Association between sarcopenia and levels of growth hormone and insulin-like growth factor-1 in the elderly

Evaluating the effect of metformin on sarcopenia: A Mendelian randomization study

Sarcopenia is prevalent among elder patients with type 2 diabetes. As a first-line medication for managing type 2 diabetes, metformin has shown controversial effects on sarcopenia. This study aims to analyze the impact of metformin on sarcopenia using Mendelian randomization analysis. We selected 30 single nucleotide polymorphisms associated with metformin used as instrumental variables from genome-wide association studies. Mendelian randomization was conducted using inverse variance weighted (IVW), Mendelian randomization Egger, and weighted median methods. Additionally, we performed heterogeneity tests, Pleiotropy analyses, and sensitivity analyses to validate our findings. The IVW method indicated a P-value of .63 and an odds ratio (OR) of 0.93 (95% CI: 0.69-1.25) for the relationship between metformin use and walking pace. For appendicular lean mass, the IVW method showed a P-value of .42 and an OR of 0.69 (95% CI: 0.28-1.70). In contrast, the IVW analysis indicated a significant relationship between metformin use and right hand grip strength, with P-value of .01 and OR (95% CI) = 0.64 (0.45-0.91), as well as for left hand grip strength, with P-value of .01 and OR (95% CI) = 0.65 (0.45-0.92). Notably, a causal relationship was established between metformin use and lower hand grip strength, while no causal relationship was found between metformin use and walking pace or appendicular lean mass. This study suggests that caution is needed regarding long-term metformin use in the context of sarcopenia.

Evaluation of Dietary Guideline Adherence and Risk of Sarcopenia in Elder Taiwanese

Dietary strategies play an important role in determining longevity and healthy aging. There is an increasing awareness of dietary factors and sarcopenia, which presents as a decline in muscle mass and function, mainly in the senior population. The aim of this study is to explore the association of adherence to the Dietary Guideline (DG) on muscle health in the elder Taiwanese. We included 410 adults aged 65 or older, of whom 189 (46.1%) were women, in the Nutrition and Health Survey in Taiwan (NAHSIT) during 2014-2016 with comprehensive records of food frequency questionnaires and 24-h dietary recalls, as well as measurements of dual-energy X-ray absorptiometry (DXA) for muscle mass and 8-m gait speed for physical performance. A novel indicator, named Healthy Eating Index for Taiwanese (HEI-TW), was developed as an amended version of HEI-2015 to assess how dietary patterns adhere to the DG of Taiwan. Participants who fulfilled "low muscle mass" and "poor physical performance" defined by the Asian Working Group for Sarcopenia (AWGS) criteria were recognized as having sarcopenia; others, in contrast, were recognized as healthy controls. Seventy-one (17.3%) participants categorized into the sarcopenia group had significantly lower mean scores of overall HEI-TW, total vegetables, unrefined grains, and dairy products. The adjusted odds ratios (95% confidence intervals) for sarcopenia were 0.98 (0.95-1.00) for overall HEI-TW, 0.78 (0.66-0.94) for total vegetables, and 0.85 (0.76-0.95) for dairy, respectively, for one unit increase in these components. In subgroup analysis stratified by sex and age, the overall HEI-TW was inversely associated with the odds of sarcopenia among men and individuals aged 75 or older. This study showed that a higher HEI-TW score adhering to Taiwan DG and abundant consumption of total vegetables and dairy products is associated with lower prevalence of muscle loss and sarcopenia in elder Taiwanese.

Exploration of Pathogenesis and Cutting-Edge Treatment Strategies of Sarcopenia: A Narrative Review

Sarcopenia a progressive and multifactorial musculoskeletal syndrome characterized by loss of muscle mass and function, poses a significant global health challenge, particularly in aging populations. Epidemiological studies reveal that sarcopenia affects approximately 5-10% of the general population, with prevalence rates escalating dramatically after age 60 to reach 10-27% in older adults. This age-associated increase contributes significantly to healthcare burdens by elevating risks of disability, frailty, and mortality. Despite its profound impact, current clinical approaches to sarcopenia remain limited. While resistance exercise and protein supplementation form the cornerstone of management, their efficacy is often constrained by poor long-term adherence and variable individual responses, highlighting the urgent need for more comprehensive and personalized treatment strategies. The pathogenesis of sarcopenia is complex and influenced by various factors, including aging, inflammation, nutritional deficits, physical inactivity, and mitochondrial dysfunction. However, the precise molecular mechanisms underlying this condition are still not fully understood. Recent research has made significant strides in elucidating the intricate mechanisms contributing to sarcopenia, revealing novel insights into its molecular and cellular underpinnings. Notably, emerging evidence points to the pivotal role of mitochondrial dysfunction, altered myokine profiles, and neuromuscular junction degeneration in sarcopenia progression. Additionally, breakthroughs in stem cell therapy, exosome-based treatments, and precision nutrition offer promising avenues for clinical intervention. This review aims to synthesize the latest advancements in sarcopenia research, focusing on the novel contributions to its pathogenesis and treatment strategies. We explore emerging trends such as the role of cellular senescence, epigenetic regulation, and targeted therapeutic interventions that could reshape future approaches to managing sarcopenia. By highlighting recent breakthroughs and cutting-edge research, we hope to advance the understanding of sarcopenia and foster the translation of these findings into effective clinical therapies.

Sarcopenia: an Aging Perspective and Management Options

There is no doubt that sarcopenia is one of the most defining characteristics of aging that negatively impacts the people's health and quality of life. The condition is characterized by the progressive and generalized loss of muscle mass and strength, affecting physical performance. It is part of aging but can be exacerbated by pathophysiological conditions like cancer and several factors such as a sedentary lifestyle, poor nutrition, chronic diseases, falls and immobilization. Numerous cellular mechanisms have been implicated in its pathogenesis, including hormonal changes, mitochondrial dysfunctions, altered apoptotic and autophagic signaling, muscle fiber composition, and inflammatory pathways. To prevent sarcopenia, exercise is one of the most effective strategies as it has a strong influence on both anabolic and catabolic muscle pathways and helps improve skeletal muscle function. A well-rounded, multicomponent exercise program that targets muscle strength, aerobic capacity, and balance is recommended for optimal results. While nutrition is essential for muscle maintenance, relying solely on dietary interventions is unlikely to fully address sarcopenia. Therefore, a combination of adequate nutrition and regular exercise is recommended to promote muscle health and function. The purpose of this study is to review sarcopenia from an aging viewpoint and discuss the role of exercise and nutrition as prevention and management options.

Towards Precision in Sarcopenia Assessment: The Challenges of Multimodal Data Analysis in the Era of AI

Sarcopenia, a condition characterised by the progressive decline in skeletal muscle mass and function, presents significant challenges in geriatric healthcare. Despite advances in its management, complex etiopathogenesis and the heterogeneity of diagnostic criteria underlie the limited precision of existing assessment methods. Therefore, efforts are needed to improve the knowledge and pave the way for more effective management and a more precise diagnosis. To this purpose, emerging technologies such as artificial intelligence (AI) can facilitate the identification of novel and accurate biomarkers by modelling complex data resulting from high-throughput technologies, fostering the setting up of a more precise approach. Based on such considerations, this review explores AI's transformative potential, illustrating studies that integrate AI, especially machine learning and deep learning, with heterogeneous data such as clinical, anthropometric and molecular data. Overall, the present review will highlight the relevance of large-scale, standardised studies to validate biomarker signatures using AI-driven approaches.

Association of blood biomarkers with frailty-A mapping review

Frailty describes a geriatric syndrome characterized by an increased vulnerability. Although a variety of potential blood-based biomarkers have been discussed for its characterization, a reliable protocol considering blood-based biomarkers for this purpose is still missing. However, a comprehensive overview on these biomarkers is necessary to understand potential molecular pathways to frailty. We, therefore, performed a mapping review to identify those blood-based biomarkers most consistently associated with frailty in community-dwelling older adults as well as possible analytical gaps according to the available literature. A proposed weighted correlation index (CI) describing the direction and consistency of the association considering the number of available publications as well as the size of the study populations was calculated for each biomarker. Overall, 72 manuscripts were critically reviewed reporting on a total of 82 biomarkers. The most consistent positive association with at least 3 articles addressing the respective biomarker in unadjusted and fully adjusted models was shown for interleukin 6 (IL-6), high-sensitivity C-reactive protein (hs-CRP), neopterin, white blood cells count, glycated hemoglobin A1c (HbA1c) and sex hormone binding-globuline (SHBG) with a CI ≥ 0.7, while for negative association hemoglobin, 25-hydroxy vitamin D, free testosterone in men and albumin with a CI ≤ -0.7 were identified.

Endothelial IGF- 1R deficiency disrupts microvascular homeostasis, impairing skeletal muscle perfusion and endurance: implications for age-related sarcopenia

Aging is associated with a progressive decline in circulating insulin-like growth factor- 1 (IGF- 1) levels in humans, which has been implicated in the pathogenesis of sarcopenia. IGF- 1 is an anabolic hormone that plays a dual role in maintaining skeletal muscle health, acting both directly on muscle fibers to promote growth and indirectly by supporting the vascular network that sustains muscle perfusion. However, the microvascular consequences of IGF- 1 deficiency in aging muscle remain poorly understood. To elucidate how impaired IGF- 1 input affects skeletal muscle vasculature, we examined the effects of endothelial-specific IGF- 1 receptor (IGF- 1R) deficiency using a mouse model of endothelial IGF- 1R knockdown (VE-Cadherin-CreERT2/Igf1rf/f mice). These mice exhibited significantly reduced skeletal muscle endurance and attenuated hyperemic response to acetylcholine, an endothelium-dependent vasodilator. Additionally, they displayed microvascular rarefaction and impaired nitric oxide-dependent vasorelaxation, indicating a significant decline in microvascular health in skeletal muscle. These findings suggest that endothelial IGF- 1R signaling is critical for maintaining microvascular integrity, muscle perfusion, and function. Impaired IGF- 1 input to the microvascular endothelium may contribute to reduced muscle blood flow and exacerbate age-related sarcopenia. Enhancing vascular health by modulating IGF- 1 signaling could represent a potential therapeutic strategy to counteract age-related muscle decline.

Growth hormone and aging: a clinical review

Aging is a complex biological process characterized by functional decline, reduced quality of life, and increased vulnerability to diseases such as type 2 diabetes, cardiovascular conditions, neurodegeneration, and cancer. Advances in medical technology have introduced the concept of aging therapies, with growth hormone (GH) and its primary mediator, insulin-like growth factor 1 (IGF-1), receiving considerable attention for their potential to counteract age-related physiological and metabolic changes. GH plays a multifaceted role in the human body, primarily influencing body composition by increasing muscle mass, reducing fat tissue, promoting bone formation, and regulating the metabolism of proteins, lipids, and glucose. Additional effects have been noted on endothelial function, cognitive performance, and circadian rhythms. This review examines the molecular mechanisms of GH in aging, its potential as an anti-aging therapy, and findings from clinical trials involving these hormones for this purpose. It also addresses the associated adverse effects, limitations, and controversies. While some studies report significant benefits, these therapies' long-term safety and efficacy in promoting healthy aging remain uncertain, highlighting the need for further research.

Prevalence and correlation of sarcopenia with Alzheimer's disease: A systematic review and meta-analysis

BACKGROUND

Sarcopenia, which is defined by a decline in skeletal muscle mass and strength associated with aging, is common among older individuals and presents considerable health dangers. Alzheimer's disease (AD) is a prevalent degenerative brain condition linked to a decrease in cognitive function. The intersection of these conditions remains underexplored. The goal of this systematic review and meta-analysis was to establish the frequency of sarcopenia in individuals with AD and investigate the relationship between sarcopenia and AD.

METHODS

We performed an extensive review of literature databases, including PubMed, Embase, Web of Science, and the Cochrane Library, through April 2024. The inclusion criteria included studies that provided data on the frequency of sarcopenia in patients with AD or that examined the odds ratios (ORs) associated with these comorbidities. R Studio (4.3.1) was utilized for conducting the statistical analyses.

RESULTS

A total of 27 studies, comprising 3902 AD patients were included. In patients with AD, the combined occurrence of sarcopenia was 33.9%, with a confidence interval (CI) of 95%, ranging from 27.6% to 40.2%. Sarcopenia was found in 31.2% (95% CI: 0.223-0.402) and 41.9% (95% CI: 0.321-0.516) of patients with mild and moderate AD, respectively. The OR for the association between AD and sarcopenia was 2.670 (95% CI: 1.566-4.555), suggesting a robust correlation.

CONCLUSION

Sarcopenia is highly prevalent in AD patients, highlighting the need for integrated care approaches to address both cognitive and physical health issues. Further research is needed to elucidate the pathophysiological links between AD and sarcopenia.

A Comparison Between Severity-Dependent Protocol and Fixed-Dose Regimen of Oral Vitamin D Supplementation on Correction of Hypovitaminosis D Among Dialysis Patients

OBJECTIVE

Low vitamin D status is associated with either low muscle mass or impaired muscle function in dialysis patients. However, there is no consensus on how best to correct hypovitaminosis D, defined as serum 25-hydroxyvitamin D level <30 ng/mL, in patients with end-stage kidney disease (ESKD). This study investigated the effect of different vitamin D supplementation regimens on sarcopenia outcomes in dialysis patients.

METHODS

This was a prospective randomized controlled trial. ESKD patients treated with maintenance hemodialysis (HD) or peritoneal dialysis with low vitamin D status on a ratio of 1:1, were randomized to either receive oral ergocalciferol utilizing a severity-dependent treatment protocol for low vitamin D status suggested by the Kidney Disease Outcomes Quality Initiative as a control group or a fixed-dose regimen of 20,000 international units/week. The changes in muscle mass were measured by bioimpedance spectroscopy, muscle strength was assessed by a hand grip dynamometer, physical performance was determined by gait speed, and muscle-related biomarkers were examined.

RESULTS

A total of 76 dialysis patients were randomized (HD = 43.4%). Baseline characteristics, including age, dialysis vintage, and muscle parameters were similar. After supplementation, the average serum 25-hydroxyvitamin D levels in the severity-dependent and fixed-dose groups were significantly elevated from 14.5 ± 7.3 to 27.2 ± 13.2 ng/mL, P < .001 and from 15.1 ± 6.4 to 28.8 ± 11.5 ng/mL, P < .001, respectively, and did not differ between groups at 6 months (P = .60). Despite comparable energy and protein intake, the mean bioimpedance spectroscopy-derived total body muscle mass normalized to height squared was significantly increased at 6 months in the fixed-dose group (14.5 ± 3.3 to 15.3 ± 3.0 kg/m2, P = .03) compared with the severity-dependent protocol (13.5 ± 2.7 to 13.7 ± 2.9 kg/m2, P = .58). In the subgroup analysis, muscle mass improvement was statistically elevated in peritoneal dialysis patients (P = .01) while unaltered among HD patients (P = .88) in the fixed-dose group. Muscle strength, gait speed, and serum insulin-like growth factor-1 level, as the mediators of muscle cell growth, were not different between the two groups at 6 months (P > .05). Neither hypercalcemia nor hyperphosphatemia was found throughout the study.

CONCLUSION

A fixed-dose ergocalciferol supplementation demonstrates similar performance in the correction of low vitamin D status but better muscle mass improvement than a severity-dependent protocol among ESKD patients. Regular dosing intervals of weekly vitamin D supplementation appear to be a promising treatment for sarcopenia among patients undergoing dialysis.

Effect and mechanism of miRNA-144-5p-regulated autophagy in older adults with Sarcopenia

BACKGROUND

Advanced aging invariably triggers an overabundance of apoptosis, stemming from diminished autophagy or a disarray in cellular autophagic processes. This, in turn, leads to an accelerated breakdown of muscle proteins, which exacerbates the ongoing deterioration of skeletal muscle and intensifies the severity of senile sarcopenia. This study aimed to investigate the role and mechanism of miRNA-regulated autophagy in senile sarcopenia.

METHODS

The miRNAs associated with sarcopenia were screened, and the target genes of significant miRNAs were predicted. The effects of significantly differentially expressed miRNA-144-5p on cell aging and autophagy were validated in vivo and in vitro.

RESULTS

The inhibition of miR-144-5p enhanced the multiplication of mouse myoblasts, increased the expression of MHC and autophagic markers LC3II/LC3I and Beclin-1, facilitated the formation of autophagosomes in mouse myoblasts, and reduced the number of aging cells and the expression of senescence-related proteins acetylated p53, p53, and p21 expression in mouse myoblasts. miR-144-5p affects myoblast senescence, myogenic differentiation, and autophagy by regulating the downstream target gene, Atg2A. Inhibiting miR-144-5p markedly increased the grip strength of the posterior limb in old mice, and the CSA of old mice and young mice was also markedly increased.

CONCLUSION

All experiments have demonstrated that miRNA-144-5p has a significant impact on the regulation of autophagy and the development of senile sarcopenia.

Associations of nutritional intake and inflammatory factors with sarcopenia in community-dwelling older adults: a cross-sectional study

PURPOSE

Sarcopenia is an age-related disease that is related to nutritional intake and chronic low-grade inflammation. The aim of this study was to investigate the association of dietary intake, inflammatory markers and sarcopenia among the community-dwelling older adults.

METHODS

A total of 1001 older adults aged 60 and above were recruited. According to the criteria established by the Asian Working Group for Sarcopenia 2019, this paper assessed the presence of sarcopenia and using a Food Frequency Questionnaire to evaluate daily dietary intake. Serum levels of inflammatory markers were measured using the ELISA method.

RESULTS

A total of 1001 participants took part in the study (mean 70.6 years), comprising 396 males and 605 females, the prevalence of sarcopenia was 19.6%. Multivariate analysis revealed that high levels of leucine, methionine, threonine, histidine, aspartic acid, calcium, zinc, and vitamin C were associated with a lower risk of sarcopenia. Higher dietary inflammatory index scores were associated with a higher risk of sarcopenia (OR  1.67, 95% CI 1.12-2.47). Higher tumor necrosis factor-like weak inducer of apoptosis (TWEAK) (OR 1.04, 95% CI 1.02-1.07) was associated with a higher risk of sarcopenia, and a lower skeletal muscle mass, strength, and physical function. Conversely, higher insulin-like growth factor-1 (IGF-1) (OR 0.83, 95% CI 0.74-0.94) and glutathione S-transferase (GST) (OR 0.75, 95% CI 0.61-0.91) were associated with a lower risk of sarcopenia.

CONCLUSIONS

This cross-sectional study revealed alterations in amino acid and micronutrient intake among older adults with sarcopenia. The levels of TWEAK were associated with an increased risk of sarcopenia, whereas IGF-1 and GST were associated with a reduced risk of sarcopenia.

The Role of Myokines in Liver Diseases

Myokine is a general term for hormones, peptides, and other substances secreted by skeletal muscle. Myokine has attracted much attention in recent years as a key substance for understanding the mechanism of "exercise and health". Skeletal muscle accounts for about 40% of the total human weight and is now recognized as an endocrine organ that produces myokines, which have physiological activity. Representative myokines include IL-6, myostatin, irisin, brain-derived neurotropic factor, fibroblast growth factor-21, and decorin. On the other hand, sarcopenia, defined by quantitative and qualitative loss of skeletal muscle, is a condition that has received much attention in recent years because of its close correlation with prognosis. In patients with chronic liver disease (CLD), sarcopenia is a common complication. Mechanisms underlying sarcopenia in CLD patients have been reported to involve protein-energy malnutrition, which is characteristic of patients with cirrhosis, signaling involved in protein synthesis and degradation, myokines such as myostatin and decorin, the ubiquitin-proteasome pathway, sex hormones such as testosterone, dysbiosis, and insulin resistance, etc., in addition to aging. Each of these pathological conditions is thought to be intricately related to each other, leading to sarcopenia. This review will summarize the relationship between CLD and myokines.

Yoga Practice as a Potential Sarcopenia Prevention Strategy in Indonesian Older Adults: A Cross-Sectional Study

Background

Sarcopenia is characterized by the progressive loss of skeletal muscle mass and poses a significant health challenge for older adults by increasing the risk of disability and decreasing quality of life. Yoga considers as a low-risk and beneficial exercise for older adults. This research aims to evaluate the potential of yoga practice as a preventive strategy against sarcopenia in Indonesian older adults.

Methods

An observational cross-sectional research was conducted including 41 older adults aged 60-87 years. The research focused on key biomarkers and functional assessments, including serum insulin-like growth factor 1 (IGF-1) levels, telomere length, gait speed, hand grip strength, and SARC-F questionnaire scores.

Results

The results showed that participants aged 71-80 years who practiced yoga for more than a year had significantly higher IGF-1 levels (p=0.04). While improvements in gait speed, hand grip strength, and SARC-F scores were observed, these changes were not statistically significant, and no significant differences were found in telomere length.

Conclusion

Yoga in older adults was associated with higher IGF-1 levels and potential improvements in upper and lower extremity strength, though these findings were not statistically significant and did not influence telomere length. Yoga practice shows potential as an emerging adjuvant option but can not be applied as a single strategy for sarcopenia prevention in older adults.

Mongan N, Mamat @ Yusof MN, Kampan NC, Chew KT, Shafiee MN. Insulin-like Growth Factor 1 (IGF1) and Its Isoforms: Insights into the Mechanisms of Endometrial Cancer

Endometrial cancer (EC) is a common gynaecological malignancy associated with metabolic dysfunctions such as obesity, diabetes and insulin resistance, as well as hormonal imbalances, particularly involving oestrogen and progesterone. These factors disrupt normal cellular metabolism, heightening the risk of developing endometrioid EC (EEC), the most prevalent subtype of EC. The insulin-like growth factor-1 (IGF1) pathway, a key regulator of growth, metabolism, and organ function, is implicated in EC progression. Recent research highlights the distinct roles of IGF1 isoforms, including IGF1-Ea, IGF1-Eb, and IGF1-Ec, in promoting tumour growth, metastasis, and hormone signalling interactions, particularly with oestrogen. This review examines the function and clinical significance of IGF-1 isoforms, emphasising their mechanisms in gynaecological physiology and their contributions to EC pathogenesis. Evidence from other cancers further underscores the relevance of IGF1 isoforms in driving tumour behaviours, offering valuable insights into their potential as biomarkers and therapeutic targets. Understanding these mechanisms provides opportunities for novel approaches to the prevention, diagnosis, and treatment of EC, improving patient outcomes and advancing the broader field of hormone-driven cancers.

Sarcopenia in MASLD-Eat to Beat Steatosis, Move to Prove Strength

The connections between sarcopenia and various chronic conditions, including type 2 diabetes (T2DM), metabolic syndrome (MetS), and liver disease have been highlighted recently. There is also a high occurrence of sarcopenia in metabolic dysfunction-associated steatotic liver disease (MASLD) patients, who are often disregarded. Both experimental and clinical findings suggest a complex, bidirectional relationship between MASLD and sarcopenia. While vitamin D, testosterone, and specific drug therapies show promise in mitigating sarcopenia, consensus on effective treatments is lacking. Recent focus on lifestyle interventions emphasizes dietary therapy and exercise for sarcopenic obesity in MASLD. Challenges arise as weight loss, a primary MASLD treatment, may lead to muscle mass reduction. The therapeutic approach to sarcopenia in morbidly obese MASLD patients also includes bariatric surgery (BS). BS induces weight loss and stabilizes metabolic imbalances, but its impact on sarcopenia is nuanced, underscoring the need for further research. Our aim is to provide a comprehensive review of the interplay between sarcopenia and MASLD and offer insight into the most recent therapeutic challenges and discoveries, as sarcopenia is often overlooked or unrecognized and poses significant challenges for managing these patients.

Sarcopenia and cachexia: molecular mechanisms and therapeutic interventions

Sarcopenia is defined as a muscle-wasting syndrome that occurs with accelerated aging, while cachexia is a severe wasting syndrome associated with conditions such as cancer and immunodeficiency disorders, which cannot be fully addressed through conventional nutritional supplementation. Sarcopenia can be considered a component of cachexia, with the bidirectional interplay between adipose tissue and skeletal muscle potentially serving as a molecular mechanism for both conditions. However, the underlying mechanisms differ. Recognizing the interplay and distinctions between these disorders is essential for advancing both basic and translational research in this area, enhancing diagnostic accuracy and ultimately achieving effective therapeutic solutions for affected patients. This review discusses the muscle microenvironment's changes contributing to these conditions, recent therapeutic approaches like lifestyle modifications, small molecules, and nutritional interventions, and emerging strategies such as gene editing, stem cell therapy, and gut microbiome modulation. We also address the challenges and opportunities of multimodal interventions, aiming to provide insights into the pathogenesis and molecular mechanisms of sarcopenia and cachexia, ultimately aiding in innovative strategy development and improved treatments.

Sarcopenia and the biological determinants of aging: A narrative review from a geroscience perspective

BACKGROUND

The physiopathology of sarcopenia shares common biological cascades with the aging process, as does any other age-related condition. However, our understanding of the interconnected pathways between diagnosed sarcopenia and aging remains limited, lacking sufficient scientific evidence.

METHODS

This narrative review aims to gather and describe the current evidence on the relationship between biological aging determinants, commonly referred to as the hallmarks of aging, and diagnosed sarcopenia in humans.

RESULTS

Among the twelve hallmarks of aging studied, there appears to be a substantial association between sarcopenia and mitochondrial dysfunction, epigenetic alterations, deregulated nutrient sensing, and altered intercellular communication. Although limited, preliminary evidence suggests a promising association between sarcopenia and genomic instability or stem cell exhaustion.

DISCUSSION

Overall, an imbalance in energy regulation, characterized by impaired mitochondrial energy production and alterations in circulatory markers, is commonly associated with sarcopenia and may reflect the interplay between aging physiology and sarcopenia biology.

A novel treatment strategy targeting cellular pathways with natural products to alleviate sarcopenia

Sarcopenia is a condition marked by a significant reduction in muscle mass and strength, primarily due to the aging process, which critically impacts muscle protein dynamics, metabolic functions, and overall physical functionality. This condition leads to increased body fat and reduced daily activity, contributing to severe health issues and a lower quality of life among the elderly. Recognized in the ICD-10-CM only in 2016, sarcopenia lacks definitive treatment options despite its growing prevalence and substantial social and economic implications. Given the aging global population, addressing sarcopenia has become increasingly relevant and necessary. The primary causes include aging, cachexia, diabetes, and nutritional deficiencies, leading to imbalances in protein synthesis and degradation, mitochondrial dysfunction, and hormonal changes. Exercise remains the most effective intervention, but it is often impractical for individuals with limited mobility, and pharmacological options such as anabolic steroids and myostatin inhibitors are not FDA-approved and are still under investigation. This review is crucial as it examines the potential of natural products as a novel treatment strategy for sarcopenia, targeting multiple mechanisms involved in its pathogenesis. By exploring natural products' multi-targeted effects, this study aims to provide innovative and practical solutions for sarcopenia management. Therefore, this review indicates significant improvements in muscle mass and function with the use of specific natural compounds, suggesting promising alternatives for those unable to engage in regular physical activity.

Causal associations between the insulin-like growth factor family and sarcopenia: a bidirectional Mendelian randomization study

Objective

Insulin-like growth factor (IGF) is closely associated with sarcopenia, yet the causal relationship of this association remains unclear. This study aims to explore the potential causal relationship between members of the IGF family and sarcopenia from a genetic perspective through bidirectional Mendelian randomization (MR) analysis using two-sample datasets.

Methods

Five genetically predicted factors of the IGF family (IGF-1, IGF-1R, IGF-2R, IGFBP-3, IGFBP-7) as one sample, while four relevant features of sarcopenia (low hand grip strength, appendicular lean mass, whole body fat-free mass, and walking pace) as another sample, in conducting a two-sample MR analysis.

Results

The forward MR results of the relationship between IGF and sarcopenia showed that elevated levels of IGF-1 reduced the risk of low hand grip strength (OR = 0.936, 95% CI=0.892-0.983, P = 0.008) and increased appendicular lean mass of the extremities and whole body fat-free mass (OR = 1.125, 95% CI=1.070-1.182,P = 0.000; OR =1.076, 95% CI=1.047-1.106, P=0.000), reduced the risk of sarcopenia. Elevated IGF-1R also favored an increase in whole body fat-free mass (OR=1.023, 95% CI=1.008-1.038, P =0.002), and the appendicular lean mass trait was more pronounced with elevated IGFBP-3 and IGFBP-7 (OR=1.034, 95% CI=1.024-1.044, P =0.000; OR=1.020, 95% CI=1.010-1.030, P=0.000). Inverse MR results of the effect of sarcopenia on IGF showed that decreased hand grip strength may elevate IGF-1 levels (OR=1.243, 95% CI=1.026-1.505,P =0.027), whereas improvements in appendicular lean mass, whole body fat-free mass traits, and increased walking pace decreased IGF-1 levels (OR=0.902, 95% CI: 0.877-0.927, P = 0.000; OR=0.903, 95% CI=0.859-0.949,P = 0.000; OR=0.209, 95% CI=0.051-0.862,P = 0.045). Also decreased hand grip strength may elevate IGF-1R levels (OR=1.454, 95% CI=1.108-1.909, P =0.007), and appendicular lean mass stimulated high expression of IGFBP-1 (OR=1.314, 95% CI=1.003-1.722, P =0.047). Heterogeneity and pleiotropy were not detected in all results, and the results were stable and reliable.

Conclusion

There is a bi-directional causal association between IGF family members and the risk of sarcopenia, which provides a more adequate basis for early biological monitoring of sarcopenia and may provide new targets for early intervention and treatment of sarcopenia.

Rodent model intervention for prevention and optimal management of sarcopenia: A systematic review on the beneficial effects of nutrients & non-nutrients and exercise to improve skeletal muscle health

Sarcopenia is a common musculoskeletal disorder characterized by degenerative processes and is strongly linked to an increased susceptibility to falls, fractures, physical limitations, and mortality. Several models have been used to explore therapeutic and preventative measures as well as to gain insight into the molecular mechanisms behind sarcopenia. With novel experimental methodologies emerging to design foods or novel versions of conventional foods, understanding the impact of nutrition on the prevention and management of sarcopenia has become important. This review provides a thorough assessment of the use of rodent models of sarcopenia for understanding the aging process, focusing the effects of nutrients, plant extracts, exercise, and combined interventions on skeletal muscle health. According to empirical research, nutraceuticals and functional foods have demonstrated potential benefits in enhancing physical performance. In preclinical investigations, the administration of herbal extracts and naturally occurring bioactive compounds yielded advantageous outcomes such as augmented muscle mass and strength generation. Furthermore, herbal treatments exhibited inhibitory effects on muscle atrophy and sarcopenia. A substantial body of information establishes a connection between diet and the muscle mass, strength, and functionality of older individuals. This suggests that nutrition has a major impact in both the prevention and treatment of sarcopenia.

Advancements in Drug Delivery Systems for the Treatment of Sarcopenia: An Updated Overview

Since sarcopenia is a progressive condition that leads to decreased muscle mass and function, especially in elderly people, it is a public health problem that requires attention from researchers. This review aims to highlight drug delivery systems that have a high and efficient therapeutic potential for sarcopenia. Current as well as future research needs to consider the barriers encountered in the realization of delivery systems, such as the route of administration, the interaction of the systems with the aggressive environment of the human body, the efficient delivery and loading of the systems with therapeutic agents, and the targeted delivery of therapeutic agents into the muscle tissue without creating undesirable adverse effects. Thus, this paper sets the framework of existing drug delivery possibilities for the treatment of sarcopenia, serving as an inception point for future interdisciplinary studies.

Assessing the causal relationship between frailty and sex hormone-binding globulin or insulin-like growth factor-1 levels: A sex-stratified bidirectional Mendelian Randomization study

BACKGROUND

The association between frailty and sex hormone-binding globulin (SHBG) or insulin-like growth factor-1(IGF-1) levels demonstrates sex differences with inconsistent conclusions. This study aims to explore the causal relationship between frailty and SHBG or IGF-1 levels through bidirectional Mendelian randomization (MR).

METHODS

We conducted two-sample bidirectional sex-stratified MR analyses using summary-level data from genome-wide association studies (GWASs) to examine the causal relationship between frailty and IGF-1 or SHBG levels, as measured by frailty index (FI) and frailty phenotype (FP). We use the random-effects inverse-variance weighted (IVW), weighted median, MR-Egger, MR-Egger intercept, and leave-one-out approaches.

RESULT

The relationship between frailty and SHBG or IGF-1 levels is inversely related, with a significant decrease in SHBG levels in females. Specifically, SHBG levels significantly decrease with FI (β = -5.49; 95 % CI: -9.67 to -1.32; FDR = 0.02) and more pronounced with FP (β = -10.14; 95 % CI: -16.16 to -4.13; FDR = 0.01), as determined by the IVW approach. However, reverse analysis shows no significant effect of IGF-1 or SHBG levels on either FI or FP (p > 0.05).

CONCLUSION

Our study indicates a negative correlation between frailty and the levels of SHBG and IGF-1. It is suggested that further research is required to establish cut-off values for SHBG and IGF-1 levels in the frailty population. This is particularly important for females at higher risk, such as those undergoing menopause, to enable comprehensive assessment and early prevention efforts. While the findings imply that reduced IGF-1 and SHBG levels may not directly contribute to frailty, it is important not to overlook the underlying mechanisms through which they may indirectly influence frailty.

The onset and the development of cardiometabolic aging: an insight into the underlying mechanisms

Metabolic compromise is crucial in aggravating age-associated chronic inflammation, oxidative stress, mitochondrial damage, increased LDL and triglycerides, and elevated blood pressure. Excessive adiposity, hyperglycemia, and insulin resistance due to aging are associated with elevated levels of damaging free radicals, inducing a proinflammatory state and hampering immune cell activity, leading to a malfunctioning cardiometabolic condition. The age-associated oxidative load and redox imbalance are contributing factors for cardiometabolic morbidities via vascular remodelling and endothelial damage. Recent evidence has claimed the importance of gut microbiota in maintaining regular metabolic activity, which declines with chronological aging and cardiometabolic comorbidities. Genetic mutations, polymorphic changes, and environmental factors strongly correlate with increased vulnerability to aberrant cardiometabolic changes by affecting key physiological pathways. Numerous studies have reported a robust link between biological aging and cardiometabolic dysfunction. This review outlines the scientific evidence exploring potential mechanisms behind the onset and development of cardiovascular and metabolic issues, particularly exacerbated with aging.

Targeting Cell Senescence and Senolytics: Novel Interventions for Age-Related Endocrine Dysfunction

Multiple changes occur in hormonal regulation with aging and across various endocrine organs. These changes are associated with multiple age-related disorders and diseases. A better understanding of responsible underling biological mechanisms could help in the management of multiple endocrine disorders over and above hormone replacement therapy (HRT). Cellular senescence is involved in multiple biological aging processes and pathologies common in elderly individuals. Cellular senescence, which occurs in many older individuals but also across the lifespan in association with tissue damage, acute and chronic diseases, certain drugs, and genetic syndromes, may contribute to such endocrine disorders as osteoporosis, metabolic syndrome, and type 2 diabetes mellitus. Drugs that selectively induce senescent cell removal, "senolytics,", and drugs that attenuate the tissue-destructive secretory state of certain senescent cells, "senomorphics," appear to delay the onset of or alleviate multiple diseases, including but not limited to endocrine disorders such as diabetes, complications of obesity, age-related osteoporosis, and cancers as well as atherosclerosis, chronic kidney disease, neurodegenerative disorders, and many others. More than 30 clinical trials of senolytic and senomorphic agents have already been completed, are underway, or are planned for a variety of indications. Targeting senescent cells is a novel strategy that is distinct from conventional therapies such as HRT, and thus might address unmet medical needs and can potentially amplify effects of established endocrine drug regimens, perhaps allowing for dose decreases and reducing side effects.

Targeting Crosstalk of Signaling Pathways among Muscles-Bone-Adipose Tissue: A Promising Therapeutic Approach for Sarcopenia

The aging process is associated with the development of a wide range of degenerative disorders in mammals. These diseases are characterized by a progressive decline in function at multiple levels, including the molecular, cellular, tissue, and organismal. Furthermore, it is responsible for various healthcare costs in developing and developed countries. Sarcopenia is the deterioration in the quality and functionality of muscles, which is extremely concerning as it manages many functions in the human body. This article reviews the molecular crosstalk involved in sarcopenia and the specific roles of many mediator molecules in establishing cross-talk between muscles, bone, and fatty tissues, eventually leading to sarcopenia. Besides, the involvement of various etiological factors, such as neurology, endocrinology, lifestyle, etc., makes it exceedingly difficult for clinicians to develop a coherent hypothesis that may lead to the well-organized management system required to battle this debilitating disease. The several hallmarks contributing to the progression of the disease is a vital question that needs to be addressed to ensure an efficient treatment for sarcopenia patients. Also, the intricate molecular mechanism involved in developing this disease requires more studies. The direct relationship of cellular senescence with aging is one of the pivotal issues contributing to disease pathophysiology. Some patented treatment strategies have been discussed, including drugs undergoing clinical trials and emerging options like miRNA and protein-enclosed extracellular vesicles. A clear understanding of the secretome, including the signaling pathways involved between muscles, bone, and fatty tissues, is extremely beneficial for developing novel therapeutics for curing sarcopenia.

Unveiling the muscle-brain axis: A bidirectional mendelian randomization study investigating the causal relationship between sarcopenia-related traits and brain aging

BACKGROUND

Observational studies suggest an association between sarcopenia-related traits and brain aging, but whether this association reflects a causal relationship remains unclear. This study aims to employ Mendelian randomization (MR) methods to investigate the causal impact of sarcopenia-related traits on brain aging.

METHODS

This study presents a comprehensive analysis of genome-wide association study (GWAS) summary data associated with sarcopenia-related traits. The data were derived from a large-scale cohort, encompassing measures such as grip strength, lean body mass, and walking pace. Measurements of brain aging were obtained from neuroimaging genetics, utilizing meta-analysis (ENIGMA) to combine magnetic resonance imaging (MRI) data from 33,992 participants. The primary methodology employed in this analysis was the inverse-variance-weighted method (IVW). Additionally, sensitivity analyses were conducted, to assess heterogeneity and pleiotropy.

RESULT

Appendicular lean mass(ALM) is negatively correlated with Pallidum aging; Whole body fat-free mass shows a negative correlation with Amygdala aging; Leg fat-free mass (left) and Leg fat-free mass (right) are negatively correlated with Pallidum aging; Usual walking pace is positively correlated with Nucleus Accumbens aging. Cerebellum WM aging is negatively correlated with Leg fat-free mass (left) and Leg fat-free mass (right); Hippocampus aging is negatively correlated with Hand grip strength (left) and Hand grip strength (right). Ventricles aging is positively correlated with Usual walking pace; Nucleus Accumbens aging is positively correlated with Leg fat-free mass (left) and Leg fat-free mass (right); Putamen aging is positively correlated with ALM.

CONCLUSION

Our study confirms that reduced muscle mass speeds up brain aging. Walking too fast raises the risk of brain aging, while maintaining or increasing appendicular lean mass, overall muscle mass, and muscle mass in both legs lowers the risk of brain aging.

Body Composition, Sarcopenia, and Serum Myokines in Acromegaly: A Narrative Review

Patients with active acromegaly have a higher percentage of lean body mass, a lower percentage of fat body mass, and an increase in their extracellular water compartment compared to healthy individuals. However, muscle function appears to be compromised in patients with acromegaly, with some experiencing worsened physical performance and sarcopenia. Myokine alterations, insulin resistance, dysregulation of protein metabolism, muscle oxidative stress, neuromuscular junction impairment, and increased ectopic intramuscular fat deposits may play roles in muscle dysfunction in patients with acromegaly.

Mitochondrial Adaptations in Aging Skeletal Muscle: Implications for Resistance Exercise Training to Treat Sarcopenia

Sarcopenia, the age-related decline in muscle mass and function, poses a significant health challenge as the global population ages. Mitochondrial dysfunction is a key factor in sarcopenia, as evidenced by the role of mitochondrial reactive oxygen species (mtROS) in mitochondrial biogenesis and dynamics, as well as mitophagy. Resistance exercise training (RET) is a well-established intervention for sarcopenia; however, its effects on the mitochondria in aging skeletal muscles remain unclear. This review aims to elucidate the relationship between mitochondrial dynamics and sarcopenia, with a specific focus on the implications of RET. Although aerobic exercise training (AET) has traditionally been viewed as more effective for mitochondrial enhancement, emerging evidence suggests that RET may also confer beneficial effects. Here, we highlight the potential of RET to modulate mtROS, drive mitochondrial biogenesis, optimize mitochondrial dynamics, and promote mitophagy in aging skeletal muscles. Understanding this interplay offers insights for combating sarcopenia and preserving skeletal muscle health in aging individuals.

Dietary Protein and Physical Exercise for the Treatment of Sarcopenia

Sarcopenia is a multifactorial age-related disorder that causes a decrease in muscle mass, strength, and function, leading to alteration of movement, risk of falls, and hospitalization. This article aims to review recent findings on the factors underlying sarcopenia and the strategies required to delay and counteract its symptoms. We focus on molecular factors linked to ageing, on the role of low-grade chronic and acute inflammatory conditions such as cancer, which contributes to the onset of sarcopenia, and on the clinical criteria for its diagnosis. The use of drugs against sarcopenia is still subject to debate, and the suggested approaches to restore muscle health are based on adequate dietary protein intake and physical exercise. We also highlight the difference in the amount and quality of amino acids within animal- and plant-based diets, as studies have often shown varying results regarding their effect on sarcopenia in elderly people. In addition, many studies have reported that non-pharmacological approaches, such as an optimization of dietary protein intake and training programs based on resistance exercise, can be effective in preventing and delaying sarcopenia. These approaches not only improve the maintenance of skeletal muscle function, but also reduce health care costs and improve life expectancy and quality in elderly people.

Biological basis and treatment of frailty and sarcopenia

In an ageing society, the importance of maintaining healthy life expectancy has been emphasized. As a result of age-related decline in functional reserve, frailty is a state of increased vulnerability and susceptibility to adverse health outcomes with a serious impact on healthy life expectancy. The decline in skeletal muscle mass and function, also known as sarcopenia, is key in the development of physical frailty. Both frailty and sarcopenia are highly prevalent in patients not only with advanced age but also in patients with illnesses that exacerbate their progression like heart failure (HF), cancer, or dementia, with the prevalence of frailty and sarcopenia in HF patients reaching up to 50-75% and 19.5-47.3%, respectively, resulting in 1.5-3 times higher 1-year mortality. The biological mechanisms of frailty and sarcopenia are multifactorial, complex, and not yet fully elucidated, ranging from DNA damage, proteostasis impairment, and epigenetic changes to mitochondrial dysfunction, cellular senescence, and environmental factors, many of which are further linked to cardiac disease. Currently, there is no gold standard for the treatment of frailty and sarcopenia, however, growing evidence supports that a combination of exercise training and nutritional supplement improves skeletal muscle function and frailty, with a variety of other therapies being devised based on the underlying pathophysiology. In this review, we address the involvement of frailty and sarcopenia in cardiac disease and describe the latest insights into their biological mechanisms as well as the potential for intervention through exercise, diet, and specific therapies.

Type 2 diabetes mellitus related sarcopenia: a type of muscle loss distinct from sarcopenia and disuse muscle atrophy

Muscle loss is a significant health concern, particularly with the increasing trend of population aging, and sarcopenia has emerged as a common pathological process of muscle loss in the elderly. Currently, there has been significant progress in the research on sarcopenia, including in-depth analysis of the mechanisms underlying sarcopenia caused by aging and the development of corresponding diagnostic criteria, forming a relatively complete system. However, as research on sarcopenia progresses, the concept of secondary sarcopenia has also been proposed. Due to the incomplete understanding of muscle loss caused by chronic diseases, there are various limitations in epidemiological, basic, and clinical research. As a result, a comprehensive concept and diagnostic system have not yet been established, which greatly hinders the prevention and treatment of the disease. This review focuses on Type 2 Diabetes Mellitus (T2DM)-related sarcopenia, comparing its similarities and differences with sarcopenia and disuse muscle atrophy. The review show significant differences between the three muscle-related issues in terms of pathological changes, epidemiology and clinical manifestations, etiology, and preventive and therapeutic strategies. Unlike sarcopenia, T2DM-related sarcopenia is characterized by a reduction in type I fibers, and it differs from disuse muscle atrophy as well. The mechanism involving insulin resistance, inflammatory status, and oxidative stress remains unclear. Therefore, future research should further explore the etiology, disease progression, and prognosis of T2DM-related sarcopenia, and develop targeted diagnostic criteria and effective preventive and therapeutic strategies to better address the muscle-related issues faced by T2DM patients and improve their quality of life and overall health.

Ablation of specific insulin-like growth factor I forms reveals the importance of cleavage for regenerative capacity and glycosylation for skeletal muscle storage

Insulin-like growth factor-I (IGF-I) facilitates mitotic and anabolic actions in all tissues. In skeletal muscle, IGF-I can promote growth and resolution of damage by promoting satellite cell proliferation and differentiation, suppressing inflammation, and enhancing fiber formation. While the most well-characterized form of IGF-I is the mature protein, alternative splicing and post-translational modification complexity lead to several additional forms of IGF-I. Previous studies showed muscle efficiently stores glycosylated pro-IGF-I. However, non-glycosylated forms display more efficient IGF-I receptor activation in vitro, suggesting that the removal of the glycosylated C terminus is a necessary step to enable increased activity. We employed CRISPR-Cas9 gene editing to ablate IGF-I glycosylation sites (2ND) or its cleavage site (3RA) in mice to determine the necessity of glycosylation or cleavage for IGF-I function in postnatal growth and during muscle regeneration. 3RA mice had the highest circulating and muscle IGF-I content, whereas 2ND mice had the lowest levels compared to wild-type mice. After weaning, 4-week-old 2ND mice exhibited higher body and skeletal muscle mass than other strains. However, by 16 weeks of age, muscle and body size differences disappeared. Even though 3RA mice had more IGF-I stored in muscle in homeostatic conditions, regeneration was delayed after cardiotoxin-induced injury, with prolonged necrosis most evident at 5 days post injury (dpi). In contrast, 2ND displayed improved regeneration with reduced necrosis, and greater fiber size and muscle mass at 11 and 21 dpi. Overall, these results demonstrate that while IGF-I glycosylation may be important for storage, cleavage is needed to enable IGF-I to be used for efficient activity in postnatal growth and following acute injury.

The mediating role of lower body muscle strength and IGF-1 level in the relationship between age and cognition. A MIDUS substudy

OBJECTIVE

Aging is a natural process associated with a decline in cognition. However, the mediating effect of physical function and circulating myokines on this relationship has yet to be fully clarified. This study investigated how muscle strength and circulating insulin-like growth factor-1 (IGF-1) levels mediate the relationship between age and cognitive functions.

SUBJECTS AND METHODS

A total of 1255 participants aged 25-74 years included in the Midlife in the United States II study were retrospectively analyzed. In this cross-sectional analysis, we applied a serial mediation model to explore the mediating effects of muscle strength and circulating IGF-1 levels on the relationship between age and cognitive functions. We included potential confounding factors related to sociodemographics, lifestyle, and health status as covariates in the model.

RESULTS

The results showed that aging had both direct and indirect effects on cognition. As predicted, muscle strength and IGF-1 levels mediated the relationship between age and specific cognitive functions. In addition, mediation analyses indicated that the association between aging and cognitive flexibility, immediate and delayed memory, and inductive reasoning were partially mediated by muscle strength and IGF-1 levels in a serial manner.

CONCLUSIONS

Our study demonstrated the serial multiple mediation roles of muscle strength and IGF-1 levels on the relationship between age and specific cognitive functions. Further longitudinal research should be performed to confirm the serial mediation results.

Blood Profiles of Community-Dwelling People with Sarcopenia: Analysis Based on the China Health and Retirement Longitudinal Study

INTRODUCTION

Routine blood factors can be economical and easily accessible candidates for sarcopenia screening and monitoring. The associations between sarcopenia and routine blood factors remain unclear. This study aimed to examine sarcopenia and blood factor associations based on a nation-wide cohort in China.

METHODS

A total of 1,307 participants and 17 routine blood indices were selected from two waves (year 2011 and year 2015) of the China Health and Retirement Longitudinal Study (CHARLS). The diagnosis of sarcopenia was based on the criteria proposed by the Asian Working Group for Sarcopenia (AWGS 2019). Generalized mixed-effects models were performed for association analyses. A logistic regression (LR) model was conducted to examine the predictive power of identifying significant blood factors for sarcopenia.

RESULTS

A higher sarcopenia risk was cross-sectionally associated with elevated blood concentrations of high-sensitivity C-reactive protein (hsCRP) (OR = 1.030, 95% CI [1.007, 1.053]), glycated hemoglobin (HbA1c) (OR = 1.407, 95% CI [1.126, 1.758]) and blood urea nitrogen (BUN) (OR = 1.044, 95% CI [1.002, 1.089]), and a decreased level of glucose (OR = 0.988, 95% CI [0.979, 0.997]). A higher baseline hsCRP value (OR = 1.034, 95% CI [1.029, 1.039]) and a greater over time change in hsCRP within 4 years (OR = 1.034, 95% CI [1.029, 1.039]) were associated with a higher sarcopenia risk. A higher BUN baseline value was related to a decreased sarcopenia risk over time (OR = 0.981, 95% CI [0.976, 0.986]), while a greater over time changes in BUN (OR = 1.034, 95% CI [1.029, 1.040]) and a smaller over time change in glucose (OR = 0.992, 95% CI [0.984, 0.999]) within 4 years were also related to a higher sarcopenia risk. LR based on significant blood factors (i.e., hsCRP, HbA1c, BUN, and glucose), and sarcopenia status in year 2015 yielded an area under the curve of 0.859 (95% CI: 0.836-0.882).

CONCLUSION

Routine blood factors involved in inflammation, protein metabolism, and glucose metabolism are significantly associated with sarcopenia. In clinical practice, plasma hsCRP, BUN, blood sugar levels, sex, age, marital status, height, and weight might be helpful for sarcopenia evaluation and monitoring.

A review on associated factors and management measures for sarcopenia in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease characterized by hyperglycemia, insulin resistance, and insufficient insulin secretion. Sarcopenia, as a new complication of diabetes, is characterized by the loss of muscle mass and the progressive decline of muscle strength and function in T2DM patients, which has a serious impact on the physical and mental health of patients. Insulin resistance, mitochondrial dysfunction, and chronic inflammation are common mechanisms of diabetes and sarcopenia. Reasonable exercise training, nutrition supplement, and drug intervention may improve the quality of life of patients with diabetes combined with sarcopenia. This article reviews the relevant factors and management measures of sarcopenia in T2DM patients, in order to achieve early detection, diagnosis, and intervention.

Restoration of epigenetic impairment in the skeletal muscle and chronic inflammation resolution as a therapeutic approach in sarcopenia

Sarcopenia is an age-associated loss of skeletal muscle mass, strength, and function, accompanied by severe adverse health outcomes, such as falls and fractures, functional decline, high health costs, and mortality. Hence, its prevention and treatment have become increasingly urgent. However, despite the wide prevalence and extensive research on sarcopenia, no FDA-approved disease-modifying drugs exist. This is probably due to a poor understanding of the mechanisms underlying its pathophysiology. Recent evidence demonstrate that sarcopenia development is characterized by two key elements: (i) epigenetic dysregulation of multiple molecular pathways associated with sarcopenia pathogenesis, such as protein remodeling, insulin resistance, mitochondria impairments, and (ii) the creation of a systemic, chronic, low-grade inflammation (SCLGI). In this review, we focus on the epigenetic regulators that have been implicated in skeletal muscle deterioration, their individual roles, and possible crosstalk. We also discuss epidrugs, which are the pharmaceuticals with the potential to restore the epigenetic mechanisms deregulated in sarcopenia. In addition, we discuss the mechanisms underlying failed SCLGI resolution in sarcopenia and the potential application of pro-resolving molecules, comprising specialized pro-resolving mediators (SPMs) and their stable mimetics and receptor agonists. These compounds, as well as epidrugs, reveal beneficial effects in preclinical studies related to sarcopenia. Based on these encouraging observations, we propose the combination of epidrugs with SCLI-resolving agents as a new therapeutic approach for sarcopenia that can effectively attenuate of its manifestations.

Highlighting the effect of reduced training volume on maintaining hormonal adaptations obtained from periodized resistance training in sarcopenic older women

BACKGROUND

This study investigated the impact of the High Intensity Interval Resistance Training (HIIRT) protocol on hormonal changes in older women.

RESEARCH DESIGN AND METHODS

Forty sarcopenic women were divided into an experimental group (EX = 30) and a control group (C = 10). The EX-group was further divided into Maintenance Training 1 (MT1 = 10), Maintenance Training 2 (MT2 = 10), and Detraining (DT = 10). The participants underwent 8 weeks of resistance training, consisting of hypertrophy and strength cycles. Following this, the EX-group had a 4-week period with no exercise or a reduced training volume. Measurements were taken at three time points.

RESULTS

After 8 weeks, the EX-group showed significant improvements in Insulin Like Growth Factor-1 (IGF-1), Myostatin (MSTN), Follistatin (Fstn), Growth Hormone (GH) and Cortisol (Cort) compared to the control group. During the volume reduction period, there were no significant differences between MT1 and MT2 groups, but both groups saw increases in IGF-1, Fstn, GH, and decreases in MSTN and Cort compared to the DT group.

CONCLUSIONS

These findings suggest that performing at least one training session per week with the HIIRT protocol is crucial for maintaining hormonal adaptations in sarcopenic older women.

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.

Correlation between sarcopenia and esophageal cancer: a narrative review

BACKGROUND

In recent years, the research on the relationship between sarcopenia before and after the treatment of esophageal cancer, as well as its impact on prognosis of esophageal cancer, has increased rapidly, which has aroused people's attention to the disease of patients with esophageal cancer complicated with sarcopenia. This review examines the prevalence of sarcopenia in patients with esophageal cancer, as well as the relationship between sarcopenia (before and after surgery or chemotherapy) and prognosis in patients with esophageal cancer. Moreover, we summarized the potential pathogenesis of sarcopenia and pharmacologic and non-pharmacologic therapies.

METHODS

A narrative review was performed in PubMed and Web of Science using the keywords ("esophageal cancer" or "esophageal neoplasm" or "neoplasm, esophageal" or "esophagus neoplasm" or "esophagus neoplasms" or "neoplasm, esophagus" or "neoplasms, esophagus" or "neoplasms, esophageal" or "cancer of esophagus" or "cancer of the esophagus" or "esophagus cancer" or "cancer, esophagus" or "cancers, esophagus" or "esophagus cancers" or "esophageal cancer" or "cancer, esophageal" or "cancers, esophageal" or "esophageal cancers") and ("sarcopenia" or "muscular atrophy" or "aging" or "senescence" or "biological aging" or "aging, biological" or "atrophies, muscular" or "atrophy, muscular" or "muscular atrophies" or "atrophy, muscle" or "atrophies, muscle" or "muscle atrophies"). Studies reporting relationship between sarcopenia and esophageal cancer were analyzed.

RESULTS

The results of the review suggest that the average prevalence of sarcopenia in esophageal cancer was 46.3% ± 19.6% ranging from 14.4 to 81% and sarcopenia can be an important predictor of poor prognosis in patients with esophageal cancer. Patients with esophageal cancer can suffer from sarcopenia due to their nutritional deficiencies, reduced physical activity, chemotherapy, and the effects of certain inflammatory factors and pathways. When classic diagnostic values for sarcopenia such as skeletal muscle index (SMI) are not available clinically, it is also feasible to predict esophageal cancer prognosis using simpler metrics, such as calf circumference (CC), five-count sit-up test (5-CST), and six-minute walk distance (6MWD).

CONCLUSIONS

Identifying the potential mechanism of sarcopenia in patients with esophageal cancer and implementing appropriate interventions may hold the key to improving the prognosis of these patients.

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.

A comprehensive review on the risks assessment and treatment options for Sarcopenia in people with diabetes

Objectives

This comprehensive review aims to examine the reciprocal interplay between Type 2 diabetes mellitus (T2DM) and sarcopenia, identify prevailing research gaps, and discuss therapeutic approaches and measures to enhance healthcare practices within hospital settings.

Methods

A thorough literature review was conducted to gather relevant studies and articles on the relationship between T2DM and sarcopenia. Various databases were searched, including Google Scholar, PubMed, Scopus, and Science Direct databases. The search terms included T2DM, sarcopenia, inflammation, insulin resistance, advanced glycation end products, oxidative stress, muscle dimensions, muscle strength, muscle performance, aging, nutrition, hormone levels, and physical activity. The collected articles were critically analysed to extract key findings and identify gaps in current research.

Results

The prevalence and incidence of metabolic and musculoskeletal disorders, notably T2DM and sarcopenia, have surged in recent years. T2DM is marked by inflammation, insulin resistance, accumulation of advanced glycation end products, and oxidative stress, while sarcopenia involves a progressive decline in skeletal muscle mass and function. The review underscores the age-related correlation between sarcopenia and adverse outcomes like fractures, falls, and mortality. Research gaps regarding optimal nutritional interventions for individuals with T2DM and sarcopenia are identified, emphasizing the necessity for further investigation in this area.

Conclusions

The reciprocal interplay between T2DM and sarcopenia holds significant importance. Further research is warranted to address knowledge gaps, particularly in utilizing precise measurement tools during clinical trials. Lifestyle modifications appear beneficial for individuals with T2DM and sarcopenia. Additionally, practical nutritional interventions require investigation to optimize healthcare practices in hospital settings.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01262-w.

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.

Low Relative Handgrip Strength Is Associated with a High Risk of Non-Alcoholic Fatty Liver Disease in Italian Adults: A Retrospective Cohort Study

Background: Non-alcoholic fatty liver disease (NAFLD) and the presence of low muscle mass (sarcopenia) represent noteworthy health issues. Handgrip strength, a muscle function indicator, is vital for sarcopenia diagnosis. We investigated the link between handgrip strength and hepatic steatosis in Italian adults. Methods: We retrospectively assessed 388 adults (≥50 years), measuring muscle function and hepatic steatosis using a dynamometer and transient elastography. We divided participants into handgrip strength tertiles. Results: 207 had NAFLD. The lowest handgrip strength tertile had a higher NAFLD prevalence (64% vs. 46%, p = 0.02). Tertiles I and II exhibited increased odds of NAFLD in comparison to tertile III, with an odds ratio of 5.30 (95% confidence interval: 2.24–12.57, p < 0.001) and 2.56 (95% confidence interval: 1.17–5.59, p = 0.01), respectively. rHGS predicted NAFLD with an AUC of 0.41 (SE = 0.029, p = 0.003). An rHGS of 1.22 achieved 18% sensitivity and 80% specificity for hepatic steatosis prediction. Conclusion: Low handgrip strength is linked to an increased susceptibility to NAFLD among the Italian population, implying its potential utility in the identification of risk for hepatic steatosis.

Liver Disease-Related Sarcopenia: A Predictor of Poor Prognosis by Accelerating Hepatic Decompensation in Advanced Chronic Liver Disease

Background Sarcopenia is considered a prognostic factor for advanced chronic liver disease (ACLD) independent of liver function, but the underlying mechanisms are unknown. Here, we investigated whether sarcopenia contributed to hepatic decompensation and worsened prognosis. Methods This was a single-center retrospective study of 708 patients with chronic liver disease who underwent magnetic resonance elastography (MRE). Magnetic resonance imaging (MRI) was used to diagnose sarcopenia and hepatic decompensation (presence of ascites). Results The incidence of sarcopenia (29% overall) and age were significantly correlated to increased liver stiffness (LS) (p < 0.01 each), but age did not differ for LS ≥ 4 kPa. Rates of thrombocytopenia and varices increased at ≥4 kPa, and ascites (n = 52) accounted for 81% of patients with ≥6 kPa LS. Age, alcoholic liver disease, C-reactive protein, sodium level, and controlling nutritional status score were extracted as factors contributing to sarcopenia (all p < 0.05). In ACLD, sarcopenia was an independent predictor of ascites (p < 0.01), and in a follow-up analysis of 163 patients without ascites at baseline, the incidence of ascites in patients with sarcopenia was significantly higher, even after adjusting for LS and liver severity (p < 0.01). The Cox proportional hazards model indicated albumin-bilirubin score and sarcopenia as independent prognostic factors (p < 0.01 each). Conclusions In ACLD, both portal hypertension and liver disease-related sarcopenia were found to occur at ≥4 kPa. Sarcopenia was accompanied by mildly decreased sodium levels and contributed to the early development of ascites and poor prognosis, independent of liver function.

Interrelationship of Sarcopenia and Cardiovascular Diseases: A Review of Potential Mechanisms and Management

Sarcopenia refers to an age-related reduction of lean body mass. It showed a reciprocal relationship with cardiovascular diseases. Thus, it is imperative to explore pathophysiological mechanisms explaining the relationship between sarcopenia and cardiovascular diseases, along with the clinical assessment, and associated management. In this review, we discuss how processes such as inflammation, oxidative stress, endothelial dysfunction, neural and hormonal modifications, as well as other metabolic disturbances influence sarcopenia as well as its association with cardiovascular diseases. Moreover, this review provides an overview of both non-pharmacological and pharmacological management for patients with sarcopenia and cardiovascular diseases, with a focus on the potential role of cardiovascular drugs to mitigate sarcopenia.

A cluster of X-linked miRNAs are de-repressed with age in mouse liver and target growth hormone signaling

Growth hormone (GH) signaling influences lifespan in a wide variety of mammalian species. We previously reported that a cluster of miRNAs located on the X-chromosome are de-repressed with age in male mouse liver, and a subset, the mir-465 family, can directly attenuate expression of the growth hormone receptor (GHR) in vitro leading to a reduction in GH signaling. Here we show that this cluster of miRNAs is also upregulated in the liver with age in females, and that calorie restriction and the Ames dwarf genotype, both known to delay aging, attenuate the upregulation of the miRNA cluster. Upregulation of mir-465 in vivo leads to a reduction in GHR mRNA in the liver and an attenuation of GH signaling, indicated by a reduction in GHR, IGF-1, IGFBP3, and ALS mRNA expression. There is a corresponding reduction in IGF-1 protein levels in the liver and plasma. These results suggest that the age-associated upregulation of the X-chromosomal cluster of miRNAs could influence lifespan.

Effects of resistance training on sarcopenia in patients with intestinal failure: A randomized controlled trial

BACKGROUND

The potential effects of resistance training on sarcopenia in patients with intestinal failure (IF) are not fully elucidated. This study aimed to explore the efficacy of a resistance training program on appendicular skeletal muscle index (ASMI), physical performance, body composition, biochemical parameters, and health-related quality of life (HRQOL) in patients with IF exhibiting sarcopenia.

METHODS

A single-center randomized controlled trial was conducted in a Chinese tertiary teaching hospital. Patients with IF exhibiting sarcopenia were randomly assigned to the exercise group or control group. Participants in the exercise group incorporated four sets of resistance training involving the limbs and abdominal and lower back muscles, six times weekly for 4 weeks. The control group received no specific intervention. The primary outcome was the between-group difference in ASMI 4 weeks after intervention. Secondary outcomes included handgrip strength, 6-m gait speed, body composition, biochemical parameters, and HRQOL.

RESULTS

A total of 60 participants (control group 30, age 51.2 ± 12.9 years, women 43.3%; exercise group 30, age 53.9 ± 14.5 years, women 56.7%) completed the 4-week intervention trial. For the primary outcome, significant intervention effects were found in ASMI between the exercise group and the control group (mean difference 0.72, 95% CI, 0.56-0.89, P < 0.001). There were notable differences in handgrip strength (mean difference 2.7, 95% CI, 1.7-3.6, P < 0.001), 6-m gait speed (mean difference 0.08, 95% CI, 0.01-0.35, P = 0.034), body composition (including total cell mass, bone mineral content, skeletal muscle mass, lean mass, visceral fat area, total body water, intracellular water, extracellular water, and segmental water-legs), and biochemical parameters (including IGF-1, prealbumin, and hemoglobin) between the two groups (P < 0.05). No significant intervention benefits were observed for other secondary outcomes, including biochemical parameters (including albumin, total bilirubin, etc.) and HRQOL (P > 0.05).

CONCLUSIONS

In this randomized clinical trial, we observed that 4 weeks of resistance training was associated with improved ASMI, physical performance, biochemical parameters (including IGF-1, prealbumin, and hemoglobin), and body composition in IF patients with sarcopenia. Resistance training can be recommended as a simple and effective method to improve sarcopenia in patients with IF.

CLINICAL TRIAL REGISTRATION

www.chictr.org.cn, identifier: ChiCTR2100051727.

Sarcopenia, a condition shared by various diseases: can we alleviate or delay the progression?

Sarcopenia is a severe condition common to various chronic diseases and it is reckoned as a major health problem. It encompasses many different molecular mechanisms that have been for a while discovered but not definitely clarified. Although sarcopenia is a disability status that leads to serious health consequences, the scarcity of suitable animal models has curtailed research addressing this disorder. Another limitation in the field of clinical investigation of sarcopenic patients is the lack of a generally accepted definition coupled with the difficulty of adopting common diagnostic criteria. In fact, both do not permit to clarify the exact prevalence rate and consequently limit physicians to establish any kind of therapeutical approach or, when possible, to adopt preventive measures. Unfortunately, there is no standardized cure, apart from doing more physical activity and embracing a balanced diet, but newly discovered substances start being considered. In this review, authors try to give an overview addressing principal pathways of sarcopenia and offer critical features of various possible interventions.