Sarcopenia in youth

Exploring the causal link between circulating cytokines and sarcopenia traits: A Mendelian randomization analysis

BACKGROUND

Previous observational studies have linked circulating cytokines to sarcopenia, but their causal relationship remains unclear. This study employed Mendelian Randomization (MR) to investigate the causal links between circulating cytokines and sarcopenia-related traits using genetic data.

METHODS

A two-sample bidirectional MR analysis was conducted using data from individuals of European ancestry, utilizing genome-wide association studies (GWAS) statistics. The study selected instrumental single nucleotide polymorphisms (SNPs) significantly associated with circulating cytokines and applied multiple MR methods, including inverse variance weighted (IVW), Weighted Median, MR-Egger, Weighted Mode, Simple Mode, and MR-PRESSO. The traits analyzed were appendicular lean mass (ALM) and grip strength. Heterogeneity, robustness, and consistency of results were assessed using Cochran's Q statistic, MR-Egger regression, and "leave-one-out" sensitivity analyses.

RESULTS

The IVM-MR analysis showed a casual association between genetically predicted circulating levels of interleukin-16 and both ALM and grip strength (ALM: OR = 0.990, 95% CI: 0.980-1.000, p = .049; grip strength: OR = 0.971, 95% CI: 0.948-0.995, p = .020). Additionally, interferon-gamma-induced protein 10 (IP-10), interleukin-1-beta (IL-1β), and hepatocyte growth factor (HGF) were correlated with ALM and vascular endothelial growth factor (VEGF), interleukin-12 (IL-12), and interleukin-5 (IL-5) with grip strength. Comparable results were confirmed via the MR-Egger, Weighted Median, Weighted Mode, and Simple Mode methods. Sensitivity analysis showed no horizontal pleiotropy to bias the causal estimates.

CONCLUSION

The results suggest a significant causal effect of inflammatory cytokines on sarcopenia, offering new avenues for therapeutic target development. However, the study's focus on a European ancestry cohort limits its generalizability to other populations. Future research should aim to include diverse ethnic groups to validate and broaden these findings, thereby enhancing our understanding of sarcopenia's mechanisms in a global context.

Obstructive sleep apnea (OSA) is associated with increased risk of early-onset sarcopenia and sarcopenic obesity: Results from NHANES 2015-2018

OBJECTIVE

This study aims to estimate the prevalence of early-onset sarcopenia and sarcopenic obesity in the United States and its relative risk due to obstructive sleep apnea (OSA).

METHODS

Data in this cross-sectional study were extracted from the National Health and Nutritional Examination Survey (NHANES) 2015-2018. Weighted multistage stratified probability sampling design was considered to estimate the prevalence of early-onset sarcopenia and sarcopenic obesity. Weighted multivariable logistic regression analyses and weighted multivariable mediation models were performed to evaluate the association between OSA and early-onset sarcopenia.

RESULTS

The prevalence of early-onset sarcopenia and early-onset sarcopenic obesity was estimated to be 5.5% and 4.6%, respectively. A higher prevalence of sarcopenia (12% V.S. 5.5%, P < 0.01) and sarcopenic obesity (10.3% V.S. 4.0%, P < 0.01) was observed among participants with OSA than those without OSA. Multivariable logistic regression models suggested that participants with OSA had higher odds ratios of suffering from early-onset sarcopenia [Odds Ratio (OR): 1.5, 95% confidence interval (CI):1.1-2.7] and early-onset sarcopenic obesity [OR: 1.8, 95% CI: 1.1-3.1] after adjusting for potential confounding variables. Mediation analyses suggested serum chronic reaction protein (CRP) mediated 23.7% (P < 0.01) & 26.2% (P < 0.01), homeostasis model assessment insulin resistance index (HOMA-IR) mediated 24.8% (P < 0.01) & 20.7% (P < 0.05), body mass index (BMI) mediated 46.4% (P < 0.05) & 49.9% (P < 0.01), HEI-2015 mediated 23.3% (P < 0.01) & 25.6% (P < 0.01), and Vitamin D mediated 7.5% (P < 0.01) & 8.5% (P < 0.01) of the potential effects of OSA on early-onset sarcopenia and sarcopenic obesity, respectively.

CONCLUSION

Early-onset sarcopenia and sarcopenic obesity were prevalent among young adults in the US. OSA is a significant independent risk factor and may induce muscle loss by unhealthy diet habits, higher BMI, chronic inflammation, insulin resistance, and Vitamin D. It was essential for clinicians to arrange appropriate screening and interventions for patients with OSA to prevent muscle loss as early as possible.

Are accelerometer-measured sitting and physical activity times associated with muscle mass and strength in healthy young adults in the UAE?

Background

A high prevalence of obesity, sedentary behavior, and physical inactivity could affect muscle mass and strength in young adults in the United Arab Emirates (UAE). Therefore, we investigated the association of sex, body mass index (BMI), and accelerometer-measured sitting and physical activity (PA) times with skeletal muscle mass index (SMI), hand grip, and thigh muscle strength in healthy young adults in the UAE.

Methods

In this cross-sectional study, 156 healthy young adults (age 21.68 ± 3.01 years, BMI 25.40 ± 4.79 kg/m2, 52.6 % women) were included. BMI and muscle mass were recorded using a bioelectrical impedance analyzer. Maximum hand grip strength and thigh muscle torque were assessed using the Jamar-smart hand-dynamometer and Biodex System-4-Pro, respectively. Participants wore a triaxial Fibion accelerometer on their anterior thigh for >10 h per day for 4-7 days to measure their sitting and PA times. Multiple linear regression analyses were used.

Results

Participants spent most of their time sitting (11.37 ± 1.10 h), followed by standing (2.92 ± 0.86 h), walking (1.58 ± 0.55 h), and vigorous intensity PA (4.79 ± 5.85 min) per 16-h day. Sex (p < 0.001) and BMI (p < 0.001) were negatively associated with all muscle mass and strength variables. Men had more muscle mass and strength than women. As BMI increased, muscle mass and muscle strength decreased. Accelerometer-measured sitting and walking times were negatively associated with concentric hamstrings (p = 0.044) and quadriceps torques (p = 0.031), respectively.

Conclusion

Sex, BMI, and accelerometer-measured sitting and walking times were associated with muscle mass and/or muscle strength in healthy young adults. Women and those with a high BMI need interventions to improve their muscle mass and strength. The paradox regarding the association of PA with muscle mass and strength in younger adults may be due to possible influences from other factors (e.g., resistance training, dietary intakes, etc.) superseding that of accelerometer-measured PA.

Influences of muscle mass loss and exercise habits and personality traits on lower limb motor function among university students

Secondary sarcopenia, a risk factor even for young people, has attracted attention because of the deterioration of physical activity and nutritional status due to lifestyle change among university students. However, studies on the factors affecting motor function and their involvement are lacking. This cross-sectional study aimed to examine the influences of muscle mass loss and exercise and sleep habits on lower limb motor function, as well as the involvement of personality traits, in 101 university students. Approximately 6% of the participants had low skeletal muscle mass index, similar to previous reports, and that only exercise habits in high school were responsible for muscle mass loss (direct effect =  - 0.493; p < 0.05), wherease low skeletal muscle mass (direct effect =  - 0.539; p < 0.01) and current exercise habits (direct effect = 0.410; p < 0.01) were responsible for lower limb motor function. Additionaly, only the personality trait of high intellectual curiosity was involved in the establishment of exercise habits in high school, but no other personality traits showed a significant effect. In the prevention of secondary sarcopenia, encouraging sustained exercise habits while considering the influence of different personality traits is expected to prevent the decline in muscle mass and motor function.

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.

Non-Pharmacological Strategies for Managing Sarcopenia in Chronic Diseases

This article focuses on a range of non-pharmacological strategies for managing sarcopenia in chronic diseases, including exercise, dietary supplements, traditional Chinese exercise, intestinal microecology, and rehabilitation therapies for individuals with limited limb movement. By analyzing multiple studies, the article aims to summarize the available evidence to manage sarcopenia in individuals with chronic diseases. The results strongly emphasize the role of resistance training in addressing chronic diseases and secondary sarcopenia. Maintaining the appropriate frequency and intensity of resistance training can help prevent muscle atrophy and effectively reduce inflammation. Although aerobic exercise has limited ability to improve skeletal muscle mass, it does have some positive effects on physical function. Building upon this, the article explores the potential benefits of combined training approaches, highlighting their helpfulness for overall quality of life. Additionally, the article also highlights the importance of dietary supplements in combating muscle atrophy in chronic diseases. It focuses on the importance of protein intake, supplements rich in essential amino acids and omega-3, as well as sufficient vitamin D to prevent muscle atrophy. Combining exercise with dietary supplements appears to be an effective strategy for preventing sarcopenia, although the optimal dosage and type of supplement remain unclear. Furthermore, the article explores the potential benefits of intestinal microecology in sarcopenia. Probiotics, prebiotics, and bacterial products are suggested as new treatment options for sarcopenia. Additionally, emerging therapies such as whole body vibration training, blood flow restriction, and electrical stimulation show promise in treating sarcopenia with limited limb movement. Overall, this article provides valuable insights into non-pharmacological strategies for managing sarcopenia in individuals with chronic diseases. It emphasizes the importance of a holistic and integrated approach that incorporates exercise, nutrition, and multidisciplinary interventions, which have the potential to promote health in the elderly population. Future research should prioritize high-quality randomized controlled trials and utilize wearable devices, smartphone applications, and other advanced surveillance methods to investigate the most effective intervention strategies for sarcopenia associated with different chronic diseases.

Relationships between sarcopenia, depressive symptoms, and the risk of cardiovascular disease in Chinese population

BACKGROUND

Previous studies had indicated that sarcopenia and depressive symptoms were associated with increased risk of cardiovascular disease (CVD). The aim of present study was to evaluate the combined effect of sarcopenia and depressive symptoms on the CVD risk.

METHODS

A total of 11,011 participants from the China Health and Retirement Longitudinal Study 2011-2020 were included. Multivariate Cox proportional hazards regression model was used to explore the associations between sarcopenia, depressive symptoms and new-onset CVD, stroke and cardiac events.

RESULTS

During the 7-year follow-up, a total of 2,388 respondents experienced CVD (including 812 stroke and 1,831 cardiac events). There is a significant additive and multiplicative interactions of sarcopenia and depressive symptoms on risk of CVD, stroke and cardiac events. Compared with those without sarcopenia and depressive symptoms, individuals with depressive sarcopenia had the highest risk of CVD, stroke and cardiac events, with the corresponding hazard ratios (95% confidence interval) were 1.43 (1.26-1.63), 1.45 (1.15-1.82) and 1.50 (1.29-1.74), respectively.

CONCLUSION

Our study indicated that there was a combined effect of sarcopenia and depressive symptoms on the risk of CVD, stroke and cardiac events. Our findings highlighted the importance of identifying sarcopenia and depressive symptoms, and intervening much earlier both in older and younger population.

Collective Weakness Is Associated With Time to Mortality in Americans

ABSTRACT

McGrath, R, McGrath, BM, Jurivich, D, Knutson, P, Mastrud, M, Singh, B, and Tomkinson, GR. Collective weakness is associated with time to mortality in Americans. J Strength Cond Res XX(X): 000-000, 2024-Using new weakness cutpoints individually may help estimate time to mortality, but their collective use could improve value. We sought to determine the associations of (a) each absolute and body size normalized cut point and (b) collective weakness on time to mortality in Americans. The analytic sample included 14,178 subjects aged ≥50 years from the 2006-2018 waves of the Health and Retirement Study. Date of death was confirmed from the National Death Index. Handgrip dynamometry measured handgrip strength (HGS). Men were categorized as weak if their HGS was <35.5 kg (absolute), <0.45 kg·kg-1 (body mass normalized), or <1.05 kg·kg-1·m-2 (body mass index [BMI] normalized). Women were classified as weak if their HGS was <20.0 kg, <0.337 kg·kg-1, or <0.79 kg·kg-1·m-2. Collective weakness categorized persons as below 1, 2, or all 3 cutpoints. Cox proportional hazard regression models were used for analyses. Subject values below each absolute and normalized cutpoint for the 3 weakness parameters had a higher hazard ratio for early all-cause mortality: 1.45 (95% confidence interval [CI]: 1.36-1.55) for absolute weakness, 1.39 (CI: 1.30-1.49) for BMI normalized weakness, and 1.33 (CI: 1.24-1.43) for body mass normalized weakness. Those below 1, 2, or all 3 weakness cut points had a 1.37 (CI: 1.26-1.50), 1.47 (CI: 1.35-1.61), and 1.69 (CI: 1.55-1.84) higher hazard for mortality, respectively. Weakness determined by a composite measure of absolute and body size adjusted strength capacity provides robust prediction of time to mortality, thus potentially informing sports medicine and health practitioner discussions about the importance of muscle strength during aging.

The prevalence of sarcopenia in spondyloarthritis patients: a meta-analysis

BACKGROUND

Spondyloarthritis (SpA) is a chronic inflammatory disorder that affects sacroiliac joints and spine, resulting in substantial disability. Sarcopenia, characterized by the loss of muscle mass and function, is a prevalent comorbidity in various chronic diseases. However, the exact prevalence of sarcopenia in SpA patients remains uncertain. The objective of this study is to conduct a systematic review and meta-analysis of the available literature to determine the prevalence of sarcopenia in SpA.

METHODS

A comprehensive search was conducted in EMBASE, MEDLINE, WEB OF SCIENCE, and COCHRANE databases to identify relevant studies published up to 2023. Studies investigating the prevalence of sarcopenia in SpA patients were included. Data on study characteristics, participant demographics, diagnostic criteria for sarcopenia, and prevalence rates were extracted. Meta-analysis was performed using a random-effects model to estimate the overall prevalence of sarcopenia in SpA patients.

RESULTS

A total of 16 studies that met the inclusion criteria were included in the systematic review. These studies encompassed a combined sample size of 999 patients with SpA. The meta-analysis findings revealed that the overall prevalence of sarcopenia in SpA patients was 25.0% (95% confidence interval: 0.127 to 0.352). Furthermore, the prevalence of presarcopenia and severe sarcopenia was found to be 21.0% and 8.7%, respectively. Subgroup analysis was conducted to examine different diagnostic criteria, subtypes, and sex of SpA in relation to sarcopenia.

CONCLUSION

This systematic review and meta-analysis provide a comprehensive overview of the prevalence of sarcopenia in SpA patients. The findings suggest a high prevalence of sarcopenia in SpA patients, emphasizing the need for targeted interventions to prevent and manage sarcopenia. And further research is needed to explore the underlying mechanisms and potential therapeutic strategies for sarcopenia in SpA.

Probiotics as Potential Therapeutic Agents: Safeguarding Skeletal Muscle against Alcohol-Induced Damage through the Gut-Liver-Muscle Axis

Probiotics have shown the potential to counteract the loss of muscle mass, reduce physical fatigue, and mitigate inflammatory response following intense exercise, although the mechanisms by which they work are not very clear. The objective of this review is to describe the main harmful effects of alcohol on skeletal muscle and to provide important strategies based on the use of probiotics. The excessive consumption of alcohol is a worldwide problem and has been shown to be crucial in the progression of alcoholic liver disease (ALD), for which, to date, the only therapy available is lifestyle modification, including cessation of drinking. In ALD, alcohol contributes significantly to the loss of skeletal muscle, and also to changes in the intestinal microbiota, which are the basis for a series of problems related to the onset of sarcopenia. Some of the main effects of alcohol on the skeletal muscle are described in this review, with particular emphasis on the "gut-liver-muscle axis", which seems to be the primary cause of a series of muscle dysfunctions related to the onset of ALD. The modulation of the intestinal microbiota through probiotics utilization has appeared to be crucial in mitigating the muscle damage induced by the high amounts of alcohol consumed.

Immunogenetic Aspects of Sarcopenic Obesity

Sarcopenic obesity (SO) is a combination of obesity and sarcopenia, with diagnostic criteria defined as impaired skeletal muscle function and altered body composition (e.g., increased fat mass and reduced muscle mass). The mechanism of SO is not yet perfectly understood; however, the pathogenesis includes aging and its complications, chronic inflammation, insulin resistance (IR), and hormonal changes. Genetic background is apparent in the pathogenesis of isolated obesity, which is most often polygenic and is characterized by the additive effect of various genetic factors. The genetic etiology has not been strictly established in SO. Still, many data confirm the existence of pathogenic gene variants, e.g., Fat Mass and Obesity Associated Gene (FTO), beta-2-adrenergic receptor (ADRB2) gene, melanocortin-4 receptor (MC4R) and others with obesity. The literature on the role of these genes is scarce, and their role has not yet been thoroughly established. On the other hand, the involvement of systemic inflammation due to increased adipose tissue in SO plays a significant role in its pathophysiology through the synthesis of various cytokines such as monocyte chemoattractant protein-1 (MCP-1), IL-1Ra, IL-15, adiponectin or CRP. The lack of anti-inflammatory cytokine (e.g., IL-15) can increase SO risk, but further studies are needed to evaluate the exact mechanisms of implications of various cytokines in SO individuals. This manuscript analyses various immunogenetic and non-genetic factors and summarizes the recent findings on immunogenetics potentially impacting SO development.

Cross-sectional association of skeletal muscle mass and strength with dietary habits and physical activity among first-year university students in Japan: Results from the KEIJI-U study

OBJECTIVE

Recently, the high prevalence of young Japanese individuals who are underweight has received attention because of the potential risk for sarcopenia. The aim of this study was to examine the prevalence and characteristics of sarcopenia in Japanese youth.

METHODS

In this cross-sectional study, we measured skeletal muscle mass using a multifrequency bioelectrical impedance analysis device and handgrip strength (HGS) and administered questionnaires on dietary habits and physical activity in 1264 first-year university students ages 18 to 20 y (838 men and 426 women). Sarcopenia was confirmed based on the presence of both low skeletal muscle mass and weak muscle strength.

RESULTS

In all, 145 men (17%) and 69 women (16%) were diagnosed as underweight. Sarcopenia was diagnosed in 8 men (1%) and 5 women (1%). There was a significantly higher prevalence of low skeletal muscle mass index (SMI) and/or weak HGS in underweight individuals than in those in other body mass index (BMI) ranges. The multivariate analyses indicated that SMI and HGS were significantly associated with BMI in both sexes. Furthermore, after adjusting for BMI, both SMI and HGS were significantly associated with physical activity in men, and SMI was significantly associated with energy intake in women.

CONCLUSIONS

First-year university students showed a high incidence of being underweight with low SMI and/or weak HGS, but the prevalence of sarcopenia was low in both sexes. There may be sex differences in factors related to muscle mass and strength, but further research is needed to clarify this.

The impact of Helicobacter pylori infection on low skeletal muscle mass risk in Chinese women over 40: a cross-sectional analysis

Background

Sarcopenia can lead to significant personal, social, and economic burdens. The diagnosis of sarcopenia heavily relies on the identification of Low Skeletal Muscle Mass (LSMM), which is an independent predictor of frailty, disability, and increased risk of death among seniors. Women have physiologically lower levels of skeletal muscle mass than men, and female sarcopenia appears to be more influenced by menopause. They also tend to have higher body fat levels than man, which increases the risk of sarcopenia obesity. On another front, it's also recognized that humans are largely prone to Helicobacter pylori (H. pylori) infection, with global prevalence rates often surpassing 50%. Nevertheless, the interconnection between H. pylori infection and LSMM remains relatively unexplored. Hence, our study specifically targeted women as the research population and sought to explore several risk factors for LSMM. Additionally, we delved into the potential correlation between LSMM and H. pylori infection in women, hoping to gain insights into potential preventative measures or treatment options that may enhance the quality of life for women affected by sarcopenia.

Methods

We conducted a cross-sectional study among women aged over 18 years undergoing physical examination. We performed 13C-urea breath test (UBT) for diagnosis of H. pylori infection and Bioelectrical impedance analysis (BIA) for the assessment of LSMM. Logistic regression models were used to analyze the associations of H. pylori infection with LSMM.

Results

This study enrolled 1984 Chinese women who were undergoing health check-ups. A univariate logistic regression analysis did not reveal a direct correlation between H. pylori infection and LSMM among this female population (OR=1.149, 95% CI 0.904-1.459, p=0.257). Yet, upon dividing the participants into age-based subgroups, an evident link was observed between H. pylori infection and LSMM in women aged 40 or above (OR=1.381, 95%CI 1.032-1.848, p= 0.030). After adjusting for variables including Age, BMI, TP, ALK, Cre, this relationship remained statistically relevant (OR=1.514, 95%CI 1.085-2.113, p= 0.015).

Conclusions

Women who are over 40 years old and currently infected with H. pylori have an increased risk of developing LSMM. Therefore, timely treatment for H. pylori eradication is recommended for this group of women to reduce the occurrence of LSMM.

Preserved Muscle Strength Despite Muscle Mass Loss After Bariatric Metabolic Surgery: a Systematic Review and Meta-analysis

BACKGROUND

Contrary to the previously known concept of muscle mass decrease following bariatric metabolic surgery, changes in muscle strength have been poorly investigated in systematic reviews. In this meta-analysis, we evaluated changes in handgrip strength (HGS) and lean mass (LM) after undergoing bariatric metabolic surgery.

METHODS

A systematic literature review using the PubMed, Embase, and Cochrane Library databases was conducted in November 2022. Longitudinal studies reporting HGS change after bariatric metabolic surgery were eligible. Pooled estimates for changes in HGS, body mass index (BMI), LM, and fat mass (FM) were calculated. Changes from baseline to the point closest to 6 months postoperatively were analyzed in trials with multiple follow-up examinations. The risk of bias was assessed using the Joanna Briggs Institute critical appraisal checklist.

RESULTS

Three randomized controlled trials and seven prospective cohort studies involving 301 patients were included. Follow-up evaluations were conducted 6 months postoperatively in all trials except for two, whose follow-up visits were at 18 weeks and 12 months, respectively. Pooled analysis showed reduced BMI (- 10.8 kg/m2; 95% confidence interval: - 11.6 to - 9.9 kg/m2), LM (- 7.4 kg; - 9.3 to - 5.4 kg), and FM (- 22.3 kg; - 25.1 to - 19.6 kg) after bariatric metabolic surgery, whereas the change in HGS was not statistically significant (- 0.46 kg; - 1.76 to 0.84 kg).

CONCLUSION

Despite the decreased body composition parameters, including muscle mass, strength was not impaired after bariatric metabolic surgery; this indicates that bariatric metabolic surgery is an effective weight management intervention that does not compromise strength.