Muscle Quality Index Research Articles

Inverse association between uric acid levels and muscle quality index in adults: a cross-sectional analysis of NHANES 2011-2014.

The objective of this study was to delineate the association between serum uric acid (UA) levels and Muscle Quality Index (MQI), assessing muscle strength relative to mass, in adults aged 20 to 59 years. Utilizing data from the National Health and Nutrition Examination Survey (NHANES) 2011-2014, this study examined the association between UA levels and MQI-a ratio of muscle strength to mass. Weighted linear models, adjusted for potential confounders, assessed the relationship, with a generalized additive model (GAM) probing for non-linear patterns. Subgroup analyses and interaction effects were conducted using weighted linear regression across diverse demographic and clinical groups to ensure the robustness and reliability of our findings. Among 5,277 participants, a significant inverse association was observed between UA levels and MQI, with a 0.08 decrease in MQI per 1mg/dL increase in UA (95% CI: -0.11 to -0.06, p < 0.001). The negative trend was dose-dependent across UA quartiles, which was most pronounced in the highest quartile (Q4: -0.28, 95% CI: -0.36 to -0.19, p < 0.001). Curve-fitting analysis revealed a consistent inverse relationship without evidence of non-linearity. Stratified analyses reinforced the core findings across all examined subgroups, highlighting the universal relevance of the observed association. Our findings demonstrate a significant inverse association between elevated serum UA levels and MQI, highlighting the potential importance of uric acid management in enhancing muscle quality among young and middle-aged adults. The consistency of this relationship across different subgroups underscores the need for targeted strategies and interventions to manage UA levels. Future research should explore longitudinal impacts and intervention outcomes to further elucidate the potential benefits of uric acid management on muscle health.

Total and appendicular body composition comparisons between near-infrared reactance spectroscopy and dual energy X-ray absorptiometry.

Near-infrared reactance spectroscopy (NIRS) has become increasingly popular in personal and professional settings now that it has been adapted to provide comprehensive body composition assessments. However, whether NIRS agrees with criterion methods remains unknown. Thus, this study aimed to determine the agreement between NIRS and DXA-derived body composition estimates. Ninety-seven participants completed body composition assessments using DXA, and first-generation (NIRSG1), second-generation (NIRSG2), and muscle-specific NIRS (NIRSFIT) devices. On a separate day, a subset of participants (n = 63) performed maximal voluntary contractions (MVC) on a handgrip dynamometer, which were used in conjunction with total appendicular lean mass (ALM) estimates to provide ratios (MVC/total ALM or MVC/ALM of the arms only) depicting muscle quality index (MQI). Fat mass, fat-free mass, body fat %, and ALM, from NIRSG2, but not bone mineral content (BMC), and NIRSFIT demonstrated equivalence (using equivalence tests) with DXA with R2 from 0.83 to 0.97; though BMC revealed concordance coefficients of 0.83 and an R2 of 0.88. MQI using total ALM from NIRS was not equivalent to DXA, but demonstrated low root mean squared error (0.08 kg/kg) and 95% limits of agreement (±0.21 kg/kg). Indices of visceral adipose tissue (iVAT) from NIRSG1 and NIRSG2 were significantly different (p < 0.001), but were both significantly associated with DXA VAT (NIRSG1 R2: 0.53; NIRSG2 R2: 0.62; both p < 0.001). NIRS appears to demonstrate acceptable agreement with DXA and continual improvements could make NIRS a viable alternative for comprehensive body composition assessments.

Prognostic significance of novel muscle quality index utilization in hospitalized adults with cancer: A secondary analysis.

This study aimed to investigate and propose novel approaches to calculate muscle quality index (MQI) using muscle mass derived from single-frequency bioelectrical impedance analysis (SF-BIA) and calf circumference in both unadjusted and body mass index (BMI)-adjusted forms. In addition, we examined their prognostic significance in patients with cancer. A secondary analysis was conducted on a prospective cohort study of patients with cancer. Handgrip strength was measured. SF-BIA was conducted to estimate appendicular lean soft tissue (ALST, in kilograms). MQI was calculated using three approaches: (1) the ratio of handgrip strength to ALST (MQISF-BIA), (2) the ratio of handgrip strength to calf circumference (MQIcalf circumference), and (3) the ratio of handgrip strength to BMI-adjusted calf circumference (MQIadj. calf circumference). Maximally selected log-rank was calculated to estimate their cutoff values to predict survival. Two hundred eighty-four patients were included (51.1% men; median age, 61 years). Solid tumors were the most frequent (89.8%). All approaches to MQI (MQISF-BIA, MQIcalf circumference, and MQIadj. calf circumference) were independent predictors of 6-month mortality. The found cutoffs were (1) MQISF-BIA (<1.52 for men, <0.63 for women), (2) MQIcalf circumference (<0.74 for men, <0.24 for women), and (3) MQIadj. calf circumference (<0.75 for men, <0.25 for women). This study introduces MQISF-BIA, MQIcalf circumference, and MQIadj. calf circumference as future potential surrogate methods for computing MQI in clinical practice when other robust procedures are unavailable, pending further validation.

Phase angle as a marker of muscle quality: A systematic review and meta-analysis

Background & aimsPhase angle (PhA) is a biomarker derived from raw bioelectrical impedance analysis (BIA) values: resistance (R) and reactance (Xc). PhA reflects cellular membrane integrity and, as a result, has been considered a marker of fluid distribution, making it a potential prognostic indicator. A growing body of research demonstrates independent associations between PhA and muscle strength, mass, and composition. In this context, PhA has the extra potential to serve as a marker of muscle quality. However, the evidence supporting its use for this purpose is not well established. This study aimed to investigate the relationship between PhA and markers of muscle quality. MethodsThis systematic review and meta-analysis (Internal Prospective Register of Systematic Reviews – PROSPERO on a registration code: CRD42024507853) focused on observational studies assessing the relationship between PhA and markers of both concepts of muscle quality: the muscle quality index (MQI: strength by a unit of mass) and the muscle composition (i.e., skeletal muscle radiodensity [SMD], muscle echogenicity, muscle fat fraction, inter- and intramuscular adiposity). Risk of bias was assessed using the Newcastle-Ottawa Scale (NOS) and Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2), while the certainty of evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Meta-analyses with a random-effects model were conducted. ResultsSeventeen studies were included in this systematic review, encompassing 2,710 participants. Meta-analyses demonstrated that PhA had a moderate positive correlation coefficient with SMD (4 studies, 924 participants; r = 0.54, 95% confidence interval (CI) 0.38 to 0.69, heterogeneity (I2) = 92%) and good accuracy (85%) for classifying low SMD (2 studies, 390 participants; Area Under the Curve – AUC pooled 0.85, 95% CI 0.78 to 0.92, I2 = 0%). PhA was inversely-moderately correlated with muscle echogenicity (8 studies, 1,401 participants; r = - 0.42, 95% CI - 0.57 to - 0.24, I2 = 82%) and positively-weakly correlated with MQI (2 studies, 191 participants; r = 0.36, 95% CI 0.21 to 0.49, I2 = 17%). All studies had a higher risk of bias. The certainty of evidence ranged from low to very low. ConclusionDespite technical challenges, this study demonstrates the potential of PhA as a surrogate marker for muscle quality, particularly expressing muscle composition (SMD). Future studies should utilize BIA with standardized protocols to potentially establish specific cutoff values for PhA, thereby enhancing its diagnostic accuracy and clinical applicability. These studies could additionally explore the mechanisms underlying the associations between PhA and muscle quality aspects. In cases where technical factors are not easily controlled, the use of standardized PhA (SPhA), which converts PhA into Z-scores, could be beneficial. Although this warrants investigation, this approach (SPhA) has the potential to account for variables such as age, sex, device differences, and health status.

Myosteatosis: diagnostic significance and assessment by imaging approaches.

Myosteatosis has emerged as an important concept in muscle health as it is associated with an increased risk of adverse health outcomes, a higher rate of complications, and increased mortality associated with ageing, chronic systemic and neuromuscular diseases, cancer, metabolic syndromes, degenerative events, and trauma. Myosteatosis involves ectopic infiltration of fat into skeletal muscle, and it exhibits a negative correlation with muscle mass, strength, and mobility representing a contributing factor to decreased muscle quality. While myosteatosis serves as an additional biomarker for sarcopenia, cachexia, and metabolic syndromes, it is not synonymous with sarcopenia. Myosteatosis induces proinflammatory changes that contribute to decreased muscle function, compromise mitochondrial function, and increase inflammatory response in muscles. Imaging techniques such as computed tomography (CT), particularly opportunistic abdominal CT scans, and magnetic resonance imaging (MRI) or magnetic resonance spectroscopy (MRS), have been used in both clinical practice and research. And in recent years, ultrasound has emerged as a promising bedside tool for measuring changes in muscle tissue. Various techniques, including CT-based muscle attenuation (MA) and intermuscular adipose tissue (IMAT) quantification, MRI-based proton density fat fraction (PDFF) and T1-T2 mapping, and musculoskeletal ultrasound (MSUS)-based echo intensity (EI) and shear wave elastography (SWE), are accessible in clinical practice and can be used as adjunct biomarkers of myosteatosis to assess various debilitating muscle health conditions. However, a stan¬dard definition of myosteatosis with a thorough understanding of the pathophysiological mechanisms, and a consensus in assessment methods and clinical outcomes has not yet been established. Recent developments in image acquisition and quantification have attempted to develop an appropriate muscle quality index for the assessment of myosteatosis. Additionally, emerging studies on artificial intelligence (AI) may provide further insights into quantification and automated assessment, including MRS analysis. In this review, we discuss the pathophysiological aspects of myosteatosis, all the current imaging techniques and recent advances in imaging assessment as potential biomarkers of myosteatosis, and the most common clinical conditions involved.

Muscle quality index is associated with depression among non-elderly US adults

PurposeMuscle Quality Index (MQI), defined as the muscle strength per unit of muscle mass, is considered an emerging indicator of health and physical function. This study aims to explore the relationship between MQI and the risk of depression among non-elderly US adults.MethodsThis cross-sectional study collected data from participants aged between 20 and 59 years old, utilizing the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2014. The MQI was calculated by dividing the handgrip strength (HGS, kg) by the arm and appendicular skeletal muscle mass (ASM, kg). Depression assessments were conducted using the Patient Health Questionnaire (PHQ-9). The relationship between MQI and the risk of depression was explored by weighted logistic regression, smooth curve fitting, and subgroup analyses.ResultsA total of 4773 participants were included in this study. After adjusting for confounding factors, low MQI levels were identified as an independent risk factor for depression (OR = 0.800, 95%CI:0.668–0.957, P = 0.015). Smooth curve fitting analysis indicated a nonlinear relationship. Subgroup analysis did not identify any specific populations.ConclusionsHigher MQI levels were closely associated with a lower risk of depression among non-elderly US adults. MQI could enhance our understanding of the link between muscle and depression and might serve as a simple functional measure for evaluating and predicting depression.

Gait speed in older adults: exploring the impact of functional, physical and social factors

Purpose: With age there is a neuromuscular and cognitive decline that impacts on functional ability. One of the most characteristic and easily recognisable signs of this decline is a decrease in usual gait speed. For older adults, gait speed is a non-invasive indicator of health and functional status and is regarded as a vital sign. As it predicts various conditions later in life, measuring usual walking speed is crucial in the clinical setting. Therefore, analysing and determining the association between walking speed and the impact of functional and socio-economic variables may facilitate the prevention of associated health problems and the maintenance of physical function in older adults. This study aims to identify the key factors that influence walking speed in older adults, as well as to examine the influence of socio-economic status on walking speed. Methods: A total of 1253 older adults (89.5% women) with a mean age of 78.1 ± 5.8 voluntarily participated in this descriptive cross-sectional study, which examines the results of functional capacity tests and socioeconomic data in older adults. To assess physical function, SPPB tests (chair stand test, balance tests, gait speed test), manual grip strength, muscle quality index, and power were conducted, in addition to measuring body composition and socioeconomic status. Results: The final regression model showed that gait speed was significantly partially explained (R2=0.35; p&lt;0.01) by the socioeconomic environment, age, balance, and relative power. At the same time, belonging to a higher socio-economic environment is linked to lower relative power (p&lt;0.01; η2=0.07). Conclusions: Exploring the factors that affect walking speed in older adults, this study highlights that age, relative power and balance are significant determinants. These clinical markers provide crucial information for designing personalized and effective interventions to promote healthy aging. Keywords: Frailty, gait speed, elderly, relative power, socioeconomic status.

Sex differences in the association between the muscle quality index and the incidence of depression: A cross-sectional study

BACKGROUND Depression presents significant challenges to mental health care. Although physical activity is highly beneficial to mental and physical health, relatively few studies have conducted on the relationship between them. AIM To investigate the association between muscle quality index (MQI) and incidence of depression. METHODS The data used in this cross-sectional study were obtained from the 2011-2014 National Health and Nutritional Examination Survey, which included information on MQI, depression, and confounding factors. Multivariable logistic regression models were employed, while taking into account the complex multi-stage sampling design. A restricted cubic spline model was utilized to investigate the non-linear relationship between the MQI and depression. Additionally, subgroup analyses were performed to identify influential factors. RESULTS The prevalence of depression in this population was 8.44%. With the adjusted model, the MQI was associated with depression in females (odds ratio = 0.68, 95% confidence interval: 0.49-0.95) but not in males (odds ratio = 1.08, 95% confidence interval: 0.77-1.52). Restricted cubic spline adjustment of all covariates showed a significant negative non-linear relationship between depression and the MQI in females. The observed trend indicated an 80% decrease in the risk of depression for each unit increase in MQI, until a value of 2.2. Subsequently, when the MQI exceeded 2.2, the prevalence of depression increased by 20% for every unit increase in the MQI. Subgroup analyses further confirmed that the MQI was negatively associated with depression. CONCLUSION The MQI was inversely correlated with depression in females but not males, suggesting that females with a higher MQI might decrease the risk of depression.

Low muscle quality index is associated with increased risk of advanced fibrosis in adult patients with nonalcoholic fatty liver disease: NHANES 2011–2014

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.

Improved trunk muscle quality in patients with stroke increases improvements in activities of daily living

BackgroundThis study aimed to determine whether an increased trunk muscle quality index (TMQI) is associated with activities of daily living (ADL) in patients ≥ 65 years of age with cerebral infarction in a convalescent rehabilitation ward. MethodsThis retrospective observational study included patients aged ≥ 65 years who were admitted for post-stroke rehabilitation in Okinawa, Japan, between May 2018 and December 2022. The TMQI was calculated at admission and discharge using bioelectrical impedance analysis. Patients were divided into two groups based on the change in the TMQI during hospitalization: increase-in-TMQI and no-increase-in-TMQI groups. Multiple regression analysis was employed to explore the impact of increased TMQI on functional independence measure (FIM) -motor gain. ResultsWe included a total of 315 patients (79.1 ± 7.9 years of age, 51.7% men) in our analyses. Over half (165 [52.4%]) of the patients exhibited an increase in TMQI scores, and 150 (47.6%) patients did not exhibit an increase. No significant difference was observed in motor FIM score and motor FIM gain at admission and discharge between the groups with and without increased TMQI. Increased TMQI was independently associated with increased FIM-motor gain (adjusted R2 = 0.340 and R2 = 0.357, coefficient = 1.736, 95% confidence interval: 0.52–2.95, P = 0.005). ConclusionsThe results of this study suggest that increased TMQI has a positive effect on the recovery of physical function in patients with stroke. Further prospective studies are needed to elucidate the relationship between increased TMQI and ADL.

Muscle quality index comparisons between Hispanics and non-Hispanic Caucasians using dual energy X-ray absorptiometry and handgrip strength.

Muscle quality index (MQI) can be computed in various ways. Also, many studies have evaluated MQI in older adults and non-Hispanic populations. The aim of this study was to compare various muscle quality indexes between Hispanics and non-Hispanic Caucasians when stratifying grip strength and appendicular lean mass measurements. 235 participants (aged 25.5 ± 9.5 for males and 26.4 ± 9.9 for females) completed a dual energy X-ray absorptiometry (DXA) scan to assess appendicular lean mass (ALM). Handgrip strength (HGS) was assessed using a handheld dynamometer. MQI was computed using four different models: 1). MQIRA: ALM and HGS of right arm and hand, respectively; 2). MQILA: ALM and HGS of left arm and hand, respectively; 3). MQIARMS: ALM and HGS of both arms and hands, respectively; and 4). MQITOTAL: ALM of upper and lower-limbs and HGS of left and right hand. Hispanic males and females exhibited lower HGS compared to Caucasians with effect sizes ranging from trivial (d = 0.17) to moderate (d = 0.80). Females demonstrated higher MQI values compared to males for MQIARMS (d = 0.70), MQIRA (d = 0.75), and MQILA (d = 0.57). However, MQITOTAL yielded a small practical effect (d = 0.33) in favor of males (3.2 ± 0.5 kg/kg vs. 3.1 ± 0.5 kg/kg). After factoring by sex and ethnicity, Hispanic males and females, compared to non-Hispanic Caucasians males and females, showed trivial-to-small practical differences (d values ranging from 0.03 to 0.39). These results demonstrate MQI models vary across sex, particularly when utilizing models that account for upper extremity strength and ALM (i.e., MQIARMS, MQIRA, and MQILA). Lastly, to establish consistency in future research, the present study recommends using MQI models that account for ALM of upper- and lower-limbs (i.e., MQITOTAL). However, research measuring muscular strength via one upper-limb (e.g., left hand) might consider measuring ALM of the corresponding arm (e.g., left arm) when computing muscle quality (e.g., MQILA).

The Role of Combined Muscle Ultrasound and Bioimpedentiometry Parameters for Sarcopenia Diagnosis in a Population of Hospitalized Older Adults.

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. 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. 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. 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.

Sex differences in the association between sleep duration and muscle quality index in adults: A cross-sectional study from NHANES 2011-2014.

The aim of this study was to investigate the association between sleep duration and muscle quality index (MQI) in middle-aged and older age groups, as limited evidence exists on this topic. In order to assess the relationship between sleep duration and MQI, a cross-sectional study was undertaken, utilizing data from the National Health and Nutrition Examination Survey (NHANES) acquired during the period from 2011 to 2014. The study comprised a total of 4598 participants aged 20 years and above. To examine the association between sleep duration and MQI, sophisticated weighted multivariate linear regression models were employed. Additionally, smooth curve fitting techniques were applied to examine the possibility of any non-linear relationship between the two variables. The average age of the adults who were enrolled in the study was 38.48±11.69 years, and 46.75% of them were female. The results of the multivariable linear regression models showed that sleep duration had a positive correlation with MQI. However, when subgroup analysis was conducted, it was found that this positive correlation only existed among women (β = 0.09, 95% CI: 0.014 to 0.167). To further confirm the differences between sexes in the relationship between sleep duration and MQI, a weighted generalized additive model (GAM) was used. This research study provides evidence that there is a positive correlation between the duration of sleep and MQI specifically in females, while no such association was observed in males. These findings shed light on the existence of gender disparities in the connection between sleep duration and MQI.

Feasibility, reliability, and validity of physical function tests and IADL survey questions in women living in rural, highland Ethiopia.

Physical function is the physical ability to fulfill one's daily roles and responsibilities. Poor physical function is detrimental to health and income-generating activities. Unfortunately, there is a lack of validated methods to measure physical function in adult women in low- and middle-income countries, including Ethiopia, the locus of this study. This study evaluated the feasibility, reliability, and validity of physical tests, including the sit-to-stand (STS) and usual gait speed (UGS) and a context-appropriate instrumental activities of daily living (IADL) survey. The results of the STS were used to calculate a muscle quality index (MQI, STS accounting for body mass and leg length). Feasibility was ascertained qualitatively based on reports from the enumerators on their ability to administer the tests. Reliability was assessed by comparing the results of the tests and questions between each visit using either Cohen's κ or Pearson's ρ. The validity of MQI was assessed using relevant participant characteristics such as age and self-reported disability. The validity of the IADL was assessed using MQI. Study participants comprised 316 women between the ages of 18 and 45 years, living in rural Tigray, Ethiopia, who had previously participated in an impact evaluation of a safety net program. Over a one-week period, participants completed the STS and UGS tests and responded to the IADL survey questions three times. MQI was determined to be a feasible, reliable, and valid physical function test for women in rural, highland Ethiopia. UGS lacked feasibility and reliability; validity was not ascertained. The IADL questions were feasible and reliable, but validity was inconclusive. In rural Ethiopia, the MQI will be a valuable tool to develop interventions for improving physical function, which will have positive impacts on health and quality of life.

Associations of upper- and lower-limb muscle strength, mass, and quality with health-related quality of life in community-dwelling older adults.

This study aimed to investigate the associations between upper- and lower-limb muscle strength, mass, and quality and health-related quality of life (HRQoL) among community-dwelling older adults. A cross-sectional study was conducted with 428 Brazilian community-dwelling older adults aged 60 to 80 years. Upper- and lower-limb muscle strength were evaluated through the handgrip strength (HGS) test and the 30-s chair stand test, respectively. Muscle mass was assessed by dual-energy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA). Muscle quality was evaluated using the muscle quality index (MQI). HRQoL was assessed using the World Health Organization Quality of Life Brief Version questionnaire. Lower-limb, but not upper-limb, muscle strength and quality were independently associated with HRQoL, particularly within the domains of physical capacity, environment, and overall HRQoL for both males and females (P < 0.05). DXA- and BIA-derived analyses provided similar results in relation to muscle mass and muscle quality. Lower-limb, but not upper-limb, muscle strength and quality were independently associated with HRQoL among community-dwelling older adults. Moreover, the results obtained from both BIA and DXA were similar, highlighting that BIA can serve as a viable surrogate method for estimating body composition in resource-limited clinical settings. Geriatr Gerontol Int 2024; 24: 683-692.

Gender-Specific Differences in Spinal Alignment and Muscle Power in Patients with Parkinson's Disease.

Parkinson's disease (PD) is an advancing neurodegenerative disorder characterized by spinal anomalies and muscular weakness, which may restrict daily functional capacities. A gender-focused examination of these effects could provide valuable insights into customized rehabilitation strategies for both sexes. This study investigates the influence of spinal alignment on lower-limb function during the sit-to-stand (STS) movement in patients with Parkinson's disease compared to healthy individuals. A cross-sectional study was conducted with 43 consecutive patients with PD (25 males and 18 females; average age 73.7 ± 7.1 years) and 42 healthy controls (22 males and 20 females; average age 69.8 ± 6.0 years). Assessments included the International Physical Activity Questionnaire (IPAQ), Hoehn and Yahr staging, and measurements of vertical deviations from several spinal landmarks. Lower-limb muscle power during the STS task was evaluated using the Muscle Quality Index (MQI). Both absolute (Watts) and relative (Watts/Kg) muscle power in the lower limbs were notably decreased in the PD group compared to the control group. Within the PD cohort, muscle power showed a negative relationship with age and a positive association with the degree of lumbar lordosis (PL-L3). Importantly, gender-specific analysis revealed that male patients with PD had significantly higher lower-limb muscle power compared to female patients with PD, highlighting the need for gender-tailored therapeutic approaches. The findings suggest that preserving lumbar lordosis is crucial for maintaining effective lower-limb muscle biomechanics in individuals with Parkinson's disease.

Strength-to-muscle radiodensity: A potential new index for muscle quality

Background & aimsAlthough it is widely recognized that muscle quality significantly influences adverse outcomes in patients with cancer, the precise definition of muscle quality remains elusive. The muscle quality index (MQI), also known as muscle-specific strength, is a relatively recent functional concept of muscle quality. It is obtained through the ratio of muscle strength to muscle mass, but its predictive value in patients with cancer remains unknown. In this study, we explored the prognostic significance of MQI in patients with cancer. Furthermore, we introduce and assess the prognostic potential of a novel muscle quality metric: the strength-to-muscle-radiodensity index (SMRi). MethodsA secondary analysis was conducted on a prospective cohort study. CT scans were opportunistically used to assess body composition parameters, including skeletal muscle mass (SM in cm2) and muscle radiodensity (SMD in HU) at the third lumbar vertebra (L3). Handgrip strength (HGS) was measured. MQICT was calculated using the ratio of HGS to SM (cm2). SMRi was calculated as the ratio of HGS to SMD (HU). For analysis purposes, low MQICT and SMRi was defined using two approaches: statistical cutoffs associated with survival, and median-based distribution data. ResultsA total of 250 patients were included (52.8% females, 52% adults, 20-90 years). Gastrointestinal tumors and stage III-IV were the most frequent diagnosis and stages. SMRi and MQICT were strongly positively correlated (ρ = 0.71 P < .001). Individual components of MQICT and SMRi were also positively correlated. Patients with both low MQICT and SMRi had shorter survival (log-rank P = .023 and P = .003, respectively). When applying median distribution cutoffs, SMRi emerged as the most accurate predictor of mortality (HR adjusted 3.18, 95% CI 1.50 to 6.75, C-index: 0.71), when compared to MQICT (HR adjusted 1.49, 95% CI 0.77 to 2.87, C-index: 0.68). ConclusionThis study introduces the concept and potential prognostic significance of the SMRi. The physiological and clinical implications of this new index warrant further investigation across a spectrum of diseases, including cancer.

Interval Versus Continuous Intradialytic Training on Muscle Quality Index and Functional Capacity in Hemodialysis Patients: a Prospective Randomized Clinical Study

INTRODUCTION. Chronic kidney disease (CKD) is an important health well-being problem globally, with increasing incidence. That tends to create an “epidemic”. Generalized muscle weakness in hemodialysis patients typically affects the lower limbs and proximal muscles. Patients experience impaired endurance and quality of life. Exercise is prescribed for these individuals to improve their physical health and prevent disease consequences. AIM. To find out the effect of interval versus continuous intradialytic training on muscle quality index and functional capacity in Hemodialysis patients. MATERIALS AND METHODS. Sixty men with chronic renal insufficiency grade 5 on hemodialysis aged from 45 to 55 years were divided into two groups using computerized block randomization: Groups (A) and (B) each containing 30 patients. They underwent 8-week program of high intensity interval training (HIIT), moderate intensity continuous training (MICT) intradialytic pedaling exercise plus hemodialysis three times per week. Pre-test and post-test evaluations have been carried out for 6-minute walk test (6MWT) and muscle quality index (MQI) of all patients. RESULTS. Both groups had a significant positive improvement in MQI and 6MWT with different proportions, patients received high intensity interval intradialytic pedaling exercise had a slightly significant improvement in MQI compared to moderate intensity continuous training group. While, moderate intensity training group had a more significant improvement in 6MWT compared to high intensity training group. CONCLUSION. Both HIIT and MICT are realistic and good options for individuals with CKD and have parallel profits on functional capability and, skeletal muscle quality and overall quality of life.

Muscle quality and major adverse cardiovascular events in post-acute myocardial infarction: A prospective cohort study

Background & aimsFunctional muscle quality, as assessed through the muscle quality index (MQI), represents a contemporary method to measure the capacity to generate force. Despite its potential, the prognostic significance of MQI remains uncertain in various clinical conditions, particularly among patients following acute myocardial infarction (AMI). In light of this, our study sought to evaluate the prognostic relevance of MQI concerning major adverse cardiovascular events (MACE) in patients following AMI. Methods and resultsThis is a secondary analysis of a prospective cohort study that included subjects aged ≥20 years from a Cardiovascular Unit Hospital. Functional muscle quality was estimated using MQI, defined as the ratio of handgrip strength (HGS) to muscle mass (MM) derived from bioelectrical impedance analysis. The outcomes included prolonged length of hospital stay, new adverse cardiovascular events (AMI, stroke and hospital readmission for unstable angina), and cardiovascular mortality. A composite score comprising all adverse events over the 1-year follow-up was calculated and defined as MACE. This study included 163 patients, with a median age of 61 years (IQ: 54–69 years), and the majority consisted of males (76.1%). Individual components of the functional muscle quality (HGS and MM) were not associated with any of the adverse outcomes. Only MQI was associated mortality over the 1-year follow-up. For each increase in MQI, the hazard of mortality decreases: adjusted HR: 0.08 (95% CI 0.01–0.84). ConclusionFunctional muscle quality assessed by the MQI may be a valuable clinical predictor of 1-year cardiovascular mortality in patients hospitalized post-AMI.

Deciphering the environmental chemical basis of muscle quality decline by interpretable machine learning models

BackgroundSarcopenia is known as a decline in skeletal muscle quality and function that is associated with age. Sarcopenia is linked to diverse health problems, including endocrine-related diseases. Environmental chemicals (ECs), a broad class of chemicals released from industry, may influence muscle quality decline. ObjectivesIn this work, we aimed to simultaneously elucidate the associations between muscle quality decline and diverse EC exposures based on the data from the 2011–2012 and 2013–2014 survey cycles in the National Health and Nutrition Examination Survey (NHANES) project using machine learning models. MethodsSix machine learning models were trained based on the EC and non-EC exposures from NHANES to distinguish low from normal muscle quality index status. Different machine learning metrics were evaluated for these models. The Shapley additive explanations (SHAP) approach was used to provide explainability for machine learning models. ResultsRandom forest (RF) performed best on the independent testing data set. Based on the testing data set, ECs can independently predict the binary muscle quality status with good performance by RF (area under the receiver operating characteristic curve = 0.793; area under the precision-recall curve = 0.808). The SHAP ranked the importance of ECs for the RF model. As a result, several metals and chemicals in urine, including 3-phenoxybenzoic acid and cobalt, were more associated with the muscle quality decline. ConclusionsAltogether, our analyses suggest that ECs can independently predict muscle quality decline with a good performance by RF, and the SHAP-identified ECs can be closely related to muscle quality decline and sarcopenia. Our analyses may provide valuable insights into ECs that may be the important basis of sarcopenia and endocrine-related diseases in United States populations.