Sarcopenia, dynapenia, and the impact of advancing age on human skeletal muscle size and strength; a quantitative review

Integrated approach to reducing polypharmacy in older people: exploring the role of oxidative stress and antioxidant potential therapy

Increased life expectancy, attributed to improved access to healthcare and drug development, has led to an increase in multimorbidity, a key contributor to polypharmacy. Polypharmacy is characterised by its association with a variety of adverse events in the older persons. The mechanisms involved in the development of age-related chronic diseases are largely unknown; however, altered redox homeostasis due to ageing is one of the main theories. In this context, the present review explores the development and interaction between different age-related diseases, mainly linked by oxidative stress. In addition, drug interactions in the treatment of various diseases are described, emphasising that the holistic management of older people and their pathologies should prevail over the individual treatment of each condition.

Sex differences in physical functioning among older adults: cross-sectional results from the OUTDOOR ACTIVE study

BACKGROUND

Maintaining good functional ability is a key component of healthy ageing and a basic requirement for carrying out activities of daily living, staying independent, and delaying admission to a nursing home. Even though women have a higher life expectancy and slower age-related muscle mass loss than men, they often show a higher prevalence of limitations in physical functioning. However, the reasons behind these sex differences are still unclear. Therefore, the aims of this study were to investigate sex differences among older adults regarding physical functioning and to study which factors are explaining these sex differences.

METHODS

Cross-sectional data from participants of the OUTDOOR ACTIVE study residing in Bremen, Germany, aged 65 to 75 years, were included in the analyses. Physical functioning was assessed via a self-administered questionnaire using the SF-36 10-item Physical Functioning Scale. Social, lifestyle, and health-related factors were also assessed using the questionnaire. Physical activity was measured objectively using wrist-worn accelerometers over seven consecutive days. Descriptive analyses with absolute and relative frequencies, means and standard deviations, as well as T-tests and chi-square tests were carried out. To test for associations between sex, physical functioning, and several individual factors, linear regressions were performed.

RESULTS

Data of 2 141 participants (52.1% female) were included in the study. Women and men showed statistically significant differences in physical functioning, with men perceiving fewer limitations than women. On average, women had a physical functioning score of 81.4 ± 19.3 and men 86.7 ± 17.0. Linear regression showed a statistically significant negative association between physical functioning score and sex (β: -0.15, 95% CL: -0.19, -0.10). The association remained statistically significant when adding individual factors to the model. All factors together were only able to explain 51% of the physical functioning-sex association with health indicators and the presence of chronic diseases being the most influential factors.

CONCLUSIONS

We found sex differences in physical functioning, with older women having more limitations than older men. The results showed that health-related factors and chronic diseases played the biggest roles in the different physical functioning scores of women and men. These findings contribute to future longitudinal, more in-depth research.

TRIAL REGISTRATION

German Clinical Trials Register DRKS00015117 (Date of registration 17-07-2018).

Fermented Yak-Kong using Bifidobacterium animalis derived from Korean infant intestine effectively relieves muscle atrophy in an aging mouse model

Yak-Kong (YK) is a small black soybean widely cultivated in Korea. It is considered to have excellent health functionality, as it has been reported to have better antioxidant efficacy than conventional black or yellow soybeans. Since YK has been described as good for the muscle health of the elderly in old oriental medicine books, this study sought to investigate the effect of fermented YK with Bifidobacterium animalis subsp. lactis LDTM 8102 (FYK) on muscle atrophy. In C2C12 mouse myoblasts, FYK elevated the expression of MyoD, total MHC, phosphorylated AKT, and PGC1α. In addition, two kinds of in vivo studies were conducted using both an induced and normal aging mouse model. The behavioral test results showed that in the induced aging mouse model, FYK intake alleviated age-related muscle weakness and loss of exercise performance. In addition, FYK alleviated muscle mass decrease and improved the expression of biomarkers including total MHC, myf6, phosphorylated AKT, PGC1α, and Tfam, which are related to myoblast differentiation, muscle protein synthesis, and mitochondrial generation in the muscle. In the normal aging model, FYK consumption did not increase muscle mass, but did upregulate the expression levels of biomarkers related to myoblast differentiation, muscle hypertrophy, and muscle function. Furthermore, it mitigated age-related declines in skeletal muscle force production and functional limitation by enhancing exercise performance and grip strength. Taken together, the results suggest that FYK has the potential to be a new functional food material that can alleviate the loss of muscle mass and strength caused by aging and prevent sarcopenia.

Association between grip strength and electrical properties measured by bioimpedance spectroscopy in women with dementia aged 77 to 97 years living in group homes

Electrical properties estimated from the electrical resistance of the human body can serve as indicators of muscle tissue status and the risk of developing sarcopenia; however, to date, at least to the best of our knowledge, no studies have performed such an assessment in older individuals with advanced dementia. The present study examined the associations between grip strength, body composition and electrical properties using bioimpedance spectroscopy (BIS) in women aged 77-97 years residing in dementia group homes. A total of 33 participants were enrolled with an average age of 88.1±5.2 years; 57.6% of the participants had moderate or severe dementia. The resistance values of the participants were measured in the whole body, upper limbs and lower limbs using BIS, and their body composition, muscle mass index and electrical properties were estimated as indicators of muscle quality. In addition, grip strength was measured and the participants were classified into three groups (high, low and non-measurable) according to their cognitive function. The effect size (partial eta-squared and Cohen's d) was also evaluated. The Shapiro-Wilk test was used to assess the distribution of each variable; variables with non-normal distributions were analyzed following log transformation. Continuous variables were analyzed using a one-way analysis of variance and the Tukey-Kramer post hoc test was used. The post hoc sample size (statistical power: 1-β) analysis revealed a power of ~80% (i.e., 76.1-88.7%), considering the minimum power for sufficient participants. No differences were found in body composition or muscle mass index among the three grip strength groups. As regards the upper limbs, the electrical properties of the characteristic frequencies were significant (P=0.006; effect size, large), and the membrane capacitance (P=0.005; effect size, large) was significantly higher in the high-dose group than in the other groups. A significant association was detected among grip strength, upper limb characteristic frequency and membrane capacitance. Hence, electrical properties may be an indicator of muscle quality in older women identified as needing care for dementia.

Osteosarcopenic adiposity (OSA) phenotype and its connection with cardiometabolic disorders: Is there a cause-and-effect?

The objectives were to examine if there is a causal relationship between osteosarcopenic adiposity (OSA) syndrome (coexistence of osteopenia/osteoporosis, sarcopenia, and excess adiposity) and cardiometabolic disorders or if these disorders initiate the development of OSA and its worsening. The search was conducted in PubMed, Scopus, and Web of Science to include articles up to the end of 2023. Of n=539 articles retrieved, n=15 met the eligibility criteria. Only studies conducted in adults and with all three body composition compartments (bone, muscle/lean, adipose) measured were considered. The results revealed that several cardiometabolic disorders, namely, hypertension, dyslipidemia (elevated total and LDL-cholesterol, lower HDL-cholesterol), insulin resistance, hyperglycemia, lower serum vitamin D, and some inflammatory markers were accompanied by OSA. In most cases, the OSA phenotype was associated with worse outcomes than cases with healthy or less impaired body composition. Our initial questions about the reciprocal cause-and-effect relationships could be surmised with more certainty for the OSA and some cardiovascular risks (hypertension, dyslipidemia) and some metabolic abnormalities (several inflammatory markers). The results of this review underscore the importance of body composition in health and from a clinical perspective, all three body composition compartments should be measured by standardized technologies using regulated diagnostic criteria to identify OSA. Randomized trials and prospective studies in diverse groups of older and younger individuals are necessary to determine if the relationships between OSA and clinical endpoints are causal and reversible through intervention and to uncover the mechanisms.

Use of computed tomography to identify muscle quality subgroups, spatial mapping, and preliminary relationships to function in those with diabetic peripheral neuropathy

BACKGROUND

Decreased muscle volume and increased muscle-associated adipose tissue (MAAT, sum of intra and inter-muscular adipose tissue) of the foot intrinsic muscle compartment are associated with deformity, decreased function, and increased risk of ulceration and amputation in those with diabetic peripheral neuropathy (DPN).

RESEARCH QUESTION

What is the muscle quality (normal, abnormal muscle, and adipose volumes) of the DPN foot intrinsic compartment, how does it change over time, and is muscle quality related to gait and foot function?

METHODS

Computed tomography was performed on the intrinsic foot muscle compartment of 45 subjects with DPN (mean age: 67.2 ± 6.4 years) at baseline and 3.6 years. Images were processed to obtain volumes of MAAT, highly abnormal, mildly abnormal, and normal muscle. For each category, annual rates of change were calculated. Paired t-tests compared baseline and follow-up. Foot function during gait was assessed using 3D motion analysis and the Foot and Ankle Ability Measure. Correlations between muscle compartment and foot function during gait were analyzed using Pearson's correlations.

RESULTS

Total muscle volume decreased, driven by a loss of normal muscle and mildly abnormal muscle (p<0.05). MAAT and the adipose-muscle ratio increased. At baseline, 51.5% of the compartment was abnormal muscle or MAAT, increasing to 55.0% at follow-up. Decreased total muscle volume correlated with greater midfoot collapse during gait (r = -0.40, p = 0.02). Greater volumes of highly abnormal muscle correlated with a lower FAAM score (r = -0.33, p = 0.03).

SIGNIFICANCE

Muscle volume loss may progress in parallel with MAAT accumulation, impacting contractile performance in individuals with DPN. Only 48.5% of the DPN intrinsic foot muscle compartment consists of normal muscle and greater abnormal muscle is associated with worse foot function. These changes identify an important target for rehabilitative intervention to slow or prevent muscle deterioration and poor foot outcomes.

CT imaging-derived phenotypes for abdominal muscle and their association with age and sex in a medical biobank

The study of muscle mass as an imaging-derived phenotype (IDP) may yield new insights into determining the normal and pathologic variations in muscle mass in the population. This can be done by determining 3D abdominal muscle mass from 12 distinct abdominal muscle regions and groups using computed tomography (CT) in a racially diverse medical biobank. To develop a fully automatic technique for assessment of CT abdominal muscle IDPs and preliminarily determine abdominal muscle IDP variations with age and sex in a clinically and racially diverse medical biobank. This retrospective study was conducted using the Penn Medicine BioBank (PMBB), a research protocol that recruits adult participants during outpatient visits at hospitals in the Penn Medicine network. We developed a deep residual U-Net (ResUNet) to segment 12 abdominal muscle groups including the left and right psoas, quadratus lumborum, erector spinae, gluteus medius, rectus abdominis, and lateral abdominals. 110 CT studies were randomly selected for training, validation, and testing. 44 of the 110 CT studies were selected to enrich the dataset with representative cases of intra-abdominal and abdominal wall pathology. The studies were divided into non-overlapping training, validation and testing sets. Model performance was evaluated using the Sørensen-Dice coefficient. Volumes of individual muscle groups were plotted to distribution curves. To investigate associations between muscle IDPs, age, and sex, deep learning model segmentations were performed on a larger abdominal CT dataset from PMBB consisting of 295 studies. Multivariable models were used to determine relationships between muscle mass, age and sex. The model's performance (Dice scores) on the test data was the following: psoas: 0.85 ± 0.12, quadratus lumborum: 0.72 ± 0.14, erector spinae: 0.92 ± 0.07, gluteus medius: 0.90 ± 0.08, rectus abdominis: 0.85 ± 0.08, lateral abdominals: 0.85 ± 0.09. The average Dice score across all muscle groups was 0.86 ± 0.11. Average total muscle mass for females was 2041 ± 560.7 g with a high of 2256 ± 560.1 g (41-50 year old cohort) and a change of - 0.96 g/year, declining to an average mass of 1579 ± 408.8 g (81-100 year old cohort). Average total muscle mass for males was 3086 ± 769.1 g with a high of 3385 ± 819.3 g (51-60 year old cohort) and a change of - 1.73 g/year, declining to an average mass of 2629 ± 536.7 g (81-100 year old cohort). Quadratus lumborum was most highly correlated with age for both sexes (correlation coefficient of - 0.5). Gluteus medius mass in females was positively correlated with age with a coefficient of 0.22. These preliminary findings show that our CNN can automate detailed abdominal muscle volume measurement. Unlike prior efforts, this technique provides 3D muscle segmentations of individual muscles. This technique will dramatically impact sarcopenia diagnosis and research, elucidating its clinical and public health implications. Our results suggest a peak age range for muscle mass and an expected rate of decline, both of which vary between genders. Future goals are to investigate genetic variants for sarcopenia and malnutrition, while describing genotype-phenotype associations of muscle mass in healthy humans using imaging-derived phenotypes. It is feasible to obtain 3D abdominal muscle IDPs with high accuracy from patients in a medical biobank using fully automated machine learning methods. Abdominal muscle IDPs showed significant variations in lean mass by age and sex. In the future, this tool can be leveraged to perform a genome-wide association study across the medical biobank and determine genetic variants associated with early or accelerated muscle wasting.

Prevalence and survival implications of malnutrition and sarcopenia in metastatic breast cancer: A longitudinal analysis

BACKGROUND

Malnutrition and sarcopenia are challenges for patients with metastatic breast cancer and have been proposed as independent prognostic factors. Very few studies have addressed the temporal evolution of these parameters and, notably, the separate and combined analysis of sarcopenia and malnutrition. This study aimed to i) determine the prevalence of malnutrition and sarcopenia, individually and combined, and their evolution over time, ii) identify risk factors for each condition, and iii) explore their impact on overall survival (OS).

METHODS

This retrospective study was conducted on 111 patients treated for at least a third-line metastatic breast cancer at the Institut Curie between January 1st and March 31st, 2018. Solitary malnutrition was defined from weight loss and body mass index values while solitary sarcopenia was defined solely based on low muscle mass. We analyzed solitary malnutrition, solitary sarcopenia, and then malnutrition with or without sarcopenia, at three key stages (T1: diagnosis of metastasis, T2: initiation of third-line treatment, and T3: 3-month re-evaluation). Univariate and multivariate logistic regression analyses were conducted to investigate the risk factors. We performed Cox proportional hazards analyses for each variable.

RESULTS

At T1, the prevalence of solitary malnutrition, solitary sarcopenia and malnutrition with or without sarcopenia was 18.6%, 36.1% and 48.9% respectively, increasing to 27.7%, 45.5% and 56.6% at T2. At T2, in multivariate logistic regression analyses, patients aged over 60 years were at an elevated risk of experiencing solitary malnutrition as well as malnutrition with or without sarcopenia, but not solitary sarcopenia. In multivariate analyses, solitary malnutrition was significantly associated with poorer OS (HR 2.2 [95% CI 1.1-4.1], p = 0.02), while solitary sarcopenia and malnutrition with or without sarcopenia showed no association.

CONCLUSION

Solitary malnutrition and sarcopenia were highly prevalent in patients with metastatic breast cancer, affecting around a quarter and half of patients respectively at third-line treatment initiation. Notably, solitary malnutrition emerged as a prognostic factor for overall survival, whereas no significant association was observed for solitary sarcopenia or malnutrition with or without sarcopenia. This highlights the critical need for early identification of patients at risk of malnutrition and the importance of timely intervention.

Association of the oxidative balance score with sarcopenia among young and middle-aged adults: findings from NHANES 2011-2018

Background

Sarcopenia is associated with oxidative stress. The Oxidative Balance Score (OBS) is commonly used to assess dietary and lifestyle exposure to oxidative stress. However, few studies in the literature have assessed the correlation between sarcopenia and OBS.

Aim

This study aimed to assess the association between OBS and sarcopenia among young and middle-aged adults in the United States using data from the National Health and Nutrition Examination Survey (NHANES).

Method

Weighted logistic regression analysis was used to investigate the association between OBS and sarcopenia based on data from NHANES 2011-2018. Subgroup analyses were performed to observe the consistency of the outcomes, and the stability of the results was tested using sensitivity analyses.

Result

The final sample included 5,525 young and middle-aged American adults. A higher OBS was associated with a lower risk of sarcopenia. In the fully adjusted model, the second (odds ratio [OR]: 0.62, 95% confidence interval [CI]: 0.41, 0.94; p = 0.023), third (OR: 0.50; 95% CI: 0.34, 0.74; p < 0.001), and highest quartiles (OR: 0.18; 95% CI: 0.11, 0.28; p < 0.001) of the OBS were associated with higher risks of sarcopenia when compared to the lowest quartile. This association was consistent across both dietary and lifestyle OBS scores. Our subgroup analysis revealed no significant differences between the subgroups of variables included in the interaction analysis. Sensitivity analyses revealed similar results.

Conclusion

Our study showed that higher antioxidant and lower antioxidant exposure may decrease the risk of developing sarcopenia. Higher OBS scores may indicate greater protection against sarcopenia; however, further clinical studies are warranted to confirm these findings.

Physical activity, sedentary behaviour, and cognitive function among older adults: A bibliometric analysis from 2004 to 2024

Because of population ageing, there will be a vast increase in the prevalence of cognitive decline and dementia. Physical activity and sedentary behaviour have been identified as modifiable lifestyle behaviours associated with these cognitive conditions. Therefore, the aim of this bibliometric analysis is to reveal the knowledge structure of the field of physical activity, sedentary behaviour, and cognitive function among older adults from 2004 to 2024, and to predict emerging research trends. A total of 1290 publications were retrieved from the Web of Science Core Collection. CiteSpace and VOSviewer were applied to conduct performance analysis, science mapping, and enrichment. T. Liu-Ambrose was the most prolific author (39 publications), and the University of British Columbia was the most prolific institution (48 publications). The USA, China, and Canada were the three most productive countries with 392, 174, and 136 publications respectively. Two research trends revealed the knowledge structure of this field, including the shift from evaluating the effectiveness of interventions on cognitive function to evaluating the effectiveness of interventions on other health-related outcomes, as well as an expansion of research on the role of physical activity and sedentary behaviour in the context of healthy ageing. Sleep, sedentary behaviour, and virtual reality may be emerging research trends and may predict directions for future research. Collectively, this bibliometric analysis provides a one-step overview of the knowledge structure in this field for researchers and other stakeholders, as well as a reference for future research.

A Case Report of Probable Secondary Sarcopenia After Intensive Care Hospitalization

Malnutrition, inflammation, comorbid diseases, and inactivity are known causes of sarcopenia. It results in clinical consequences like fractures, falls, low quality of life, cognitive dysfunction, and mortality. Especially in the treatment of patients with prolonged immobilization syndrome, management should not only focus on functional limitations but patients should also be evaluated and followed up for sarcopenia. In this case report, we present the management of probable secondary sarcopenia in the intensive care unit as a result of urosepsis and discuss it in the light of the literature.

Relationship of endogenous plasma concentrations of β-hydroxy β-methyl butyrate (HMB) with frailty in community dwelling older adults with type-2 diabetes mellitus

BACKGROUND

Supplementation with β-hydroxy β-methyl butyrate (HMB) appears to be effective in preserving muscle in older adults. However, the association between endogenously produced HMB with frailty has not been studied in people with chronic disease.

OBJECTIVES

The purpose of this study is to explore whether an association exists between endogenous HMB levels and frailty status in older adults with type-2 diabetes mellitus (T2DM).

METHODS

Data were taken from the Toledo Study of Healthy Ageing, a community-dwelling aged (65 years+) cohort. Frailty was assessed at baseline and at 2.99 median years according to the Frailty Phenotype (FP) standardized to our population and the Frailty Trait Scale 12 (FTS12). The associations between HMB levels and frailty were assessed using three nested multivariate logistic regressions and segmented by sex. Glucose, HMB and glucose interaction, age and body composition were used as covariables.

RESULTS

255 participants (mean age 75.3 years, 52.94% men) were included. HMB levels showed an inverse cross-sectional association with frailty, which was modified when the interaction term HMB*glucose was included, remaining significant only for FTS12 [OR (95% CI): 0.436 (0.253, 0.751), p-value 0.003]. The association between HMB endogenous levels and FTS12 appears to be independent of sex, in which the association was maintained after adjusting for the covariates. However, there appears to be threshold points for glucose levels, above which the protective effect of HMB is lost: 145.4 mg/dl adjusted by gender for the whole sample and 149.6 mg/dl and 138.9 mg/dl for men and women, respectively. Endogenous HMB levels were not found to be associated with incident frailty.

CONCLUSIONS

Cross-sectional analysis revealed that endogenous HMB levels were inversely associated with frailty as assessed by the FTS12 in older people with T2DM. This association was found to be dependent on circulating fasted glucose levels.

Direct and acute effects of advanced glycation end products on proteostasis in isolated mouse skeletal muscle

Advanced glycation end products (AGEs) have been implicated in several skeletal muscle dysfunctions. However, whether the adverse effects of AGEs on skeletal muscle are because of their direct action on the skeletal muscle tissue is unclear. Therefore, this study aimed to investigate the direct and acute effects of AGEs on skeletal muscle using an isolated mouse skeletal muscle to eliminate several confounders derived from other organs. The results showed that the incubation of isolated mouse skeletal muscle with AGEs (1 mg/mL) for 2-6 h suppressed protein synthesis and the mechanistic target of rapamycin signaling pathway. Furthermore, AGEs showed potential inhibitory effects on protein degradation pathways, including autophagy and the ubiquitin-proteasome system. Additionally, AGEs stimulated endoplasmic reticulum (ER) stress by modulating the activating transcription factor 6, PKR-like ER kinase, C/EBP homologous protein, and altered inflammatory cytokine expression. AGEs also stimulated receptor for AGEs (RAGE)-associated signaling molecules, including mitogen-activated protein kinases. These findings suggest that AGEs have direct and acute effect on skeletal muscle and disturb proteostasis by modulating intracellular pathways such as RAGE signaling, protein synthesis, proteolysis, ER stress, and inflammatory cytokines.

Machine-learning classifier models for predicting sarcopenia in the elderly based on physical factors

AIM

As the size of the elderly population gradually increases, musculoskeletal disorders, such as sarcopenia, are increasing. Diagnostic techniques such as X-rays, computed tomography, and magnetic resonance imaging are used to predict and diagnose sarcopenia, and methods using machine learning are gradually increasing. This study aimed to create a model that can predict sarcopenia using physical characteristics and activity-related variables without medical diagnostic equipment, such as imaging equipment, for the elderly aged 60 years or older.

METHODS

A sarcopenia prediction model was constructed using public data obtained from the Korea National Health and Nutrition Examination Survey. Models were built using Logistic Regression, Support Vector Machine (SVM), XGBoost, LightGBM, RandomForest, and Multi-layer Perceptron Neural Network (MLP) algorithms, and the feature importance of the models trained with the algorithms, except for SVM and MLP, was analyzed.

RESULTS

The sarcopenia prediction model built with the LightGBM algorithm achieved the highest test accuracy, of 0.848. In constructing the LightGBM model, physical characteristic variables such as body mass index, weight, and waist circumference showed high importance, and activity-related variables were also used in constructing the model.

CONCLUSIONS

The sarcopenia prediction model, which consisted of only physical characteristics and activity-related factors, showed excellent performance. This model has the potential to assist in the early detection of sarcopenia in the elderly, especially in communities with limited access to medical resources or facilities. Geriatr Gerontol Int 2024; 24: 595-602.

Uncovering sarcopenia and frailty in older adults by using muscle ultrasound-A narrative review

Muscle ultrasound is a valuable non-invasive and cost-effective method in assessing muscle mass and structure, both of which are significant indicators for the development of sarcopenia and frailty in elderly individuals. Sarcopenia refers to the loss of muscle mass and strength that occurs with age, whereas frailty is a complex geriatric syndrome characterized by reduced physical function and an increased susceptibility to negative health outcomes. Both conditions are prevalent in older adults and are associated with higher risks of falls, disability, and mortality. By measuring muscle size and structure and several other ultrasound parameters, including muscle thickness, cross-sectional area, echogenicity (brightness in the ultrasound image), pennation angle, and fascicle length ultrasound can assist in identifying sarcopenia and frailty in older adults. In addition, ultrasound can be used to evaluate muscle function such as muscle contraction and stiffness, which may also be affected in sarcopenia and frailty. Therefore, muscle ultrasound could lead to better identification and tracking of sarcopenia and frailty. Such advancements could result in the implementation of earlier interventions to prevent or treat these conditions, resulting in an overall improvement in the health and quality of life of the elderly population. This narrative review describes the benefits and challenges when using ultra-sound for the evaluation of frailty and sarcopenia.

Indirect calorimetry directed feeding and cycling in the older ICU population: a pilot randomised controlled trial

BACKGROUND

Older critically ill patients experience rapid muscle loss during stay in an intensive care unit (ICU) due to physiological stress and increased catabolism. This may lead to increased ICU length of stay, delayed weaning from ventilation and persistent functional limitations. We hypothesized that with optimal nutrition and early physical therapy acting in synergism, we can reduce muscle mass loss and improve functional outcomes.

METHODS

This was a prospective, single blinded randomized, controlled single-center pilot study to compare the lean muscle mass (measured at bilateral quadriceps femoris using ultrasound) of older ICU patients at 4 time points over 14 days between the control and intervention groups. The control group received standard weight-based empiric feeding and standard ICU physiotherapy. The intervention group received indirect calorimetry directed feeding adjusted daily and 60 min per day of cycle ergometry. 21 patients were recruited and randomized with 11 patients in the control arm and 10 patients in the intervention arm. Secondary outcome measures included ICU and hospital mortality, length of stay, functional assessments of mobility and assessment of strength.

RESULTS

Median age was 64 in the control group and 66 in the intervention group. Median calories achieved was 24.5 kcal/kg per day in the control group and 23.3 kcal/kg per day in the intervention group. Cycle ergometry was applied to patients in the intervention group for a median of 60 min a day and a patient had a median of 8.5 sessions in 14 days. Muscle mass decreased by a median of 4.7cm2 in the right quadriceps femoris in the control group and 1.8cm2 in the intervention group (p = 0.19), while the left quadriceps femoris decreased by 1.9cm2 in the control group and 0.1cm2 in the intervention group (p = 0.51).

CONCLUSION

In this pilot study, we found a trend towards decrease muscle loss in bilateral quadriceps femoris with our combined interventions. However, it did not reach statistical significance likely due to small number of patients recruited in the study. However, we conclude that the intervention is feasible and potentially beneficial and may warrant a larger scale study to achieve statistical significance.

TRIAL REGISTRATION

This study was registered on Clinicaltrials.gov on 30th May 2018 with identifier NCT03540732.

Care of The Older Fighter: Position Statement of the Association of Ringside Physicians

Older Fighters are defined as combat sports athletes older than 35 years, based on heightened medical risks and historical classification. Age-related changes to the neurological, cardiopulmonary, endocrinological, thermoregulatory, osmoregulatory, and musculoskeletal systems increase these athletes' risks for injury and may prolong their recovery. These age-related risks warrant special considerations for competition, licensure, prefight medical clearance, in-fight supervision, post-fight examination, and counseling regarding training practices and retirement from combat sports. Neurological considerations include increased risk of intracranial lesions, intracranial hemorrhage, and sequelae from traumatic brain injury (TBI), warranting more comprehensive neurological evaluation and neuroimaging. Increased risk of myocardial ischemia and infarction warrant careful assessment of cardiac risk factors and scrutiny of cardiovascular fitness. Older fighters may take longer time to recover from musculoskeletal injury; post-injury clearance should be individualized.

Sleeping more than 8 h: a silent factor contributing to decreased muscle mass in Chinese community-dwelling older adults

BACKGROUND

Muscle mass loss is an age-related process that can be exacerbated by lifestyle, environmental and other factors, but can be mitigated by good sleep. The objective of this study was to investigate the correlation between varying time lags of sleep duration and the decline in muscle mass among individuals aged 60 years or older by using real-world health monitoring data obtained from wearable devices and smart home health monitoring devices.

METHODS

This study included 86,037 observations from 2,869 participants in the Mobile Support System database. Missing data were supplemented by multiple imputation. The investigation utilized generalized estimating equations and restricted cubic spline curve to examine the relationship between sleep duration and low muscle mass. Various lag structures, including 0, 1, 2, 0-1, 0-2, and 1-2 months, were fitted, and the interaction effect of observation time with sleep duration was estimated for each lag structure. Additionally, subgroup analyses were conducted. The models were adjusted for various covariates, including gender, age, body mass index, footsteps, smoking status, drinking status, marital status, number of chronic diseases, number of medications, diabetes mellitus, hyperlipidemia, coronary artery disease, respiratory disease, and musculoskeletal disease and an interaction term between time and sleep duration.

RESULTS

The results of the generalized estimating equation showed a significant correlation (p < 0.001) between sleep duration of 8 h or more and low muscle mass in older adults, using 6-7 h of sleep as a reference. This effect was seen over time and prolonged sleep accumulated over multiple months had a greater effect on muscle mass loss than a single month. The effect of long sleep duration on muscle mass loss was significantly greater in females than in males and greater in the over-75 than in the under-75 age group. Restricted cubic spline plots showed a non-linear relationship between sleep duration and low muscle mass (p < 0.001).

CONCLUSIONS

This study found an association between sustained nighttime sleep of more than eight hours and decreased muscle mass in older adults, especially older women.

The Effect of Antihypertensive Therapy on Skeletal Muscle Mass and Bone Mineral Density in Patients With End-Stage Kidney Disease

OBJECTIVE

Sarcopenia and osteoporosis substantially influence health and lifespan. However, the variables affecting skeletal muscle mass (SMM) or bone mineral density (BMD) remain unknown.

DESIGN AND METHODS

From August 1, 2018 to July 31, 2019, we conducted a single-center, observational cohort study with 291 Japanese adult patients on maintenance hemodialysis due to end-stage kidney disease, who had their femoral neck BMD measured using dual-energy X-ray absorptiometry. After 1-year follow-up, we measured annual changes of BMD (ΔBMD) and SMM (ΔSMM), which were calculated through a modified creatinine index (mg/kg/day) using age, sex, serum creatinine, and single-pooled Kt/V for urea. The factors associated with ΔSMM/ΔBMD or progressive loss of SMM/BMD, defined as ΔSMM/ΔBMD < 0 per year, respectively, were analyzed with multivariable, linear regression or logistic regression models.

RESULTS

The median age of the patients was 66 years and 33% were female. Dialysis vintage and β-blocker-use were inversely correlated to ΔSMM. In comparison to nonusers, β-blockers users had 2.5-fold higher SMM loss odd ratios [95% confidence interval, 1.3-4.8]. The risk for SMM loss caused by β-blockers was not increased in users of renin-angiotensin system inhibitors. The ΔBMD was negatively correlated to the usage of calcium channel blockers. The risk of developing osteosarcopenia, which was defined as annual loss of both SMM and BMD, increased in calcium channel blockers users.

CONCLUSIONS

The use of β-blockers is associated with an elevated risk of developing sarcopenia, whereas renin-angiotensin system inhibitors may minimize this effect in patients with end-stage kidney disease. Use of calcium channel blocker therapy was associated with a faster decline of BMD.

Age-wise examination of the association of obesity based on body mass index and waist circumference with metabolic diseases in comprehensive health checkup participants

Aim

Body mass index and waist circumference are used for obesity diagnosis and screening of visceral fat; however, their evidence in older adults is insufficient. This study investigated the age-specific association of body mass index and waist circumference with metabolic diseases, assessing their applicability as diagnostic criteria for individuals aged ≥65 years.

Methods

Analysis included 46,324 individuals aged ≥18 years, categorized into five age groups: 18-44, 45-54, 55-64, 65-74, and ≥75 years. Logistic regression analyses identified associations between obesity and metabolic diseases, stratified by age and sex.

Results

Men with obesity based on body mass index had a significantly high risk of hypertension, diabetes mellitus, and dyslipidemia across all age groups (all, p < 0.05). Obesity based on waist circumference was significantly positively associated with all metabolic diseases (all, p < 0.05). Women with obesity based on body mass index and waist circumference had a significantly high risk of all metabolic diseases across all age groups (all, p < 0.05), except for diabetes mellitus in individuals aged ≥75 years.

Conclusions

Participants with obesity based on body mass index and waist circumference exhibited a high risk of hypertension, diabetes mellitus, and dyslipidemia among those aged 18-74 years and men aged ≥75 years. This study contributes to the early prevention and control of metabolic diseases.

Tetramethylpyrazine Nitrone alleviates D-galactose-induced murine skeletal muscle aging and motor deficits by activating the AMPK signaling pathway

Tetramethylpyrazine nitrone (TBN), a novel derivative of tetramethylpyrazine (TMP) designed and synthesized by our group, possesses multi-functional mechanisms of action and displays broad protective effects in vitro and in animal models of age-related brain disorders such as stroke, Alzheimer's disease (AD), Amyotrophic Lateral Sclerosis (ALS) and Parkinson's disease (PD). In the present report, we investigated the effects of TBN on aging, specifically on muscle aging and the associated decline of motor functions. Using a D-galactose-induced aging mouse model, we found that TBN could reverse the levels of several senescence and aging markers including p16, p21, ceramides, and telomere length and increase the wet-weight ratio of gastrocnemius muscle tissue, demonstrating its efficacy in ameliorating muscle aging. Additionally, the pharmacological effects of TBN on motor deficits (gait analysis, pole-climbing test and grip strength test), muscle fibrosis (hematoxylin & eosin (HE), Masson staining, and αSMA staining), inflammatory response (IL-1β, IL-6, and TNF-α), and mitochondrial function (ATP, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were also confirmed in the D-galactose-induced aging models. Further experiments demonstrated that TBN alleviated muscle aging and improved the decline of age-related motor deficits through an AMPK-dependent mechanism. These findings highlight the significance of TBN as a potential anti-aging agent to combat the occurrence and development of aging and age-related diseases.

A narrative review investigating the potential effect of lubrication as a mitigation strategy for whey protein-associated mouthdrying

Whey is consumed by active adults to aid muscle recovery and growth, the general population as a nutritious convenient food, and by older adults to prevent sarcopenia due to its high leucine content. However, whey protein has poor consumer acceptance in this latter demographic, partially due to mouthdrying. This is thought to result from electrostatic interactions between whey and salivary proteins, mucoadhesion to the oral mucosa, and the inherent astringency of acidity. Previous unsuccessful mitigation strategies include viscosity, sweetness and fat manipulation. This literature review reveals support for increasing lubrication to reduce mouthdrying. However, of the 50 papers reviewed, none have proposed a method by which whey protein could be modified as an ingredient to reduce mouthdrying in whey-fortified products. This review recommends the use of modern technologies to increase lubrication as a novel mitigation strategy to reduce mouthdrying, with the potential to increase consumer acceptance.

Relationship between sacral-abdominal wall distance, movement performance, and spinal alignment in osteoporosis: a retrospective study

BACKGROUND

Aging is associated with muscle atrophy, as typified by sarcopenia. Loss of abdominal muscle strength can cause abdominal wall laxity. The purpose of this study was to investigate the relationship between the sacral vertebra-abdominal wall distance (SAD) and movement performance using a simple lateral spine X-ray image for measuring the SAD.

METHODS

In this retrospective study, we included women aged ≥ 65 years who were attending the outpatient clinic for osteoporosis at our hospital. A total of 287 patients (mean age ± SD, 76.8 ± 7.1 years) with measured SAD were included in the analysis. Patients were divided into two groups based on SAD cutoff (160 mm) and age (75 years), respectively. The patients were examined using the two-foot 20 cm rise test, 3 m Timed Up and Go (TUG) test, two-step test, open-eyed one-leg standing time, and spinal alignment. Normally distributed data are expressed as means (standard deviations) and non-normally distributed data as medians (interquartile range), depending on the results of the Kolmogorov-Smirnov test. Student's t-test and χ2 test were used for between-group comparisons. Regression analysis was performed with SAD as the objective variable. A two-sided p < 0.05 was considered statistically significant.

RESULTS

The shorter SAD group performed better in the two-step test, TUG test, and open-eyed one-leg standing time (p < 0.001) as well as in the two-foot 20 cm rise test (p < 0.01) compared to the longer SAD group. Spinal alignment was better in the shorter SAD group than in the longer SAD group, with a shorter sagittal vertical axis (p < 0.001), smaller pelvic tilt (p < 0.001), and greater sacral slope (p < 0.05).

CONCLUSION

SAD was associated with posterior pelvic tilt and movement performance parameters. In addition to testing for osteoporosis, movement performance parameters should be evaluated in women with osteoporosis who are aged ≥ 65 and have greater SAD (≥ 160 mm in this study). The SAD is a new assessment method, and further research is required to verify its validity and reproducibility. This is the first attempt to determine how age and SAD affect movement performance in older adults.

YTHDF2 governs muscle size through a targeted modulation of proteostasis

The regulation of proteostasis is fundamental for maintenance of muscle mass and function. Activation of the TGF-β pathway drives wasting and premature aging by favoring the proteasomal degradation of structural muscle proteins. Yet, how this critical post-translational mechanism is kept in check to preserve muscle health remains unclear. Here, we reveal the molecular link between the post-transcriptional regulation of m6A-modified mRNA and the modulation of SMAD-dependent TGF-β signaling. We show that the m6A-binding protein YTHDF2 is essential to determining postnatal muscle size. Indeed, muscle-specific genetic deletion of YTHDF2 impairs skeletal muscle growth and abrogates the response to hypertrophic stimuli. We report that YTHDF2 controls the mRNA stability of the ubiquitin ligase ASB2 with consequences on anti-growth gene program activation through SMAD3. Our study identifies a post-transcriptional to post-translational mechanism for the coordination of gene expression in muscle.

Effects of a nighttime melatonin ingestion on dynamic postural balance and muscle strength the following morning in people living with multiple sclerosis: A preliminary study

BACKGROUND

Decreased endogenous melatonin concentrations in people with multiple sclerosis (PwMS) are associated with fatigue and pain that impair postural balance and muscle strength. Melatonin ingestion had analgesic and anti-fatigue effects. However, the acute effect of exogenous melatonin on dynamic postural stability and muscle strength has not been studied yet in PwMS. This study aimed to investigate the safety and the efficacy of a nighttime melatonin intake on dynamic postural balance and lower-extremity muscle strength the following morning in PwMS.

METHODS

Fourteen PwMS (28.36 ± 6.81 years) were assessed (8 a.m.) pre- and post-acute intake of melatonin or placebo (6mg, 30 minutes before nocturnal bedtime). Evaluated parameters included dynamic postural balance (force platform), lower-extremity muscle strength [Five-Repetition Sit-To-Stand Test (5-STST)], hand dexterity (Nine-Hole Peg Test), nociceptive pain [Visual Analogue Scale (VAS)], neuropathic pain [Neuropathic Pain 4 Questions (DN4)], sleep quality and fatigue perception [Hooper Index (HI)].

RESULTS

In the frontal plane, melatonin reduced the center of pressure (CoP) path length (CoPL), CoPL in the anteroposterior axis (CoPLY) and CoP sway area (CoPAr) compared with placebo by 7.56% (p=0.02, Cohens'd (d)=1.24), 19.27% (p<0.001, d=2.60) and 13.82% (p<0.001, d=2.02), respectively. Melatonin induced a higher decrease in these posturographic parameters compared with placebo in the sagittal plane [CoPL: 9.10% (p=0.005, d=1.02), CoPLY: 4.29% (p=0.025, d=1.07) and CoPAr: 7.45% (p=0.038, d=0.74)]. Melatonin decreased 5-STST duration as well as VAS, DN4, HI-fatigue and HI-sleep scores compared with placebo by 8.19% (p=0.008, d=1.19), 5.74% (p=0.04, d=0.82), 27.30% (p=0.023, d=0.98), 40.15% (p=0.044, d=0.85) and 30.16% (p=0.012, d=1.10), respectively.

CONCLUSION

This preliminary study, among PwMS, showed that acute melatonin ingestion was safe and efficient for improving dynamic postural stability and lower-extremity muscle strength probably through its analgesic and anti-fatigue effects.

Exercise-induced vitamin D receptor and androgen receptor mediate inhibition of IL-6 and STAT3 in muscle

Background

Skeletal muscle produces interleukin-6 (IL-6) during exercise as a myokine. Although IL-6 is required for skeletal muscle regeneration, its action increases the expression of myostatin and other proteins involved in muscle atrophy, resulting in skeletal muscle atrophy. In this study, we clarified the effects exercise-induced vitamin D receptor (VDR) and androgen receptor (AR) expression on IL-6 and signal transducer and activator of transcription 3 (STAT3) in vivo and in vitro.

Method

C2C12 myotubes were subjected to electric pulse stimulation (EPS) in vitro. To evaluate VDR and AR function, a VDR/AR agonist and antagonist were administered before EPS to C2C12 myotubes. C57BL6 mice underwent 4 weeks of exercise. The expression levels of proteolytic-associated genes, including CCAAT/enhancer-binding protein delta (C/EBPδ) and myostatin, were measured by quantitative real-time polymerase chain reaction, and phosphorylated and total STAT3 levels were measured by Western blot analysis.

Result

The expression of VDR and AR mRNA was induced following EPS in C2C12 myotubes. IL-6 mRNA expression was also increased with a peak at 6 h after EPS and p-STAT3/STAT3 ratio reciprocally decreased. Although VDR/AR agonist administration decreased IL-6 mRNA expression and p-STAT3/STAT3 ratio, these two endpoints increased after treatment with VDR/AR antagonist, respectively. Exercise in mice also increased the expression of VDR/AR and IL-6 mRNA and decreased p-STAT3/STAT3 ratio.

Conclusion

Exercise-induced VDR and AR expression results in the suppression of IL-6 mRNA and STAT3 phosphorylation in skeletal muscle.

The Effects of Photobiomodulation on Knee Function, Pain, and Exercise Tolerance in Older Adults: A Meta-analysis of Randomized Controlled Trials

OBJECTIVE

To assess whether photobiomodulation therapy (PBMT) enhances the benefits of exercise in older adults.

DATA SOURCES

PubMed, Scopus, Medline, and Web of Science, dated to February 2023.

STUDY SELECTION

All included studies were randomized controlled trials of PBMT combined with exercise co-intervention in persons 60 years and older.

OUTCOME MEASURES

Western Ontario and McMaster University Osteoarthritis Index (WOMAC-total, pain, stiffness and function), perceived pain intensity, timed Up and Go (TUG) Test, 6-min walk test (6MWT), muscle strength, and knee range of motion were included.

DATA EXTRACTION

Two researchers independently performed data extraction. Article data were extracted in Excel and summarized by a third researcher.

DATA SYNTHESIS

The meta-analysis included 14 of the 1864 studies searched in the database. No statistical differences were found between the treatment and control groups in terms of WOMAC-stiffness (mean difference [MD]=-0.31, 95% confidence interval [CI] -0.64 to 0.03), TUG (MD=-0.17, 95% CI -0.71 to 0.38), 6MWT (MD=32.2, 95% CI -44.62 to 109.01), or muscle strength (standardized mean difference=0.24, 95% CI -0.02 to 0.50). However, statistically significant differences were found for WOMAC-total (MD=-6.83, 95% CI -12.3 to -1.37), WOMAC-pain (MD=-2.03, 95% CI -4.06 to -0.01), WOMAC-function (MD=-5.03, 95% CI -9.11 to -0.96), visual analog scale/numeric pain rating scale (MD=-1.24, 95% CI -2.43 to -0.06), and knee range of motion (MD=1.47, 95% CI 0.07 to 2.88).

CONCLUSIONS

In older adults who exercise regularly, PBMT can potentially provide additional pain relief, improve knee joint function, and increase knee joint range of motion.

Examination of knee extensor and valgus moment arms of the patellar tendon in older individuals with and without knee osteoarthritis

BACKGROUND

Joint moment arm is a major element that determines joint torque. This study aimed to investigate factors associated with knee extensor and valgus moment arms of the patellar tendon in older individuals with and without knee osteoarthritis.

METHODS

Thirty-six participants with knee osteoarthritis (mean age, 78.1 ± 6.0 years) and 43 healthy controls (mean age, 73.0 ± 6.3 years) were analyzed. Magnetic resonance images (MRI) from the knee joint and thigh were acquired using a 3.0 T MRI scanner. The three-dimensional moment arm was defined as the distance between the contact point of the tibiofemoral joint and the patellar tendon line. The three-dimensional moment arm was decomposed into sagittal and coronal components, which were calculated as knee extensor and valgus moment arms, respectively. Quadriceps muscle volume, epicondylar width, bisect offset, Insall-Salvati ratio, and Kellgren-Lawrence grade were assessed. Multiple regression analyses were performed in the healthy control and knee osteoarthritis groups, with knee extensor and valgus moment arms as dependent variables.

FINDINGS

Knee extensor moment arm was significantly associated with epicondylar width and the Insall-Salvati ratio in the healthy control group and with Kellgren-Lawrence grade, epicondylar width, and quadriceps muscle volume in the knee osteoarthritis group. Valgus knee moment arm was significantly associated with bisect offset in both the groups.

INTERPRETATION

Knee size, osteoarthritis severity, and quadriceps muscle volume affect the knee extensor moment arm in knee osteoarthritis, whereas lateral patellar displacement affects the valgus knee moment arms in older individuals with and without knee osteoarthritis.

Fuzhuan brick tea extract ameliorates obesity-induced skeletal muscle atrophy by alleviating mitochondrial dysfunction in mice

Fuzhuan brick tea (FBT) is a post-fermented tea fermented by the fungus Eurotium cristatum and is mainly produced in Hunan Province, China. Our previous study revealed that FBT extract prevents obesity by increasing energy expenditure and mitochondrial content in mice. Therefore, in this study, we hypothesized that FBT extract could be effective in alleviating obesity-induced muscle atrophy by addressing mitochondrial dysfunction, and aimed to explore the underlying molecular mechanism of FBT extract in high-fat diet-induced obese mice. FBT extract increased skeletal muscle weight and size, myosin heavy chain isoforms, and muscle performance in obese mice. Additionally, FBT extract reduced obesity-induced intramuscular lipids, skeletal muscle inflammation, and the expression of skeletal muscle atrophy markers, and increased the expression of fibronectin type III domain-containing protein 5 in skeletal muscles. Obesity-induced skeletal muscle mitochondrial dysfunction was improved by FBT extract as analyzed through mitochondrial morphology, fatty acid oxidation, respiratory chain complexes, and mitochondrial dynamics and biogenesis. Epigallocatechin, a major bioactive compound in FBT extract, attenuated palmitic acid-induced muscle atrophy by regulating mitochondrial functions in C2C12 cells. In conclusion, FBT extract may prevent obesity-induced muscle atrophy by alleviating mitochondrial dysfunction in mice.

Association between dynapenia and cognitive decline in community-dwelling older Japanese adults: The IRIDE Cohort Study

AIM

Muscle mass and strength correlate with cognitive function; however, it remains unclear whether dynapenia (i.e., muscle weakness with preserved muscle mass) is relevant. This study aimed to explore whether dynapenia is associated with global cognitive function in community-dwelling older Japanese adults.

METHODS

This cross-sectional study used data from the Integrated Research Initiative for Living Well with Dementia Cohort Study, which pooled data from five community-based geriatric cohorts. Dynapenia was defined as muscle weakness without muscle mass loss according to the Asian Working Group for Sarcopenia criteria. Cognitive function was assessed using the Mini-Mental State Examination (MMSE). An ordered logistic regression analysis was conducted with dynapenia as the exposure and with cognitive decline stages, defined as an MMSE score of 27-30 for normal cognition, 24-26 for possible cognitive decline, and <24 for cognitive decline, as the outcome, stratified by sex and adjusted for age, muscle mass, education, alcohol consumption, smoking habits, living alone, and non-communicable diseases.

RESULTS

We analyzed data for 3338 participants (2162 female) with preserved muscle mass. Of these, 449 (13.5%) had dynapenia, and 79 (2.4%) exhibited cognitive decline. Multivariate odds ratios (95% confidence interval) for cognitive decline among those with dynapenia, compared with those without dynapenia, were 1.51 (1.02-2.24) for males and 2.08 (1.51-2.86) for females.

CONCLUSIONS

Muscle weakness is associated with cognitive decline, even in individuals with preserved muscle mass. Further studies are needed to better understand the association between muscle weakness and cognitive decline over time in order to develop dementia prevention strategies for those with dynapenia. Geriatr Gerontol Int 2024; 24: 123-129.

Obstacles to the Early Diagnosis and Management of Sarcopenia: Current Perspectives

Research in sarcopenia has grown exponentially over the last 15 years in geriatrics and gerontology, as well as other specialties, including oncology and hepatology. There is now strong evidence for the role of resistance exercise to prevent declines in muscle strength and function, especially when combined with nutritional optimization with protein supplementation. However, there remains a disparity between research evidence and clinical practice. There are multiple factors for this, which relate to the current diagnostic criteria for sarcopenia, practical and logistical aspects of diagnosis of sarcopenia, clinician knowledge of both diagnosis and management, and the availability of pathways for interventions. Sarcopenia is currently defined based on the identification of muscle strength, in combination with muscle size or quality, below cut-off thresholds at a single timepoint. This defines sarcopenia as a binary process of either present or not present, thus early diagnosis can be challenging. In this article, we summarize current obstacles to early diagnosis and management of sarcopenia in clinical practice, and make recommendations to how these might be overcome. This includes our recommendation of incorporation of handgrip strength measurement into standard care, to enable dynamic assessment and identification of early declines in handgrip strength, so that interventions can be implemented to prevent disability.

Associations of micronutrient dietary patterns with sarcopenia among US adults: a population-based study

Background

Current epidemiological evidence points to an association between micronutrient (MN) intake and sarcopenia, but studies have focused on single MN, and no combined effects on MNs have been reported. The aim of this study was to investigate the relationship between different MN intake patterns and sarcopenia and skeletal muscle mass.

Methods

We performed a population-based cross-sectional study, with a total of 5,256 U.S. adults aged 20-59 years, and we collected total daily MN intake and appendicular skeletal muscle mass measured by Dual-Energy X-ray Absorptiometry (DXA). Principal component analysis (PCA) was used to obtain nutrient patterns and principal component scores based on the intake of 14 MNs, and logistic regression analysis was used to assess the effects of single MN and MN intake patterns on sarcopenia and muscle mass.

Results

We defined three MN intake patterns by PCA: (1) adherence to VitB-mineral, high intake of vitamin B and minerals; (2) adherence to VitAD-Ca-VB12, high intake of vitamin A, vitamin D, calcium and vitamin B12; and (3) adherence to Antioxidant Vit, high intake of antioxidant vitamins A, C, E, and K. These three nutrient patterns explained 73.26% of the variance of the population. A negative association was observed between most single MN intakes and sarcopenia, and after adjusting for confounders, adherence to the highest tertile of the three nutrient patterns was associated with a lower risk of sarcopenia and relatively higher skeletal muscle mass compared to the lowest adherence. In subgroup analysis, MN intake patterns were significantly correlated with sarcopenia in middle-aged females.

Conclusion

Nutritional patterns based on MN intake were significantly related to sarcopenia, indicating that MNs interact with each other while exerting their individual functions, and that MN dietary patterns may provide promising strategies for preventing the loss of muscle mass, with further prospective studies warranted in the future.

Mitochondrial Quantity and Quality in Age-Related Sarcopenia

Sarcopenia, the age-associated decline in skeletal muscle mass and strength, is a condition with a complex pathophysiology. Among the factors underlying the development of sarcopenia are the progressive demise of motor neurons, the transition from fast to slow myosin isoform (type II to type I fiber switch), and the decrease in satellite cell number and function. Mitochondrial dysfunction has been indicated as a key contributor to skeletal myocyte decline and loss of physical performance with aging. Several systems have been implicated in the regulation of muscle plasticity and trophism such as the fine-tuned and complex regulation between the stimulator of protein synthesis, mechanistic target of rapamycin (mTOR), and the inhibitor of mTOR, AMP-activated protein kinase (AMPK), that promotes muscle catabolism. Here, we provide an overview of the molecular mechanisms linking mitochondrial signaling and quality with muscle homeostasis and performance and discuss the main pathways elicited by their imbalance during age-related muscle wasting. We also discuss lifestyle interventions (i.e., physical exercise and nutrition) that may be exploited to preserve mitochondrial function in the aged muscle. Finally, we illustrate the emerging possibility of rescuing muscle tissue homeostasis through mitochondrial transplantation.

Precision MRI phenotyping of muscle volume and quality at a population scale

Introduction: Magnetic resonance imaging (MRI) enables direct measurements of muscle volume and quality, allowing for an in-depth understanding of their associations with anthropometric traits, and health conditions. However, it is unclear which muscle volume measurements: total muscle volume, regional measurements, measurements of muscle quality: intermuscular adipose tissue (IMAT) or proton density fat fraction (PDFF), are most informative and associate with relevant health conditions such as dynapenia and frailty. Methods: We have measured image-derived phenotypes (IDPs) including total and regional muscle volumes and measures of muscle quality, derived from the neck-to-knee Dixon images in 44,520 UK Biobank participants. We further segmented paraspinal muscle from 2D quantitative MRI to quantify muscle PDFF and iron concentration. We defined dynapenia based on grip strength below sex-specific cut-off points and frailty based on five criteria (weight loss, exhaustion, grip strength, low physical activity and slow walking pace). We used logistic regression to investigate the association between muscle volume and quality measurements and dynapenia and frailty. Results: Muscle volumes were significantly higher in male compared with female participants, even after correcting for height while, IMAT (corrected for muscle volume) and paraspinal muscle PDFF were significantly higher in female compared with male participants. From the overall cohort, 7.6% (N = 3,261) were identified with dynapenia, and 1.1% (N = 455) with frailty. Dynapenia and frailty were positively associated with age and negatively associated with physical activity levels. Additionally, reduced muscle volume and quality measurements were associated with both dynapenia and frailty. In dynapenia, muscle volume IDPs were most informative, particularly total muscle exhibiting odds ratios (OR) of 0.392, while for frailty, muscle quality was found to be most informative, in particular thigh IMAT volume indexed to height squared (OR = 1.396), both with p-values below the Bonferroni-corrected threshold (p < 8.8 × 10 - 5 ). Conclusion: Our fully automated method enables the quantification of muscle volumes and quality suitable for large population-based studies. For dynapenia, muscle volumes particularly those including greater body coverage such as total muscle are the most informative, whilst, for frailty, markers of muscle quality were the most informative IDPs. These results suggest that different measurements may have varying diagnostic values for different health conditions.

Molecular and Structural Alterations of Skeletal Muscle Tissue Nuclei during Aging

Aging is accompanied by a progressive loss of skeletal muscle mass and strength. The mechanisms underlying this phenomenon are certainly multifactorial and still remain to be fully elucidated. Changes in the cell nucleus structure and function have been considered among the possible contributing causes. This review offers an overview of the current knowledge on skeletal muscle nuclei in aging, focusing on the impairment of nuclear pathways potentially involved in age-related muscle decline. In skeletal muscle two types of cells are present: fiber cells, constituting the contractile muscle mass and containing hundreds of myonuclei, and the satellite cells, i.e., the myogenic mononuclear stem cells occurring at the periphery of the fibers and responsible for muscle growth and repair. Research conducted on different experimental models and with different methodological approaches demonstrated that both the myonuclei and satellite cell nuclei of aged skeletal muscles undergo several structural and molecular alterations, affecting chromatin organization, gene expression, and transcriptional and post-transcriptional activities. These alterations play a key role in the impairment of muscle fiber homeostasis and regeneration, thus contributing to the age-related decrease in skeletal muscle mass and function.

"Impact of aging on maximal oxygen uptake adjusted for lower limb lean mass, total body mass, and absolute values in runners"

Performance in endurance sports decreases with aging, which has been primarily attributed to cardiovascular and musculoskeletal aging; however, there is still no clear information on the factors that are most affected by aging. The aim of this study was to compare two groups of runners (< 50 and > 50 years of age) according to their absolute, weight-adjusted maximal oxygen uptake (V̇O2max), lower limb lean mass-adjusted V̇O2max, ventilatory threshold, and respiratory compensation point (RCP). A total of 78 male recreational long-distance runners were divided into Group 1 (38.12 ± 6.87 years) and Group 2 (57.55 ± 6.14 years). Participants were evaluated for body composition, V̇O2max, VT, and RCP. Group 1 showed higher absolute and body mass-adjusted V̇O2max (4.60 ± 0.57 l·min-1 and 61.95 ± 8.25 ml·kg-1·min-1, respectively) than Group 2 (3.77 ± 0.56 l·min-1 and 51.50 ± 10.22 ml·kg-1·min-1, respectively), indicating a significant difference (p < 0.001, d =  - 1.46 and p < 0.001, d =  - 1.16). Correspondingly, Group 1 showed a significantly higher lower limb lean mass-adjusted V̇O2max (251.72 ± 29.60 ml·kgLM-1·min-1) than Group 2 (226.36 ± 43.94 ml·kgLM-1·min-1) (p = 0.008, d =  - 0.71). VT (%V̇O2max) (p = 0.19, d = 0.19) and RCP (%V̇O2max) (p = 0.24, d = 0.22) did not differ between the groups. These findings suggest that both variables that are limited by central or peripheral conditions are negatively affected by aging, but the magnitude of the effect is higher in variables limited by central conditions. These results contribute to our understanding of how aging affects master runners.

Prevalence and factors associated with sarcopenia among older adults in a post-acute hospital in Singapore

BACKGROUND

Sarcopenia is common in older adults worldwide, but its prevalence varies widely owing to differences in diagnostic criteria, population sampled, and care setting. We aimed to determine the prevalence and factors associated with sarcopenia in patients aged 65 and above admitted to a post-acute hospital in Singapore.

METHODS

This was a cross-sectional study of 400 patients recruited from a community hospital in Singapore. Data including socio-demographics, physical activity, nutritional status, cognition, clinical and functional status, as well as anthropometric measurements were collected. Sarcopenia was defined using the Asian Working Group for Sarcopenia 2019 criteria [AWGS2019].

RESULTS

Of the 383 patients with complete datasets, overall prevalence of sarcopenia was 54% while prevalence of severe sarcopenia was 38.9%. Participants with increased age, male gender and a low physical activity level were more likely to be sarcopenic, while those with higher hip circumference and higher BMI of ≥27.5m/kg2 were less likely to be sarcopenic. Other than the above-mentioned variables, cognitive impairment was also associated with severe sarcopenia.

CONCLUSIONS

More than 1 in 2 older adults admitted to a post-acute hospital in Singapore are sarcopenic. There is an urgent need to address this important clinical syndrome burden and to identify patients at risk of sarcopenia in post-acute settings in Singapore for early intervention.

Prospective associations between changes in physical activity and sedentary time and subsequent lean muscle mass in older English adults: the EPIC-Norfolk cohort study

BACKGROUND

The longitudinal associations between physical behaviours and lean muscle mass indices need to be better understood to aid healthy ageing intervention development.

METHODS

We assessed physical behaviours (total physical activity, moderate-to-vigorous physical activity (MVPA), light physical activity, total sedentary time and prolonged sedentary bout time) for 7 days using hip-worn accelerometers. We also assessed domain-specific physical behaviours (walking, cycling, gardening and housework time) with self-report questionnaires at baseline (2006-2011) and follow-up (2012-2016) in the European Prospective Investigation into Cancer (EPIC)-Norfolk study. We assessed body composition using dual-energy X-ray absorptiometry (DEXA) at follow-up in 1535 participants (≥ 60 years at baseline). From this, we derived appendicular lean muscle mass (ALM) indices (% relative ALM = (ALM/total body weight)*100), body mass index (BMI)-scaled ALM (ALM/BMI, kg/kg/m2) and height-scaled ALM (ALM/height2, kg/m2)). We evaluated the prospective associations of both baseline and change in physical behaviours with follow-up muscle mass indices using multivariable linear regression.

RESULTS

Over 5.5 years (SD 14.8) follow-up, higher baseline accelerometer-measured physical activity and lower sedentary time were associated with higher subsequent relative ALM and BMI-scaled ALM, but not height-scaled ALM (e.g. 0.02% higher subsequent relative ALM per minute/day of baseline MVPA for men). Greater increases in physical activity and greater declines in sedentary time variables were associated with higher subsequent relative ALM and BMI-scaled ALM, but not height-scaled ALM (e.g. 0.001 kg/kg/m2 subsequent BMI-scaled ALM and 0.04% subsequent relative ALM per min/day/year increases in LPA over follow-up; 0.001 kg/kg/m2 subsequent BMI-scaled ALM and -0.03% subsequent relative ALM per min/day/year less of total sedentary time over follow-up). Greater increases in women's cycling and gardening over follow-up were associated with greater subsequent relative ALM (cycling 0.9% per hour/week/year; gardening 0.2% per hour/week/year) and BMI-scaled ALM (cycling 0.03 kg/kg/m2 per hour/week/year; gardening 0.004 kg/kg/m2 per hour/week/year).

CONCLUSION

Physical behaviours across all intensities, and in women more specifically cycling and gardening, may help prevent age-related declines in muscle mass.

Differences in Functional Capacity between Oncologic and Non-Oncologic Populations: Reference Values

This study is focused on the fact that in the context of increasing global aging and cancer diagnoses, additional challenges arise in clinical care. Adequate functionality and body composition are key to coping with antineoplastic treatment, which can lead to better treatment tolerance, survival, and quality of life. This is a cross-sectional comparative study focused on the assessment and comparison of body composition and functionality between cancer patients and a reference population, with the aim of establishing meaningful baseline values. Techniques such as manual dynamometry, the Five-Times Sit-to-Stand test, and bioimpedance were used to collect data from 374 oncologic patients and 1244 reference individuals. The results reveal significant disparities in functionality and body composition among participants, and provide age group-specific adjusted baseline values for those diagnosed with cancer. These findings may have crucial clinical implications for applying particular cut-off points designed for this population group, which makes the assessment process faster and more accurate, enhances the capacity of medical personnel to act quickly, and improves the management of frailty in cancer patients.

Uric acid formation is driven by crosstalk between skeletal muscle and other cell types

Hyperuricemia is implicated in numerous pathologies, but the mechanisms underlying uric acid production are poorly understood. Using a combination of mouse studies, cell culture studies, and human serum samples, we sought to determine the cellular source of uric acid. In mice, fasting and glucocorticoid treatment increased serum uric acid and uric acid release from ex vivo-incubated skeletal muscle. In vitro, glucocorticoids and the transcription factor FoxO3 increased purine nucleotide degradation and purine release from differentiated muscle cells, which coincided with the transcriptional upregulation of AMP deaminase 3, a rate-limiting enzyme in adenine nucleotide degradation. Heavy isotope tracing during coculture experiments revealed that oxidation of muscle purines to uric acid required their transfer from muscle cells to a cell type that expresses xanthine oxidoreductase, such as endothelial cells. Last, in healthy women, matched for age and body composition, serum uric acid was greater in individuals scoring below average on standard physical function assessments. Together, these studies reveal skeletal muscle purine degradation is an underlying driver of uric acid production, with the final step of uric acid production occurring primarily in a nonmuscle cell type. This suggests that skeletal muscle fiber purine degradation may represent a therapeutic target to reduce serum uric acid and treat numerous pathologies.

Dietary intake of micronized avian eggshell membrane in aged mice reduces circulating inflammatory markers, increases microbiota diversity, and attenuates skeletal muscle aging

Introduction

Avian eggshell membrane (ESM) is a complex extracellular matrix comprising collagens, glycoproteins, proteoglycans, and hyaluronic acid. We have previously demonstrated that ESM possesses anti-inflammatory properties in vitro and regulates wound healing processes in vivo. The present study aimed to investigate if oral intake of micronized ESM could attenuate skeletal muscle aging associated with beneficial alterations in gut microbiota profile and reduced inflammation.

Methods

Elderly male C57BL/6 mice were fed an AIN93G diet supplemented with 0, 0.1, 1, or 8% ESM. Young mice were used as reference. The digestibility of ESM was investigated using the static in vitro digestion model INFOGEST for older people and adults, and the gut microbiota profile was analyzed in mice. In addition, we performed a small-scale pre-clinical human study with healthy home-dwelling elderly (>70 years) who received capsules with a placebo or 500 mg ESM every day for 4 weeks and studied the effect on circulating inflammatory markers.

Results and discussion

Intake of ESM in elderly mice impacted and attenuated several well-known hallmarks of aging, such as a reduction in the number of skeletal muscle fibers, the appearance of centronucleated fibers, a decrease in type IIa/IIx fiber type proportion, reduced gene expression of satellite cell markers Sdc3 and Pax7 and increased gene expression of the muscle atrophy marker Fbxo32. Similarly, a transition toward the phenotypic characteristics of young mice was observed for several proteins involved in cellular processes and metabolism. The digestibility of ESM was poor, especially for the elderly condition. Furthermore, our experiments showed that mice fed with 8% ESM had increased gut microbiota diversity and altered microbiota composition compared with the other groups. ESM in the diet also lowered the expression of the inflammation marker TNFA in mice and in vitro in THP-1 macrophages. In the human study, intake of ESM capsules significantly reduced the inflammatory marker CRP. Altogether, our results suggest that ESM, a natural extracellular biomaterial, may be attractive as a nutraceutical candidate with a possible effect on skeletal muscle aging possibly through its immunomodulating effect or gut microbiota.

Effect of breakfast protein intake on muscle mass and strength in adults: a scoping review

BACKGROUND

The distribution of protein intake throughout the day is frequently skewed, with breakfast having the lowest protein intake across all age groups. There is no review that addresses the association between breakfast protein intake and muscle mass and strength.

OBJECTIVE

This scoping review aims to summarize the literature on the relationship between protein intake during breakfast and muscle mass and strength in adults.

METHODS

This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. Two independent reviewers screened and appraised the articles identified from 3 electronic databases (Medline, Web of Science, and Scopus) that focused on protein intake per meal and its impact on muscle-related outcomes.

RESULTS

A total of 14 763 articles were retrieved from 3 databases, and after the screening process, 15 articles were included for analysis. Approximately 58.8% of findings from 11 studies examining the association between high protein intake during breakfast and muscle mass indicated an increase in muscle mass among participants. Half of 6 studies (50.0%) exploring the relationship between high protein intake at breakfast and muscle strength demonstrated an increase in muscle strength. Consuming high amounts of protein at breakfast or more protein in the morning than in the evening was associated with an increase in the skeletal muscle index and lean body mass.

CONCLUSION

Protein consumption at breakfast revealed potential benefits in increasing muscle mass across 5 studies involving an elderly population and 2 studies encompassing middle-aged women and young men in our review. However, the relationship between protein intake at breakfast and muscle strength remains unclear. Further high-quality randomized controlled trials are required to examine whether adults can preserve skeletal muscle health outcomes by consuming higher amounts of protein at breakfast.

Ultrasound for measurement of skeletal muscle mass quantity and muscle composition/architecture in critically ill patients: A scoping review on studies' aims, methods, and findings

AIMS

This scoping review aimed to identify, explore, and map the objectives, methodological aspects, and results of studies that used ultrasound (US) to assess skeletal muscle (SM) in critically ill patients.

METHODS

A scoping review was conducted according to the Joanna Briggs Institute's methodology. All studies that evaluated SM parameters from the US in patients admitted to the intensive care unit (ICU) were considered eligible. We categorized muscle thickness and cross-sectional area as parameters for assessing SM quantity, while echogenicity, fascicle length, and pennation angle analysis were used to evaluate muscle "quality" (composition/architecture). A literature search was conducted using four databases for articles published until December 2022. Independent reviewers selected the studies and extracted data. Descriptive statistics were calculated to present the results.

RESULTS

A total of 107 studies were included, the majority of which were prospective cohort studies (59.8 %) conducted in general ICUs (49.5 %). The most frequent objective of the studies was to evaluate SM quantity depletion during the ICU stay (25.2 %), followed by determining whether a specific intervention would modify SM (21.5 %). Most studies performed serial SM evaluations (76.1 %). The rectus femoris muscle thickness was evaluated in most studies (67.9 %), followed by the rectus femoris cross-sectional area (54.3 %) and the vastus intermedius muscle thickness (40.2 %). The studies demonstrated the feasibility and reproducibility of US for SM evaluation, especially related to quantitative parameters. Most studies (70.3 %) reported significant SM quantity depletion during hospitalization. However, the accuracy of the US in measuring SM varied across the studies.

CONCLUSIONS

The lack of detailed description and standardization in the protocols adopted by the studies included in this scoping review precludes the translation of the evidence related to US for SM assessment into clinical practice.

The roles of sex hormones in the pathophysiology of age-related sarcopenia and frailty

Background

Sarcopenia is an age-related condition characterized by a progressive and systemic decline in skeletal muscle mass, quality, and strength. The incidence of sarcopenia contains sex-specific aspects, indicating the contribution of sex hormones to its pathophysiology. This review focuses on changing trends in sarcopenia, discusses alterations in definitions and diagnostic criteria, and emphasizes the association between sarcopenia and sex hormones.

Methods

A literature search was performed on PubMed for related articles published between 1997 and December 2023 using appropriate keywords.

Main Findings Results

Advances in research have emphasized the significance of muscle quality and strength over muscle mass, resulting in new diagnostic criteria for sarcopenia. Androgens demonstrated anabolic effects on skeletal muscles and played a significant role in the pathophysiology of sarcopenia. In clinical settings, androgen replacement therapy has exhibited certain positive outcomes for treating sarcopenia, despite concerns about potential side effects. Conversely, estrogen is involved in skeletal muscle maintenance, but the detailed mechanisms remain unclear. Moreover, results regarding the clinical application of estrogen replacement therapy for treating sarcopenia remained inconsistent.

Conclusion

The elucidation of molecular mechanisms that involve sex hormones is eagerly awaited for novel therapeutic interventions for sarcopenia.

The relationship between lifestyles and sarcopenia-related traits: A two-sample Mendelian randomization study

OBJECTIVE

To investigate the causal association between lifestyles (smoking, drinking consumption and physical activity) and sarcopenia-related traits by Mendelian randomized analysis.

METHODS

Instrumental variables from the genome-wide association study were used for analysis. The exposure factors were lifestyle factors, including smoking, alcohol consumption, moderate physical activity and vigorous physical activity, and the outcome variables were low hand grip strength and appendicular lean mass. The inverse variance weighted (IVW) method and other MR methods were used for analysis. Heterogeneity test, sensitivity analysis and pleiotropy analysis were performed.

RESULTS

According to a primary causal effects model with MR analyses by the IVW method, smoking was a decreased risk of low hand grip strength (odds ratio (OR) = 0.899, 95% confidence interval (CI) = 0.829-0.974, P = 0.010), while alcohol consumption was a significant correlation with low hand grip strength (OR = 1.137, 95% CI = 1.020-1.267, P = 0.020). There was no significant relationship between smoking, alcohol, and appendicular lean mass. In addition, moderate or vigorous physical showed no significant correlation with low hand grip strength and appendicular lean mass.

CONCLUSION

This study demonstrated that smoking may be causally related to a lower risk of low hand grip strength, while alcohol may increase the risk of low hand grip strength. There was no causal relationship between physical activity and sarcopenia-related traits.

Dynapenic Abdominal Obesity Increases Risk for Falls Among Adults Aged ≥50 Years: A Prospective Analysis of the Irish Longitudinal Study on Ageing

BACKGROUND

There is a scarcity of studies examining the longitudinal relationship between dynapenic abdominal obesity (DAO; ie, impairment in muscle strength and high waist circumference) and future fall risk. Therefore, we aimed to investigate the prospective association between DAO at baseline and falls occurring during 2 years of follow-up in a nationally representative sample of middle-aged and older individuals from Ireland.

METHODS

Data from 2 consecutive waves of the Irish Longitudinal Study on Ageing survey were analyzed. Dynapenia was defined as handgrip strength of <26 kg for men and <16 kg for women. Abdominal obesity was defined as a waist circumference of >88 cm for women and >102 cm for men. DAO was assessed at Wave 1 (2009-2011) and was defined as having both dynapenia and abdominal obesity. Falls occurring between Wave 1 and Wave 2 (2012-2013) were self-reported. Multivariable logistic regression analysis was conducted.

RESULTS

Data on 5 275 individuals aged ≥50 years were analyzed (mean [standard deviation {SD}] age 63.2 [8.9] years; 48.8% males). After adjustment for potential confounders, compared to no dynapenia and no abdominal obesity at baseline, DAO was significantly associated with 1.47 (95% confidence interval [CI]: 1.14-1.89) times higher odds for falls at 2-year follow-up. Dynapenia alone (odds ratio [OR] = 1.08; 95% CI: 0.84-1.40) and abdominal obesity alone (OR = 1.09; 95% CI: 0.91-1.29) were not significantly associated with falls at follow-up.

CONCLUSIONS

DAO increased the risk for falls among middle-aged and older adults in Ireland. Interventions to prevent or reverse DAO may be beneficial for fall reduction.

Preventative and therapeutic potential of tocotrienols on musculoskeletal diseases in ageing

Musculoskeletal health is paramount in an ageing population susceptible to conditions such as osteoporosis, arthritis and fractures. Age-related changes in bone, muscle, and joint function result in declining musculoskeletal health, reduced mobility, increased risk of falls, and persistent discomfort. Preserving musculoskeletal wellbeing is essential for maintaining independence and enhancing the overall quality of life for the elderly. The global burden of musculoskeletal disorders is significant, impacting 1.71 billion individuals worldwide, with age-related muscle atrophy being a well-established phenomenon. Tocotrienols, a unique type of vitamin E found in various sources, demonstrate exceptional antioxidant capabilities compared to tocopherols. This characteristic positions them as promising candidates for addressing musculoskeletal challenges, particularly in mitigating inflammation and oxidative stress underlying musculoskeletal disorders. This review paper comprehensively examines existing research into the preventive and therapeutic potential of tocotrienols in addressing age-related musculoskeletal issues. It sheds light on the promising role of tocotrienols in enhancing musculoskeletal health and overall wellbeing, emphasizing their significance within the broader context of age-related health concerns.

Feasibility of using chest computed tomography (CT) imaging at the first lumbar vertebra (L1) level to assess skeletal muscle mass: a retrospective study

Background

Skeletal muscle mass is an essential parameter for diagnosing sarcopenia. The gold standard for assessing skeletal muscle mass is using computed tomography (CT) to measure skeletal muscle area at the third lumbar vertebra (L3) level. This study aims to investigate whether skeletal muscle mass could be evaluated at the first lumbar vertebra (L1) level using images obtained from routine chest CT scans.

Methods

Skeletal muscle index (SMI, cm2/m2) and skeletal muscle density (SMD, HU) are commonly used to measure relative muscle mass and the degree of fat infiltration. This study used CT images at the L1 level to measure the skeletal muscle area (SMA, cm2) in 815 subjects from the health examination center. Linear regression analysis was used to explore the association between L1 and L3 measurements. The receiver operating characteristic (ROC) analysis was used to assess the predictive performance of L1 SMI for sarcopenia. The sex-specific cut-off values for low skeletal muscle mass in patients under the age of 60 were determined using the following formula: "mean - 1.28 × standard deviation." A multivariate linear regression model was established.

Results

A significantly higher SMI at the L1 level was found in males than in females (43.88 ± 6.33 cm2/m2 vs 33.68 ± 5.03 cm2/m2; P < 0.001). There were strong correlations between measures at the L1 and L3 levels in both the total subject and sex-specific analyses. A negative association was found between age and L3 SMI in males (r = -0.231, P = 0.038). Both body mass index (BMI) and body surface area (BSA) were positively associated with L1 SMI in both males and females. A multivariate analysis was used to establish a prediction rule to predict SMI at the L3 level. The assessment of consistency and interchangeability between predicted and actual SMI at the L3 level yielded moderately good results. Considering the significant differences observed between male and female participants, the sex-specific cut-off values of the L1 SMI for defining low skeletal muscle mass were 36.52 cm2/m2 in males and 27.29 cm2/m2 in females.

Conclusions

Based on a population from central China, the correlated indicators obtained at the L1 level from routine chest CT scans may serve as effective surrogate markers for those at the L3 level in assessing overall skeletal muscle mass.

Frailty in Traumatic Brain Injury-The Significance of Temporal Muscle Thickness

BACKGROUND

Temporal muscle thickness (TMT) on cranial CT scans has recently been identified as a prognostic imaging parameter for assessing a patient's baseline frailty. Here, we analyzed whether TMT correlates with Traumatic brain injury (TBI) severity and whether it can be used to predict outcome(s) after TBI.

METHODS

We analyzed the radiological and clinical data sets of 193 patients with TBI who were admitted to our institution and correlated the radiological data with clinical outcomes after stratification for TMT.

RESULTS

Our analyses showed a significant association between high TMT and increased risk for intracranial hemorrhage (p = 0.0135) but improved mRS at 6 months (p = 0.001) as compared to patients with low TMT. Congruent with such findings, a lower TMT was associated with falls and reduced outcomes at 6 months (p < 0.0001 and p < 0.0001).

CONCLUSION

High TMT was robustly associated with head trauma sequelae but was also associated with good clinical outcomes in TBI patients. These findings consolidate the significance of TMT as an objective marker of frailty in TBI patients; such measurements may ultimately be leveraged as prognostic indicators.

Associations between PBMC whole genome transcriptome, muscle strength, muscle mass, and physical performance in healthy home-dwelling older women

Increasing age is accompanied by many changes, including declining functional skeletal muscle health and immune dysfunction. Peripheral blood mononuclear cells (PBMCs) are circulating cells that assemble an immune response, but their whole genome transcriptome has not been studied in the context of age-related muscle health. Consequently, this article explored associations between three muscle variables indicative of functional muscle health - maximum handgrip strength (muscle strength), appendicular skeletal muscle mass index (ASMI, muscle mass), and gait speed (physical performance) - and two groups of bioinformatics-generated PBMC gene expression features (gene expression-estimated leukocyte subset proportions and gene clusters). We analyzed cross-sectional data from 95 home-dwelling healthy women ≥ 70 years, using "cell-type identification by estimating relative subsets of RNA transcripts" (CIBERSORT) to estimate leukocyte subset proportions and "weighted correlation network analysis" (WGCNA) to generate gene clusters. Associations were studied using linear regression models and relevant gene clusters were subjected to gene set enrichment analysis using gene ontology. Gait speed and ASMI associated with CIBERSORT-estimated monocyte proportions (β =  - 0.090, 95% CI = (- 0.146, - 0.034), p-value = 0.002 for gait speed, and β =  - 0.206, 95% CI = (- 0.385, - 0.028), p-value = 0.024 for ASMI), and gait speed associated with CIBERSORT-estimated M2 macrophage proportions (β =  - 0.026, 95% CI = (- 0.043, - 0.008), p-value = 0.004). Furthermore, maximum handgrip strength associated with nine WGCNA gene clusters, enriched in processes related to immune function and skeletal muscle cells (β in the range - 0.007 to 0.008, p-values < 0.05). These results illustrate interactions between skeletal muscle and the immune system, supporting the notion that age-related functional muscle health and the immune system are closely linked.