OBJECTIVE: Muscle quantity, defined as appendicular lean mass (ALM); muscle quality, defined as the ratio of muscle strength to ALM; and bioelectrical impedance analysis (BIA)-derived phase angle (PhA) are determinants of physical performance. We examined whether muscle quality indices were significant predictors of the whole-body reaction time (WBRT) in healthy female and male adults aged 20-91 years.
METHODS: Data from 5164 adults (2869 women and 2295 men; mean age ± standard deviation, 60.9 ± 15.6 years) were analyzed. Height and weight were measured, and body mass index was calculated. ALM was estimated using a previously validated 8-electrode multi-frequency BIA. PhA was measured at 50 kHz using a BIA device. Knee extension strength (KES), leg extension power (LEP), and flexibility were examined. The ALM to weight (ALM/weight), KES to ALM (KES/ALM), and LEP to KES (LEP/KES) ratios were calculated. In the WBRT test, participants were asked to stand on a force plate and jump upright as quickly as possible in response to a light stimulus. The WBRT was divided into the response initiation and motion execution phases.
RESULTS: ALM/weight, KES/ALM, LEP/KES, PhA, and flexibility were significant independent predictors of WBRT and the time of the motion execution phase (p < 0.001). However, PhA was not a significant predictor of the time of response initiation phase.
CONCLUSIONS: Muscle quantity (ALM/weight), muscle quality (KES/ALM and LEP/KES), PhA, and flexibility are determinants of WBRT test performance, particularly in the motion execution phase.

UNASSIGNED: The objective of this study is to understand the role of vitamin B12 supplementation in improving skeletal muscle function among the elderly.
UNASSIGNED: A literature review in the Medline database was conducted to understand the association between vitamin B12 and muscle function in Section A. In Section B, 28 healthy elderly participants aged ≥60 years were recruited in a cross-sectional design for estimation of plasma vitamin B12 status and assessment of upper limb muscle strength Maximal voluntary contraction (MVC) and muscle quality (expressed as MVC/total muscle mass). Participants were grouped based on vitamin B12 status into vitamin B12-depleted (<148 pmol/L) and replete (≥148 pmol/L) groups. In a quasi-experimental study design, the vitamin B12-depleted group (n = 14) received daily oral vitamin B12 supplementation of 100 μg for 3 months. All the study measures were repeated post-supplementation.
UNASSIGNED: Vitamin B12 deficiency was identified to contribute adversely to muscle strength, quality, and physical performance among older people in the extensive literature review. The pilot intervention study showed significant improvement in MVC and muscle quality (p < 0.050) post-vitamin B12 supplementation, comparable to the vitamin B12-replete group.
UNASSIGNED: Vitamin B12 may have a crucial role in the maintenance of muscle function. 3-month oral vitamin B12 supplementation among subclinical vitamin B12 deficient elderly improved muscle strength and quality and reached levels similar to the vitamin B12 replete group.

Background: Sarcopenia has been recognized as a determining factor in surgical outcomes and is associated with an increased risk of postoperative complications and readmission. Diagnosis is currently based on clinical guidelines, which includes assessment of skeletal muscle mass but not quality. Ultrasound has been proposed as a useful point-of-care diagnostic tool to assess muscle quality, but no validated cut-offs for sarcopenia have been reported. Using novel automated artificial intelligence (AI) software to interpret ultrasound images may assist in mitigating the operator-dependent nature of the modality. Our study aims to evaluate the fidelity of AI-aided ultrasound as a reliable and reproducible modality to assess muscle quality and diagnose sarcopenia in surgical patients. Methods: Thirty-six adult participants from an outpatient clinic were recruited for this prospective cohort study. Sarcopenia was diagnosed according to Asian Working Group for Sarcopenia (AWGS) 2019 guidelines. Ultrasonography of the rectus femoris muscle was performed, and images were analyzed by an AI software (MuscleSound® (Version 5.69.0)) to derive muscle parameters including intramuscular adipose tissue (IMAT) as a proxy of muscle quality. A receiver operative characteristic (ROC) curve was used to assess the predictive capability of IMAT and its derivatives, with area under the curve (AUC) as a measure of overall diagnostic accuracy. To evaluate consistency between ultrasound users of different experience, intra- and inter-rater reliability of muscle ultrasound parameters was analyzed in a separate cohort using intraclass correlation coefficients (ICC) and Bland-Altman plots. Results: The median age was 69.5 years (range: 26-87), and the prevalence of sarcopenia in the cohort was 30.6%. The ROC curve plotted with IMAT index (IMAT% divided by muscle area) yielded an AUC of 0.727 (95% CI: 0.551-0.904). An optimal cut-off point of 4.827%/cm2 for IMAT index was determined with a Youden\'s Index of 0.498. We also demonstrated that IMAT index has excellent intra-rater reliability (ICC = 0.938, CI: 0.905-0.961) and good inter-rater reliability (ICC = 0.776, CI: 0.627-0.866). In Bland-Altman plots, the limits of agreement were from -1.489 to 1.566 and -2.107 to 4.562, respectively. Discussion: IMAT index obtained via ultrasound has the potential to act as a point-of-care evaluation for sarcopenia screening and diagnosis, with good intra- and inter-rater reliability. The proposed IMAT index cut-off maximizes sensitivity for case finding, supporting its use as an easily implementable point-of-care test in the community for sarcopenia screening. Further research incorporating other ultrasound parameters of muscle quality may provide the basis for a more robust diagnostic tool to help predict surgical risk and outcomes.

Muscle quality index (MQI) is a novel indicator reflecting the quality of skeletal muscles. The association between MQI and the development of advanced fibrosis in patients with nonalcoholic fatty liver disease (NAFLD) is unknown. We investigated the association of low MQI with advanced fibrosis among adults with NAFLD using a nationally representative sample of the US population. Adults with NAFLD who participated in the National Health and Nutrition Examination Survey (NHANES) 2011-2014 were included. Sex-specific standard was used to define low and extremely low MQI. Univariate and multivariate logistic regressions were used to assess the association between MQI level and advanced fibrosis. In the study, 3758 participants with NAFLD were included. The prevalence of low and extremely low MQI was 11.7% (95% CI 10.4-13.0%) and 2.2% (95% CI 1.6-2.8%), respectively. Among these participants, 96 were assessed to have advanced fibrosis. Individuals with low [(odds ratio (OR) 2.45, 95% confidence interval (CI) 1.22-4.91)] and extremely low MQI (OR 10.48, 95% CI 3.20-34.27) were associated with advanced fibrosis in multivariable analysis. A linear trend relationship was also observed between MQI level and the risk of advanced fibrosis (Ptrend = 0.001). Subgroup and sensitivity analyses yielded similar results to the main analyses. Decreased MQI is highly prevalent, and is associated with an increased risk of advanced fibrosis in adult US population with NAFLD.

BACKGROUND: For the study of quantitative and qualitative muscle parameters, ultrasound and bioelectric impedance analysis are reliable, non-invasive, and reproducible. The aim of this study was to test the combined role of those techniques for the diagnosis of sarcopenia in a population of hospitalized older males and females.
METHODS: A total of 70 subjects were recruited, including 10 healthy adults and 60 hospitalized elderly patients with a good level of independence and cooperation, with and without sarcopenia. The rectus femoris cross-sectional area (CSA), thickness, echogenicity, and compressibility were measured with ultrasound echography. The phase angles (PhAs) and skeletal muscle mass were calculated by bioimpedence analysis. The muscle quality index (MQI) was calculated as the product of CSA and PhA.
RESULTS: Muscle compressibility was greater and PhA was lower in sarcopenic when compared with non-sarcopenic subjects. The threshold values for sarcopenia diagnosis in both sexes of CSA, of PhA, and of the MQI were identified. The obtained CSA values showed an AUC of 0.852 for women and 0.867 for men, PhA of 0.792 in women and 0.898 in men, while MQI was 0.900 for women and 0.969 for men.
CONCLUSIONS: The newly calculated cut-off values of CSA, PhA, and MQI predicted the presence of sarcopenia with good sensitivity and specificity values. The use of the MQI proved to be more promising than the separate use of CSA and PhA in both male and female subjects.

BACKGROUND: Falling is an important public health issue because of its prevalence and severe consequences. Evaluating muscle performance is important when assessing fall risk. The study aimed to identify factors [namely muscle capacity (strength, quality, and power) and spatio-temporal gait attributes] that best discriminate between fallers and non-fallers in older adults. The hypothesis is that muscle quality, defined as the ratio of muscle strength to muscle mass, is the best predictor of fall risk.
METHODS: 184 patients were included, 81% (n = 150) were women and the mean age was 73.6 ± 6.83 years. We compared body composition, mean grip strength, spatio-temporal parameters, and muscle capacity of fallers and non-fallers. Muscle quality was calculated as the ratio of maximum strength to fat-free mass. Mean handgrip and power were also controlled by fat-free mass. We performed univariate analysis, logistic regression, and ROC curves.
RESULTS: The falling patients had lower muscle quality, muscle mass-controlled power, and mean weighted handgrip than the non-faller. Results showing that lower muscle quality increases fall risk (effect size = 0.891). Logistic regression confirmed muscle quality as a significant predictor (p < .001, OR = 0.82, CI [0.74; 0.89]). ROC curves demonstrated muscle quality as the most predictive factor of falling (AUC = 0.794).
CONCLUSIONS: This retrospective study showed that muscle quality is the best predictor of fall risk, above spatial and temporal gait parameters. Our results underscore muscle quality as a clinically meaningful assessment and may be a useful complement to other assessments for fall prevention in the aging population.

BACKGROUND: The aging process induces neural and morphological changes in the human musculoskeletal system, leading to a decline in muscle mass, strength and quality. These alterations, coupled with shifts in muscle metabolism, underscore the essential role of physical exercise in maintaining and improving muscle quality in older adults. Muscle quality\'s morphological domain encompasses direct assessments of muscle microscopic and macroscopic aspects of muscle architecture and composition. Various tools exist to estimate muscle quality, each with specific technical requirements. However, due to the heterogeneity in both the studied population and study methodologies, there is a gap in the establishment of reference standards to determine which are the non-invasive and direct tools to assess muscle quality after exercise interventions. Therefore, the purpose of this review is to obtain an overview of the non-invasive tools used to measure muscle quality directly after exercise interventions in healthy older adults, as well as to assess the effects of exercise on muscle quality.
METHODS: To address the imperative of understanding and optimizing muscle quality in aging individuals, this review provides an overview of non-invasive tools employed to measure muscle quality directly after exercise interventions in healthy older adults, along with an assessment of the effects of exercise on muscle quality.
RESULTS: Thirty four studies were included. Several methods of direct muscle quality assessment were identified. Notably, 2 studies harnessed CT, 20 utilized US, 9 employed MRI, 2 opted for TMG, 2 adopted myotonometry, and 1 incorporated BIA, with several studies employing multiple tests. Exploring interventions, 26 studies focus on resistance exercise, 4 on aerobic training, and 5 on concurrent training.
CONCLUSIONS: There is significant diversity in the methods of direct assessment of muscle quality, mainly using ultrasound and magnetic resonance imaging; and a consistent positive trend in exercise interventions, indicating their efficacy in improving or preserving muscle quality. However, the lack of standardized assessment criteria poses a challenge given the diversity within the studied population and variations in methodologies.. These data emphasize the need to standardize assessment criteria and underscore the potential benefits of exercise interventions aimed at optimizing muscle quality.

Background: Decline in muscle quality is associated with poorer health in community-dwelling older adults. Although there is evidence that malnutrition is associated with the decline of muscle quality in older adults, few analyses have considered important factors related to muscle quality. Aim: The purpose of this study was to determine the relationship between muscle quality and nutritional status in community-dwelling older adults, taking into account muscle mass, muscle strength, and amount of physical activity. Methods: This was a cross-sectional study. Data were obtained from a health checkup program in Japan. Participants were older adults aged ≥65 years living in the community who participated in the health checkup program. The data collected were echo intensity, scores on the Global Leadership Initiative on Malnutrition criteria, skeletal muscle mass, grip strength, physical activity level, and demographic data. Multiple regression analysis was used to examine the association between muscle quality and nutritional status. Results: Data were analyzed for 50 participants (mean age 77.62 years, standard deviation 6.16 years, 78.0% women). Multiple regression analysis showed that nutritional status affected muscle quality even when various factors were taken into account (B = 6.95, β = 0.31, p = 0.04, 95% confidence interval: 0.01-0.62). Conclusion: The observed association suggests that providing nutritional support for older adults living in the community may be a useful strategy to maintain muscle quality.

Objectives. Phase angle muscle imaging has been proposed by phase angle electrical impedance tomography (ΦEIT) under electrical muscle stimulation (EMS) for long-term monitoring of muscle quality improvement, especially focusing on calf muscles.Approach. In the experiments, twenty-four subjects are randomly assigned either to three groups: control group (CG,n= 8), low voltage intensity of EMS training group (LG,n= 8), and optimal voltage intensity of EMS training group (OG,n= 8).Main results. From the experimental results, phase angle distribution imagesФare cleared reconstructed by ФEIT as four muscle compartments over five weeks experiments, which are called theM1muscle compartments composed of gastrocnemius muscle,M2muscle compartments composed of soleus muscle,M3muscle compartments composed of tibialis-posterior muscle, flexor digitorum longus muscle, and flexor pollicis longus muscle, andM4muscle compartment composed of the tibialis anterior muscle, extensor digitorum longus muscle, and peroneus longus muscle.Фis inversely correlated with age, namely theФdecreases with increasing age. A paired samplest-test was conducted to elucidate the statistical significance of spatial-mean phase angle in all domain <Ф>Ωand in each muscle compartment <Ф>Mwith reference to the conventional phase angle Ф by bioelectrical impedance analysis, muscle grey-scaleGmuscleby ultrasound, and maximal dynamic strengthSMaxby one-repetition maximum test.Significance. From thet-test results, <Ф>Ωhave good correlation with Ф andSMax. In the OG, <ФW5>Ω,ФW5, and (SMax)W5were significantly higher than in the first week (n= 8,p< 0.05). A significant increase in the phase angle of bothM1andM4muscle compartments is observed after five weeks in LG and OG groups. Only the OG group shows a significant increase in the phase angle ofM2muscle compartment after five weeks. However, no significant changes in the spatial-mean phase angle ofM3compartment are observed in each group. In conclusion, ФEIT satisfactorily monitors the response of each compartment in calf muscle to long-term EMS training.

UNASSIGNED: Muscle and bone tissue are interrelated throughout their developmental processes via paracrine and endocrine pathways. Osteosarcopenia has emerged with the growing data proving the high rate of simultaneous occurrence of sarcopenia and osteoporosis. We aimed to evaluate the relationship between osteoporosis, and muscle quality by grading the fatty infiltration in paraspinal muscles according to the Goutallier classification in magnetic resonance imaging (MRI).
UNASSIGNED: Data of postmenopausal patients who underwent MRI for low back pain were analyzed retrospectively. Lumbar spine and femoral neck bone mineral density (BMD) were measured by using dual energy X-ray absorptiometry (DXA). Grade of paraspinal muscle fatty infiltration for each level of lumbar vertebrae including L1-L2, L2-L3, L3-L4, was evaluated separately according to Goutallier classification system.
UNASSIGNED: A total of 91 postmenopausal women were included in the study. The mean age of the study population was 60.5 ± 11. Lumbar vertebrae L1-L4 total T-scores and BMD g/cm2 were lower in patients with higher grades of Goutallier classification (P = 0.031 and P = 0.023, respectively). The distribution of the severity of fatty degeneration was significantly higher in the osteoporosis/osteopenia group at all 3 disc levels. No significant correlation was observed between femoral neck BMD and paraspinal muscle fat infiltration.
UNASSIGNED: There is a strong relationship between osteoporosis of the lumbar spine and paraspinal muscle quality, which can be considered as a reflection of osteosarcopenia. The Goutailler classification can be an effective and easy method in the evaluation of muscle quality with MRI.