Toward the recognition and management of sarcopenia in routine clinical care

The role of TGF-β signaling in muscle atrophy, sarcopenia and cancer cachexia

Skeletal muscle, comprising a significant proportion (40 to 50 percent) of total body weight in humans, plays a critical role in maintaining normal physiological conditions. Muscle atrophy occurs when the rate of protein degradation exceeds protein synthesis. Sarcopenia refers to age-related muscle atrophy, while cachexia represents a more complex form of muscle wasting associated with various diseases such as cancer, heart failure, and AIDS. Recent research has highlighted the involvement of signaling pathways, including IGF1-Akt-mTOR, MuRF1-MAFbx, and FOXO, in regulating the delicate balance between muscle protein synthesis and breakdown. Myostatin, a member of the TGF-β superfamily, negatively regulates muscle growth and promotes muscle atrophy by activating Smad2 and Smad3. It also interacts with other signaling pathways in cachexia and sarcopenia. Inhibition of myostatin has emerged as a promising therapeutic approach for sarcopenia and cachexia. Additionally, other TGF-β family members, such as TGF-β1, activin A, and GDF11, have been implicated in the regulation of skeletal muscle mass. Furthermore, myostatin cooperates with these family members to impair muscle differentiation and contribute to muscle loss. This review provides an overview of the significance of myostatin and other TGF-β signaling pathway members in muscular dystrophy, sarcopenia, and cachexia. It also discusses potential novel therapeutic strategies targeting myostatin and TGF-β signaling for the treatment of muscle atrophy.

The 10-Item Physical Function Scale as a Sarcopenia Screening Tool for Patients on Hemodialysis

OBJECTIVE

We investigated the accuracy of the 10-item Physical Function (PF-10) questions of the SF-36 quality of life questionnaire as a sarcopenia screening tool among patients on hemodialysis.

METHODS

A cross-sectional, multicenter study that included adult patients on hemodialysis. The revised European Working Group on Sarcopenia in Older People was used to diagnose sarcopenia. The 10 questions about daily activities from the SF-36 quality of life questionnaire were used to appoint the PF-10, where the final score could range from 10 to 30, and the lower the worse the physical function. The PF-10 accuracy to identify confirmed sarcopenia (low muscle strength + low muscle mass) was assessed through a receiver operating characteristic curve and the cutoff was calculated using the Youden index.

RESULTS

One hundred eighty-five patients were included (median 59 years; 45% female). Prevalence of confirmed sarcopenia was 31.4%. The median PF-10 score was 23 (interquartile range: 17-27) and a significant association with all sarcopenia measurements was found (all P < .05). The best cutoff calculated from the receiver operating characteristic curve was ≤26 points (area under the curve = 0.69, 95% confidence interval 0.61-0.77) with sensitivity and specificity of 96.6% and 71.0%, respectively. Moreover, patients with ≤26 points (n = 133, 72%) had a higher prevalence of low muscle strength by handgrip (53 vs. 19%; P < .001) and 5-time sit-to-stand (41 vs. 10%; P < .001), low gait speed (44 vs. 19%; P = .002), confirmed sarcopenia (39 vs. 11%; P < .001), and severe sarcopenia (26 vs. 4%; P = .001), but not low muscle mass (49 vs. 35%; P = .08), in comparison with those >26 points (n = 52, 28%).

CONCLUSION

The PF-10 may be a useful physical dysfunction and sarcopenia screening tool in patients on hemodialysis. A PF-10 threshold of around 26 points appeared to display the fairest accuracy for diagnosing sarcopenia.

Sarcopenia in subjects with Alzheimer's disease: prevalence and comparison of agreement between EGWSOP1, EGWSOP2, and FNIH criteria

BACKGROUND

Sarcopenia is an age-related clinical syndrome characterized by the progressive loss of muscle mass and muscle strength. It appears to be closely linked to dementia, particularly Alzheimer's disease (AD); however, its prevalence among AD patients remains unclear. In this study, we assessed differences in sarcopenia prevalence between non-demented individuals and AD patients. Moreover, we assessed sex-specific differences in sarcopenia prevalence and explored the diagnostic value of the Muscle Quality Index (MQI) for diagnosing sarcopenia among AD patients.

METHOD

Cross-sectional study including 145 patients with probable AD and 51 older adults with normal cognition. Sarcopenia was diagnosed according to the criteria of the European Working Group on Sarcopenia in Older People (EWGSOP1 and EWGSOP2) and of the Foundation for the National Institutes of Health (FNIH). The MQI was computed as the ratio of handgrip strength to skeletal muscle mass.

RESULTS

No significant difference in sarcopenia prevalence was observed between AD patients and controls. Prevalence ranged from 3.4 to 23.4% in AD patients and from 2 to 11.8% in controls, depending on diagnostic criteria. Prevalence was higher using EWGSOP1 and decreased using EWGSOP2 and FNIH. Prevalence was higher in males than in females with AD. The MQI was lower in AD patients than in controls (95%CI: - 0.23, - 0.05, p < 0.001), but displayed poor diagnostic accuracy in identifying sarcopenia cases.

CONCLUSIONS

AD patients and controls show comparable sarcopenia prevalence. Sarcopenia prevalence is higher in males than females among AD patients and higher when using EWGSOP1 compared to FNIH and EWGSOP2 criteria.

Targeting cardiac and cerebrovascular risks of sarcopenia: Is it time to screen for muscle health?

This Editorial comments on the article by Jauffret et al. in this issue.

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

BACKGROUND

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

RESEARCH DESIGN AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Muscle mass loss measured with portable ultrasound in hospitalized older adults: The ECOSARC study

OBJECTIVES

The main objective was to analyze the evolution of muscle of the Quadriceps Rectus Femoris (QRF) between admission and discharge, in older adults hospitalized with an acute medical disease in Acute Geriatric Units (AGUs).

DESIGN

Prospective multicentric observational cohort study.

SETTING

Seven AGUs from University Hospitals in Spain.

PARTICIPANTS

Hospitalized adults ≥ 70 years old, able to ambulate and without severe dementia.

MEASUREMENTS

Ultrasound measurements of QRF were acquired at 2/3 distal between anterior-superior iliac spine and patella in both legs by trained Geriatricians. Ultrasound Chison model ECO2 was used. QRF area, thickness, edema, echogenicity, and fasciculations were measured.

RESULTS

From the complete sample (n = 143), in 45 (31.5%) participants, ultrasound images were classified as non-valid by an expert radiologist. Mean age was 87.8 (SD 5.4). Mean hospital stay 7.6 days (SD 4.3). From those with valid images, 36 (49.3%), 2 (2.7%), and 35 (47.9%) presented a decrease, equal values, or an increase in QRF area from baseline to discharge, respectively, and 37 (50.0%), 2 (2.7%), and 35 (47.3%) presented a decrease, equal values, or an increase in QRF thickness, respectively. 26 (35.6%) presented a decrease in more than 0.2 cm2 of QRF area, and 23 (31.1%) a decrease in more than 0.1 cm of QRF thickness. Only 4 (5.4%) patients presented new edema, while 13 (17.6%) worsened echogenicity.

CONCLUSION

One third of older adults develop significant muscle loss during a hospitalization for acute medical diseases.

TRIAL REGISTRATION NUMBER

NCT05113758.

Preclinical assessment of rodent jumping power with a novel electrical stimulation-assisted device

Sarcopenia is a progressive loss of muscle mass and strength that is associated with increasing the risk of falls, musculoskeletal diseases, and chronic metabolic diseases. However, the animal models adopted to study sarcopenia face limitations since the functional tests conducted on human cannot be directly adapted to animals because the animals do not follow instructions. Moreover, current preclinical research tools for muscle function assessment, such as the rotarod, grip strength, and treadmill, have limitations, including low-intensity simple movements, evaluator subjectivity, and limited power indicators. Hence, in this study, we present a new jumping-power assessment tool in a preclinical rodent model to demonstrate muscle functions. To overcome the light weight and command issues in the rodent model, we developed an electrical stimulation-assisted jump power assessment device. Precisely, the device utilizes a load cell with a 0.1 g resolution and a 50 points/s data acquisition rate to capture the short period of the mouse jump. Additionally, interdigitated electrodes are used to electrically stimulate the mice and make them jump. While our primary focus in this article is the validation of the newly developed jump power assessment device, it is worth noting that this tool has several potential utilities. These include the phenotypic comparison of sarcopenia models, the exploration of muscle function reduction mechanisms, muscle function-related blood biomarkers, and the evaluation of drug intervention effects.

"We want more": perspectives of sarcopenic older women on the feasibility of high-intensity progressive resistance exercises and a whey-protein nutrition intervention

This qualitative study is nested within a 12-week pilot randomized-controlled, two-arm trial involving high-intensity progressive resistance training (PRT) or PRT with a multi-nutrient, whey-protein supplementation (PRT+WP) in sarcopenic older adults (trial registration no: TCTR20230703001). The aim was to investigate sarcopenic participants' perceptions and barriers to this multi-modal intervention strategy that may accelerate "real-world" implementation. Eighteen older adults (one man) with possible sarcopenia were invited to join the study, of whom 16 women were randomized to a thrice-weekly PRT (n = 8) program (80% of 1-repetitive maximum, six resistance band exercises) only or PRT plus daily weekday milk-based WP supplementation (PRT+WP, n = 8). Muscle strength (handgrip and 5-times sit-to-stand), mass (dual-energy X-ray absorptiometry), performance (Short Physical Performance Battery and stair ascent-descent), and nutrition status (Mini Nutritional Assessment) were assessed for changes. We randomly selected eight women for the semi-structured interview. Post-intervention, eight (50%) women were sarcopenia-free, six (38%) remained in possible sarcopenia, one (6%) improved to sarcopenia, and one (6%) deteriorated from possible to severe sarcopenia. There were no significant between-group differences, but significant within-group improvements (p < 0.05) were detected for handgrip strength (PRT+WP 5.0 kg, d = 0.93; PRT 6.1 kg, d = 0.55), 5-times sit-to-stand time (PRT 2.0 s, d = 1.04), nutrition score (PRT+WP 3.44, d = 0.52; PRT 1.80, d = 0.44), and stair ascent time (PRT+WP 0.97 s, d = 0.77; PRT 0.75 s, d = 0.97). Our thematic analyses identified four main themes, namely, (1) perceived benefits, (2) sustaining behavior changes, (3) challenges in participating, and (4) improved wellbeing. Participants expressed how they initially were skeptical and doubted that they could complete the exercises or tolerate the milk-based WP supplements. However, they reported positive experiences and benefits felt from strength gains, increased confidence, and better physical abilities. Participants were surprised by the zero adverse effects of WP supplements. The women wanted more nutritional information and structured, guided exercise programs and suggested a community-based implementation. In conclusion, our findings showed PRT was well received and may support reduced risks of sarcopenia. No added benefits were seen with the addition of WP supplementation, but a larger sample is required to address this question. Overall, older (previously sarcopenic) Malay women indicated that they want more multi-modal programs embedded in their community.

Macrophage Involvement in Aging-Associated Skeletal Muscle Regeneration

The skeletal muscle is a dynamic organ composed of contractile muscle fibers, connective tissues, blood vessels and nerve endings. Its main function is to provide motility to the body, but it is also deeply involved in systemic metabolism and thermoregulation. The skeletal muscle frequently encounters microinjury or trauma, which is primarily repaired by the coordinated actions of muscle stem cells (satellite cells, SCs), fibro-adipogenic progenitors (FAPs), and multiple immune cells, particularly macrophages. During aging, however, the capacity of skeletal muscle to repair and regenerate declines, likely contributing to sarcopenia, an age-related condition defined as loss of muscle mass and function. Recent studies have shown that resident macrophages in skeletal muscle are highly heterogeneous, and their phenotypes shift during aging, which may exacerbate skeletal muscle deterioration and inefficient regeneration. In this review, we highlight recent insight into the heterogeneity and functional roles of macrophages in skeletal muscle regeneration, particularly as it declines with aging.

Exercise to Prevent and Manage Frailty and Fragility Fractures

PURPOSE OF REVIEW

This review identifies exercise-based recommendations to prevent and manage frailty and fragility fractures from current clinical practice guidelines. We also critically assess recently published literature in relation to exercise interventions to mitigate frailty and fragility fractures.

RECENT FINDINGS

Most guidelines presented similar recommendations that included the prescription of individually tailored, multicomponent exercise programs, discouragement of prolonged sitting and inactivity, and combining exercise with optimal nutrition. To target frailty, guidelines recommend supervised progressive resistance training (PRT). For osteoporosis and fragility fractures, exercise should include weight-bearing impact activities and PRT to target bone mineral density (BMD) at the hip and spine, and also incorporate balance and mobility training, posture exercises, and functional exercise relevant to activities of daily living to reduce falls risk. Walking as a singular intervention has limited benefits for frailty and fragility fracture prevention and management. Current evidence-based clinical practice guidelines for frailty, osteoporosis, and fracture prevention recommend a multifaceted and targeted approach to optimise muscle mass, strength, power, and functional mobility as well as BMD.

"SARCOPENIA MEASURED BY ULTRASOUND IN HOSPITALIZED OLDER ADULTS" (ECOSARC): multi-centre, prospective observational study protocol

BACKGROUND

Measurement of muscle mass and function, and thereafter, screening and diagnosis of sarcopenia, is a challenge and a need in hospitalized older adults. However, it is difficult in complex real-world old patients, because usually they are unable to collaborate with clinical, functional, and imaging testing. Ultrasound measurement of quadriceps rectus femoris (QRF) provides a non-invasive, real-time assessment of muscle quantity and quality, and is highly acceptable to participants with excellent inter-rater and intra-rater variability. However, normative data, protocol standardization, and association with longitudinal outcomes, needs further research and consensus.

METHODS

Prospective exploratory multicenter study in older adults admitted to Acute Geriatric Units (AGUs) for medical reasons. 157 subjects from 7 AGUs of Spain were recruited between May 2019 and January 2022. Muscle ultrasound measurements of the anterior vastus of the QRF were acquired on admission and on discharge, using a previously validated protocol, using a Chieson model ECO2 ultrasound system (Chieson Medical Technologies, Co. Ltd, Wimxu District Wuxi, Jiangsu, China). Measurements included the cross-sectional area, muscle thickness in longitudinal view, intramuscular central tendon thickness, echogenicity, and the presence or absence of edema and fasciculations. Functional, nutritional, and DXA measurements were provided. Clinical follow-up was completed at discharge, and 30 and 90 days after discharge. Variations between hospital admission and discharge ultrasound values, and the relationship with clinical variables, will be analyzed using paired t-tests, Wilcoxon tests, or Mc Nemar chi-square tests when necessary. Prevalence of sarcopenia will be calculated, as well as sensitivity and specificity of ultrasound measurements to determine sarcopenia. Kappa analysis will be used to analyze the concordance between measurements, and sensitivity analysis will be conducted for each participating center.

DISCUSSION

The results obtained will be of great interest to the scientific geriatric community to assess the utility and validity of ultrasound measurements for the detection and follow-up of sarcopenia in hospitalized older adults, and its association with adverse outcomes.

TRIAL REGISTRATION

NCT05113758. Registration date: November 9^th 2021. Retrospectively registered.

Symptoms of Sarcopenia and Physical Fitness through the Senior Fitness Test

INTRODUCTION

Physical fitness concerns a set of attributes related to the ability to perform physical activity that may justify the symptoms reported by the elderly in the context of sarcopenia.

OBJECTIVE

This study aimed to investigate the relationship between the perception (symptomatology) of physical functioning (what the person thinks they are capable of) and the capacity itself for physical functioning in elderly people in northern Brazil.

METHODS

Cross-sectional study that analyzed 312 elderly people (72.6 ± 7.8 years) from the city of Novo Aripuanã, Amazonas, Brazil. Sarcopenia symptomatology was assessed using the SARC-F, a 5-item questionnaire designed for screening sarcopenia in older individuals in five domains: strength, walking aids, difficulty getting up from a chair, difficulty climbing stairs, and falls. Physical fitness was assessed by the Senior Fitness Test (SFT) battery including balance evaluated with the short version of the Fullerton Advanced Balance scale (FAB).

RESULTS

ROC curve analysis revealed that the tests with the greatest ability to discriminate participants with significant symptoms for sarcopenia (≥4 points on SARC-F) were arm curl and 6 min walk: the probability of suspected sarcopenia increased exponentially with an arm curl < 11.5 reps for men (se = 71%; sp = 69%; AUC = 0.706, 95% CI: 0.612-0.788; p = 0.013) and women (se = 81%; sp = 51%; AUC = 0.671, 95% CI: 0.601-0.735; p ≤ 0.001) or with a 6-min walk <408.5 m for men (se = 71%; sp = 63%; AUC = 0.720, 95% CI: 0.628-0.690; p = 0.001) and <366.0 m for women (se = 69%; sp = 58%; AUC = 0.692, 95% CI: 0.623-0.755; p = 0.0001).

CONCLUSIONS

Physical fitness assessed through the senior fitness test, particularly the 30-s-arm curl test and the 6-min walk test, can discriminate for suspected symptoms of sarcopenia.

Food insecurity as a risk factor of sarcopenic obesity in older adults

Sarcopenic obesity is characterized by the loss of muscle strength, mass and muscle functionality and increased adipose tissue (obesity) according to different criteria and cut-off points. The prevalence of sarcopenic obesity among older adults is growing worldwide, and many factors are involved in its development. Diet and food security have been described as the main contributors to the development of obesity and sarcopenia. Food insecurity consists of limited or uncertain access to adequate and nutritious foods. This narrative review aims to summarize the existing data on food insecurity as a risk factor for sarcopenic obesity in the elderly.