Sarcopenia: current concepts

Assessment of the Daily Living Activities of Older People (2004-2023): A Bibliometric and Visual Analysis

With a rapidly aging global population, comprehending the risks associated with older people's activities of daily living is increasingly important; yet, interdisciplinary analyses remain rare. By providing a bibliometric overview of the capability risks associated with older people's activities of daily living, in order to identify prevailing trends and future directions in the field, the study aims to fill this gap. Using CiteSpace software to analyze data from 928 articles published between 2004 and 2023, the study results demonstrate the growing interest in the capability risks of older people's activities of daily living, with the United States leading in the number of publications, and geriatrics emerging as the dominant discipline. Notably, Institut National de la Sante et de la Recherche Medicale (Inserm) in France emerges as a pivotal contributor in the field. Key research topics encompass risk factors associated with a decline in daily activities and disease-related studies, with emerging trends in cognitive function and instrumental activity research. Future research should prioritize the development of predictive mechanisms for daily living trends, exploration of caregiving solutions, and promotion of interdisciplinary collaboration. This study highlights promising avenues for further research, emphasizing the importance of predictive modeling, innovative caregiving strategies, and interdisciplinary cooperation in addressing capability risks in the activities of daily living of older people.

Opportunistic CT for Prediction of Adverse Postoperative Events in Patients with Spinal Metastases

The purpose of this study was to assess the value of body composition measures obtained from opportunistic abdominal computed tomography (CT) in order to predict hospital length of stay (LOS), 30-day postoperative complications, and reoperations in patients undergoing surgery for spinal metastases. 196 patients underwent CT of the abdomen within three months of surgery for spinal metastases. Automated body composition segmentation and quantifications of the cross-sectional areas (CSA) of abdominal visceral and subcutaneous adipose tissue and abdominal skeletal muscle was performed. From this, 31% (61) of patients had postoperative complications within 30 days, and 16% (31) of patients underwent reoperation. Lower muscle CSA was associated with increased postoperative complications within 30 days (OR [95% CI] = 0.99 [0.98-0.99], p = 0.03). Through multivariate analysis, it was found that lower muscle CSA was also associated with an increased postoperative complication rate after controlling for the albumin, ASIA score, previous systemic therapy, and thoracic metastases (OR [95% CI] = 0.99 [0.98-0.99], p = 0.047). LOS and reoperations were not associated with any body composition measures. Low muscle mass may serve as a biomarker for the prediction of complications in patients with spinal metastases. The routine assessment of muscle mass on opportunistic CTs may help to predict outcomes in these patients.

Association of Handgrip Strength and Cardiovascular Disease Risk Among Middle-Aged Postmenopausal Women: An Analysis of the Korea National Health and Nutrition Examination Survey 2014-2019

Purpose

Handgrip strength is an indicator of overall muscle strength and has been associated with an increased risk of cardiovascular disease. Evidence suggests that menopause is a risk factor for cardiovascular disease in women, and muscle strength decreases progressively after menopause. Despite the prognostic importance of the decline in muscle strength and increased cardiovascular disease risk among postmenopausal women, evidence of their association is limited. This study aimed to investigate the relationship between handgrip strength and cardiovascular disease risk among postmenopausal, middle-aged Korean women.

Patients and Methods

Using pooled cohort equations, we calculated the 10-year risk of atherosclerotic cardiovascular disease (ASCVD) among postmenopausal women (N = 2019) aged 50-64 years without cardiovascular disease history from the 2014-2019 Korea National Health and Nutrition Examination Survey. Relative grip strength was defined as measured grip strength divided by body mass index. Logistic regression analysis of a complex sampling design was performed to evaluate the association between relative grip strength and a predicted 10-year ASCVD risk ≥7.5%.

Results

The average handgrip strength was 24.8 kg, and 5.2% of women were considered for sarcopenia (<18 kg). The quartile-stratified relative grip strength was negatively associated with 10-year ASCVD risk (p < 0.001). In the multiple logistic regression analysis, the adjusted odds ratio for the highest relative grip strength quartile was 0.53 (95% confidence interval [CI]: 0.36-0.78), and that of the group who breastfed for more than 12 months was 1.75 (95% CI: 1.36-2.25) for 10-year ASCVD risk.

Conclusion

Increased handgrip strength may be associated with lower cardiovascular disease risk among middle-aged postmenopausal women in Korea. Our findings provide critical evidence regarding the importance of increasing handgrip strength among postmenopausal, middle-aged women to reduce cardiovascular disease risk. Handgrip strength measurement might be a valuable screening tool for cardiovascular disease prevention.

Body composition and chemotherapy toxicities in breast cancer: a systematic review of the literature

PURPOSE

Breast cancer is the most diagnosed cancer in women with chemotherapy being a common treatment. Toxicities due to chemotherapy can result in dose reduction, delay, and early cessation of treatment, which along with causing distress for individuals during their cancer treatment might also reduce the therapeutic effect. The purpose of this systematic review is to examine the role of body composition on chemotherapy toxicities in women with breast cancer.

METHODS

A systematic search of the literature was completed on electronic databases Pubmed, Embase, CINHAHL, and Cochrane. Studies were included if the direct effect of body composition on chemotherapy toxicities was reported and excluded if body composition could not be isolated. A critical appraisal of the studies included was performed using McMasters University Critical Review Form for Quantitative Studies.

RESULTS

Eleven studies were included with a total of 2881 female participants. All studies reported significant relationships between body composition and chemotherapy toxicities; however, individual parameters differed between the studies. Adding to the heterogeneity, different thresholds were reported to determine both sarcopenia and myosteatosis, making it difficult to identify a common finding.

CONCLUSION

This review suggests that body composition may be an important factor in predicting the severity of chemotherapy toxicities during treatment for breast cancer; however, the lack of international consensus as to thresholds in the literature for sarcopenia and myosteatosis may result in bias. The review supports the need for further prospective studies, allowing for more robust, pre-determined data collection, to better understand the implications of body composition on toxicities and benefits of using body composition to individualize chemotherapy dosing.

IMPLICATIONS FOR CANCER SURVIVORS

Toxicities due to chemotherapy can result in treatment being unable to be completed as planned, potentially resulting in poorer survival outcomes. Improved knowledge in this area may give rise to a more reliable way of individualizing chemotherapy dosage to help mitigate this risk.

Association between the triglyceride glucose index and low skeletal muscle mass: a cross-sectional study

OBJECTIVES

Triglyceride glucose (TyG) represents a consistent surrogate biomarker and index of insulin resistance (IR), IR has also been linked to skeletal muscle mass loss (SMM-L). Here, we evaluated the association between SMM-L and the TyG index (TyGi).

DESIGN

An analytical cross-sectional study.

SETTING

Tertiary care hospitals.

PARTICIPANTS

36 275 participants who underwent health checks between 1 January 2013 and 31 December 2020.

PRIMARY AND SECONDARY OUTCOME MEASURES

A bioelectrical impedance analysis was used to assess the body composition, SMM-L was defined as low ASMI (total limb lean mass/height2) and TyGi was calculated as ln(triglycerides (mg/dL)×fasting blood glucose (mg/dL)/2).

RESULTS

A total of 36 275 subjects were included in the study, of which 58.46% were male, with a mean age of 43.74±12.33 years. The prevalence of low skeletal muscle mass (SMM) was 17.7% and the mean TyGi was 8.56±0.64. TyGi was found to be significantly correlated with low SMM in all subjects (OR 1.87, 95% CI 1.75 to 2.00, p<0.001), with higher correlations seen in younger subjects (OR 1.97, 95% CI 1.77 to 2.20, p<0.001), and remaining significant in middle age (OR 1.95, 95% CI 1.77 to 2.14, p<0.001), old age (OR 1.73, 95% CI 1.38 to 1.16, p<0.001), men (OR 1.60, 95% CI 1.46 to 1.76, p<0.001) and women (OR 2.59, 95% CI 2.39 to 2.87, p<0.001).

CONCLUSIONS

These data demonstrated a significant independent interaction between TyGi and low SMM in all subjects regardless of sex and age subgroups in the general population.

Higher systemic immune-inflammation index is associated with sarcopenia in individuals aged 18-59 years: a population-based study

The association between the systemic immune-inflammation index (SII) and the risk of sarcopenia has not yet been revealed. The purpose of this study was to investigate the relationship between the SII and sarcopenia in individuals aged 18-59 years. All data for this study are from the National Health and Nutrition Examination Survey (NHANES) database, including 7258 participants (age range: 18-59 years). We divided SII values by quartiles (quartiles 1-4: 0.3-3.1, 3.2-4.4, 4.4-6.2, and 6.2-58.5). We constructed a multivariate logistic regression model to assess the association between the SII and the risk of sarcopenia, and an interaction test was run to test the stability of the model and identify high-risk individuals with sarcopenia. Compared to nonsarcopenia participants, sarcopenia patients had a significantly higher SII value (weighted average: 6.65 vs. 5.16) (P = 0.002). Multivariate logistic regression results showed a positive linear relationship between the SII and sarcopenia (OR [odds ratio] = 1.12, 95% CI [confidence interval] 1.03-1.21). Compared to the quartile 1 group, the quartile 4 group was associated with a higher risk of sarcopenia (OR = 3.94, 95% CI 1.42-10.94). Compared with the quartile 1 group, the OR value of the quartile 2 to quartile 4 groups showed an upwards trend (Ptrend < 0.001) as the level of SII increased. Subgroup analysis also indicate that the correlation between higher SII values and the risk of sarcopenia was stable. There was a significant positive linear relationship between SII and sarcopenia, indicating that higher SII values can increase the risk of sarcopenia in individuals aged 18-59 in the United States. The findings of this study will be beneficial in promoting the use of SII alone or in combination with other tools for the risk screening of sarcopenia in communities or large populations.

Familial Correlation and Heritability of Hand Grip Strength in Korean Adults (Korea National Health and Nutrition Examination Survey 2014 to 2019)

BACKGRUOUND

The onset and progression of sarcopenia are highly variable among individuals owing to genetic and environmental factors. However, there are a limited number of studies measuring the heritability of muscle strength in large numbers of parent-adult offspring pairs. We aimed to investigate the familial correlation and heritability of hand grip strength (HGS) among Korean adults.

METHODS

This family-based cohort study on data from the Korea National Health and Nutrition Examination Survey (2014 to 2019) included 5,004 Koreans aged ≥19 years from 1,527 families. HGS was measured using a digital grip strength dynamometer. Familial correlations of HGS were calculated in different pairs of relatives. Variance component methods were used to estimate heritability.

RESULTS

The heritability estimate of HGS among Korean adults was 0.154 (standard error, 0.066). Correlation coefficient estimates for HGS between parent-offspring, sibling, and spouse pairs were significant at 0.07, 0.10, and 0.23 (P<0.001, P=0.041, and P<0.001, respectively). The total variance in the HGS phenotype was explained by additive genetic (15.4%), shared environmental (11.0%), and unique environmental (73.6%) influences. The odds of weak HGS significantly increased in the offspring of parents with weak HGS (odds ratio [OR], 1.69-3.10; P=0.027-0.038), especially in daughters (OR, 2.04-4.64; P=0.029-0.034).

CONCLUSION

HGS exhibits a familial correlation and significant heritable tendency in Korean adults. Therefore, Asian adults, especially women, who have parents with weak HGS, need to pay special attention to their muscle health with the help of healthy environmental stimuli.

Sarcopenic Obesity in Community-Dwelling Spanish Adults Older than 65 Years

Sarcopenic obesity (SO) is diagnosed when sarcopenia and obesity coexist in patients. The objective of this study was to determine the prevalence of SO under different diagnostic criteria in community-dwelling Spanish adults aged over 65 years residing in Valencia (Spain). The research was conducted as an observational and cross-sectional study with a sample size of 202 subjects. To diagnose sarcopenia, we used the tests proposed by the European Working Group on Sarcopenia in Older People in 2019 (EWGSOP2): SARC-F, grip strength, sit-to-stand, gait speed, Appendicular Skeletal Muscle Mass (ASMM), and Short Physical Performance Battery (SPPB). For obesity diagnosis, we used body mass index (BMI), waist circumference (WC), total body fat percentage (%TBF), and tricipital skinfold (TS). The prevalence of SO was 16.5% in women and 29% in men, according to any of the diagnostic criteria used to determine obesity. A higher proportion of SO was observed as age increased in both groups, although no significant differences were found. Most values obtained in tests related to SO diagnosis were worse in the group affected by the disease; however, there were two exceptions related to the amount of ASMM. In total, 18.8% of the participants presented SO according to any diagnostic criteria related to obesity. Our results suggest significant differences in the number of SO cases depending on diagnostic criteria used to determine the participants' obesity. BMI, WC, and TBF% were shown as principal variables to be included in obesity diagnosis within the SO construct. These findings underscore the need to unify criteria to standardize the diagnosis of SO in the global population.

Computed tomography-defined sarcopenia as a risk factor for short-term postoperative complications in oral cancer patients with free flap reconstruction: A retrospective population-based cohort study

BACKGROUND

Postoperative complications after free flap reconstruction for oral cancer can increase cost and prolong hospitalization. This study explored risk factors for complications, focusing on sarcopenia.

METHODS

The study explored the associations between computed tomography-defined sarcopenia and the occurrence of postoperative complications, adjusted for age, gender, smoking, alcohol, ASA scoring, clinical stage of tumor, tumor site, type of free flap used, presence of tracheotomy, and blood test parameters.

RESULTS

Of 253 patients, 17.39% (44/253) of oral cancer patients had comorbid sarcopenia. Univariate analysis showed an overall postoperative complication rate of 65.90% in the sarcopenia group and 51.67% in the non-sarcopenia group. Multivariate modeling showed sarcopenia and smoking were major risk factors for total and respiratory complications, increasing the risks by over two-fold. No factors significantly impacted surgery-specific complications.

CONCLUSIONS

This study identified sarcopenia as a risk factor for postoperative complications in oral cancer patients undergoing flap reconstruction.

Advances in the relationship between temporal muscle thickness and prognosis of patients with glioblastoma: a narrative review

The most dangerous variety of glioma, glioblastoma, has a high incidence and fatality rate. The prognosis for patients is still bleak despite numerous improvements in treatment approaches. We urgently need to develop clinical parameters that can evaluate patients' conditions and predict their prognosis. Various parameters are available to assess the patient's preoperative performance status and degree of frailty, but most of these parameters are subjective and therefore subject to interobserver variability. Sarcopenia can be used as an objective metric to measure a patient's physical status because studies have shown that it is linked to a bad prognosis in those with cancers. For the purpose of identifying sarcopenia, temporal muscle thickness has demonstrated to be a reliable alternative for a marker of skeletal muscle content. As a result, patients with glioblastoma may use temporal muscle thickness as a potential marker to correlate with the course and fate of their disease. This narrative review highlights and defines the viability of using temporal muscle thickness as an independent predictor of survival in glioblastoma patients, and it evaluates recent research findings on the association between temporal muscle thickness and prognosis of glioblastoma patients.

Pre-existing sarcopenia and swallowing outcomes in acute stroke patients

BACKGROUND & AIMS

This study aimed to investigate the associations of pre-existing sarcopenia with swallowing function, oral intake level, and aspiration pneumonia in patients with acute stroke.

METHODS

This observational study included patients (≥60 years of age) with acute ischemic stroke or intracerebral hemorrhage within 7 days of onset who were screened for sarcopenia, malnutrition, and swallowing difficulties in a stroke-care unit within 48 h of admission. Sarcopenia was defined by the Asian Working Group on Sarcopenia 2019 as having a low calf circumference, handgrip strength, and appendicular muscle mass index. The primary outcome was impaired oral intake (functional oral intake scale <5 points) at 3, 7, and 14 days after admission, and the secondary outcome was aspiration pneumonia during hospitalization.

RESULTS

We enrolled 350 patients (median age of 77 years; 63% males) who underwent the aforementioned screening. Sarcopenia was diagnosed in 34% of patients, and malnutrition was found in 66% of patients with sarcopenia. When compared with the comparison group (defined as patients with either or both normal calf circumference and handgrip strength), the sarcopenia group had significantly lower tongue pressure and a higher prevalence of dysphagia. Sarcopenia was associated with functional oral intake scale <5 at 7 days (adjusted odds ratio [OR], 4.72; 95% confidence interval [CI], 1.91-11.71); p = 0.002) and 14 days (adjusted OR, 3.93; 95% CI, 1.47-10.53; p = 0.006) and with aspiration pneumonia during hospitalization (adjusted OR, 6.12; 95% CI, 1.63-22.94; p = 0.007).

CONCLUSION

Acute stroke patients with sarcopenia may have weakness of the swallowing-related muscles which may lead to impaired oral intake and aspiration pneumonia.

Understanding NK cell biology for harnessing NK cell therapies: targeting cancer and beyond

Gene-engineered immune cell therapies have partially transformed cancer treatment, as exemplified by the use of chimeric antigen receptor (CAR)-T cells in certain hematologic malignancies. However, there are several limitations that need to be addressed to target more cancer types. Natural killer (NK) cells are a type of innate immune cells that represent a unique biology in cancer immune surveillance. In particular, NK cells obtained from heathy donors can serve as a source for genetically engineered immune cell therapies. Therefore, NK-based therapies, including NK cells, CAR-NK cells, and antibodies that induce antibody-dependent cellular cytotoxicity of NK cells, have emerged. With recent advances in genetic engineering and cell biology techniques, NK cell-based therapies have become promising approaches for a wide range of cancers, viral infections, and senescence. This review provides a brief overview of NK cell characteristics and summarizes diseases that could benefit from NK-based therapies. In addition, we discuss recent preclinical and clinical investigations on the use of adoptive NK cell transfer and agents that can modulate NK cell activity.

Lack of association between serum myonectin levels and sarcopenia in older Asian adults

Myonectin is a muscle-secreted factor that helps maintain homeostasis in the body by regulating several functions, including lipid metabolism. Previous studies suggested that myonectin may play a role in muscle health in an autocrine manner, but its impact on human skeletal muscle is still unclear. We aimed to investigate the relationship of serum myonectin levels with sarcopenia and related muscle parameters. We conducted a cross-sectional study of 142 older adults whose muscle mass, grip strength, gait speed, chair stands, and short physical performance battery (SPPB) were evaluated in the geriatric clinic of a tertiary medical center. Sarcopenia was defined based on Asian-specific cutoff values, and circulating myonectin levels were measured using an enzyme immunoassay. Before and after adjusting for age, sex, and body mass index, the serum myonectin level was not significantly different when the patients were stratified by status of sarcopenia, muscle mass, muscle strength, and physical performance. Furthermore, whether given as a continuous variable or divided into quartile groups, the serum myonectin level had no association with the skeletal muscle mass, grip strength, gait speed, chair stand test, or SPPB score. Our findings did not confirm the potential role of myonectin in muscle metabolism observed in experimental research. Thus, serum myonectin levels cannot predict the risk of sarcopenia in older Asian adults.

Mitochondrial transplantation as a possible therapeutic option for sarcopenia

With advancing age, the skeletal muscle phenotype is characterized by a progressive loss of mass, strength, and quality. This phenomenon, known as sarcopenia, has a negative impact on quality of life and increases the risk of morbidity and mortality in older adults. Accumulating evidence suggests that damaged and dysfunctional mitochondria play a critical role in the pathogenesis of sarcopenia. Lifestyle modifications, such as physical activity, exercise, and nutrition, as well as medical interventions with therapeutic agents, are effective in the management of sarcopenia and offer solutions to maintain and improve skeletal muscle health. Although a great deal of effort has been devoted to the identification of the best treatment option, these strategies are not sufficient to overcome sarcopenia. Recently, it has been reported that mitochondrial transplantation may be a possible therapeutic approach for the treatment of mitochondria-related pathological conditions such as ischemia, liver toxicity, kidney injury, cancer, and non-alcoholic fatty liver disease. Given the role of mitochondria in the function and metabolism of skeletal muscle, mitochondrial transplantation may be a possible option for the treatment of sarcopenia. In this review, we summarize the definition and characteristics of sarcopenia and molecular mechanisms associated with mitochondria that are known to contribute to sarcopenia. We also discuss mitochondrial transplantation as a possible option. Despite the progress made in the field of mitochondrial transplantation, further studies are needed to elucidate the role of mitochondrial transplantation in sarcopenia. KEY MESSAGES: Sarcopenia is the progressive loss of skeletal muscle mass, strength, and quality. Although the specific mechanisms that lead to sarcopenia are not fully understood, mitochondria have been identified as a key factor in the development of sarcopenia. Damaged and dysfunctional mitochondria initiate various cellular mediators and signaling pathways, which largely contribute to the age-related loss of skeletal muscle mass and strength. Mitochondrial transplantation has been reported to be a possible option for the treatment/prevention of several diseases. Mitochondrial transplantation may be a possible therapeutic option for improving skeletal muscle health and treating sarcopenia. Mitochondrial transplantation as a possible treatment option for sarcopenia.

Important Concepts in Protein Nutrition, Aging, and Skeletal Muscle: Honoring Dr Douglas Paddon-Jones (1969-2021) by Highlighting His Research Contributions

This review is a tribute to honor Dr Douglas Paddon-Jones by highlighting his career research contributions. Dr Paddon-Jones was a leader in recognizing the importance of muscle health and the interactions of physical activity and dietary protein for optimizing the health span. Aging is characterized by loss of muscle mass and strength associated with reduced rates of muscle protein synthesis (MPS) and the ability to repair and replace muscle proteins. Research from the team at the University of Texas Medical Branch in Galveston discovered that the age-related decline in MPS could be overcome by increasing the quantity or quality of dietary protein at each meal. Dr Paddon-Jones was instrumental in proposing and testing a "protein threshold" of ∼30 g protein/meal to optimize MPS in older adults. Dr Paddon-Jones demonstrated that physical inactivity greatly accelerates the loss of muscle mass and function in older adults. His work in physical activity led him to propose the "Catabolic Crisis Model" of muscle size and function losses, suggesting that age-related muscle loss is not a linear process, but the result of acute periods of disuse associated with injuries, illnesses, and bed rest. This model creates the opportunity to provide targeted interventions via protein supplementation and/or increased dietary protein through consuming high-quality animal-source foods. He illustrated that nutritional support, particularly enhanced protein quantity, quality, and meal distribution, can help preserve muscle health during periods of inactivity and promote health across the life course.

Sex Differences in Inflammation and Muscle Wasting in Aging and Disease

Only in recent years, thanks to a precision medicine-based approach, have treatments tailored to the sex of each patient emerged in clinical trials. In this regard, both striated muscle tissues present significant differences between the two sexes, which may have important consequences for diagnosis and therapy in aging and chronic illness. In fact, preservation of muscle mass in disease conditions correlates with survival; however, sex should be considered when protocols for the maintenance of muscle mass are designed. One obvious difference is that men have more muscle than women. Moreover, the two sexes differ in inflammation parameters, particularly in response to infection and disease. Therefore, unsurprisingly, men and women respond differently to therapies. In this review, we present an up-to-date overview on what is known about sex differences in skeletal muscle physiology and disfunction, such as disuse atrophy, age-related sarcopenia, and cachexia. In addition, we summarize sex differences in inflammation which may underly the aforementioned conditions because pro-inflammatory cytokines deeply affect muscle homeostasis. The comparison of these three conditions and their sex-related bases is interesting because different forms of muscle atrophy share common mechanisms; for instance, those responsible for protein dismantling are similar although differing in terms of kinetics, severity, and regulatory mechanisms. In pre-clinical research, exploring sexual dimorphism in disease conditions could highlight new efficacious treatments or recommend implementation of an existing one. Any protective factors discovered in one sex could be exploited to achieve lower morbidity, reduce the severity of the disease, or avoid mortality in the opposite sex. Thus, the understanding of sex-dependent responses to different forms of muscle atrophy and inflammation is of pivotal importance to design innovative, tailored, and efficient interventions.

Depletion of CD206+ M2-like macrophages induces fibro-adipogenic progenitors activation and muscle regeneration

Muscle regeneration requires the coordination of muscle stem cells, mesenchymal fibro-adipogenic progenitors (FAPs), and macrophages. How macrophages regulate the paracrine secretion of FAPs during the recovery process remains elusive. Herein, we systemically investigated the communication between CD206⁺ M2-like macrophages and FAPs during the recovery process using a transgenic mouse model. Depletion of CD206⁺ M2-like macrophages or deletion of CD206⁺ M2-like macrophages-specific TGF-β1 gene induces myogenesis and muscle regeneration. We show that depletion of CD206⁺ M2-like macrophages activates FAPs and activated FAPs secrete follistatin, a promyogenic factor, thereby boosting the recovery process. Conversely, deletion of the FAP-specific follistatin gene results in impaired muscle stem cell function, enhanced fibrosis, and delayed muscle regeneration. Mechanistically, CD206⁺ M2-like macrophages inhibit the secretion of FAP-derived follistatin via TGF-β signaling. Here we show that CD206⁺ M2-like macrophages constitute a microenvironment for FAPs and may regulate the myogenic potential of muscle stem/satellite cells.

Frailty and benign prostatic hyperplasia: The thrilling underlying impact

Background: World population is aging. The number of individuals aged over 65 are expected to be 71 million only in the US. 43% of this population will be men. Benign prostatic hyperplasia (BPH), defined as the benign neoplasm of the prostate gland affects 8% of men by their forties, but 90% of men over 90 years old. Lower urinary tract symptoms (LUTS) can be caused by an enlarged prostate, and it seems to be associated more with older and frailer individuals. Methods: The purpose of this study is to review the potential interplay between frailty syndrome and benign prostatic hyperplasia. A thorough MEDLINE/PubMed non-systematic literature review was conducted from 1990 to March of 2022. The terms used for the search were “frailty and benign prostatic hyperplasia” and “low muscle mass and benign prostatic hyperplasia”. Results: It seems that, frailty poses a negative impact on the prognosis of patients with BPH, as it is associated with increased incidence of LUTS. In addition, frailty seems to be a strong predictor concerning surgical procedure failure and mortality following invasive procedures for BPH. Prostatic stent placement on the other hand appears to be the ideal solution for frail patients. Conclusions: BPH has a strong association with frailty and increasing age.

Metabolomic profiles to explore biomarkers of severe sarcopenia in older men: A pilot study

BACKGROUND

The pathophysiology of sarcopenia is complex and multifactorial; however, it has not yet been fully elucidated. Identifying metabolomic profiles may help clarify the mechanisms underlying sarcopenia.

OBJECTIVE

This pilot study explored potential noninvasive biomarkers of severe sarcopenia through metabolomic analysis in community-dwelling older men.

METHODS

Twenty older men (mean age: 81.9 ± 2.8 years) were selected from the Korean Frailty and Aging Cohort Study. Participants with severe sarcopenia (n = 10) were compared with non-sarcopenic, age- and body mass index-matched controls (n = 10). Severe sarcopenia was defined as low muscle mass, low muscle strength, and low physical performance using the Asian Working Group for Sarcopenia 2019 criteria. Non-targeted metabolomic profiling of plasma metabolites was performed using capillary electrophoresis time-of-flight mass spectrometry and absolute quantification was performed in target metabolites.

RESULTS

Among 191 plasma metabolic peaks, the concentrations of 10 metabolites significantly differed between severe sarcopenia group and non-sarcopenic controls. The plasma concentrations of L-alanine, homocitrulline, N-acetylserine, gluconic acid, N-acetylalanine, proline, and sulfotyrosine were higher, while those of 4-methyl-2-oxovaleric acid, 3-methyl-2-oxovaleric acid, and tryptophan were lower in participants with severe sarcopenia than in non-sarcopenic controls (all, p < 0.05). Among the 53 metabolites quantified as target metabolites, L-alanine (area under the receiver operating characteristic curve [AUC] = 0.760; p = 0.049), gluconic acid (AUC = 0.800; p = 0.023), proline (AUC = 0.785; p = 0.031), and tryptophan (AUC = 0.800; p = 0.023) determined the presence of severe sarcopenia.

CONCLUSIONS

Plasma metabolomic analysis demonstrated that L-alanine, gluconic acid, proline, and tryptophan may be potential biomarkers of severe sarcopenia. The identified metabolites can provide new insights into the underlying pathophysiology of severe sarcopenia and serve as the basis for preventive interventions.

Sarcopenic Dysphagia Is Associated With Mortality in Institutionalized Older Adults

OBJECTIVE

To estimate mortality associated with sarcopenic dysphagia.

DESIGN

A 3-year follow-up cohort.

SETTING AND PARTICIPANTS

Ninety-five nursing home residents were evaluated to determine the baseline presence or absence of oropharyngeal dysphagia and followed up for 3 years.

METHODS

The primary outcome was the risk of death. Dysphagia was assessed using a volume-viscosity swallow test. We used an algorithm to determine sarcopenic dysphagia based on grip strength, walking speed, calf circumference, and exclusion of neurologic or structural causes of dysphagia. We constructed 3 subgroups: without dysphagia, nonsarcopenic dysphagia, and sarcopenic dysphagia. Cox proportional regression analyses were used to predict the risk of death.

RESULTS

Thirty-five percent of participants had no dysphagia, 20% nonsarcopenic dysphagia, and 45% sarcopenic dysphagia. Sarcopenic dysphagia was independently associated with a higher risk of death [hazard ratio (HR) 2.44, 95% CI 1.02-5.80, P = .043] than without dysphagia. In addition, a higher Charlson Comorbidity Index score was associated with a higher risk of death (HR 1.33, 95% CI 1.01-1.75, P = .040).

CONCLUSIONS AND IMPLICATIONS

This study shows that sarcopenic dysphagia was associated with increased mortality among institutionalized older adults. These deaths could be potentially preventable.

Ultrasound Measurements of Rectus Femoris and Locomotor Outcomes in Patients with Spinal Cord Injury

Patients with incomplete spinal cord injury have decreased mobility, and many do not recover walking ability. The purpose of this study was to investigate rectus femoris muscle thickness and echo intensity on ultrasound and functional outcomes in these patients. This was a prospective cohort study in an inpatient rehabilitation center, which recruited 40 consecutive patients with incomplete spinal cord injury. The patients underwent an ultrasound assessment at 6 weeks post-injury. Ultrasound measurements were performed using B-mode ultrasound scanning and standardized protocols. Functional outcomes on discharge, including Lower Extremity Muscle Score (LEMS), Functional Independence Measure (FIM), and Walking Index for Spinal Cord Injury II (WISCI II), were measured. Rectus femoris muscle thickness was significantly correlated with discharge LEMS (Spearman’s rho = 0.448; p = 0.004), FIM motor subscale (Spearman’s rho = 0.595; p < 0.001), FIM walk subscale (Spearman’s rho = 0.621; p < 0.001) and WISCI II (Spearman’s rho = 0.531; p < 0.001). The rectus femoris echo intensity was also significantly correlated with discharge LEMS (Spearman’s rho = −0.345; p = 0.029), FIM motor subscale (Spearman’s rho = −0.413; p = 0.008), FIM walk subscale (Spearman’s rho = −0.352; p = 0.026), and WISCI II (Spearman’s rho = −0.355; p = 0.025). We report that a relationship exists between rectus femoris muscle ultrasonographic characteristics and muscle function and ambulatory outcomes after inpatient rehabilitation. Ultrasound muscle measurements are potentially useful in assessing muscle wasting and function in patients with spinal cord injury.

SarQoL Questionnaire in Community-Dwelling Older Adults under EWGSOP2 Sarcopenia Diagnosis Algorithm: A New Screening Method?

This article is an observational and cross-sectional study that related the result obtained in the questionnaire for the evaluation of quality of life related to muscle mass (SarQoL) and the prevalence of sarcopenic pathology measured under the EWGSOP2 algorithm. Participants were 202 community-dwelling older adults living in Valencia, Spain. The prevalence of sarcopenia in men was 28.9%, while in women it was 26.2%. In the case of the SarQoL questionnaire, the mean score obtained for men was 75.5 and 72.6 for women, showing significant differences in both sexes between the results obtained by the group with and without sarcopenia. After the exhaustive data analysis, a high discriminative capacity for sarcopenic disease was found in the SarQoL questionnaire total score and in domains 2 (locomotion), 4 (functionality) and 5 (activities of daily living). In accordance with the existing controversy regarding the use of SARC-F as a screening method for sarcopenia, the authors pointed out the capacity of domain 2 (locomotion) in isolation as a possible screening method for this disease, exposing a high risk of suffering sarcopenia when scores in this domain were below 60 points. Further research is needed to develop new lines of research as these showed in this work, as well as new and easily applicable screening methods for sarcopenia in clinical practice, that allow a rapid detection of this disease in the community.

Prevention of Loss of Muscle Mass and Function in Older Adults during COVID-19 Lockdown: Potential Role of Dietary Essential Amino Acids

As the COVID-19 pandemic became a global emergency, social distancing, quarantine, and limitations in outdoor activities have resulted in an environment of enforced physical inactivity (EPI). A prolonged period of EPI in older individuals accelerates the deterioration of skeletal muscle health, including loss of muscle mass and function, commonly referred to as sarcopenia. Sarcopenia is associated with an increased likelihood of the progression of diabetes, obesity, and/or depression. Well-known approaches to mitigate the symptoms of sarcopenia include participation in resistance exercise training and/or intake of balanced essential amino acids (EAAs) and high-quality (i.e., containing high EEAs) protein. As the pandemic situation discourages physical exercise, nutritional approaches, especially dietary EAA intake, could be a good alternative for counteracting against EPI-promoted loss of muscle mass and function. Therefore, in the present review, we cover (1) the impact of EPI-induced muscle loss and function on health, (2) the therapeutic potential of dietary EAAs for muscle health (e.g., muscle mass and function) in the EPI condition in comparison with protein sources, and finally (3) practical guidelines of dietary EAA intake for optimal anabolic response in EPI.

High-Fat Diet Impairs Muscle Function and Increases the Risk of Environmental Heatstroke in Mice

Environmental heat-stroke (HS) is a life-threatening response often triggered by hot and humid weather. Several lines of evidence indicate that HS is caused by excessive heat production in skeletal muscle, which in turn is the result of abnormal Ca2+ leak from the sarcoplasmic reticulum (SR) and excessive production of oxidative species of oxygen and nitrogen. As a high fat diet is known to increase oxidative stress, the objective of the present study was to investigate the effects of 3 months of high-fat diet (HFD) on the HS susceptibility of wild type (WT) mice. HS susceptibility was tested in an environmental chamber where 4 months old WT mice were exposed to heat stress (41 °C for 1 h). In comparison with mice fed with a regular diet, mice fed with HFD showed: (a) increased body weight and accumulation of adipose tissue; (b) elevated oxidative stress in skeletal muscles; (c) increased heat generation and oxygen consumption during exposure to heat stress; and finally, (d) enhanced sensitivity to both temperature and caffeine of isolated muscles during in-vitro contracture test. These data (a) suggest that HFD predisposes WT mice to heat stress and (b) could have implications for guidelines regarding food intake during periods of intense environmental heat.

Differences by age in the obesity paradox in severe burns

BACKGROUND

Many studies show a "obesity paradox", which seems to protect against death. Whether an obesity paradox space is present in severe burn patients remains a matter of great debate. Most research on the obesity paradox of burn injuries is classified by body mass index (BMI) rather than by age.

OBJECTIVE

To investigate whether the obesity paradox exists in severe burn patients stratified by age.

METHODS

Retrospective analysis was performed on 490 patients with severe burns who were ≥ 18 years of age and were admitted to Fujian Medical University Union Hospital from January 2005 to December 2020. Demographic and clinical characteristics were collected, including age, BMI, total body surface area (TBSA), presence of inhalation injury, abbreviated burn severity index (ABSI) score, diabetes comorbidities, hypertension comorbidities, and in-hospital mortality. The patients were divided into the younger group (18 ≤ age<65 years) and the older group (age ≥ 65 years). The important variables of the two groups were compared. The predictive value of BMI stratified by age on in-hospital mortality was evaluated by binary logistic regression analysis and the Cochran's and Mantel-Haenszel statistics.

RESULTS

A total of 490 patients were selected for this study, and were divided into the younger group (413) and the elderly group (77) according to their ages. In the younger group, logistic regression analyses indicated that high BMI remained significantly and independently associated with decreased in-hospital mortality (P = 0.021). That is, in-hospital mortality decreased by 17.8% when BMI increased by 1 kg/m². In the older group, BMI was not associated with in-hospital mortality (P = 0.808). In the younger group, the results of Pearson's chi-square test was less than 0.05, indicating a correlation between BMI and prognosis. In the older group, the conclusion was contrary with, no correlation between BMI and prognosis. If the confounding factors of age were not considered, this results in no correlation between BMI and prognosis. In the younger group, the survival/death ratio of patients with overweight and obesity was 2.078 times that of patients with normal weight.

CONCLUSION

In this study of patients with severe burns, overweight and obesity had protective effect on burn injury in the younger group (18 ≤ age<65 years), but not in the older group (age ≥ 65 years). Investigating the obesity paradox in burn patients needs to consider age differences. However, multicentre clinical trials are needed to verify the results.

Relationship between oseteoporosis with fatty infiltration of paraspinal muscles based on QCT examination

INTRODUCTION

To investigate the correlation between paraspinal muscles features and osteoporosis in lumbar spine.

MATERIALS AND METHODS

A total of 367 subjects who underwent quantitative computed tomography (QCT) examination were enrolled in this study. QCT pro workstation was used to obtain the mean bone mineral density (BMD) of the lower lumbar spine. Fat fraction (FF) and cross-section area (CSA) of the paraspinal muscles at the corresponding levels were measured. All participants were divided into normal, osteopenia, and osteoporosis groups. One-way ANOVA and independent samples t tests were performed to compare differences between groups. Pearson and Spearman correlation coefficients and partial correlation analysis after controlling for confounding factors were used to analyze the correlation between BMD and paraspinal muscles measurements.

RESULTS

Among the 367 participants included, 116 were in the normal group, 130 in the osteopenia group and 121 in the osteoporosis group. There were significant differences among the three groups for the mean and multifidus FF. BMD showed negative correlations with the FF of the paraspinal muscles. Multifidus and mean FF showed the best correlation (r = - 0.654, - 0.777). There were also significant differences in the mean and multifidus FF between different age groups, while after controlling for confounding factors, there was no correlation between age and FF of the paraspinal muscles.

CONCLUSION

This preliminary study demonstrated the association of BMD with fatty infiltration of paraspinal muscles. Different muscles might have specific effects in different sex and age groups.

Effects of Otago Exercise Program on serum Interleukin-6 level in older women

Background

Otago Exercise Program (OEP) has been demonstrated to minimize the risk of falling in older adults by improving muscular strength and balance. Meanwhile, reduced IL-6 level serves as a biomarker of regular physical activity.

Objective

Analyzing OEP effect on decreased IL-6 level in elderly women.

Methods

This study used a randomized control trial design from October 2020 to May 2021. 26 participants were divided into a treatment group (13 participants) and a control group (13 participants). The treatment group received OEP for 8 weeks, in which the OEP was carried out 3 times during the first week. On the other hand, the control group did not get intervention. The IL-6 level was measured 2 times, before and after OEP. The measurement results were analyzed using paired t-test and independent t-test, which were declared significant if p < 0.05.

Results

The participants' average IL-6 level at pretest and posttest was 4.77 ± 1.71 pg/mL and 4.57 ± 1.74 pg/mL, respectively. The IL-16 level of the treatment group at pretest and posttest was 4.22 ± 1.72 pg/mL and 3.97 ± 1.67 pg/mL, respectively (t = 1.058; 95% CI = −0.770 – 0.267; p = 0.311). Meanwhile, the IL-6 level of the control group at pretest and posttest was 5.30 ± 1.59 pg/mL and 5.16 ± 1.65 pg/mL, respectively (t = 0.382; 95% CI = −0.969 – 0.680; p = 0.709). The ΔIL-6 level in the treatment and control group was −0.25 ± 0.85 pg/mL and −0.14 ± 1.36 pg/mL, respectively (t = 0.240; 95% CI = −1.030 – 0.815; p = 0.813).

Conclusion

The OEP didn't lower serum IL-6 levels after eight weeks.

•

Otago Exercise Program (OEP) is an easy exercise that increases physical activity.

•

The OEP can reduce interleukin-6 (IL-6) level when performed >8 weeks (3 x/weeks).

•

The OEP minimizes the risk of fractures in elderly women.

Association of the Mediterranean Dietary Quality Index with handgrip strength and muscle endurance: A cross‐sectional study

Mediterranean diet is a healthy eating pattern associated with various health advantages. Different scoring methods of adherence to this diet have been used to investigate the association between the Mediterranean diet and muscle outcomes. The present study aimed to investigate the association of the Mediterranean Dietary Quality Index (Med‐DQI) with handgrip strength (HS) and muscle endurance (ME). The current cross‐sectional study involved 268 Iranian adults aged 18–70 years. Anthropometric measures were evaluated. We used the 168‐item food frequency questionnaire (FFQ) to develop the Med‐DQI score. The Med‐DQI score ranges from 0 to 14 (lower score suggests higher adherence to Mediterranean diet). HS was measured by a digital handgrip dynamometer, and ME was the amount of time to reach a maximum of 50% of grip strength. Multiple regression analysis was used to determine the association of Med‐DQI and its components with HS and ME. Med‐DQI score was not associated with mean handgrip strength (MHS) (p = .34) and mean muscle endurance (MME) (p = .69) in the crude model. The associations remained insignificant after the adjustment of covariates (p = .16, .31, respectively). Among the components of Med‐DQI, cholesterol, meats, fish, and cereals were positively correlated with MHS (p < .001 for all). Meats (p = .02), olive oil (p < .001), cereals (p = .04), fruits and vegetables (p < .001 for all) were also positively correlated with MME. According to our findings, Med‐DQI score is not associated with MHS and MME in a population of Iranian adults. Further longitudinal studies are required to confirm these findings.

Effect of resisted exercise on autonomic cardiac modulation in elderly women: STROBE-compliant study

Heart rate variability (HRV) is an important cardiac health marker, with lower values indicating a reduction in vagal control of cardiac rhythm and decreasing significantly with advancing age. In this study, we evaluated the effects of strength exercises for the upper and lower limbs on cardiac autonomic modulation in elderly women.We registered 29 participants using a portable RS800CX heart rate monitor to record the RR intervals. For the collection of HRV data, the volunteers remained seated at rest for 10 minutes. After the rest period, the participants performed the exercises. Immediately after the exercise protocol, the subjects remained seated at rest for 30 minutes. HRV indices were analyzed in the following periods: rest, 0 to 10 minutes, 5 to 10 minutes, 10 to 20 minutes, and 20 to 30 minutes. Systolic arterial pressure and diastolic arterial pressure were measured in the following periods: rest, immediately after exercise, and 30 minutes after exercise.Regarding the mean of the RR intervals, heart rate, and indexes of the time and frequency domains surveyed, there were no statistically significant differences between the 4 moments in the protocols for upper and lower limbs. No significant differences were found in systolic and diastolic pressures between the 3 time points surveyed in the protocols for the upper and lower limbs.Resistance exercises performed with low-intensity loads and a greater number of repetitions did not promote significant variations in cardiac autonomic modulation and blood pressure levels, showing good safety in elderly women.

Identification of traumatic acid as a potential plasma biomarker for sarcopenia using a metabolomics-based approach

BACKGROUND

The pathogenesis of sarcopenia is complex and has not been well explored. Identifying biomarkers is a promising strategy for exploring the mechanism of sarcopenia. This study aimed to identify potential biomarkers of sarcopenia through a metabolomic analysis of plasma metabolites in elderly subjects (≥65 years of age) vs. younger adults (<65 years of age).

METHODS

Of the 168 candidates in the Comprehensive Geriatric Assessment and Frailty Study of Elderly Outpatients, 24 elderly subjects (≥65 years of age) with sarcopenia were age and sex matched with 24 elderly subjects without sarcopenia. In addition, 24 younger adults were recruited for comparison. Muscle strength, gait speed, and metabolic and inflammatory parameters, including plasma tumour necrosis factor-α, C-reactive protein, irisin, and growth differentiation factor 15 (GDF-15) levels were assessed. Metabolomic analysis was carried out using the plasma metabolites.

RESULTS

Seventy-two participants were enrolled, including 10 (41.6%) men and 14 (58.3%) women in both groups of elderly subjects. The median ages of elderly subjects with and without sarcopenia were 82 (range: 67-88) and 81.5 (range: 67-87) years, respectively. Among the 242 plasma metabolic peaks analysed among these three groups, traumatic acid was considered as a sarcopenia-related metabolite. The plasma traumatic acid signal intensity level was significantly higher in elderly subjects with sarcopenia than in elderly subjects without sarcopenia [591.5 (inter-quartile range, IQR: 491.5-664.5) vs. 430.0 (IQR: 261.0-599.5), P = 0.0063]. The plasma concentrations of traumatic acid were 15.8 (IQR: 11.5-21.7), 21.1 (IQR: 16.0-25.8), and 24.3 (IQR: 18.0-29.5) ppb in younger adults [age range: 23-37 years, 12 (50%) men], elderly subjects without sarcopenia, and elderly subjects with sarcopenia, respectively, thereby depicting an increasing tendency (P for trend = 0.034). This pattern was similar to that of GDF-15, a recognized sarcopenia-related factor. Plasma traumatic acid concentrations were also positively correlated with the presence of hypertension (r = 0.25, P = 0.034), glucose AC (r = 0.34, P = 0.0035), creatinine (r = 0.40, P = 0.0006), and GDF-15 levels (r = 0.25, P = 0.0376), but negatively correlated with the Modification of Diet in Renal Disease-simplify-glomerular filtration rate (r = -0.50, P < 0.0001). Similarly, plasma GDF-15 concentrations were associated with these factors.

CONCLUSIONS

Traumatic acid might represent a potential plasma biomarker of sarcopenia. However, further studies are needed to validate the results and investigate the underlying mechanisms.

Systematic Review of Diagnostic Tools and Interventions for Sarcopenia

Diagnosis of rare incurable diseases is important. Specific evaluation methods and standards for sarcopenia differ according to each sarcopenia-related medical association. This study aimed to identify the tools that are currently used to diagnose sarcopenia and to systematically review various interventions for sarcopenia. We intended to provide basic information to help establish standard diagnostic and therapeutic methods for sarcopenia. We collected and analyzed published journal articles, including gray literature and dissertations, from 11 domestic and international databases. The search terms were “sarcopenia/sarcopenic”, “combined (complex/circuit) exercise”, “resistance (muscle) exercise”, and “aerobic exercise”. The tools used for sarcopenia diagnosis were inconsistent across the studies. Circuit exercise combined with aerobic exercise and strength training was the most common intervention method, followed by strength training and aerobic exercise. We identified several diagnostic and evaluation criteria across the articles. Essentially, this systematic review confirms the importance of diagnostic criteria for sarcopenia and compares interventions. Hopefully, the criteria for the diagnosis and evaluation of sarcopenia will become clear in the future. In addition, the results of this study may provide basic information for rehabilitation treatment for rare and incurable diseases.

Simulated microgravity accelerates aging of human skeletal muscle myoblasts at the single cell level

Earth's gravity is essential for maintaining skeletal muscle mass and function in the body. The role of gravity in the myogenic mechanism has been studied with animal experiments in the International Space Station. Recently, gravity-control devices allow to study the effects of gravity on cultured cells on the ground. This study demonstrated that simulated microgravity accelerated aging of human skeletal muscle myoblasts in an in-vitro culture. The microgravity culture induced a significant decrease in cell proliferation and an enlargement of the cytoskeleton and nucleus of cells. Similar changes are often observed in aged myoblasts following several passages. In fact, by the microgravity culture the expression of senescence associated β-Gal was significantly enhanced, and some muscle-specific proteins decreased in the enlarged cells. Importantly, these microgravity effects remained with the cells even after a return to normal gravity conditions. Consequently, the microgravity-affected myoblasts demonstrated a reduced capability of differentiation into myotubes. In the body, it is difficult to interpret the disability of microgravity-affected myoblasts, since muscle regeneration is linked to the supply of new myogenic cells. Therefore, our in-vitro cell culture study will be advantageous to better understand the role of each type of myogenic cell in human muscle without gravitational stress at the single cell level.

Relationship Between Low Skeletal Muscle Mass and Arteriosclerosis in Western China: A Cross-Sectional Study

Objectives: This study explored the prevalence and the correlation between low muscle mass and arteriosclerosis in different gender and age groups, to increase the attention paid to the risk factors of arteriosclerosis in the young and middle-aged population. Methods: This was an analytical, cross-sectional study. Data were obtained from healthy individuals recruited from the Health Management Center of W Hospital. The brachial-ankle pulse-wave velocity was used as an indicator of arteriosclerosis, and a bioelectrical impedance analysis was used to assess the body composition. Results: A total of 36,374 subjects (men, 58.4%; women, 41.6%; mean age, 43.74 ± 12.34 years [range, 18-80 years]) participated in this study. The prevalence of low skeletal muscle mass and arteriosclerosis was 17.7 and 53.1%, respectively, in all subjects. Low skeletal muscle mass was significantly associated with arteriosclerosis (OR: 1.435, 95% CI: 1.343-1.533, P < 0.001) in all subjects, and the association remained significant in young age (OR: 1.506, 95% CI: 1.353-1.678, P < 0.001), middle-age (OR: 1.329, 95% CI: 1.195-1.479, P < 0.001), and old age (OR: 1.676, 95% CI: 1.191-2.358, P = 0.003), and also significant in men (OR: 1.559, 95% CI: 1.396-1.740, P < 0.001) and women (OR: 1.266, 95% CI: 1.143-1.401, P < 0.001). Conclusions and Implications: Our results show that the prevalence of low muscle mass and arteriosclerosis is high in the general population, even among middle-aged people and young people, and confirmed that there is a significant independent association between low skeletal muscle mass and arteriosclerosis in all subjects and in different age and gender subgroups.

The Impact of Milk Fat Globule Membrane with Exercise on Age-Related Degeneration of Neuromuscular Junctions

Morphological changes in neuromuscular junctions (NMJs), which are synapses formed between α-motor neurons and skeletal muscle fibers, are considered to be important in age-related motor dysfunction. We have previously shown that the intake of dietary milk fat globule membrane (MFGM) combined with exercise attenuates age-related NMJ alterations in the early phase of aging. However, it is unclear whether the effect of MFGM with exercise on age-related NMJ alterations persists into old age, and whether intervention from old age is still effective when age-related changes in NMJs have already occurred. In this study, 6- or 18-month-old mice were treated with a 1% MFGM diet and daily running wheel exercise until 23 or 24 months of age, respectively. MFGM treatment with exercise was effective in suppressing the progression of age-related NMJ alterations in old age, and even after age-related changes in NMJs had already occurred. Moreover, the effect of MFGM intake with exercise was not restricted to NMJs but extended to the structure and function of peripheral nerves. This study demonstrates that MFGM intake with exercise may be a novel approach for improving motor function in the elderly by suppressing age-related NMJ alterations.

Neuroprotective effects of exercise on the aging human neuromuscular system

Human biological aging from maturity to senescence is associated with a gradual loss of muscle mass and neuromuscular function. It is not until very old age (>80 years) however, that these changes often manifest into functional impairments. A driving factor underlying the age-related loss of muscle mass and function is the reduction in the number and quality of motor units (MUs). A MU consists of a single motoneuron, located either in the spinal cord or the brain stem, and all of the muscle fibres it innervates via its peripheral axon. Throughout the adult lifespan, MUs are slowly, but progressively lost. The compensatory process of collateral reinnervation attempts to recapture orphaned muscle fibres following the death of a motoneuron. Whereas this process helps mitigate loss of muscle mass during the latter decades of adult aging, the neuromuscular system has fewer and larger MUs, which have lower quality connections between the axon terminal and innervated muscle fibres. Whether this process of MU death and degradation can be attenuated with habitual physical activity has been a challenging question of great interest. This review focuses on age-related alterations of the human neuromuscular system, with an emphasis on the MU, and presents findings on the potential protective effects of lifelong physical activity. Although there is some discrepancy across studies of masters athletes, if one considers all experimental limitations as well as the available literature in animals, there is compelling evidence of a protective effect of chronic physical training on human MUs. Our tenet is that high-levels of physical activity can mitigate the natural trajectory of loss of quantity and quality of MUs in old age.

Altered Ca2+ Handling and Oxidative Stress Underlie Mitochondrial Damage and Skeletal Muscle Dysfunction in Aging and Disease

Skeletal muscle contraction relies on both high-fidelity calcium (Ca²⁺) signals and robust capacity for adenosine triphosphate (ATP) generation. Ca²⁺ release units (CRUs) are highly organized junctions between the terminal cisternae of the sarcoplasmic reticulum (SR) and the transverse tubule (T-tubule). CRUs provide the structural framework for rapid elevations in myoplasmic Ca²⁺ during excitation-contraction (EC) coupling, the process whereby depolarization of the T-tubule membrane triggers SR Ca²⁺ release through ryanodine receptor-1 (RyR1) channels. Under conditions of local or global depletion of SR Ca²⁺ stores, store-operated Ca²⁺ entry (SOCE) provides an additional source of Ca²⁺ that originates from the extracellular space. In addition to Ca²⁺, skeletal muscle also requires ATP to both produce force and to replenish SR Ca²⁺ stores. Mitochondria are the principal intracellular organelles responsible for ATP production via aerobic respiration. This review provides a broad overview of the literature supporting a role for impaired Ca²⁺ handling, dysfunctional Ca²⁺-dependent production of reactive oxygen/nitrogen species (ROS/RNS), and structural/functional alterations in CRUs and mitochondria in the loss of muscle mass, reduction in muscle contractility, and increase in muscle damage in sarcopenia and a wide range of muscle disorders including muscular dystrophy, rhabdomyolysis, central core disease, and disuse atrophy. Understanding the impact of these processes on normal muscle function will provide important insights into potential therapeutic targets designed to prevent or reverse muscle dysfunction during aging and disease.

The Mitochondrial Na+/Ca2+ Exchanger Inhibitor CGP37157 Preserves Muscle Structure and Function to Increase Lifespan and Healthspan in Caenorhabditis elegans

We have reported recently that the mitochondrial Na⁺/Ca²⁺ exchanger inhibitor CGP37157 extends lifespan in Caenorhabditis elegans by a mechanism involving mitochondria, the TOR pathway and the insulin/IGF1 pathway. Here we show that CGP37157 significantly improved the evolution with age of the sarcomeric regular structure, delaying development of sarcopenia in C. elegans body wall muscle and increasing the average and maximum speed of the worms. Similarly, CGP37157 favored the maintenance of a regular mitochondrial structure during aging. We have also investigated further the mechanism of the effect of CGP37157 by studying its effect in mutants of aak-1;aak-2/AMP-activated kinase, sir-2.1/sirtuin, rsks-1/S6 kinase and daf-16/FOXO. We found that this compound was still effective increasing lifespan in all these mutants, indicating that these pathways are not involved in the effect. We have then monitored pharynx cytosolic and mitochondrial Ca²⁺ signalling and our results suggest that CGP37157 is probably inhibiting not only the mitochondrial Na⁺/Ca²⁺ exchanger, but also Ca²⁺ entry through the plasma membrane. Finally, a transcriptomic study detected that CGP37157 induced changes in lipid metabolism enzymes and a four-fold increase in the expression of ncx-6, one of the C. elegans mitochondrial Na⁺/Ca²⁺ exchangers. In summary, CGP37157 increases both lifespan and healthspan by a mechanism involving changes in cytosolic and mitochondrial Ca²⁺ homeostasis. Thus, Ca²⁺ signalling could be a promising target to act on aging.

Improper Remodeling of Organelles Deputed to Ca2+ Handling and Aerobic ATP Production Underlies Muscle Dysfunction in Ageing

Proper skeletal muscle function is controlled by intracellular Ca2+ concentration and by efficient production of energy (ATP), which, in turn, depend on: (a) the release and re-uptake of Ca2+ from sarcoplasmic-reticulum (SR) during excitation-contraction (EC) coupling, which controls the contraction and relaxation of sarcomeres; (b) the uptake of Ca2+ into the mitochondrial matrix, which stimulates aerobic ATP production; and finally (c) the entry of Ca2+ from the extracellular space via store-operated Ca2+ entry (SOCE), a mechanism that is important to limit/delay muscle fatigue. Abnormalities in Ca2+ handling underlie many physio-pathological conditions, including dysfunction in ageing. The specific focus of this review is to discuss the importance of the proper architecture of organelles and membrane systems involved in the mechanisms introduced above for the correct skeletal muscle function. We reviewed the existing literature about EC coupling, mitochondrial Ca2+ uptake, SOCE and about the structural membranes and organelles deputed to those functions and finally, we summarized the data collected in different, but complementary, projects studying changes caused by denervation and ageing to the structure and positioning of those organelles: a. denervation of muscle fibers-an event that contributes, to some degree, to muscle loss in ageing (known as sarcopenia)-causes misplacement and damage: (i) of membrane structures involved in EC coupling (calcium release units, CRUs) and (ii) of the mitochondrial network; b. sedentary ageing causes partial disarray/damage of CRUs and of calcium entry units (CEUs, structures involved in SOCE) and loss/misplacement of mitochondria; c. functional electrical stimulation (FES) and regular exercise promote the rescue/maintenance of the proper architecture of CRUs, CEUs, and of mitochondria in both denervation and ageing. All these structural changes were accompanied by related functional changes, i.e., loss/decay in function caused by denervation and ageing, and improved function following FES or exercise. These data suggest that the integrity and proper disposition of intracellular organelles deputed to Ca2+ handling and aerobic generation of ATP is challenged by inactivity (or reduced activity); modifications in the architecture of these intracellular membrane systems may contribute to muscle dysfunction in ageing and sarcopenia.

Can High-Intensity Interval Training Promote Skeletal Muscle Anabolism?

Exercise training in combination with optimal nutritional support is an effective strategy to maintain or increase skeletal muscle mass. A single bout of resistance exercise undertaken with adequate protein availability increases rates of muscle protein synthesis and, when repeated over weeks and months, leads to increased muscle fiber size. While resistance-based training is considered the 'gold standard' for promoting muscle hypertrophy, other modes of exercise may be able to promote gains in muscle mass. High-intensity interval training (HIIT) comprises short bouts of exercise at or above the power output/speed that elicits individual maximal aerobic capacity, placing high tensile stress on skeletal muscle, and somewhat resembling the demands of resistance exercise. While HIIT induces rapid increases in skeletal muscle oxidative capacity, the anabolic potential of HIIT for promoting concurrent gains in muscle mass and cardiorespiratory fitness has received less scientific inquiry. In this review, we discuss studies that have determined muscle growth responses after HIIT, with a focus on molecular responses, that provide a rationale for HIIT to be implemented among populations who are susceptible to muscle loss (e.g. middle-aged or older adults) and/or in clinical settings (e.g. pre- or post-surgery).

Voluntary wheel running with and without follistatin overexpression improves NMJ transmission but not motor unit loss in late life of C57BL/6J mice

Sarcopenia, or pathological loss of muscle mass and strength during aging, is an important contributor to loss of physical function in older adults. Sarcopenia is a multifactorial syndrome associated with intrinsic muscle and upstream neurological dysfunction. Exercise is well-established as an effective intervention for sarcopenia, but less is known about the long-term neurobiological impact of exercise. The goals of this study were to investigate the effects of exercise, alone or in combination with follistatin (FST) overexpression (antagonist of myostatin), on neuromuscular junction transmission and motor unit numbers in mice between the age of 22 and 27 months, ages at which prior studies have demonstrated that some motor unit loss is already evident. C57BL/6J mice underwent baseline assessment and were randomized to housing with or without voluntary running wheels and injection with adeno-associated virus to overexpress FST or vehicle. Groups for comparison included sedentary and running with and without FST. Longitudinal assessments showed significantly increased muscle mass and contractility in the 'running plus FST' group, but running, with and without FST, showed no effect on motor unit degeneration. In contrast, running, with and without FST, demonstrated marked improvement of neuromuscular junction transmission stability.

Healthy Aging-Nutrition Matters: Start Early and Screen Often

The amount of time spent in poor health at the end of life is increasing. This narrative review summarizes consistent evidence indicating that healthy dietary patterns and maintenance of a healthy weight in the years leading to old age are associated with broad prevention of all the archetypal diseases and impairments associated with aging including: noncommunicable diseases, sarcopenia, cognitive decline and dementia, osteoporosis, age-related macular degeneration, diabetic retinopathy, hearing loss, obstructive sleep apnea, urinary incontinence, and constipation. In addition, randomized clinical trials show that disease-specific nutrition interventions can attenuate progression-and in some cases effectively treat-many established aging-associated conditions. However, middle-aged and older adults are vulnerable to unhealthy dietary patterns, and typically consume diets with inadequate servings of healthy food groups and essential nutrients, along with an abundance of energy-dense but nutrient-weak foods that contribute to obesity. However, based on menu examples, diets that are nutrient-dense, plant-based, and with a moderately low glycemic load are better equipped to meet the nutritional needs of many older adults than current recommendations in US Dietary Guidelines. These summary findings indicate that healthy nutrition is more important for healthy aging than generally recognized. Improved public health messaging about nutrition and aging, combined with routine screening and medical referrals for age-related conditions that can be treated with a nutrition prescription, should form core components of a national nutrition roadmap to reduce the epidemic of unhealthy aging.

Birthweight, lifetime obesity and physical functioning in mid-adulthood: a nationwide birth cohort study

BACKGROUND

Evidence is scant on long-term implications of childhood obesity and body mass index (BMI) gains over the life-course for poor physical functioning (PF). The objective was to establish whether (i) birthweight and BMI across the life-course, (ii) BMI gains at specific life-stages and (iii) age of obesity onset were associated with PF at 50 y.

METHODS

In the 1958 British birth cohort (n = 8674), BMI (kg/m2) was calculated using height and weight [measured (7, 11, 16, 33 and 45 y); self-reported (23 and 50 y)]. PF was assessed at 50 y using the validated PF subscale of the Short-form 36 survey; the bottom (gender-specific) 10% was classified as poor PF. Missing data were imputed via multiple imputation. Associations were examined using logistic regression, adjusting for health and social factors.

RESULTS

Birthweight was not associated with PF. At each adult age, odds of poor PF were highest for obese (vs normal), e.g. for 23 y obesity the odds ratio (OR)adjusted for poor PF was 2.28 (1.34, 3.91) and 2.67 (1.72, 4.14) in males and females respectively. BMI gains were associated with poor PF, e.g. for females, ORadjusted per standard deviation (SD) in BMI gain 16-23 y was 1.28 (1.13, 1.46); for BMI gains 45-50 y it was 1.36 (1.11, 1.65). Longer duration of obesity was associated with poor PF, e.g. in males, ORadjusted was 2.32 (1.26, 4.29) for childhood obesity onset and 1.50 (1.16, 1.96) for mid-adulthood onset (vs never obese, P-trend < 0.001).

CONCLUSION

Obesity, BMI gains, and earlier obesity onset were associated with poor PF in mid-adulthood, reinforcing the importance of preventing and delaying obesity onset.

Nutrition status mediates the association between cognitive decline and sarcopenia

In this study, we investigated whether nutrition status mediates the relationship between cognitive decline and sarcopenia. Sarcopenia was assessed in 4023 community-dwelling older adults from West China using the AWGS 2014 diagnostic criteria. Cognitive function and nutrition status were assessed using the 10-item Short Portable Mental Status Questionnaire (SPMSQ) and Mini Nutrition Assessment-Short Form (MNA-SF) scale, respectively. Mediation model regression analysis demonstrated that nutrition status was negatively associated with sarcopenia (β = -0.521; 95% CI: -0.583 to -0.459). The indirect effects of cognitive decline on sarcopenia were significant after adjusting for age, sex, and ethnicity (β = 0.015; 95% CI: 0.012 to 0.017), but the direct effects of cognitive decline on sarcopenia were not statistically significant after adding nutrition status as a parameter in the mediation model analysis (β = -0.001; 95% CI: -0.008 to 0.005). Structural equation model (SEM) framework pathway analysis confirmed the association between nutrition status, cognitive decline, and sarcopenia. These findings demonstrate that the negative effects of cognitive decline on sarcopenia were mediated by nutrition status. We therefore postulate that maintaining a good nutrition status delays the negative effects of cognitive decline on sarcopenia in older adults.

Association of objectively measured physical fitness with health-related quality of life of mid-life women: the FLAMENCO project

OBJECTIVES

This study aimed to explore the association of physical fitness with health-related quality of life (HRQoL) in mid-life women and to examine the potential independent association of physical fitness components with the physical and mental components from the 36-Item Short-Form Health Survey (SF-36) in this population.

METHODS

This cross-sectional study comprised 183 mid-life women from southern Spain who participated in the FLAMENCO project. Body composition was measured through an impedanciometer, a stadiometer, and dual-energy X-ray absorptiometry. Physical fitness was objectively measured with the Senior Fitness Test battery (cardiorespiratory fitness, flexibility, and dynamic balance/agility) plus handgrip strength (muscle strength). The SF-36 questionnaire was used to assess HRQoL of the participants.

RESULTS

All the physical fitness components were associated with the SF-36 physical function (all p < 0.05) except for lower-body flexibility. The rest of the physical fitness components showed associations with most of the SF-36 dimensions (all p < 0.05). Dynamic balance/agility and upper-body flexibility were independently associated with the SF-36 physical component scale, explaining 15% and 17% of the SF-36 physical component scale, respectively. Any physical fitness component showed independent associations with the SF-36 mental component scale.

CONCLUSIONS

Greater physical fitness levels are associated with better HRQoL of mid-life women. Dynamic balance/agility and upper-body flexibility were the strongest independent physical fitness components associated with the SF-36 physical component scale.

Parathyroid hormone levels and aging: Effect on balance

Falls result in multiple adverse health outcomes including mortality in older persons. Impaired balance is known to increase the risk of falls. Numerous factors play a role in the etiology of balance disturbance. Among the calciotropic hormones, the role of vitamin D in falls risk has been extensively studied. There is evolving interest in the role of parathyroid hormone (PTH) in this area. Elevated PTH hormone levels have been associated with age-related syndromes such as frailty, osteoporosis, and sarcopenia. Among the existing studies, most have focused on muscle strength with few studies evaluating its role in balance disturbances. In this chapter, we will summarize the aspects of PTH and aging, its biological effects on muscle, and the known associations between PTH and balance.

Associations of Handgrip Strength and Handgrip Strength Asymmetry With Depression in the Elderly in Korea: A Cross-sectional Study

Objectives

Recent studies have suggested that assessing handgrip strength (HGS) asymmetry together with HGS may be helpful for evaluating problems in geriatric patients. This study aimed to identify whether HGS asymmetry, weakness, or both were associated with depression in Korean older adults.

Methods

This study included 4274 subjects from the sixth and seventh Korea National Health and Nutrition Examination Survey. Depression was measured using the Patient Health Questionnaire-9. The maximum HGS of the dominant hand was used as a representative value. HGS symmetry was categorized by the ratio of the HGS of the dominant hand to that of non-dominant hand. The odds ratio (OR) for depression was calculated according to the HGS and its symmetry.

Results

In total, 240 (12.5%) men and 534 (22.7%) women had depression. HGS or HGS asymmetry showed no statistically significant associations with depression in elderly men. Elevated odds of depression were observed in elderly women with low HGS (OR, 1.93; 95% confidence interval [CI], 1.33 to 2.81) or prominent HGS asymmetry (OR, 1.46; 95% CI, 1.02 to 2.08). There was a positive additive interaction between asymmetric HGS and weakness, as women with low and prominently asymmetric HGS showed higher odds of depression (OR, 3.77; 95% CI, 2.16 to 6.59) than women with high and symmetric HGS.

Conclusions

Depression in elderly Korean women was associated with both low and asymmetric HGS. Our findings support the potential value of HGS asymmetry as an indicator of HGS.