What is dynapenia?

Older age is associated with decreased overall shoulder strength but not direction-specific differences in the three-dimensional feasible torque space

Shoulder strength is reduced in older adults but has only been assessed in planar motions that do not reflect the diverse requirements of daily tasks. We quantified the impact of age on strength spanning the three degrees of freedom relevant to shoulder function, referred to as the feasible torque space. We hypothesized that the feasible torque space would differ with age and expected this age-effect to reflect direction-specific deficits. We measured strength in 32 directions to characterize the feasible torque space of the shoulder in participants without shoulder pain or tendinous pathology (n = 39, 19-86 years). We modeled the feasible torque space for each participant as an ellipsoid, computed the ellipsoid size and direction-specific metrics (ellipsoid position, orientation, and shape), and then tested the effect of age on each metric. Age was negatively associated with ellipsoid size (a measure of overall strength magnitude; -0.0033 ± 0.0007 (Nm/kg)/year, p < 0.0001). Contrary to our expectation, the effect of age on the direction-specific metrics did not reach statistical significance. The effect of age did not differ significantly between male and female participants. Three-dimensional strength measurements allowed us to constrain the direction of participants' maximum torque production and characterize the entire feasible torque space. Our findings support a generalized shoulder strengthening program to address age-related shoulder weakness in those without pain or pathology. Clinical exam findings of imbalanced weakness may suggest underlying pathology beyond an effect of age. Longitudinal studies are needed to determine the positive or negative impact of our results.

Muscle strength in ostensibly healthy non-diabetic subjects

BACKGROUND/PURPOSE

Sarcopenia and decreased muscle strength (dynapenia) are emerging health issues. However, the study exploring muscle strength changes of both upper and lower limbs at the same time among all age groups is rare. This study aims to investigate the muscle strength and to establish a muscle strength norm of an ostensibly healthy non-diabetic Asian population.

METHODS

From 2018 June to 2020 March, subjects (aged from 20 to <80 years old) undergoing health checkup in Good Liver Medical Examination Center and National Taiwan University Hospital Geriatrics and Gerontology Department were enrolled. A battery of muscle power examinations including handgrip strength (HGS), five times sit-to-stand test (5TSTS), and one-leg standing test (OLST) were performed.

RESULTS

A total of 183 participants was enrolled, consisting of 92 females and 91 males. The finding shows the strongest HGS, best 5TSTS, and the longest OLST of both genders appeared in the 20-29-year-old group. Age, gender, and palm length are significantly related to HGS, whereas age is the only factor affecting 5TSTS and OLST. It revealed a progressive decline during ageing process, especially after age 60. Finally, Z-score and T-score norms of these were established.

CONCLUSION

These data will be useful as normal controls for muscle strength of specific disease groups. The application of the cutoffs from these data and their comparisons with the recommended cutoffs from various guidelines worth further exploration.

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.

Associating frailty and dynamic dysregulation between motor and cardiac autonomic systems

Frailty is a geriatric syndrome associated with the lack of physiological reserve and consequent adverse outcomes (therapy complications and death) in older adults. Recent research has shown associations between heart rate (HR) dynamics (HR changes during physical activity) with frailty. The goal of the present study was to determine the effect of frailty on the interconnection between motor and cardiac systems during a localized upper-extremity function (UEF) test. Fifty-six individuals aged 65 or above were recruited and performed the previously developed UEF test consisting of 20-s rapid elbow flexion with the right arm. Frailty was assessed using the Fried phenotype. Wearable gyroscopes and electrocardiography were used to measure motor function and HR dynamics. In this study, the interconnection between motor (angular displacement) and cardiac (HR) performance was assessed, using convergent cross-mapping (CCM). A significantly weaker interconnection was observed among pre-frail and frail participants compared to non-frail individuals (p < 0.01, effect size = 0.81 ± 0.08). Using logistic models, pre-frailty and frailty were identified with sensitivity and specificity of 82%-89%, using motor, HR dynamics, and interconnection parameters. Findings suggested a strong association between cardiac-motor interconnection and frailty. Adding CCM parameters in a multimodal model may provide a promising measure of frailty.

Prediction of 1-year change in knee extension strength by neuromuscular properties in older adults

Improving muscle strength and preventing muscle weakness are important for older adults. The change in strength can be effectively explained by skeletal muscle mass and neural factors. Neural factors are important for older adults because the variation of neural components is greater in older than in young adults, and any decline in strength cannot solely be explained by a decrease in skeletal muscle mass. The purpose of the present study was to investigate whether skeletal muscle mass or motor unit firing properties could explain the change in muscle strength after 1 year. Thirty-eight older adults (75.0 ± 4.7 years, 156.6 ± 7.7 cm, 55.5 ± 9.4 kg, 26 women) performed maximum voluntary knee extension and their skeletal muscle mass was measured using a bioimpedance device. During a submaximal contraction task, high-density surface electromyography was recorded and the signals were decomposed into individual motor unit firing. As an index of motor unit firing properties, the slope and y-intercept (MU intercept) were calculated from the regression line between recruitment thresholds and firing rates in each participant. After 1 year, their maximum knee extension torque was evaluated again. A stepwise multiple regression linear model with sex and age as covariates indicated that MU intercept was a significant explanation with a negative association for the 1-year change in muscle strength (β =  - 0.493, p = 0.004), but not skeletal muscle mass (p = 0.364). The results suggest that neural components might be predictors of increasing and decreasing muscle strength rather than skeletal muscle mass.

Prevalence and impact of sarcopenia in individuals with heart failure with reduced ejection fraction (the SARC-HF study): A prospective observational study protocol

Sarcopenia, a clinical syndrome primarily associated with reduced muscle mass in the elderly, has a negative impact on quality of life and survival. It can occur secondarily to other diseases such as heart failure (HF), a complex clinical syndrome with high morbidity and mortality. The simultaneous occurrence of these two conditions can worsen the prognosis of their carriers, especially in the most severe cases of HF, as in patients with reduced left ventricular ejection fraction (LVEF). However, due to the heterogeneous diagnostic criteria for sarcopenia, estimates of its prevalence present a wide variation, leading to new criteria having been recently proposed for its diagnosis, emphasizing muscle strength and function rather than skeletal muscle mass. The primary objective of this study is to evaluate the prevalence of sarcopenia and/or dynapenia in individuals with HF with reduced LVEF according to the most recent criteria, and compare the gene and protein expression of those patients with and without sarcopenia. The secondary objectives are to evaluate the association of sarcopenia and/or dynapenia with the risk of clinical events and death, quality of life, cardiorespiratory capacity, ventilatory efficiency, and respiratory muscle strength. The participants will answer questionnaires to evaluate sarcopenia and quality of life, and will undergo the following tests: handgrip strength, gait speed, dual-energy X-ray absorptiometry, respiratory muscle strength, cardiopulmonary exercise, as well as genomic and proteomic analysis, and dosage of N-terminal pro-B-type natriuretic peptide and growth differentiation factor-15. An association between sarcopenia and/or dynapenia with unfavorable clinical evolution is expected to be found, in addition to reduced quality of life, cardiorespiratory capacity, ventilatory efficiency, and respiratory muscle strength.

Differential association between physical activity behaviours and dynapenia by comorbid diseases in community-dwelling Korean older adults

BACKGROUND

Physical activity (PA) behaviours and comorbid diseases are associated with muscle strength. However, the association between dynapenia and detailed PA behaviours, including participation in aerobic and resistance exercises and sedentary behaviour (SB), in relation to comorbid diseases has not yet been investigated. Using nationwide data, this study aimed to evaluate the independent association of dynapenia with detailed PA behaviour (participation in aerobic and resistance exercises and SB), and assess the differential associations of detailed PA behaviour with dynapenia according to comorbid diseases with prevalent sarcopenia.

METHODS

A total of 7,558 community-dwelling older adults aged ≥ 65 years who were included in the Korea National Health and Nutrition Examination Survey from 2014 to 2019 were included in the present study. Cross-sectional associations between PA behaviours (participation in aerobic exercise, participation in resistance exercise, and SB) and dynapenia were analysed using complex-sample multivariable-adjusted logistic regression models according to the type of comorbid disease (cardiovascular disease [CVD], diabetes mellitus [DM], and chronic lung disease [CLD]).

RESULTS

Sufficient aerobic exercise, sufficient resistance exercise, and low sedentary time of < 420 min/day showed independent negative associations with dynapenia (odds ratio [OR], 0.71; 95% confidence interval [CI], 0.60-0.83; OR, 0.54; 95% CI, 0.42-0.69; and OR, 0.84; 95% CI, 0.72-0.97, respectively). Among the participants with CVD or CLD, the associations of sufficient resistance exercise (OR, 0.46; 95% CI, 0.26-0.82 and OR, 0.51; 95% CI, 0.35-0.75 for CVD and CLD, respectively) and low sedentary time (OR, 0.66; 95% CI, 0.45-0.98 and OR, 0.71; 95% CI, 0.55-0.93 for CVD and CLD, respectively) with dynapenia were significant, whereas the association of sufficient aerobic exercise with dynapenia was insignificant. Meanwhile, in participants with DM, sufficient aerobic exercise (OR, 0.70; 95% CI, 0.52-0.94) and sufficient resistance exercise (OR, 0.45; 95% CI, 0.29-0.70) were independently associated with dynapenia, whereas no association between SB and dynapenia was found.

CONCLUSION

We observed an independent inverse association between PA behaviours and dynapenia. Disease-specific associations between each PA behaviour (sufficient aerobic exercise, sufficient resistance exercise, and low sedentary time) and dynapenia differed in the older adults. Therefore, these differences should be acknowledged during interventions for this population.

Associations of Dynapenic Abdominal Obesity and Frailty Progression: Evidence from Two Nationwide Cohorts

The associations of dynapenic abdominal obesity and transitions with frailty progression remain unclear among middle-aged and older adults. We included 6937 participants from the China Health and Retirement Longitudinal Study (CHARLS) and 3735 from the English Longitudinal Study of Aging (ELSA). Participants were divided into non-dynapenia and non-abdominal obesity (ND/NAO), abdominal obesity alone (AO), dynapenia alone (D), and dynapenic abdominal obesity (D/AO). Frailty status was assessed by the frailty index (FI), and a linear mixed-effect model was employed to analyze the associations of D, AO, D/AO, and transitions with frailty progression. Participants with AO, D, and D/AO had increased FI progression compared with ND/NAO in both cohorts. D/AO possessed the greatest additional annual FI increase of 0.383 (95% CI: 0.152 to 0.614), followed by D and AO in the CHARLS. Participants with D in the ELSA had the greatest magnitude of accelerated FI progression. Participants who transitioned from ND/NAO to D and from AO to D/AO presented accelerated FI progression in the CHARLS and ELSA. In conclusion, dynapenic abdominal obesity, especially for D/AO and D, presented accelerated frailty progression. Our findings highlighted the essential intervention targets of dynapenia and abdominal obesity for the prevention of frailty progression.

Dynapenic Abdominal Obesity and Metabolic Health in Non-Geriatric Patients with Obesity

Background: Dynapenic abdominal obesity (DAO) is the combination of low muscle strength and high central adiposity, which can lead to functional and cardiometabolic impairments. Objective: The aim of this study was to examine the relationship between DAO and metabolic parameters in non-geriatric patients with obesity. Methods: All patients seen in the obesity outpatient clinic during a random month, along with 30 healthy individuals, were included in the study. Body mass index (BMI), waist circumference (WC), hip circumference (HC), serum fasting blood glucose, triglyceride, high-density lipoprotein, low-density lipoprotein (LDL), insulin, and glycated hemoglobin (HbA1c) levels were measured. Muscle function tests were conducted. Hypertension and diabetes mellitus diagnoses were recorded. DAO was determined using handgrip strength and WC. Metabolic syndrome was defined based on International Diabetes Federation (IDF) criteria. Data were analyzed using SPSS. Results: A total of 106 individuals participated in the study, including 76 individuals with obesity as the case group and 30 healthy individuals as the control group. In the case group, BMI, WC, HC, and chair stand test results were higher compared to the control group. There was no significant difference between the case and control groups in terms of gait speed or handgrip test results. In the case group, 30 people (39.5%) had dynapenic obesity (DO), and in the control group, 8 people (26.7%) had DO. There was no significant difference in DO rates between the case and control groups. In the case group, the HbA1c level was higher in DO (+) group than DO (-) group. In the control group, DO (+) group had higher LDL and HbA1c level than DO (-) group. No significant difference was observed in other search parameters between the DO (+) and DO (-) groups in both the case and control groups. Conclusion: DAO is common among people with obesity and contributes to a poor prognosis, increased morbidity, and mortality. Therefore, including its treatment in the management of obesity is crucial for individuals of all age ranges.

Motor unit firing patterns in older adults with low skeletal muscle mass

Muscular dysfunctions involving a decline in muscle strength are often induced by loss of muscle mass in older adults. Understanding neural activation in older adults in addition to muscular characteristics may be important to prevent such age-related dysfunctions. This study aimed to investigate the difference in motor unit firing patterns between community-dwelling older individuals with normal and low skeletal muscle mass. Sixty-six older adults (62-90 years) performed muscle strength and function tests. On conducting high-density surface electromyography of the vastus lateralis, individual motor unit firing properties were assessed. Individual motor units were divided into three different recruitment threshold groups and their firing rates were compared. The skeletal muscle quantity and quality were assessed using bioimpedance methods and ultrasound images. They were divided into two groups according to sarcopenia criteria: a normal group (n = 39) and presarcopenia group with low skeletal muscle mass but normal physical functions (n = 21). Skeletal muscle mass and muscle thickness were greater and echo intensity was lower in the normal group than presarcopenia group. Motor units in normal older adults fired at different rates with a hierarchy depending on their recruitment threshold, observed as a normal phenomenon. However, motor units in the presarcopenia group fired without showing the hierarchical pattern. The results suggest that older adults with low skeletal muscle mass exhibited an abnormal neural input pattern, in addition to declines in muscle quantity and quality.

Effects of photobiomodulation therapy on the functional performance of healthy individuals: a systematic review with meta-analysis

The aim of this study is to assess the effect of photobiomodulation therapy (PBMT) on functional performance concerning strength, fatigue, and functional capacity in healthy individuals. This systematic review with meta-analysis involved searches on data platforms and active searches of randomized clinical trials, focusing on PBMT as the sole intervention. Primary outcomes assessed included strength, fatigue, and functional capacity. Three reviewers screened studies by title and abstract using Rayyan, and data were extracted using a specific form. Bias risk was assessed using RoB2, and confidence in the evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). The RevMan was used for meta-analysis. Sixteen studies were included, totaling 340 individuals (183 males and 157 women). Most articles presented a low risk of bias. Variability was observed in device types and application domains, including wavelengths (655-905 nm), power (10-200 nW), energy (0.6-30 J per point), and time (30-100 s per point). PBMT improved fatigue recovery (mean difference: 5.87; 95% CI 3.83, 7.91). There was no enhancement in strength (peak torque: mean difference 12.40; 95% CI -5.55, 30.55; one-repetition maximum test: mean difference 39.97, 95% CI -2.44, 82.38; isometric and isokinetic strength: mean difference 2.77, 95% CI -14.90, 20.44) nor improvement in short-term (mean difference 0.67, 95% CI -0.58, 1.91) and long-term (mean difference 18.44, 95% CI -55.65, 92.54) functional capacity. PBMT may aid in favoring fatigue recovery in healthy individuals; however, there's no evidence to support PBMT enhancing strength or improving functional capacity.

The combined deleterious effects of multiple sclerosis and ageing on neuromuscular function

BACKGROUND

The prevalence of older (>60 years) people with multiple sclerosis (pwMS) is increasing. This introduces numerous challenges, as both MS and ageing independently contribute to the deterioration of neuromuscular function.

AIM

The aim was to compare the neuromuscular function in pwMS and healthy controls (HC) across three age groups: young, middle-aged, and old.

METHODS

Using a cross-sectional study design, the maximal muscle strength (Fmax) and rate of force development (RFD) of the knee extensors (KE) and plantar flexors (PF) were assessed using an isokinetic dynamometer. In addition, voluntary activation (VA) and resting twitch (RT) were measured using the interpolated twitch technique.

RESULTS

The Fmax, RFD, and VA of the KE were reduced in pwMS compared to HC across age groups. In pwMS, reductions were observed in PF Fmax, RFD, and RT, predominantly in the middle-aged and old age groups. Reductions increased with age in KE for both groups (except for VA) but in PF only for pwMS. The "trajectory" differed between pwMS and HC, as pwMS showed reductions from young to middle age, while HC showed reductions from middle to old age in KE.

CONCLUSION

The combined negative effects of MS and ageing on neuromuscular function were especially present in the PF but also substantial in the KE. RFD showed large deficits for pwMS compared to HC across age groups. The findings can partly be explained by a reduction in VA and RT, but further investigations of neural regulation are needed to explain large RFD deficits.

May the Force Be with Youth: Foundational Strength for Lifelong Development

ABSTRACT

Today's youth are weaker than previous generations, and measurable reductions in physical fitness are beginning to emerge. Without targeted initiatives that recognize the foundational importance of resistance training, weaker children and adolescents may be more likely to experience the inevitable consequences of neuromuscular dysfunction and less likely to experience the pleiotropic benefits of exercise and sport. Early exposure to strength-building activities is needed to prepare today's youth for ongoing participation in varied physical activities throughout this developmental phase of life. The novel iceberg of physical development is a metaphoric image that illustrates the sequential and cumulative influence of muscular strength on motor skills and physical abilities. Efforts to enhance the physical capacity of youth should include resistive skills that improve basic movement patterns and enhance motoric competence. A shift in our conceptual thinking about youth resistance training is needed to alter the current trajectory toward physical inactivity and related comorbidities.

Modifiable kidney disease risk factors among nondiabetic adults with obesity from the Multi-Ethnic Study of Atherosclerosis

OBJECTIVE

It is unknown whether weight change or physical fitness is associated with chronic kidney disease (CKD) risk among nondiabetic adults with obesity.

METHODS

This was a prospective, longitudinal cohort study of adults with obesity without baseline CKD or diabetes enrolled in the Multi-Ethnic Study of Atherosclerosis (MESA). Linear mixed-effects and multistate models were adjusted for demographics, time-varying covariates including blood pressure, and comorbidities these were used to examine associations of weight change and slow walking pace (<2 miles/h) with (i) rate of annual estimated glomerular filtration rate (eGFR) decline and (ii) incident CKD, defined as eGFRCr-Cys  < 60 mL/min/1.73 m2 , and tested for interaction by baseline hypertension status.

RESULTS

Among 1208 included MESA participants (median BMI 33.0 kg/m2 [interquartile range 31.2-35.9]), 15% developed CKD. Slow walking pace was associated with eGFR decline (-0.27 mL/min/1.73 m2 /year; 95% CI: -0.42 to -0.12) and CKD risk (adjusted hazard ratio 1.48; 95% CI: 1.08 to 2.01). Weight gain was associated with CKD risk (adjusted hazard ratio 1.34; 95% CI: 1.02 to 1.78 per 5 kg weight gain from baseline). There was no significant interaction by baseline hypertension status.

CONCLUSIONS

Slow walking pace and weight gain were associated with CKD risk among adults with obesity who did not have diabetes at baseline.

Association between Chronic Kidney Disease and Dynapenia in Elderly Koreans

Chronic kidney disease (CKD) is caused by various factors such as chronic inflammation, oxidative stress, and obesity. Loss of muscle strength and mass is a negative prognostic factor for CKD. Therefore, in this study, we aimed to investigate the association between CKD and dynapenia in the Korean elderly. To this end, we analyzed 7029 participants from the 2014-2019 Korean National Health and Nutrition Examination Survey (KNHANES) aged ≥65 years. After adjusting for all of the covariates that could affect the results, such as physical examinations, lifestyle factors, and exercise, the association between CKD and dynapenia was found to be significant, at 1.207 (95% CI: 1.056-1.379) in CKD stage 2 and 1.790 (95% CI: 1.427-2.246) in CKD stage 3a-5. However, when sexes were analyzed separately, women were significant in both CKD stage 2 and stage 3-5 compared to normal, but only in stage 3-5 for men. Additionally, the prevalence of dynapenia increased significantly as the stage of CKD increased (normal, stage 2, and stage 3-5: 18.5%, 20.8%, and 32.3% in men and 27.5%, 34.4%, and 46.1% in women, respectively). Thus, CKD is significantly related to dynapenia, especially in women, when stratified by sex.

Causal influence of muscle weakness on cardiometabolic diseases and osteoporosis

The causal roles of muscle weakness in cardiometabolic diseases and osteoporosis remain elusive. This two-sample Mendelian randomization (MR) study aims to explore the causal roles of muscle weakness in the risk of cardiometabolic diseases and osteoporosis. 15 single nucleotide polymorphisms (SNPs, P < 5 × 10-8) associated with muscle weakness were used as instrumental variables. Genetic predisposition to muscle weakness led to increased risk of coronary artery disease (inverse variance weighted [IVW] analysis, beta-estimate: 0.095, 95% confidence interval [CI]: 0.023 to 0.166, standard error [SE]:0.036, P-value = 0.009) and reduced risk of heart failure (weight median analysis, beta-estimate: - 0.137, 95% CI - 0.264 to - 0.009, SE:0.065, P-value = 0.036). In addition, muscle weakness may reduce the estimated bone mineral density (eBMD, weight median analysis, beta-estimate: - 0.059, 95% CI - 0.110 to - 0.008, SE:0.026, P-value = 0.023). We found no MR associations between muscle weakness and atrial fibrillation, type 2 diabetes or fracture. This study provides robust evidence that muscle weakness is causally associated with the incidence of coronary artery disease and heart failure, which may provide new insight to prevent and treat these two cardiometabolic diseases.

A cross-sectional study of ageing at the mouse neuromuscular junction and effects of an experimental therapeutic approach for dynapenia

Despite prior efforts to understand and target dynapenia (age-induced loss of muscle strength), this condition remains a major challenge that reduces the quality of life in the aged population. We have focused on the neuromuscular junction (NMJ) where changes in structure and function have rarely been systematically studied as a dynamic and progressive process. Our cross-sectional study found neurotransmission at the male mouse NMJ to be biphasic, displaying an early increase followed by a later decrease, and this phenotype was associated with structural changes to the NMJ. A cross-sectional characterization showed that age-induced alterations fell into four age groups: young adult (3-6 months), adult (7-18 months), early aged (19-24 months), and later aged (25-30 months). We then utilized a small molecule therapeutic candidate, GV-58, applied acutely during the later aged stage to combat age-induced reductions in transmitter release by increasing calcium influx during an action potential, which resulted in a significant increase in transmitter release. This comprehensive study of neuromuscular ageing at the NMJ will enable future research to target critical time points for therapeutic intervention. KEY POINTS: Age-induced frailty and falls are the leading causes of injury-related death and are caused by an age-induced loss of muscle strength due to a combination of neurological and muscular changes. A cross-sectional approach was used to study age-induced changes to the neuromuscular junction in a mouse model, and physiological changes that were biphasic over the ageing time course were found. Changes in physiology at the neuromuscular junction were correlated with alterations in neuromuscular junction morphology. An acutely applied positive allosteric gating modifier of presynaptic voltage-gated calcium channels was tested as a candidate therapeutic strategy that could increase transmitter release at aged neuromuscular junctions. These results provide a detailed time course of age-induced changes at the neuromuscular junction in a mouse model and test a candidate therapeutic strategy for weakness.

Cross-Sectional Study on the Association Between Respiratory Muscle Strength and Dynapenic Abdominal Obesity in Community-Dwelling Older Adults

Purpose

Impaired respiratory muscle strength has been associated with some geriatric syndromes. However, no studies have previously evaluated the relationship between respiratory muscle strength and dynapenic abdominal obesity. This study aimed to analyze whether there is an association between respiratory muscle strength and abdominal obesity, dynapenia and dynapenic abdominal obesity (DAO) in community-dwelling older adults.

Patients and Methods

Cross-sectional study conducted with community-dwelling older adults (n=382 / 70.03 ± 7.3 years) from Macapá, Amapá, Brazil. Respiratory muscle strength was assessed by measuring maximal inspiratory and expiratory pressures (MIP and MEP, respectively), using an analog manovacuometry. DAO was defined as the combination of dynapenia (grip strength < 26 kgf for men and < 16 kgf for women) and abdominal obesity (abdominal circumference > 102 cm for men and > 88 cm for women). We performed descriptive and inferential statistical analyses using the student's t-test for independent and related samples and linear regression model.

Results

Older adults with abdominal obesity, dynapenia, and DAO presented lower mean values (obtained and obtained versus predicted; except abdominal obesity versus MIP) for maximal respiratory pressures compared to individuals without these conditions. However, the adjusted analysis only indicated an association between MIP and the following conditions: dynapenia (MIP - β =-0.171; p<0.001), abdominal obesity (MIP - β=0.102; p=0.042), and DAO (MIP - β=-0.101; p=0.028).

Conclusion

Older adults with abdominal obesity, dynapenia, and DAO showed impaired maximal respiratory pressures. The results of the adjusted analysis indicate that inspiratory muscle strength may require greater attention by health professionals aiming at preventing respiratory complications and improving respiratory health care in older people with these conditions.

Prevalence of dynapenia and overlap with disability, depression, and executive dysfunction

OBJECTIVE

This study aims to investigate handgrip strength and dynapenia prevalence among older adults stratified by Brazilian macroregions. Additionally, we aim to evaluate the overlap between dynapenia and Instrumental Activities of Daily Living (IADL) disability, depression, and executive dysfunction on a national basis and by each Brazilian macroregion.

METHODS

This cross-sectional analysis was based on data from the Brazilian Longitudinal Study of Aging (ELSI-Brazil). A multistage cluster sample design was used, with a representative population-based study of non-institutionalized community-dwelling Brazilians aged ≥ 50 years from 70 municipalities across all five macroregions of the country. The outcome variable was dynapenia. Covariables were IADL disability, depression, and executive dysfunction. The Brazilian macroregions were used for stratification. In addition, the following additional variables were included: age group, gender, education level, macroregions (North, Northeast, Southeast, South, and Midwest), self-reported health, multimorbidity, and falls.

RESULTS

A total of 8,849 (94%) of the sample provided complete information for the handgrip strength assessment and were included in this analysis. Dynapenia prevalence was higher in North and Northeast regions (28.5% and 35.1%, respectively). We identified statistically significant differences between different macroregions for dynapenia, IADL disability, and verbal fluency, with worse values in the North and Northeast regions. In the North and Northeast macroregions, nearly half of the subjects that presented executive dysfunction and IADL disability also had dynapenia. There was a more significant overlap in the prevalence of all four conditions in the North and Northeast regions (4.8% and 5.5%, respectively), whereas the overlap was smaller in the South (2.3%). There was also a smaller overlap in the prevalence of dynapenia and depression in the South (5.8%) compared with other macroregions.

CONCLUSIONS

Macroregions in Brazil exhibit marked differences in the prevalence of dynapenia and in its overlap with IADL disability, depression, and executive dysfunction.

Waist-to-height ratio and dynapenic abdominal obesity in users of hemodialysis services

BACKGROUND AND AIMS

Abdominal obesity and decreased muscle strength are risk factors for individuals on hemodialysis. Thus, the combination of these two factors known as dynapenic abdominal obesity acts as an important marker of the nutritional status of this population. Therefore, the objective of the work was to investigate the association between abdominal obesity, dynapenia, and sociodemographic, clinical, and nutritional factors in individuals with chronic kidney disease undergoing hemodialysis.

METHODS AND RESULTS

Cross-sectional study with 940 individuals undergoing hemodialysis in southeastern Brazil. Dynapenic abdominal obesity was defined by the combination of the presence of abdominal obesity, indicated by the waist-to-height ratio, and the reduction in muscle strength, measured by handgrip strength. Binary logistic regression was performed to calculate the odds ratio (OR) and the respective confidence intervals (95% CI). Dynapenic abdominal obesity was present in 45.42% of the study population. We found that being 18-59 years (OR: 3.17; 95% CI 2.35-4.28; p < 0.001) and being overweight (OR: 2.58; 95% CI 1.92-3.47; p < 0.001) increased the chances for the presence of dynapenic abdominal obesity; however, the habit of consuming meals away from home (OR: 0.63; 95% CI 0.47-0.85; p = 0.003) and having preserved behavioral adductor muscle thickness (OR: 0.52; 95% CI 0.38-0.71; p < 0.001) are considered protective factors.

CONCLUSION

Dynapenic abdominal obesity, present in individuals on hemodialysis, may represent a valid nutritional tool for assessing cardiovascular risk and mortality in this population, in order to implement the most effective preventive and/or therapeutic intervention possible.

Dietary protein intake and mortality among survivors of liver cirrhosis: a prospective cohort study

BACKGROUND

Liver cirrhosis is a worldwide burden and is associated with poor clinical outcomes, including increased mortality. The beneficial effects of dietary modifications in reducing morbidity and mortality are inevitable.

AIM

The current study aimed to evaluate the potential association of dietary protein intake with the cirrhosis-related mortality.

METHODS

In this cohort study, 121 ambulatory cirrhotic patients with at least 6 months of cirrhosis diagnosis were followed-up for 48 months. A 168-item validated food frequency questionnaire was used for dietary intake assessment. Total dietary protein was classified as dairy, vegetable and animal protein. We estimated crude and multivariable-adjusted hazard ratios (HRs) with 95% confidence intervals (CIs), applying Cox proportional hazard analyses.

RESULTS

After full adjustment for confounders, analyses showed that total (HR = 0.38, 95% CI = 0.2-1.1, p trend = 0.045) and dairy (HR = 0.38, 95% CI = 0.13-1.1, p trend = 0.046) protein intake was associated with a 62% lower risk of cirrhosis-related mortality. While a higher intake of animal protein was associated with a 3.8-fold increase in the risk of mortality in patients (HR = 3.8, 95% CI = 1.7-8.2, p trend = 0.035). Higher intake of vegetable protein was inversely but not significantly associated with mortality risk.

CONCLUSION

A comprehensive evaluation of the associations of dietary protein intake with cirrhosis-related mortality indicated that a higher intakes of total and dairy protein and a lower intakes of animal protein are associated with a reduced risk of mortality in cirrhotic patients.

Sarcopenia and Cardiovascular Diseases

Sarcopenia is the loss of muscle strength, mass, and function, which is often exacerbated by chronic comorbidities including cardiovascular diseases, chronic kidney disease, and cancer. Sarcopenia is associated with faster progression of cardiovascular diseases and higher risk of mortality, falls, and reduced quality of life, particularly among older adults. Although the pathophysiologic mechanisms are complex, the broad underlying cause of sarcopenia includes an imbalance between anabolic and catabolic muscle homeostasis with or without neuronal degeneration. The intrinsic molecular mechanisms of aging, chronic illness, malnutrition, and immobility are associated with the development of sarcopenia. Screening and testing for sarcopenia may be particularly important among those with chronic disease states. Early recognition of sarcopenia is important because it can provide an opportunity for interventions to reverse or delay the progression of muscle disorder, which may ultimately impact cardiovascular outcomes. Relying on body mass index is not useful for screening because many patients will have sarcopenic obesity, a particularly important phenotype among older cardiac patients. In this review, we aimed to: (1) provide a definition of sarcopenia within the context of muscle wasting disorders; (2) summarize the associations between sarcopenia and different cardiovascular diseases; (3) highlight an approach for a diagnostic evaluation; (4) discuss management strategies for sarcopenia; and (5) outline key gaps in knowledge with implications for the future of the field.

Relationship between lipid profiles and reduced handgrip strength (dynapenia) in hospitalized patients with cirrhosis

BACKGROUND

Dynapenia embraces clinical significance and predictive value separated from skeletal muscle loss among cirrhosis. Moreover, alterations in lipid levels may impact muscle function. It has yet to elucidate the relationship between lipid profiles and muscle strength weakness. We sought to explore which lipid metabolism indicator could be useful to identify patients with dynapenia in daily practice.

METHODS

A retrospective observational cohort study enrolling 262 cirrhotic patients. Analysis of the receiver operating characteristic (ROC) curve was performed to determine the discriminatory cutoff for dynapenia. Multivariate logistic regression was conducted to assess the association between total cholesterol (TC) and dynapenia. Also, we established a model based on the classification and regression tree method.

RESULTS

ROC implicated a cutoff of TC ≤ 3.37 mmol/L to identify dynapenia. Patients with TC ≤ 3.37 mmol/L showed significantly lower handgrip strength (HGS; 20.0 vs. 24.7 kg, P  = 0.003), lower hemoglobin, lower platelet, lower white blood cell count, lower sodium and higher prothrombin-international normalized ratio. A positive correlation was found between TC and HGS values ( r  = 0.1860, P  = 0.003). TC remained a significant association with dynapenia after controlling for variables including age, sex, BMI, and the presence of ascites. The decision tree incorporating TC, BMI, and age had a sensitivity of 71.4%, specificity of 64.9%, and an area under ROC of 0.681.

CONCLUSION

TC ≤ 3.37 mmol/L was significantly associated with the presence of dynapenia. Assessing TC may be helpful for identifying dynapenic patients with cirrhosis in the health care or hospital setting.

Functional brain changes in sarcopenia: evidence for differential central neural mechanisms in dynapenic older women

BACKGROUND

The European Working Group on Sarcopenia in Older People (EWGSOP2) recently revised its definition and diagnostic criteria for sarcopenia, placing muscle strength at the forefront. The pathogenesis of dynapenia (or low muscle strength) is still not fully understood, but there is emerging evidence that central neural factors constitute critical determinants.

METHODS

Our cross-sectional study included 59 community-dwelling older women (mean age 73.1 ± 4.9 years). Participants underwent detailed skeletal muscle assessments for muscle strength defined by handgrip strength and chair rise time measurements using the recently published EWGSOP2 cut-off points. Functional magnetic resonance imaging (fMRI) was assessed during the performance of a cognitive dual-task paradigm, consisting of a baseline, two single-tasks (motor and arithmetic) and one dual-task (motor and arithmetic combined).

RESULTS

Forty-seven percent (28/59) of participants were classified as dynapenic. fMRI results revealed a differential recruitment of motor circuits in the brain during the dual-task condition in dynapenic as compared with non-dynapenic participants. In particular, while the brain activity during the single-tasks did not differ between the two groups, only during the dual-task non-dynapenic participants showed significant increased activation in dorsolateral prefrontal and premotor cortex, and in supplementary motor area as compared to dynapenic participants.

CONCLUSION

Our results point to a dysfunctional involvement of brain networks associated with motor control in dynapenia in a multi-tasking paradigm. A better knowledge of the link between dynapenia and brain functions could provide new impulses in the diagnosis and interventions for sarcopenia.

Effects of Neuromuscular Training on Physical Performance in Older People: A Systematic Review

This systematic review aimed to assess the available evidence on the effects of neuromuscular training on physical performance in older adults. A literature search was conducted across four databases (Psychology and Behavioral (EBSCO), Scopus, Web of Science and PubMed). The PRISMA guidelines were followed. The PEDro scale and Cochrane risk of bias tool were used to assess the quality of and risk of bias in the studies, respectively. The protocol was registered in PROSPERO (code: CRD42022319239). The outcomes were muscle strength, cardiorespiratory fitness, postural balance and gait speed. From 610 records initially found, 10 were finally included in the systematic review, involving 354 older people with a mean age of 67.3 years. Nine of them reported significant changes in at least one variable related to physical performance in the intervention compared to the control groups. The neuromuscular training caused significant improvements in postural balance, flexibility, cardiorespiratory fitness, strength power of the upper and lower limbs and autonomy. The available evidence indicates that neuromuscular training has a positive effect on some variables of physical performance, especially in postural balance; however, the methodological quality and certainty of the evidence in the available literature are limited. Therefore, a greater number of high-quality studies are required to draw definitive conclusions.

Prognostic value of liver damage assessed through direct bilirubin levels and skeletal muscle weakness in patients with heart failure

BACKGROUND

Patients with heart failure (HF) often exhibit signs of liver dysfunction such as high bilirubin concentrations, leading to physical dysfunction and poor prognosis. Nevertheless, the relationship between direct bilirubin (DB), a fractionated form of total bilirubin, and dynapenia remains unclear, as does their effect on prognosis.

OBJECTIVES

This study investigated the association between DB concentrations and dynapenia in patients with HF.

METHODS

This retrospective study included patients with HF who underwent assessments for DB concentration, and handgrip and leg strengths to evaluate dynapenia and muscle weakness, respectively. Multiple logistic regression analyses examined the associations of DB with muscle strength and dynapenia. Additionally, we examined the prognostic value of comorbid high DB concentrations (≥0.5 mg/dL) and dynapenia. The endpoint was all-cause mortality.

RESULTS

Of 853 inpatients, high DB was identified in 147 and dynapenia in 377 (44.2%). Multiple regression analysis revealed that high DB was independently associated with decreased muscle strength (handgrip strength, P = 0.027; leg strength, P = 0.002). After adjusting for covariates, the high DB group (odds ratio: 1.800, 95% confidence interval [CI]: 1.203-2.695, P = 0.004) had a significantly higher risk of dynapenia than the low DB group. During the follow-up period, 189 patients died (median, 1.77 years; interquartile range, 0.64-3.81 years). The risk of death was significantly higher in the high DB and dynapenia group, even after adjusting for HF severity (hazard ratio: 2.610, 95% CI: 1.680-4.051, P<0.001).

CONCLUSIONS

High DB is associated with muscle weakness, and when combined with dynapenia, DB predicts a poorer prognosis in patients with HF.

In vivo potentiation of muscle torque is enhanced in female mice through estradiol-estrogen receptor signaling

Estradiol affects several properties of skeletal muscle in females including strength. Here, we developed an approach to measure in vivo posttetanic twitch potentiation (PTP) of the anterior crural muscles of anesthetized mice and tested the hypothesis that 17β-estradiol (E2) enhances PTP through estrogen receptor (ER) signaling. Peak torques of potentiated twitches were ∼40%-60% greater than those of unpotentiated twitches and such PTP was greater in ovary-intact mice, or ovariectomized (Ovx) mice treated with E2, compared with Ovx mice (P ≤ 0.047). PTP did not differ between mice with and without ERα ablated in skeletal muscle fibers (P = 0.347). Treatment of ovary-intact and Ovx mice with ERβ antagonist and agonist (PHTPP and DPN, respectively) did not affect PTP (P ≥ 0.258). Treatment with G1, an agonist of the G protein-coupled estrogen receptor (GPER), significantly increased PTP in Ovx mice from 41 ± 10% to 66 ± 21% (means ± SD; P = 0.034). Collectively, these data indicate that E2 signals through GPER, and not ERα or ERβ, in skeletal muscles of female mice to augment an in vivo parameter of strength, namely, PTP.NEW & NOTEWORTHY A novel in vivo approach was developed to measure potentiation of skeletal muscle torque in female mice and highlight another parameter of strength that is impacted by estradiol. The enhancement of PTP by estradiol is mediated distinctively through the G-protein estrogen receptor, GPER.

Association of physical function and body composition with falls in pre-frail older adults with poor physical performance: A cross-sectional study

BACKGROUND

Falls in pre-frail older adults is often attributed to poor physical performance, lower muscle quality and quantity. The aims of our study were to determine (i) demographics, physical function, and body composition in pre-frail older adults with poor physical performance (ii) characteristics of fallers amongst those with poor physical performance and (iii) association of physical function and body composition measures with falls in pre-frail older adults with poor physical performance.

METHODS

Cross-sectional study of 328 pre-frail community-dwelling older adults ≥ 60 years. Data was collected on demographics, cognition, short physical performance battery (SPPB) and gait speed. Poor physical performance was defined by SPPB ≤ 9, 5x chair-stand time ≥12 s or gait speed <1 m/s. InBody S10 used to measure body composition.

RESULTS

Mean age 72.51 years, 185(56.4%) females, 276(84.1%) of Chinese ethnicity and 257 (78.4%) had poor physical performance. Within the poor performers, SPPB balance (OR 0.50; 95% CI 0.27-0.92; p = 0.025) and 5x-chair-stand (OR 1.09; 95% CI 1.01-1.18; p = 0.038) in addition to higher body fat percentage, fat mass index, fat mass to fat free mass ratio, all segmental lean masses except for left leg and body cell mass were significantly associated with falls.

CONCLUSIONS

Longer chair-stand time, lower balance, low muscle and high fat mass are associated with falls in poor performers and could serve as screening tools for those at increased risk of falls. The findings from our study need to be validated prospectively in a larger population study.

Evaluation of serum miRNAs expression in frail and robust subjects undergoing multicomponent exercise protocol (VIVIFRAIL)

BACKGROUND

Frailty, defined as physical performance impairment, is a common condition in older adults and can anticipate the development of sarcopenia, a geriatric syndrome characterized by loss of muscle strength and mass. microRNAs (miRNAs) are short molecules of RNA endowed with the ability to modulate gene expression; miRNAs are present in serum and are considered potential biomarkers for several diseases. Serum concentration of miR-451a, miR-93-5p, miR-155-5p, miR-421-3p, miR-425-5p, miR-495-3p and miR-744-5p was recently shown to be altered in sarcopenic patients.

METHODS

We verified if a particular miRNAs pattern could be detected in frailty as well by analyzing these molecules in 50 frail and 136 robust subjects. Additionally, a subgroup of these subjects (15 frail and 30 robust) underwent a 12-week program based on a multicomponent exercise protocol (VIVIFRAIL) consisting of resistance training, gait retraining, and balance training. After the program, serum miRNAs concentration was measured again, to verify whether the physical activity had an effect on their concentration. Moreover, clinical characteristics and indicators of physical performance of all subjects were compared before and after intervention to verify the effect of the VIVIFRAIL program.

RESULTS

At the end of the multicomponent exercise program, Short Physical Performance Battery (SPPB) score as well right and left handgrip (p < 0.05) were significantly increased in frail subjects; right and left handgrip significantly were increased also in robust subjects (p < 0.05). Interestingly, the variation of SPPB was significantly higher in frail compared to robust subjects (p < 0.0001). Moreover, at the end of the program, in frail compared to robust subjects: miR-451a serum concentration was significantly increased (frail: 6.59 × 10⁴; 1.12 × 10⁴-2.5 × 10⁵ c/ng; robust: 2.31 × 10⁴; 1.94 × 10³-2.01 × 10⁵ c/ng) (p < 0.05); and 2) miR-93-5p and miR-495-3p serum concentration was reduced, whereas that of miR-155-5p was significantly increased (p < 0.05 in both cases). Serum concentration of miR-93-5p and miR-495-3p was decreased, and that of miR-155-5p was increased at the end of the program in robust subjects alone, statistical significance being reached for miR-93-5p alone (p = 0.02).

CONCLUSION

These results suggest that serum miR-451a should be investigated as a potential biomarker for frailty and show that the VIVIFRAIL multicomponent program modulates circulatory miRNAs expression, at least in older adults.

Preoperative decline in skeletal muscle strength of patients with cardiovascular disease affects postoperative pulmonary complication occurrence: a single-center retrospective study

BACKGROUND

Dynapenia, defined as age-related skeletal muscle strength decline, has been reported as a poor prognostic factor in patients with cardiovascular disease. Decline in skeletal muscle strength (DS), the main symptom of dynapenia, may be an important clinical indicator in patients undergoing cardiac surgery. However, the relationship between DS and postoperative pulmonary complication occurrence is unclear. Herein, we investigated the relationship between preoperative DS and postoperative pulmonary complication occurrence in patients undergoing cardiac surgery.

METHODS

We enrolled 125 patients who underwent cardiac surgery. DS was determined by low grip strength and quadriceps isometric strength. The patients were divided into DS and non-DS groups. The relationship between the clinical characteristics and preoperative physical function was compared, and factors associated with postoperative pulmonary complication occurrence were investigated using multivariate logistic regression analysis.

RESULTS

There were 42 (33.6%) patients in the DS group and 83 (66.4%) patients in the non-DS group. Compared with the non-DS group, the DS group was significantly older and had a higher body mass index and Japan SCORE (operative mortality rate and major complication rate). The DS group also had a lower estimated glomerular filtration rate and preoperative Barthel index than the non-DS group. Furthermore the DS group had a significantly higher incidence of postoperative pulmonary complications and length of intensive care unit stay, and their postoperative rehabilitation was prolonged compared to the non-DS group. Multivariate logistic regression analysis revealed that DS was a determinant of postoperative pulmonary complications (odds ratio 4.26, 95% confidence interval 1.63‒11.14).

CONCLUSIONS

We showed that preoperative DS was an independent risk factor for postoperative pulmonary complications in patients undergoing cardiac surgery. Skeletal muscle strength before cardiac surgery may be an important clinical indicator for predicting the prognosis of patients from post-surgery to discharge and for planning postoperative rehabilitation programs.

The Association between Non-Alcoholic Fatty Liver Disease and Dynapenia in Men Diagnosed with Type 2 Diabetes Mellitus

Background: Dynapenia and non-alcoholic fatty liver disease (NAFLD) are common, especially in the middle and advanced-age diabetic male population. We aimed to examine the clinical features, NAFLD severity, and parameters associated with the presence of dynapenia in type 2 diabetes mellitus (T2DM) cases. Material and Methods: One hundred thirty-five male patients diagnosed with T2DM between 45 and 65 years of age were included. Patients were staged by ultrasonography according to NAFLD status. Results: There were significant differences in muscle strength, upper arm circumference, calf circumference, and up-and-go test scores between the mild-moderate-severe and non-NAFLD groups (p < 0.001 for all). The frequency of dynapenia was lower, and arm and calf circumferences were higher in patients without NAFLD. The muscle strength, upper arm circumference, calf circumference, and up-and-go test scores were significantly lower in the dynapenic group compared to the non-dynapenic group (p < 0.005 for all). The prevalence of dynapenia increased along with the increase in NAFLD stages (p < 0.001). Conclusions: We detected a significant association between NAFLD and dynapenia in middle-aged men with T2DM. As muscle strength decreases, the amount of fat in the liver increases, and as the fat in the liver increases, muscle strength decreases.

Dynapenic Abdominal Obesity and Risk of Heart Disease among Middle-Aged and Older Adults: A Prospective Cohort Study

OBJECTIVES

The vicious cycle of dynapenia and abdominal obesity may have synergistic detrimental impacts on health. We aim to investigate the prospective association between dynapenic abdominal obesity and the risk of heart disease among middle-aged and older adults.

DESIGN

A prospective cohort study.

SETTING

English Longitudinal Study of Ageing, 2002-2019.

PARTICIPANTS

A total of 4734 participants aged 50 years and older were included.

MEASUREMENTS

Individuals were divided into non-dynapenia/non-abdominal obesity (ND/NAO), non-dynapenia/abdominal obesity (ND/AO), dynapenia/non-abdominal obesity (D/NAO), and dynapenia/abdominal obesity (D/AO) according to grip strength and waist circumference at baseline. The Cox proportional hazards models were used to obtain the hazard ratios (HRs) of incident heart disease associated with dynapenia and abdominal obesity after adjusting for potential confounding factors.

RESULTS

During a median follow-up of 9.5 years, 1040 cases of heart disease were recorded. Compared with ND/NAO group, the multivariable HRs were 1.05 (0.92, 1.21) for ND/AO group, 1.31 (0.96, 1.81) for D/NAO group, and 1.39 (1.03, 1.88) for D/AO group. The significant association of D/AO with incident heart disease was detected in women but not in men [HR = 1.55 (1.07, 2.24) and 1.06 (0.60, 1.88), respectively]. Among middle-aged adults, significant associations of D/NAO and D/AO with incident heart disease were observed [HR = 2.46 (1.42, 4.29) and 1.74 (1.02, 2.97), respectively].

CONCLUSION

Both D/NAO and D/AO might increase the risk of developing heart disease, highlighting the importance of dynapenia and obesity early screening for heart disease prevention.

Reduced muscle strength in patients with long-COVID-19 syndrome is mediated by limb muscle mass

Understanding the impact of COVID-19 on muscle strength may help to elucidate the organ systems that contribute to acute and chronic COVID-19 sequelae. We questioned whether patients with postdischarge symptoms after COVID-19 had compromised muscle strength compared with a control group, and if this potential relationship was mediated by the lower appendicular lean mass index (ALMI). A total of 99 patients with long-COVID-19 and 97 control participants were screened. Maximal grip strength was assessed with a TKK 5101 digital dynamometer, and leg extension 1RM was measured using EGYM Smart Strength machines. Body composition (fat mass percentage, lean mass, visceral fat, and appendicular lean mass index) was determined using a whole body dual-energy X-ray densitometer. Results showed that grip strength and leg extension strength were significantly higher in controls than in COVID-19 survivors (mean [SD], 32.82 [10.01] vs. 26.94 [10.33] kg; difference, 5.87 kg; P < 0.001) and (mean [SD], 93.98 [33.73] vs. 71.59 [33.70] kg; difference, 22.38 kg; P < 0.001), respectively). The relationship between long-COVID syndrome and grip/leg strength levels was partly mediated by ALMI, which explained 52% of the association for grip strength and 39% for leg extension. Our findings provide novel insights into the mechanisms underlying the relationship between long-COVID syndrome and grip/leg strength levels, supporting the negative effects of long-COVID syndrome on muscle function.NEW & NOTEWORTHY The causes of post-COVID-19 syndrome are uncertain. Limb muscle wasting common to patients with COVID-19 limits daily activities and exercise. In this cross-sectional study, we found that patients with long-COVID-19 syndrome had significantly lower absolute and relative muscle strength measurements than control participants. Interestingly, we identified that these relationships were mostly mediated by limb muscle mass. Our data thus suggest that the evident reduced upper and lower muscle mass is a putative cause of-or contributor to-the functional limitation of patients with long-COVID-19 syndrome.

Low muscle strength and low phase angle predicts greater risk to mortality than severity scales (APACHE, SOFA, and CURB-65) in adults hospitalized for SARS-CoV-2 pneumonia

Introduction

The acute physiology and chronic health evaluation (APACHE), sepsis-related organ failure assessment (SOFA), score for pneumonia severity (CURB-65) scales, a low phase angle (PA) and low muscle strength (MS) have demonstrated their prognostic risk for mortality in hospitalized adults. However, no study has compared the prognostic risk between these scales and changes in body composition in a single study in adults with SARS-CoV-2 pneumonia. The great inflammation and complications that this disease presents promotes immobility and altered nutritional status, therefore a low PA and low MS could have a higher prognostic risk for mortality than the scales. The aim of the present study was to evaluate the prognostic risk for mortality of PA, MS, APACHE, SOFA, and CURB-65 in adults hospitalized with SARS-CoV-2 pneumonia.

Methodology

This was a longitudinal study that included n = 104 SARS-CoV-2-positive adults hospitalized at General Hospital Penjamo, Guanajuato, Mexico, the PA was assessed using bioelectrical impedance and MS was measured with manual dynamometry. The following disease severity scales were applied as well: CURB-65, APACHE, and SOFA. Other variables analyzed were: sex, age, CO-RADS index, fat mass index, body mass index (BMI), and appendicular muscle mass index. A descriptive analysis of the study variables and a comparison between the group that did not survive and survived were performed, as well as a Cox regression to assess the predictive risk to mortality.

Results

Mean age was 62.79 ± 15.02 years (31-96). Comparative results showed a mean PA of 5.43 ± 1.53 in the group that survived vs. 4.81 ± 1.72 in the group that died, p = 0.030. The mean MS was 16.61 ± 10.39 kg vs. 9.33 ± 9.82 in the group that died, p = 0.001. The cut-off points for low PA was determined at 3.66° and ≤ 5.0 kg/force for low grip strength. In the Cox multiple regression, a low PA [heart rate (HR) = 2.571 0.726, 95% CI = 1.217-5.430] and a low MS (HR = 4.519, 95% CI = 1.992-10.252) were associated with mortality.

Conclusion

Phase angle and MS were higher risk predictors of mortality than APACHE, SOFA, and CURB-65 in patients hospitalized for COVID-19. It is important to include the assessment of these indicators in patients positive for SARS-CoV-2 and to be able to implement interventions to improve them.

Are Skeletal Muscle Changes during Prolonged Space Flights Similar to Those Experienced by Frail and Sarcopenic Older Adults?

Microgravity exposure causes several physiological and psychosocial alterations that challenge astronauts' health during space flight. Notably, many of these changes are mostly related to physical inactivity influencing different functional systems and organ biology, in particular the musculoskeletal system, dramatically resulting in aging-like phenotypes, such as those occurring in older persons on Earth. In this sense, sarcopenia, a syndrome characterized by the loss in muscle mass and strength due to skeletal muscle unloading, is undoubtedly one of the most critical aging-like adverse effects of microgravity and a prevalent problem in the geriatric population, still awaiting effective countermeasures. Therefore, there is an urgent demand to identify clinically relevant biological markers and to underline molecular mechanisms behind these effects that are still poorly understood. From this perspective, a lesson from Geroscience may help tailor interventions to counteract the adverse effects of microgravity. For instance, decades of studies in the field have demonstrated that in the older people, the clinical picture of sarcopenia remarkably overlaps (from a clinical and biological point of view) with that of frailty, primarily when referred to the physical function domain. Based on this premise, here we provide a deeper understanding of the biological mechanisms of sarcopenia and frailty, which in aging are often considered together, and how these converge with those observed in astronauts after space flight.

Bioenergetic Evaluation of Muscle Fatigue in Murine Tongue

Muscle fatigue is the diminution of force required for a particular action over time. Fatigue may be particularly pronounced in aging muscles, including those used for swallowing actions. Because risk for swallowing impairment (dysphagia) increases with aging, the contribution of muscle fatigue to age-related dysphagia is an emerging area of interest. The use of animal models, such as mice and rats (murine models) allows experimental paradigms for studying the relationship between muscle fatigue and swallowing function with a high degree of biological precision that is not possible in human studies. The goal of this article is to review basic experimental approaches to the study of murine tongue muscle fatigue related to dysphagia. Traditionally, murine muscle fatigue has been studied in limb muscles through direct muscle stimulation and behavioral exercise paradigms. As such, physiological and bioenergetic markers of muscle fatigue that have been validated in limb muscles may be applicable in studies of cranial muscle fatigue with appropriate modifications to account for differences in muscle architecture, innervation ratio, and skeletal support. Murine exercise paradigms may be used to elicit acute fatigue in tongue muscles, thereby enabling study of putative muscular adaptations. Using these approaches, hypotheses can be developed and tested in mice and rats to allow for future focused studies in human subjects geared toward developing and optimizing treatments for age-related dysphagia.

Use It or Lose It? A Meta-Analysis on the Effects of Resistance Training Cessation (Detraining) on Muscle Size in Older Adults

This review aimed to explore the effect of resistance training cessation (detraining) on muscle size in older adults. Five databases were searched to find eligible studies. Their methodological quality was assessed using the PEDro checklist. The data were pooled in a random-effects meta-analysis. Six studies, with eight groups, were included in the review. Resistance training interventions lasted from 9 to 24 weeks. The detraining duration was from 12 to 52 weeks. Studies were classified as being of fair or good methodological quality. Compared to the baseline data, muscle size significantly increased following the resistance training intervention (Cohen's d: 0.99; 95% confidence interval: 0.63, 1.36). Compared to the post-resistance training data, there was a significant decrease in muscle size following training cessation (Cohen's d: -0.83; 95% confidence interval: -1.30, -0.36). In subgroup analyses, there was no significant decrease in muscle size following 12-24 weeks of training cessation (Cohen's d: -0.60; 95% confidence interval: -1.21, 0.01). There was a significant decrease in muscle size following 31-52 weeks of training cessation (Cohen's d: -1.11; 95% confidence interval: -1.75, -0.47). In summary, resistance training increases muscle size in older adults. In contrast, training cessation is associated with a decrease in muscle size. However, the loss of muscle size might be related to detraining duration, with greater muscle loss occurring during longer duration detraining periods. Future studies are required to establish the time course of muscle size changes during detraining in older adults.

Association of Low Handgrip Strength with Chemotherapy Toxicity in Digestive Cancer Patients: A Comprehensive Observational Cohort Study (FIGHTDIGOTOX)

In the FIGHTDIGO study, digestive cancer patients with dynapenia experienced more chemotherapy-induced neurotoxicities. FIGHTDIGOTOX aimed to evaluate the relationship between pre-therapeutic handgrip strength (HGS) and chemotherapy-induced dose-limiting toxicity (DLT) or all-grade toxicity in digestive cancer patients. HGS measurement was performed with a Jamar dynamometer. Dynapenia was defined according to EWGSOP2 criteria (<27 kg (men); <16 kg (women)). DLT was defined as any toxicity leading to dose reduction, treatment delay, or permanent discontinuation. We also performed an exploratory analysis in patients below the included population’s median HGS. A total of 244 patients were included. According to EWGSOP2 criteria, 23 patients had pre-therapeutic dynapenia (9.4%). With our exploratory median-based threshold (34 kg for men; 22 kg for women), 107 patients were dynapenic (43.8%). For each threshold, dynapenia was not an independent predictive factor of overall DLT and neurotoxicity. Dynapenic patients according to EWGSOP2 definition experienced more hand-foot syndrome (p = 0.007). Low HGS according to our exploratory threshold was associated with more all-grade asthenia (p = 0.014), anemia (p = 0.006), and asthenia with DLT (p = 0.029). Pre-therapeutic dynapenia was not a predictive factor for overall DLT and neurotoxicity in digestive cancer patients but could be a predictive factor of chemotherapy-induced anemia and asthenia. There is a need to better define the threshold of dynapenia in cancer patients.

Untargeted muscle tissue metabolites profiling in young, adult, and old rats supplemented with tocotrienol-rich fraction

The greatest significant influence on human life span and health is inevitable ageing. One of the distinguishing characteristics of ageing is the gradual decrease of muscle mass and physical function. There has been growing evidence that tocotrienol can guard against age-associated chronic diseases and metabolic disorders. This study aimed to elucidate the effects of tocotrienol-rich fraction (TRF) on muscle metabolomes and metabolic pathways in ageing Sprague Dawley (SD) rats. Three months, 9 months, and 21 months old male SD rats were divided into control and treated groups with 10 rats per group. Rats in control and treated groups were given 60 mg/kg body weight/day of palm olein and 60 mg/kg body weight/day of TRF, respectively, via oral gavage for 3 months. Muscle performance was assessed at 0 and 3 months of treatment by measuring muscle strength and function. Our results showed that TRF treatment caused a significant increase in the swimming time of the young rats. Comparison in the control groups showed that metabolites involved in lipid metabolisms such as L-palmitoyl carnitine and decanoyl carnitine were increased in ageing. In contrast, several metabolites, such as 3-phosphoglyceric acid, aspartic acid and aspartyl phenylalanine were decreased. These findings indicated that muscle metabolomes involved in lipid metabolism were upregulated in aged rats. In contrast, the metabolites involved in energy and amino acid metabolism were significantly downregulated. Comparison in the TRF-supplemented groups showed an upregulation of metabolites involved in energy and amino acid metabolism. Metabolites such as N6-methyl adenosine, spermine, phenylalanine, tryptophan, aspartic acid, histidine, and N-acetyl neuraminic acid were up-regulated, indicating promotion of amino acid synthesis and muscle regeneration. Energy metabolism was also improved in adult and old rats with TRF supplementation as indicated by the upregulation of nicotinamide adenine dinucleotide and glycerol 3-phosphate compared to the control group. In conclusion, the mechanism underlying the changes in skeletal muscle mass and functions in ageing was related to carbohydrate, lipid and amino acid metabolism. Tocotrienol supplementation showed beneficial effects in alleviating energy and amino acid synthesis that may promote the regeneration and renewal of skeletal muscle in ageing rats.

Gait Characteristics of Dynapenia, Sarcopenia, and Presarcopenia in Community-Dwelling Japanese Older Women: A Cross-Sectional Study

Age-related decline in skeletal muscle mass and function are risk factors for reduced walking ability. This study aimed to understand the characteristic gait parameters of presarcopenia (low muscle mass only), dynapenia (low muscle function only), and sarcopenia (low muscle mass and function), which have differing skeletal muscle characteristics. Skeletal muscle mass, grip strength, and gait parameters (walking speed, cadence, step length, step width, gait angle, foot angle, stance time, swing time, and double stance time) were evaluated in 307 older Japanese women. Low muscle function was determined by grip strength and normal walking speed. Participants were assessed and divided into the normal (60.9%, n = 187), presarcopenia (25.7%, n = 79), dynapenia (5.2%, n = 16), and sarcopenia (8.1%, n = 25) groups. When compared to the normal group, the sarcopenia group had significantly slower walking speed and shorter step length (p < 0.05); the dynapenia group had significantly slower walking speed, smaller cadence, shorter step length, wider step width, and longer stance time (p < 0.05); and the presarcopenia group showed no differences. Skeletal muscle function may therefore be more strongly related to reduced walking function in older adults than body composition factors. The decrease in walking function was most pronounced in older women with dynapenia.

Gender difference in appendicular muscle strength: determinant of the quality of life in the older Taiwanese

Background: The loss of skeletal muscle mass by aging determines the health status and the quality of life (QoL).

Objective: To examine the relationships between appendicular muscle strength and the QoL of elderly adults in gender difference.

Methods: This was a cross-sectional study, in which 690 subjects who participated in older adults health examination in the health management center of Tri-Service General Hospital from 2018 to 2021. A structured questionnaire was used to collect basic demographic data. The 12-Item Short Form Survey (SF-12) was used to evaluate the QoL of subjects. Their grip strength and gait speed were measured, and Dual-energy X-ray absorptiometry was used to measure muscle mass and other body composition data. Multivariate regression analysis was used to examine the relationships between upper and lower limb muscle strength and the QoL of older adults.

Results: In men, legs muscle mass percentage (LegsMM%) (β = 3.67; 95% CI: 0.64–6.69; p = 0.018) and gait speed (β = 6.09; 95% CI: 3.88–8.30; p < 0.001) were positively associated with physical component summary (PCS) scores, and gait speed (β = 4.63; 95% CI: 2.66–6.60; p < 0.001) was also related to an improvement mental component summary (MCS) scores. In women, arms muscle mass percentage (ArmsMM%) (β = 6.50; 95% CI: 2.34–10.66; p = 0.002) and grip strength (β = 10.54; 95% CI: 6.27–14.81; p < 0.001) had the greatest effect on improving PCS scores, whereas grip strength (β = 7.58; 95% CI 4.00–11.17; p < 0.001) was also found to help improve MCS scores.

Conclusions: Men should focus on lower limb training, whereas females should focus on upper limb training to effectively improve their QoL. Appropriate exercise interventions should be designed for different genders for the promotion of the healthy aging policy.

The importance of biological sex in cardiac cachexia

Cardiac cachexia is a catabolic muscle wasting syndrome observed in approximately 1 in 10 heart failure patients. Increased skeletal muscle atrophy leads to frailty and limits mobility which impacts quality of life, exacerbates clinical care, and is associated with higher rates of mortality. Heart failure is known to exhibit a wide range of prevalence and severity when examined across individuals of different ages and with co-morbidities related to diabetes, renal failure and pulmonary dysfunction. It is also recognized that men and women exhibit striking differences in the pathophysiology of heart failure as well as skeletal muscle homeostasis. Given that both skeletal muscle and heart failure physiology are in-part sex dependent, the diagnosis and treatment of cachexia in heart failure patients may depend on a comprehensive examination of how these organs interact. In this review we explore the potential for sex-specific differences in cardiac cachexia. We summarize advantages and disadvantages of clinical methods used to measure muscle mass and function and provide alternative measurements that should be considered in preclinical studies. Additionally, we summarize sex-dependent effects on muscle wasting in preclinical models of heart failure, disuse, and cancer. Lastly, we discuss the endocrine function of the heart and outline unanswered questions that could directly impact patient care.

Muscle Weakness and Walking Slowness for the Identification of Sarcopenia in the Older Adults from Northern Brazil: A Cross-Sectional Study

Background: This study aimed to analyze the prevalence of sarcopenia in elderly people from Northern Brazil according to muscle weakness or walking slowness. Methods: The sample consisted of 312 elderly people (72.6 ± 7.8 years). For walking slowness, a gait speed ≤ 0.8 m/s was used as a cut-off value, and for muscle weakness the following handgrip strength criteria were used for men and women, respectively: CI: <27.0/16.0 kg; CII: <35.5/20.0 kg; CIII: grip strength corrected for body mass index (BMI) < 1.05/0.79; CIV: grip strength corrected for total fat mass: <1.66/0.65; CV: grip strength corrected for body mass: <0.45/0.34. Results: Walking speed was reduced in 27.0% of women and 15.2% of men (p < 0.05). According to grip strength criteria, 28.5% of women and 30.4% of men (CI), 58.0% of women and 75.0% of men (CII), 66.0% of women and 39.3% of men (CIII), 28.8% of women and 19.6% of men (CIV), and 56.5% of women and 50.0% of men (CV) were identified as having sarcopenia. Conclusions: Walking slowness is more prevalent in women and muscle weakness is more prevalent in men in Northern Brazil. Walking slowness proved to be more concordant with muscle weakness in both sexes when the CI for handgrip strength was adopted.

Sarcopenia and cardiovascular risk indices: Its impact on cardiovascular events and mortality in dialysis patients

BACKGROUND

Sarcopenia is a common complication in end-stage renal disease. Low muscle strength and muscle mass are risk factors for cardiovascular disease and mortality in patients undergoing dialysis. We studied the relation between sarcopenia and pre-atherosclerotic markers and its effect on cardiovascular events and death in dialysis patients.

METHODS

We measured muscle strength, muscle mass, carotid intima-media thickness, and pulse wave velocity in 106 patients. Sarcopenia was diagnosed according to the EWGSOP-2 suggestions. Patients with low muscle strength and low muscle mass were considered sarcopenic. The follow-up period for cardiovascular events and mortality was 24 months.

RESULTS

The mean age and dialysis duration were 57.4 ± 16.6 and 6.5 ± 4.9 years, respectively. Of all patients, 53 (50%) were male and 70 (66%) were on hemodialysis treatment. Sarcopenia and low muscle strength were seen in 47.1% and 88.7%, respectively. Hemodialysis patients were more likely to be sarcopenic than peritoneal dialysis patients (p = 0.001). Ferritin and Kt/V levels were higher, and body mass index was lower significantly in sarcopenic patients (p < 0.001). There was no significant difference in carotid intima-media thickness and pulse wave velocity measurements between the groups (p = 0.62 and p = 0.68, respectively). There was no statistically significant difference in cardiovascular events and mortality in cases with and without sarcopenia (p = 0.43 and p = 0.17, respectively).

CONCLUSION

There was no association between sarcopenia and pre-atherosclerotic markers, cardiovascular events, and all-cause mortality in dialysis patients. Techniques to detect low muscle strength and muscle mass need standardization, and new specific cut-off levels must be defined for dialysis patients.

The relationship between radiological paraspinal lumbar measures and clinical measures of sarcopenia in older patients with chronic lower back pain

Objectives

Sarcopenia is postulated to be an influential factor in chronic low back pain. The aim of this study is to evaluate the relationship between traditional clinical measures of sarcopenia and novel radiographic methods which evaluate overall muscle status, such as adjusted psoas cross-sectional area (APCSA) and degree of fat infiltration (%FI) in paraspinal muscles, in patients with chronic low back pain.

Methods

Prospective study performed at our institution from 01/01/19-01/04/19. Inclusion criteria were patients ≥65 years old not requiring surgical intervention presenting to a low back pain assessment clinic.

Results

25 patients were identified (mean age: 73 years, 62% male). On spearman's analyses, %FI shared a significant relationship with hand grip strength (r = -0.37; p=0.03), chair rise (r=0.38; p=0.03), SC (r=0.64; p<0.01), and visual analogue scale scores (r=-0.14; p=0.02). Comparably, a statistically significant correlation was evident between APCSA and %FI (r=-0.40; p=0.02) on analysis.

Conclusion

The results of our study demonstrate a statistically significant relationship between APCSA and %FI in the multifidus and erector spinae muscles. Further significant associations of relatability were depicted with traditional clinical measures of sarcopenia. Thus, %FI may be a supplemental indicator of the sarcopenic status of patients presenting with chronic low back pain.

Association between physical activity and dynapenia in older adults with COPD: a nationwide survey

We aimed to examine the association between physical activity (PA) level and dynapenia in older adults with chronic obstructive pulmonary disease (COPD), and whether it varied with sex and obesity status. The current cross-sectional study included total of 1033 community-dwelling participants with COPD aged 65–79 from the Korean National Health and Nutrition Examination Survey. In the multivariable model, high and moderate PA levels were significantly associated with lower odds of dynapenia than low PA levels (high PA level: odds ratio [OR] = 0.26, 95% confidence interval [CI] = 0.09–0.74; moderate PA level: OR = 0.55, 95% CI = 0.35–0.87). This inverse association was observed only in males with COPD (high PA level: OR = 0.17, CI = 0.04–0.65; moderate PA level: OR = 0.49, 95% CI = 0.27–0.88) and the normal-weight group (18.5 ≤ body mass index (BMI) < 25 kg/m²; high PA level: OR = 0.21, 95% CI = 0.05–0.88; moderate PA level: OR = 0.48, 95% CI = 0.27–0.86). In older community-dwelling patients with COPD, a negative dose-dependent relationship exists between PA level and dynapenia. The independent associations between PA level and dynapenia was significant in men and in participants with normal weight.

The acute effects of action observation on muscle strength/weakness and corticospinal excitability in older adults

Muscle weakness is a critical problem facing many older adults. Interventions targeting nervous system plasticity may show promise in enhancing strength. The purpose of this study was to examine the acute effects of action observation on muscular strength characteristics and corticospinal excitability in older adults. Isometric wrist flexion strength characteristics and corticospinal excitability of the first dorsal interosseous (FDI) were measured in 14 older adults (mean age = 73 years) in response to observation of (1) STRONG contractions of the hand/wrist, (2) WEAK contractions of the hand/wrist, and (3) a CONTROL condition. Results from repeated measures analyses of variance (ANOVAs) indicated that rate of torque development at 200 ms (RTD200) significantly decreased from PRE to POST observation for CONTROL and WEAK, but not STRONG. No other ANOVAs were significant. However, effect sizes indicated that maximal voluntary contraction (MVC) peak torque showed moderate declines following WEAK (d = − 0.571) and CONTROL (d = − 0.636), but not STRONG (d = 0.024). Similarly, rate of torque development at 30 (RTD30), 50 (RTD50), and 200 (RTD200) ms showed large declines from PRE to POST after WEAK and CONTROL, but small changes following STRONG. FDI motor-evoked potential (MEP) amplitude tended to increase over time, but these results were variable. There was a pronounced effect from PRE to 8MIN (d = 0.954) during all conditions. Action observation of strong contractions may exert a preservatory effect on muscular strength. More work is needed to determine whether this is modulated by increased corticospinal excitability. The study was prospectively registered (ClinicalTrials.gov Identifier: NCT03946709).