Assessment Of Muscle Function Research Articles

Start with muscle mass or muscle strength in diagnosis and management of sarcopenia? A systematic review of guidance documents.

Sarcopenia has garnered extensive attention in clinical practice since its high prevalence and significant impact on clinical outcomes. Multiple organizations have published guidance documents on sarcopenia, offering evidence-based recommendations for clinical practice and/or research. We aimed to appraise the methodological quality of the included documents and synthesize available recommendations for the screening, diagnosis, and intervention of sarcopenia. We conducted a search on PubMed, Embase, Scopus, Cochrane Library, China National Knowledge Infrastructure, guideline database, and guideline organizations and professional societies websites for clinical practices, consensus statements and position papers in terms of sarcopenia, muscle atrophy or muscle loss published before April 17, 2023. The AGREE II instrument was used by three independent reviewers to assess the methodological quality of these documents. Thirty-six guidance documents published between 2010 and 2023 were included. Seven documents fulfilled ≥ 50% of all the AGREE II domains. Seven underwent a Delphi process and six graded the strength of the recommendations. The process of screening (n=21), early diagnosis of sarcopenia (n=12), diagnosis of sarcopenia and severe sarcopenia (n=10), and management (n=21) were increasingly recommended. SARC-F (n=14) was the most recommended screening tool, and the assessment of muscle function was considered the first step in diagnosing sarcopenia. The management strategy for both age-related and disease-related sarcopenia mainly focused on exercise and nutrition intervention. The guidance documents have provided referential recommendations that have great guiding significance. But the inconsistency in recommendations and variation in methodological rigour suggests that high-quality evidence is lacking yet.

Muscle fatigue detection based on sEMG signal using autocorrelation function and neural networks

Abstract Feature extraction from an recorded surface electromyography (sEMG) signal plays an important role in identifying and quantifying the characteristics of muscle activities. These features can be used for various applications like muscle function assessment, muscle fatigue detection, etc. Common features extracted from sEMG signal are time-domain or frequency-domain features. However, features which are sensitive to uncertainties in the signal like noise, movement artifacts, and outliers should be avoided. Autocorrelation function (ACF), which is a measure of similarity between a signal and its time delayed version, is considered in this work as a feature to overcome the impact of noise, artifacts, and outliers. An artificial neural network (ANN) is developed to differentiate between fatigue and non-fatigue conditions using the calculated ACF from sEMG segments. The performance of an ANN model that can be adapted by means of various regularization methods was investigated. The proposed ANN model achieved an accuracy of about 97.62 %, a precision of about 95.50 % and a sensitivity of about 100 % in the classification of fatigue and non-fatigue sEMG segments, outperforming k-means and linear support vector machine approaches that served as references.

Short-term treatment of Tat-Beclin1 and endurance exercise enhances autophagy and increases grip strength in old male mice but not in female

Sarcopenia is a geriatric disease causing loss of muscle mass and function, ultimately declining quality of life and causing death. Despite substantial efforts to prevent sarcopenia, there are no approved drugs for treating this muscle disease. Autophagy, a critical process for maintaining muscle health, offers potential avenues for intervention. However, an integrative therapy comprised of an autophagic-specific compound and endurance exercise in old animals has yet to be tested. We hypothesize that combining Tat-Beclin1 (a potent autophagy-specific inducer) and endurance exercise improves muscle force and autophagy in both male and female old mice. Female and male mice at 23 months of age were divided into four groups: Control, Tat-Beclin1 (TB), endurance exercise (Exe), and TB+Exe. Short-term combined treatment underwent for one month. Exercise training at moderate intensity (70% of running peak test) was performed on Mondays, Wednesdays, and Fridays. Tat-Beclin1 administration (15 mg/kg/day) was conducted on Tuesdays and Thursdays. We assessed muscle function through forelimb grip strength and muscle autophagic markers by western blotting. There was no difference in grip strength in female groups. In contrast, there was an increase in grip strength in treated male mice (p<0.05; TB, Exe, and TB+Exe vs. Control group). Notably, the combination treatment in the TB+Exe group outperformed the individual treatments (TB and Exe groups) in enhancing grip strength (p=0.05). Beclin1 and GLIPR2 (a novel autophagic suppressor) were unchanged in both male and female mice. Sequestosome/p62 was decreased in males only, indicating autophagy cargo degradation. Our findings demonstrate that a short-term treatment of Tat-Beclin1 combined with endurance exercise improves grip strength (muscle force) and autophagy in old male mice. Notably, female mice did not exhibit a similar response to the short-term treatment, suggesting that a more extended therapy duration may be necessary to explore potential benefits for female mice. This synergy of an autophagic-specific agonist with endurance exercise may represent a novel strategy to tackle sarcopenia. Camden Health Research Initiative - Startup fundings. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Novel Method to Assess Treatment Effcacy in Preclinical Peripheral Arterial Disease Studies

Background: Peripheral arterial disease (PAD), a condition caused by atherosclerotic narrowing or occlusion of blood vessels in the lower extremities, affects ~200 million adults globally and lacks effective treatment options to improve limb function. Cilostazol is the only approved pharmacological treatment option for PAD patients, but its effect on walking performance is modest and the drug is not widely used clinically. Over the past several decades, numerous therapies (drug, gene, and cell-based) have shown promise in the preclinical setting but failed to achieve primary outcomes in clinical trials. While the failure of therapeutic translation is complex, most preclinical studies have employed perfusion recovery as a primary outcome variable whereas most clinical trials in PAD patients employ the six-minute walk test. Although perfusion is an important contributor to limb function and walking performance, assessing preclinical therapeutics solely via perfusion recovery may be a flawed approach. Objective: To address the need for a more comprehensive method to assess the effcacy of preclinical PAD therapeutics, we aimed to develop a protocol to assess hindlimb function that incorporates assessment of muscle power and perfusion across a six-minute testing period. Methods: To assess muscle contractile performance, the tibialis anterior or plantarflexor muscles were carefully exposed and the distal tendon mounted to the force-length controller (Aurora Scientific) and the muscles were stimulated via the sciatic nerve in anesthetized C57BL6 mice. After obtaining isometric forces, a six-minute functional test was performed using repeated isotonic (shortening) contractions against a submaximal load (30% or 45% of the reference force). Muscle fatigue was measured as a change in power across the testing period. Throughout the test, laser Doppler flowmetry was used to measure muscle blood flow. Hindlimb ischemia was used as an experimental model of PAD. Results: In healthy mice without PAD, the test produced the expected dose-dependent relationship between fatigue and workload with contractions performed at 30% of the reference force having less fatigue compared to 45% of the reference force ( P=0.0051), without a significant difference in muscle blood flow between the conditions. Compared the mice that received a sham surgery, those subjected to hindlimb ischemia displayed significantly lower maximal isometric forces (1514 ± 118 mN vs. 880 ± 85 mN, P=0.0001) and power at 35% maximal force (280 ± 12 vs. 105 ± 46 watts/kg, P=0.0002). Whereas sham mice lost ~25% power across the six-minute test, HLI mice displayed a ~70% loss of power. Regarding muscle blood flow, sham mice increased blood flow ~250% whereas HLI mice were only able to increase blood flow to ~105% ( P<0.001). Conclusions: This newly developed protocol successfully combines isotonic muscle function and limb perfusion assessments in the hindlimb of mice and can detect differences between healthy and PAD mice. Future work is needed to fully evaluate the accuracy and sensitivity of this method to select therapeutics in preclinical PAD models. This study was supported by National Institutes of Health (NIH) grant R01-HL149704 (T.E.R.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Radiopharmaceuticals for Skeletal Muscle PET Imaging.

The skeletal muscles account for approximately 40% of the body weight and are crucial in movement, nutrient absorption, and energy metabolism. Muscle loss and decline in function cause a decrease in the quality of life of patients and the elderly, leading to complications that require early diagnosis. Positron emission tomography/computed tomography (PET/CT) offers non-invasive, high-resolution visualization of tissues. It has emerged as a promising alternative to invasive diagnostic methods and is attracting attention as a tool for assessing muscle function and imaging muscle diseases. Effective imaging of muscle function and pathology relies on appropriate radiopharmaceuticals that target key aspects of muscle metabolism, such as glucose uptake, adenosine triphosphate (ATP) production, and the oxidation of fat and carbohydrates. In this review, we describe how [18F]fluoro-2-deoxy-D-glucose ([18F]FDG), [18F]fluorocholine ([18F]FCH), [11C]acetate, and [15O]water ([15O]H2O) are suitable radiopharmaceuticals for diagnostic imaging of skeletal muscles.

Ultrasound Elastography in Benign Gynecology: A Scoping Review.

To perform a scoping review of the literature in which ultrasound elastography (UE) has been used in benign gynecology and identify avenues for its use in future research and clinical implementations. A structured search of EMBASE, Medline and Cochrane databases was conducted (last search date April 15th, 2022). Eligible studies included adult participants with female pelvic anatomy. English language papers focusing on the utility of ultrasound elastography applied to benign gynecology were included. Narrative reviews, conference abstracts, and letters to the editor were excluded. Two independent reviewers screened titles and abstracts for inclusion, a third reviewer was consulted in cases of disagreement. Study quality was assessed by a checklist for study implementation and elastography technique. Extracted data included elastography technology, gynecologic application, opportunities for clinical implementation, and strengths and limitations. The search returned 2026 studies. A total of 40 studies, published between 2013 and 2022, were retained for data extraction. Studies most frequently used shear wave elastography as the method of UE (n = 23), followed by strain elastography (n = 13) and acoustic radiation force impulse (n = 4). Most common clinical applications for UE were the diagnosis of adenomyosis and uterine fibroids (27.5%), assessment of pelvic floor muscle function (22.5%), and describing the elastic properties of polycystic ovaries (17.5%) and the uterine cervix (15.0%). Limitations of the technology were identified as the lack of published reference values for gynecologic organs and difficulties in assessing tissues deep to the transducer. Future research is needed to validate the use of ultrasound elastography in gynecology under both normal and pathologic conditions.

Effects of photobiomodulation therapy on muscle function in individuals with multiple sclerosis

BackgroundIn people with multiple sclerosis (pwMS), muscle fatigue and weakness are common issues that can interfere with daily activities. Photobiomodulation therapy (PBMT), comprising light in a 600–1100 nm bandwidth, is a low-level laser therapy thought to improve muscle performance in non-disease populations, in part, by improving mitochondrial function and thus, might be beneficial in pwMS. Given this potential, we aimed to investigate the effects of PBMT on muscle performance in pwMS, both in the short-term and over an extended period. MethodsThis study consisted of two parts with a randomized double-blind crossover design. In study I, muscle function was assessed in four sessions before and after PBMT in ambulatory pwMS (N = 17, F = 14) as follows: maximal voluntary contraction (MVC) and muscle fatigue of the right tibialis anterior (TA) muscle was compared at baseline and following a two-min submaximal fatiguing contraction. Then, PBMT was administered to the belly of TA muscle at different doses of energy of an active device (40 J, 80 J, 120 J) or placebo. The muscle function assessment was then repeated. Outcome variables: muscle force recovery (%), muscle fatigue (%). Statistical tests included McNemar's exact test, Wilcoxon signed-rank test, and the Friedman test. In study II, a subgroup from study I (N = 12, F = 11) received individualized doses (i.e., best dose-effect observed in study I) of active, or placebo PBMT, which was administered on the TA muscle for two weeks. Muscle function assessments were performed pre- and post-PBMT in four sessions similar to study I. Outcome variables: Baseline strength (N), endurance time (s), and muscle fatigue (%). The Wilcoxon signed-rank test was used for statistical analysis. Values are reported as mean (SD). ResultsIn study I, participants who received a high dose of PBMT showed significant improvement in force recovery (101.89 % (13.55 %)) compared to the placebo group (96.3 % (18.48 %); p = 0.03). Muscle fatigue did not significantly improve with either active PBMT or placebo. In study II, active PBMT resulted in a significant improvement in muscle strength compared to both the baseline (pre-PBMT = 162.70 N (37.52 N); post-PBMT = 185.56 N (33.95 N); p = 0.01) and the placebo group (active PBMT: mean-change = 22.87 N (23.67 N); placebo: mean-change = −4.12 N (31.95 N); p = 0.02). Endurance time and muscle fatigue did not show significant improvement with either active PBMT or placebo. ConclusionOur findings suggest that an individualized dose of PBMT might improve muscle performance, including force recovery and strength in individuals with mild-moderate MS. Therefore, PBMT might be a novel therapeutic modality, either as a standalone treatment or in combination with other interventions, to improve muscle performance in pwMS.

Quantitative tools to assess pelvic floor muscle function - systematic review.

Urinary incontinence is pelvic floor muscles dysfunction, most often caused by a weakening of their strength. There are no guidelines on how to evaluate pelvic floor muscle function. Palpation is the most popular method of assessing pelvic floor muscle function, but it is subjective. The aim of the study was to review the objective methods used in the assessment of pelvic floor muscle function in women with urinary incontinence. A systematic literature review of the PubMed database was performed using the following keywords: ["Pelvic Floor" (mh)] AND [("Pelvic Floor Disorders" (mh)] OR ["Urinary Incontinence" (mh)]. The search was limited to English-language works published from 2011 to 2021. The inclusion criteria were interventional studies in which the pelvic floor muscle function of women with urinary incontinence was assessed using quantitative tools. Methods that cannot be used in the clinic were excluded from the analysis. Fifty-two articles were included in the analysis and five methods assessing the function of pelvic floor muscle were distinguished: manometry, electromyography (EMG), ultrasonography (USG), dynamometry, accelerometry. Manometry, EMG and USG are the most common objective methods of assessing pelvic floor muscle function. When taking measurements, it is important to choose the right position of the patient. The use of objective tools to assess the function of the pelvic floor muscle and obtaining quantitative and/or qualitative data allows us to precisely diagnose and monitor the treatment and rehabilitation progress.

Integrating Wearable Textiles Sensors and IoT for Continuous sEMG Monitoring.

Surface electromyography is a technique used to measure the electrical activity of muscles. sEMG can be used to assess muscle function in various settings, including clinical, academic/industrial research, and sports medicine. The aim of this study is to develop a wearable textile sensor for continuous sEMG monitoring. Here, we have developed an integrated biomedical monitoring system that records sEMG signals through a textile electrode embroidered within a smart sleeve bandage for telemetric assessment of muscle activities and fatigue. We have taken an "Internet of Things"-based approach to acquire the sEMG, using a Myoware sensor and transmit the signal wirelessly through a WiFi-enabled microcontroller unit (NodeMCU; ESP8266). Using a wireless router as an access point, the data transmitted from ESP8266 was received and routed to the webserver-cum-database (Xampp local server) installed on a mobile phone or PC for processing and visualization. The textile electrode integrated with IoT enabled us to measure sEMG, whose quality is similar to that of conventional methods. To verify the performance of our developed prototype, we compared the sEMG signal recorded from the biceps, triceps, and tibialis muscles, using both the smart textile electrode and the gelled electrode. The root mean square and average rectified values of the sEMG measured using our prototype for the three muscle types were within the range of 1.001 ± 0.091 mV to 1.025 ± 0.060 mV and 0.291 ± 0.00 mV to 0.65 ± 0.09 mV, respectively. Further, we also performed the principal component analysis for a total of 18 features (15 time domain and 3 frequency domain) for the same muscle position signals. On the basis on the hierarchical clustering analysis of the PCA's score, as well as the one-way MANOVA of the 18 features, we conclude that the differences observed in the data for the different muscle types as well as the electrode types are statistically insignificant.

Partial Pressure of End-Tidal Oxygen and Blood Lactate During Cardiopulmonary Exercise Testing in Healthy Older Participants and Patients at Risk of Cardiac Disease.

The partial pressure of end-tidal oxygen (PETO2) and end-tidal oxygen concentration (ETO2) are among the indices that can be measured by exhaled gas analysis. Several observational studies have shown that skeletal muscle function is impaired in patients with cardiac disease; thus, the assessment of skeletal muscle function is important. Additionally, although it has recently been suggested that the difference in PETO2 from rest to the ventilatory anaerobic threshold (VAT) reflects oxygen availability in peripheral factors, primarily skeletal muscle, the evidence for this is not well established. Therefore, we hypothesized and investigated whether increased blood lactate (BLa) levels, resulting from decreased skeletal muscle and mitochondrial oxygen availability, and PETO2 dynamics during cardiopulmonary exercise testing (CPET) would be related. All participants performed the symptomatic limited CPET, and their BLa levels were measured. The difference in PETO2 and ETO2 from rest to VAT determined by the V-slope method (ΔPETO2 and ΔETO2) was calculated and compared with the increase in BLa due to exercise testing. We recruited 22 healthy older participants (nine males; 69.4 ± 6.8 years) and 11 patients with cardiovascular risk (eight males; 73.0 ± 8.8 years). ΔPETO2 and ΔETO2 did not differ between the two groups (P = 0.355 and P = 0.369, respectively), showing no correlation between increase in BLa from rest to VAT, but were significantly correlated with an increase in BLa from rest to the end of exercise (ΔPETO2, P = 0.030; ΔETO2, P = 0.029). The correlation was particularly pronounced among those at cardiovascular risk (ΔPETO2, P = 0.012; ΔETO2, P = 0.011). ΔPETO2 and ΔETO2 from rest to VAT during CPET may be useful as indices reflecting skeletal muscle oxygen utilization capacity.

P332 The role of Handgrip Strength in Nutritional Status Assessment of Patients with Inflammatory Bowel Disease. A cross-sectional study

Abstract Background Inflammatory bowel disease (IBD) has been extremely prevalent in recent years. Multiple factors such as chronic inflammation, insufficient nutrient intake, malabsorption and high energy requirements during disease flares increase the risk of malnutrition and impaired body composition leading to complications such as thromboembolism, prolonged hospital stay and surgery. Nutritional status assessment through screening tools, anthropometry and body composition analysis requires experienced personnel and is time consuming. The purpose of this single center cross-sectional study is to assess nutritional status of patients with IBD and investigate various methods for the early detection of malnutrition. Methods Eligible participants were patients diagnosed with Corhn’s disease (CD) or ulcerative colitis (UC) from August to October 2023. Exclusion criteria comprised corticosteroid or diuretic treatment and high output stoma or fistulas. Nutrition status was assessed with Subjective Global Assessment (SGA). Body composition analysis was performed with bioelectric impedance analysis (BIA, Bodystat Quadscan 4000). Handgrip strength (HGS) was measured to detect reduced muscle activity through Jamar dynamometer. BIA derived values were compared to reference values from epidemiological studies. Quality of life impairment evaluated through Inflammatory Bowel Disease Questionnaire (IBDQ). Data was analyzed with SPSS Statistics 29.0.1. Results 104 patients were included (68 with CD, 36 with UC) with a mean age of 46 years (20-79). Based on body mass index (BMI) of the examined sample: 2% were underweight, 47% normal, 31% overweight and 18% obese. Body composition analysis revealed high level fat mass in 50% of females and in 48% of males. Fat free mass index (FFMI) was found low in 30% of females and in 17.5% of males, respectively. Not significant differences were observed between patients with CD and UC. Malnutrition assessment through SGA revealed 7 (6%) severely and 10 (7%) moderately malnourished patients. HGS was negatively strongly correlated with SGA (R2=0.52) and the percentage of fat mass (R2=0.51), whereas positively moderately correlated with FFMI (R2=0.48) and IBDQ score (R2=0.30). Conclusion A large percentage of patients with IBD appear to have disturbed body composition and higher levels of fat mass compared to healthy population. Handgrip strength measurement is a fast and cost-effective method of muscle function assessment that correlates well with nutritional status and quality of life. Further studies are needed to validate these findings and incorporate handgrip strength measurement in every day clinical practice to detect malnourished patients.

Circulating Hsa-miR499a-5p as markers in dysmobility syndrome patients: a new index for diagnosing dysmobility syndrome based on osteoporosis and predicting fracture risk.

Dysmobility syndrome based on osteoporosis (ODS) is a disease characterized by low bone mass and low muscle mass. Its features are high fracture and high fall risk. Falls and fractures are the most important factors affecting the quality of life and lifespan of ODS. However, there is no serum marker for the evaluation of ODS patients.Our previous studies have shown that the expression of circulating miRNA is stable and is a good marker for disease diagnosis. Therefore, this study aims to explore potential serum markers of ODS. A total of 78 subjects were included in this study. The data including appendicular skeletal muscle mass index, bone mineral density, bone metabolism markers, and other relevant information were collected for analysis. Real-time quantitative polymerase chain reaction was used to detect 19 miRNAs associated with muscle mass reduction. The correlation of quantitative data was analyzed by Pearson. The receiver operating characteristic curve was used to evaluate the performance of miRNA as a biomarker. In this study, we found that the muscle mass and strength of patients with ODS are significantly reduced and are negatively correlated with the risk of fracture. The hsa-miR-499a-5p is specifically downregulated in ODS, and is positively correlated with muscle mass and strength, and negatively correlated with the risk of fracture. Compared with muscle mass and strength, hsa-miR-499a-5p has better sensitivity and specificity as a diagnostic marker. hsa-miR-499a-5p is a potential serum biomarker for assessing muscle function and predicting fall or fracture risk in the ODS population.

Muscle function assessment of the hindlimbs in healthy dogs using acoustic myography

IntroductionImpaired muscle function is a frequent consequence of musculoskeletal disorders in dogs. Musculoskeletal disorders, especially stifle joint diseases, are common in dogs and assessment of muscle function in dogs is clinically relevant. Acoustic myography (AMG) is a non-invasive method to assess muscle activity. Quantifying muscle function in normal dogs could help identify clinically relevant changes in dogs with orthopaedic disease and allow targeted interventions to improve recovery in these. The objectives of the study were to characterize hindlimb muscle function in healthy dogs using AMG and to investigate the repeatability and reproducibility of AMG in dogs. MethodsHealthy dogs (15–40 kg) without musculoskeletal disorders were recruited and screened for eligibility to participate in the study. The muscle activity in four hindlimb muscles related to the stifle was assessed using AMG. The degree of symmetry between the hindlimbs in these dogs was investigated and the reliability of AMG was evaluated. Results and conclusionsThe study population comprised 21 dogs. Reference intervals and symmetry indices for AMG scores of the hindlimb muscles were identified, with highest variability for the E-scores. For all AMG-scores, same-day variation was lower than between days variation, and both were lowest for S- and T-scores. Further investigation is needed to establish if AMG can enable discrimination between dogs with altered muscle function and healthy dogs.

Inspiratory Muscle Dysfunction Mediates and Predicts a Disease Continuum of Hypercapnic Failure in Chronic Obstructive Pulmonary Disease.

Advanced chronic obstructive pulmonary disease (COPD) is associated with chronic hypercapnic failure. The present work aimed to comprehensively investigate inspiratory muscle function as a potential key determinant of hypercapnic respiratory failure in patients with COPD. Prospective patient recruitment encompassed 61 stable subjects with COPD across different stages of respiratory failure, ranging from normocapnia to isolated nighttime hypercapnia and daytime hypercapnia. Arterialized blood gas analyses and overnight transcutaneous capnometry were used for patient stratification. Assessment of respiratory muscle function encompassed body plethysmography, maximum inspiratory pressure (MIP), diaphragm ultrasound, and transdiaphragmatic pressure recordings following cervical magnetic stimulation of the phrenic nerves (twPdi) and a maximum sniff manoeuvre (Sniff Pdi). Twenty patients showed no hypercapnia, 10 had isolated nocturnal hypercapnia, and 31 had daytime hypercapnia. Body plethysmography clearly distinguished patients with and without hypercapnia but did not discriminate patients with isolated nocturnal hypercapnia from those with daytime hypercapnia. In contrast to ultrasound parameters and transdiaphragmatic pressures, only MIP reflected the extent of hypercapnia across all three stages. MIP values below -48 cmH2O predicted nocturnal hypercapnia (area under the curve = 0.733, p = 0.052). In COPD, inspiratory muscle dysfunction contributes to progressive hypercapnic failure. In contrast to invasive tests of diaphragm strength only MIP fully reflects the pathophysiological continuum of hypercapnic failure and predicts isolated nocturnal hypercapnia.

SEMG-based Sarcopenia risk classification using empirical mode decomposition and machine learning algorithms.

Early detection of the risk of sarcopenia at younger ages is crucial for implementing preventive strategies, fostering healthy muscle development, and minimizing the negative impact of sarcopenia on health and aging. In this study, we propose a novel sarcopenia risk detection technique that combines surface electromyography (sEMG) signals and empirical mode decomposition (EMD) with machine learning algorithms. First, we recorded and preprocessed sEMG data from both healthy and at-risk individuals during various physical activities, including normal walking, fast walking, performing a standard squat, and performing a wide squat. Next, electromyography (EMG) features were extracted from a normalized EMG and its intrinsic mode functions (IMFs) were obtained through EMD. Subsequently, a minimum redundancy maximum relevance (mRMR) feature selection method was employed to identify the most influential subset of features. Finally, the performances of state-of-the-art machine learning (ML) classifiers were evaluated using a leave-one-subject-out cross-validation technique, and the effectiveness of the classifiers for sarcopenia risk classification was assessed through various performance metrics. The proposed method shows a high accuracy, with accuracy rates of 0.88 for normal walking, 0.89 for fast walking, 0.81 for a standard squat, and 0.80 for a wide squat, providing reliable identification of sarcopenia risk during physical activities. Beyond early sarcopenia risk detection, this sEMG-EMD-ML system offers practical values for assessing muscle function, muscle health monitoring, and managing muscle quality for an improved daily life and well-being.

Long-term assessment of functional capacity, muscle function, lung function, and quality of life in survivors of ventilator-associated pneumonia

Background and objectiveThe many patients who develop ventilator-associated pneumonia (VAP) have generated numerous VAP survivors who are not followed up in the long term. This study aimed, primarily, to evaluate the long-term functional capacity, as measured using the Glittre-ADL test (TGlittre), of VAP survivors and, secondarily, to calculate the correlations of TGlittre with muscle and lung function. MethodsThis cross-sectional study evaluated 30 VAP survivors 10 months after discharge from the intensive care unit. The participants underwent the following assessments: TGlittre; respiratory muscle strength; handgrip strength (HGS); spirometry; Functional Assessment of Chronic Therapy (FACIT-F); and Short Form-36 (SF-36). ResultsThe median TGlittre time was 95 (81–130)% of predicted, and 30 % of the participants performed poorly on TGlittre. One-third of the participants had abnormal spirometry results. TGlittre time was correlated with weight (rs = −0.412, P = 0.023), body index mass (BMI, rs = −0.400, P = 0.029), forced vital capacity (FVC, rs = −0.401, P = 0.030), HGS (rs = −0.571, P = 0.0009), FACIT-F score (rs = −0.405, P = 0.026), and different SF-36 domain scores. Participants who returned to work had a shorter TGlittre time than those who did not (89 (69–104) vs. 129 (102–183)% predicted). Multiple linear regression indicated that FVC and BMI explained 39 % of TGlittre variability. ConclusionVAP survivors had suboptimal functional capacity, low lung function, and general fatigue 10 months after discharge. The longer the TGlittre time was, the worse the lung function, muscle function, general fatigue, and quality of life were and the less likely the patient was to have returned to work.

Addressing the Main Barrier to Sarcopenia Identification: Utility of Practical Office-Based Bioimpedance Tools Vs. Dual Energy X-ray Absorptiometry (DXA) Body Composition for Identification of Low Muscle Mass in Older Adults.

Sarcopenia is associated with increased morbidity and mortality. Clinically, sarcopenia can be overlooked, especially in obesity. Sarcopenia diagnostic criteria include muscle mass (MM) and function assessments. Muscle function can be readily assessed in a clinic setting (grip strength, chair stand test). However, MM requires dual-energy X-ray absorptiometry (DXA) Body Composition (BC) or other costly tools, not readily available. Observational cohort pilot study of independently mobile, community dwelling older adults, comparing MM using two office-based, direct-to-consumer bioimpedance (BIA) scales (Ozeri® [manufactured in China] and OMRON® [OMRON HBF-510® Full Body Sensor, Shiokoji Horikawa, Kyoto, Japan] to DXA. The OMRON differs from the Ozeri scale because the OMRON also includes hand sensors. The European Working Group on Sarcopenia in Older People (EWGSOP) DXA or BIA low MM diagnostic cut-offs were used to classify participants as having low or normal MM. Fifty participants: 11 men, 39 women. Forty-two completed DXA. Age 75.8 yrs [67-90]. 81% obese based on body fat cut-offs. With DXA [ASM/height2], 15 had low MM. Using BIA [mmass/height2], 7 with Ozeri, and 27 with OMRON, had low MM. Positive predictive value for low MM versus DXA (as the gold standard) for Ozeri was 73.3% and OMRON was 92.8%. Good correlation between BIA scales and DXA for body fat estimates. OMRON captured all low MM participants identified by DXA plus all on DXA diagnostic borderline. Prevalence of obesity was high. Clinically, sarcopenic obese is the most difficult phenotype, as obesity masks low muscle mass. Low cost, readily available, direct-to-consumer BIA BC scales, especially with hand sensors, provide immediate, reliable information on muscle and fat mass. This can prompt appropriate investigation and/or intervention for sarcopenia or sarcopenic obesity.

Age influences the specific force and fatigability of the external abdominal obliques but not pectoralis major muscles

In the elderly, airway infections are associated with impaired airway defense behaviors, leading to an increased risk of airway infection. The muscles of the chest and abdominal wall are essential for performing effective airway defense manoeuvres, however, very little is known about their function in aging. Here in the 6- and 24-months old Fischer 344 rat model of aging, we assess the contractility and fatigability of chest (the pectoralis major muscle) and abdominal wall (external abdominal oblique) muscles. We assessed muscle function using an ex vivo approach, measuring isometric specific forces normalised to muscle CSA, via a platinum plate field stimulations at a range of frequencies (5–150 Hz) for 1 s. Surprisingly, we did not observe any effect of age on the specific force and fatigue properties of the pectoral muscle. However, in 24-months old rats, EAO specific force was reduced by ∼32 %. These finding suggest that not all respiratory muscles are equally vulnerable to age-associated weakness.

Isolated cardiac muscle contracting against a real-time model of systemic and pulmonary cardiovascular loads.

Isolated cardiac tissues allow a direct assessment of cardiac muscle function and enable precise control of experimental loading conditions. However, current experimental methods do not expose isolated tissues to the same contraction pattern and cardiovascular loads naturally experienced by the heart. In this study, we implement a computational model of systemic-pulmonary impedance that is solved in real time and imposed on contracting isolated rat muscle tissues. This systemic-pulmonary model represents the cardiovascular system as a lumped-parameter, closed-loop circuit. The tissues performed force-length work-loop contractions where the model output informed both the shortening and restretch phases of each work-loop. We compared the muscle mechanics and energetics associated with work-loops driven by the systemic-pulmonary model with that of a model-based loading method that only accounts for shortening. We obtained results that show simultaneous changes of afterload and preload or end-diastolic length of the muscle, as compared with the static, user-defined preload as in the conventional loading method. This feature allows assessment of muscle work output, heat output, and efficiency of contraction as functions of end-diastolic length. The results reveal the behavior of cardiac muscle as a pump source to achieve load-dependent work and efficiency outputs over a wider range of loads. This study offers potential applications of the model to investigate cardiac muscle response to hemodynamic coupling between systemic and pulmonary circulations in an in vitro setting.NEW & NOTEWORTHY We present the use of a "closed-loop" model of systemic and pulmonary circulations to apply, for the first time, real-time model-calculated preload and afterload to isolated cardiac muscle preparations. This method extends current experimental protocols where only afterload has been considered. The extension to include preload provides the opportunity to investigate ventricular muscle response to hemodynamic coupling and as a pump source across a wider range of cardiovascular loads.

Acoustic radiation force impulse shear wave elastography quantifies upper limb muscle in patients with Duchenne muscular dystrophy

We investigated whether the upper limb muscle stiffness quantified by the acoustic radiation force impulse shear wave elastography (ARFI/SWE) is a potential biomarker for age-related muscle alteration and functional decline in patients with Duchenne muscular dystrophy (DMD). 37 patients with DMD and 30 typically developing controls (TDC) were grouped by age (3–8, 9–11, and 12–18 years). ARFI/SWE measured the biceps and deltoid muscle's shear wave velocities (SWVs). Performance of Upper Limb Module (PUL 1.2 module) assessed muscle function in DMD patients. Mann Whitney test compared muscle SWVs between DMD and TDC, stratified by three age groups. We used analysis of variance with Bonferroni correction to compare muscle SWVs between DMD and TDC and correlated muscle SWVs with PUL results in the DMD group. Results showed that the SWVs of biceps differentiated DMD patients from TDC across age groups. Younger DMD patients (3–8 years) exhibited higher SWVs (p = 0.013), but older DMD patients (12–18 years) showed lower SWVS (p = 0.028) than same-aged TDC. DMD patients had decreasing biceps SWVs with age (p < 0.001), with no such age effect in TDC. The SWVs of deltoid and biceps positively correlated with PUL scores (r = 0.527 ∼ 0.897, P < 0.05) and negatively correlated with PUL timed measures (r = −0.425 ∼ −0.542, P < 0.05) in DMD patients. Our findings suggest that ARFI/SWE quantifying the SWVs in upper limb muscle could be a potential biomarker to differentiate DMD from TDC across ages and that DMD patients showed age-related muscle alteration and limb functional decline.