcopenia in multiple regression models, such that each 1 ng/ml increase in IGF-1 was associated with 1% decline in odds of sarcopenia in women (p = 0.095). Our findings support differential pathophysiological mechanisms for sarcopenia that, if corroborated, may have clinical utility in guiding sex-specific targeted interventions for community-dwelling older adults.

Effects of elastic band resistance training and nutritional supplementation on physical performance of institutionalised elderly--A randomized controlled trial

OBJECTIVES

To evaluate the effects of elastic band resistance training in combination with nutrient supplementation on muscular strength and the ability to perform mobility-related activities of daily living in older adults living in retirement care facilities.

DESIGN

Randomized controlled trial, with a 6-month intervention period.

SETTING

A retirement care facility, Vienna, Austria.

PARTICIPANTS

One hundred and seventeen older adults (14 males (12%) and 103 females (88%)), aged 65 to 97 years (mean age: 82.8 ± 6.0), having a mini-mental state examination score ≥ 23 and no chronic diseases posing a medical contraindication to training therapy.

INTERVENTION

Participants were randomly assigned, but stratified by sex, to one of three intervention groups: supervised resistance exercise training (RT), RT in combination with nutrient supplementation (RTS), or cognitive training group (CT). All interventions were performed two times a week for 6 months. RT was designed to train all major muscle groups using elastic bands. The nutrient supplement (rich in proteins, vitamin D, B2, B12) was distributed every morning as well as after each RT session.

MEASUREMENTS

A battery of motor ability tests and functional test were performed prior to as well as following 3 months and finally after 6 months of intervention. These tests included isokinetic torque measurements of the knee extensors and flexors in concentric mode at 60 and 120°/s, isometric handgrip strength, senior arm-lifting test, chair stand test, maximum walking speed and a 6-minute walking test (6 MWT).

RESULTS

A repeated-measures ANOVA analysis revealed significant improvements in physical function of lower (p=0.002) and upper extremities (p=0.006) for RT and/or RTS in comparison to CT. For isokinetic measurements, 6 MWT, and gait speed time effects (p<0.05) were detected without any group × time interaction effects. Dropouts showed lower performance in chair stand test (p=0.012), 6 MWT (p=0.003), and gait speed (p=0.013) at baseline than that of the finishers of the study.

CONCLUSION

Six months of a low intensity resistance exercise using elastic bands and own body weight is safe and beneficial in improving functional performance of institutionalised older people. Multinutrient supplementation did not offer additional benefits to the effects of RT in improving muscular performance.