Changes In Muscle Quality Research Articles

Specific tension of human muscle in vivo: a systematic review.

The intrinsic force production capability of human muscle can be expressed as "Specific Tension," or, the maximum force generated per cross-sectional area of muscle fibers. This value can be used to determine, for example, whether muscle quality changes during exercise, atrophy, disease, or hypertrophy. A value of 22.5 N/cm2 for mammalian muscle has generally become accepted based on detailed studies of small mammals. Determining the specific tension of human muscle is much more challenging as almost all determinations are indirect. Calculation of human muscle specific tension requires an understanding of that muscle's contribution to joint torque, its activation magnitude, tendon compliance, and joint moment arm. Determining any of these parameters is technically challenging in humans and thus, it is no surprise that human specific tension values reported vary from 2 to 73 N/cm2. In this systematic review, we screened 1,506 published papers and identified the 30 studies published between 1983 and 2023 that used appropriate methods and which reported 96 human specific tension values. We weighted each parameter based on whether it was directly measured, estimated, or calculated based on the literature, with decreasing weighting used, the more indirect the methods. Based on this exhaustive review of the relevant human literature, we suggest that the most accurate value that should be used for human muscle specific tension is 26.8 N/cm2.

Comparative Analyses of Muscle Quality in Hooked, Trawl-Net, and Radar-Net Hairtail (Trichiurus haumela) during Thermal Processing.

To investigate and compare the changes in muscle quality of hooked, trawl-net, and radar-net hairtail (Trichiurus haumela, HH, TH, and RH) during thermal processing, the physicochemical properties of three kinds of hairtail were determined under heating at 30, 50, 70 and 90 °C for 10 min. Additionally, the muscle tissues were observed via Oil Red O (ORO) staining, Masson staining, and scanning electron microscopy (SEM). The results showed that with increased heating temperature, pH, L*, b*, chewiness, and gumminess in hairtail muscle increased, while a* and shearing force decreased. The springiness, relative contents of hydrophobic and disulfide bonds, myosin surface hydrophobicity, and TCA-soluble peptide content increased first and then decreased. However, the relative contents of ionic and hydrogen bonds showed an opposite trend. Histological observations revealed that heating disrupted hairtail muscle tissue, manifested by the blurriness and disorder of myofibrils and breakage of myofibrillar bundle membranes. The RH muscle exhibited the highest chewiness, gumminess, and chemical force levels, accompanied by the lowest content of TCA-soluble peptide. Furthermore, the RH muscle presented the greatest fat droplet content, diffusivity, and integrity of collagen and myofibers. Correlation analysis revealed a close correlation between muscle quality and protein function in HH, TH, and RH. This study provides a theoretical basis for the difference in muscle quality in three different types of hairtail.

Assessment of Age-Related Differences in Lower Leg Muscles Quality Using Radiomic Features of Magnetic Resonance Images.

Sarcopenia, characterised by a decline in muscle mass and strength, affects the health of the elderly, leading to increased falls, hospitalisation, and mortality rates. Muscle quality, reflecting microscopic and macroscopic muscle changes, is a critical determinant of physical function. To utilise radiomic features extracted from magnetic resonance (MR) images to assess age-related changes in muscle quality, a dataset of 24 adults, divided into older (male/female: 6/6, 66-79years) and younger (male/female: 6/6, 21-31years) groups, was used to investigate the radiomics features of the dorsiflexor and plantar flexor muscles of the lower leg that are critical for mobility. MR images were processed using MaZda software for feature extraction. Dimensionality reduction was performed using principal component analysis and recursive feature elimination, followed by classification using machine learning models, such as support vector machine, extreme gradient boosting, and naïve Bayes. A leave-one-out validation test was used to train and test the classifiers, and the area under the receiver operating characteristic curve (AUC) was used to evaluate the classification performance. The analysis revealed that significant differences in radiomic feature distributions were found between age groups, with older adults showing higher complexity and variability in muscle texture. The plantar flexors showed similar or higher AUC than the dorsiflexors in all models. When the dorsiflexor muscles were combined with the plantar flexor muscles, they tended to have a higher AUC than when they were used alone. Radiomic features in lower-leg MR images reflect ageing, especially in the plantar flexor muscles. Radiomic analysis can offer a deeper understanding of age-related muscle quality than traditional muscle mass assessments.

Multi-omics reveals the molecular mechanism of muscle quality changes in common carp (Cyprinus carpio) under two aquaculture systems

Preliminary experiments in our laboratory have demonstrated that common carp (Cyprinus carpio) cultivated for two months in land-based container recirculating aquaculture systems (C-RAS) exhibit superior muscle quality compared to those raised in traditional pond systems (TP). To elucidate the molecular mechanisms underlying muscle quality variations in common carp cultured under two aquaculture systems, transcriptomic and metabolomic analyses were performed on muscle tissues of specimens aged 11 to 23 months. Comparison of muscle histological sections between the two groups indicated a significantly lower long diameter of muscle fibers in the C-RAS group compared to the TP group (P < 0.01). Conversely, the muscle fiber density was significantly higher in the C-RAS group than in the TP group (P < 0.05). Transcriptomic and metabolomic analyses identified 3390 differentially expressed genes (DEGs)—1558 upregulated and 1832 downregulated—and 181 differentially expressed metabolites (DEMs)—124 upregulated and 57 downregulated—between the groups. Based on integrated transcriptomic and metabolomic analyses, the significant differences focus on metabolic pathways involving glycolysis/gluconeogenesis, arginine and proline metabolism, arginine biosynthesis, and purine metabolism. The study revealed that the muscle quality of common carp in two aquaculture systems is primarily regulated through improvements in energy metabolism, amino acid metabolism, fatty acid metabolism, and purine metabolism. These metabolic processes play significant roles in promoting muscle fiber hyperplasia and hypertrophy, enhancing muscle flavor, and increasing muscle antioxidant capacity. This study provides new insights into the molecular and metabolic pathways that control muscle quality in common carp under different environmental factors.

Effects of Resistance Exercise and Essential Amino Acid Intake on Muscle Quality, Myokine, and Inflammation Factors in Young Adult Males.

Recently, many studies have been devoted to discovering nutrients for exercise-like effects. Resistance exercise and the intake of essential amino acids (EAAs) are known to be factors that can affect muscle mass and strength improvement. The purpose of this study was to investigate changes in muscle quality, myokines, and inflammation in response to resistance exercise and EAA supplementation. Thirty-four males volunteered to participate in this study. They were assigned to four groups: (1) placebo (CO), (2) resistance exercise (RE), (3) EAA supplementation, and (4) RE + EAA supplementation. Body composition, muscle quality, myokines, and inflammation were measured at baseline and four weeks after treatment. Lean body fat had decreased in both RE and RE + EAA groups. Lean body mass had increased in only the RE + EAA group. In all groups except for CO, irisin, myostatin A, and TNF-α levels had decreased. The grip strength of the right hand and trunk flexion peak torque increased in the RE group. The grip strength of the left hand, trunk flexion peak torque, and knee flexion peak torque of the left leg were increased in RE + EAA. RE, EAA, and RE + EAA could effectively improve the muscle quality, myokine, and inflammation factors of young adult males. This finding highlights the importance of resistance exercise and amino acid intake.

Changes in muscle quality and biomarkers of neuromuscular junctions and muscle protein turnover following 12 weeks of resistance training in older men.

The present study aimed to investigate the effects of 12 weeks of resistance training (RT) on body composition [fat mass (FM), lean body mass (LBM)], muscle quality upper and lower (MQU, MQL), muscle size [cross sectional area (CSA), quadriceps cross-sectional area (QCSA)], biomarkers of neuromuscular junctions [C-terminal agrin fragment (CAF)], and muscle protein turnover [N-terminal peptide (P3NP), 3-methylhistidine (3MH), skeletal muscle-specific isoform of troponin T (sTnT)] in older men. Thirty elderly men (age 66.23 ± 0.57 years) were randomly divided into two groups: resistance training group (RT, n=15) and control group (CON, n=15). Participants in RT performed resistance training protocols with the intensity of 60% one-repetition maximum (3 × /week, 4 sets of the six exercise circuits). Blood samples were assessed before (pre-test) and after (post-test) a 12-week intervention. The ANCOVA (2 × 2; group × time; with the baseline variable as the covariate) revealed significant interaction effects; the greater increases for LBM (P < 0.001), CSA (P < 0.001), QCSA (P < 0.001), MQU (P < 0.05), MQL (P < 0.01), 3MH (P < 0.05) were noted in RT than CON, and greater decreases for FM (P < 0.001) and CAF (P < 0.001) in RT than CON. No interaction effect was found for P3NP and sTnT. The time effect was found for all variables besides P3NP in RT, but no time effect was revealed in CON. The 12-week RT was an effective strategy for improving the concentrations of neuromuscular junction biomarkers such as 3-MH and CAF in older adults, and may lead to favourable changes in body composition, muscle quality, and muscle size.

Effect of aquatic exercise versus standard care on paraspinal and gluteal muscles morphology in individuals with chronic low back pain: a randomized controlled trial protocol

BackgroundLow back pain (LBP) is one of the most disabling diseases and a major health issue. Despite the evidence of a link between paraspinal and gluteal muscle dysfunction and LBP, it is unknown whether aquatic exercises can lead to improvements in paraspinal and gluteal muscle morphology and function, and whether improvements in overall muscle health are associated with improvements in patients’ outcomes. The unique properties of water allow a water-based exercise program to be tailored to the needs of those suffering from LBP. This study uses magnetic resonance imaging (MRI) to investigate the effect of an aquatic exercise program versus standard exercise on 1) paraspinal and gluteal muscle size, quality and strength and 2) pain, disability, and psychological factors (pain related fear, depression, anxiety, sleep quality) in chronic LBP.MethodsThis study will include 34 participants with chronic non-specific LBP and moderate to severe disability, aged between 18 and 65, who will be randomly assigned (1:1) to the aquatic exercise group or land-based standard care exercise group. Both groups will receive 20 supervised sessions, twice per week over 10 weeks. MRIs will be obtained along the lumbosacral spine (L1-L5) and pelvis at the start and end of the intervention to assess the effect of each exercise intervention on paraspinal and gluteal muscle size and quality. Pre- to post-intervention changes in all outcomes between each group will be assessed, and the association between the changes in back muscle quality and clinical outcomes will be examined. Between-subjects repeated measure analysis of variance will be used to examine the changes in paraspinal muscle morphology over the different time points. Linear mixed models will be used to assess whether baseline scores can modify the response to the exercise therapy treatment.DiscussionThis study will determine if water-based exercises targeting the lower back and gluteal muscles can lead to important changes in muscle quality and function, and their possible relation with patients’ pain and functional improvements. Our findings will have strong clinical implications and provide preliminary data to design a community program to better support individuals with chronic LBP.Trial registrationNCT05823857, registered prospectively on April 27th, 2023.

Quality changes in gazami crab (Portunus trituberculatus) during refrigeration

Gazami crab (Portunus trituberculatus) is prone to spoilage during storage and transportation. More research is needed to determine how to reliably show its freshness and explain the mechanism of quality deterioration. We hypothesized that proteins extracted from crabs can be biomarkers to detect crab muscle quality changes. This work used physicochemical and proteomic approaches to investigate protein biomarkers and molecular mechanisms driving changes in gazami crab muscle quality after long-term refrigeration. It was shown that 66 differentially abundant proteins (DAPs) were closely associated with pH and texture and can be used as biomarkers to assess crab muscle freshness. According to bioinformatics studies, ribosomes and autophagy were significant mechanisms in crab rotting. These findings provided new concepts and a theoretical foundation for evaluating the freshness of refrigerated gazami crab and help uncover the molecular mechanism of its quality deterioration.

Muscular Adaptations to Concurrent Resistance Training and High-Intensity Interval Training in Adults with Type 2 Diabetes: A Pilot Study.

This pilot study aimed to compare the effects of eight weeks of concurrent resistance training (RT) and high-intensity interval training (HIIT) vs. RT alone on muscle performance, mass and quality in adults with type 2 diabetes (T2DM). Twelve T2DM adults were randomly allocated to the RT + HIIT (n = 5) or RT (n = 7) group. Before and after training, maximal oxygen uptake (VO2max), muscle strength and power were evaluated by calorimetry, dynamometry and one-repetition maximum (1RM) test. Quadriceps muscle volume was determined by MRI, and muscle quality was estimated. After RT, VO2max (+12%), knee muscle power (+20%), quadriceps muscle volume (+5.9%) and quality (leg extension, +65.4%; leg step-up, +223%) and 1RM at leg extension (+66.4%), leg step-up (+267%), lat pulldown (+60.9%) and chest press (+61.2%) significantly increased. The RT + HIIT group improved on VO2max (+27%), muscle volume (+6%), muscle power (+9%) and 1RM at lat pulldown (+47%). No other differences were detected. Among groups, changes in muscle quality at leg step-up and leg extension and VO2max were significantly different. The combination of RT and HIIT effectively improves muscle function and size and increases cardiorespiratory fitness in adults with T2DM. However, HIIT combined with RT may interfere with the development of muscle quality.

Changes In Muscle Quality Identified By Shear-Wave Elastography And Association With Sarcopenia Parameters

Changes In Muscle Quality Identified By Shear-Wave Elastography And Association With Sarcopenia Parameters

Effect of yoga intervention on skeletal muscle linked glucose homeostasis in pre-diabetic individuals: Study protocol for a randomized controlled trial

BackgroundThe pre-diabetic stage is important in terms of identification and timely management due to its reversible nature. Along with other factors, insulin resistance in skeletal muscle is often considered as primary defect before development of overt hyperglycemia and Diabetes Mellitus (DM). Physical exercises are beneficial in prevention of DM by improving skeletal muscle mediated glucose metabolism. Evidence suggests that Yoga interventions appear to be equal and/or superior to exercise in most outcome measures. As the Yogic postures are relatable to exercises, they are considered to improve skeletal muscle function and reverse the pre-diabetic stage. MethodsThis open-labelled, randomized clinical study is planned to evaluate effect of Yoga interventions on muscle mass, strength, endurance and flexibility which are direct/indirect indicators of fat deposition in skeletal muscles. Association between changes in muscle quality/ functionality and glycemic control will also be explored. With ethics committee permission, 120 pre-diabetic individuals of either sex between age group of 35–49 years with BMI range of 25–35 kg/m2 and family history of Type 2 Diabetes Mellitus (T2DM) will be recruited after obtaining written informed consent. They will be randomly allocated to either Yoga or exercise group by computer generated randomized method in a 1:1 ratio. One group will receive defined Yoga interventions, while other group will receive fixed program of physical exercises. Prior to initiating this 12-week study, both groups will undergo a training session for 4 weeks under supervision of a trained instructor. The outcome measures will be parameters related to muscle quality/functionality and glucose metabolism markers. DiscussionOur study aims to explore practicality of Yoga in pre-diabetic stage on skeletal muscle related glycemic control, which is novel. Additionally, the study will generate awareness about pre-diabetes and provide people with active coping skills for reversing it.

Changes in muscle quality identified by shear-wave elastography and association with sarcopenia.

This study aimed to investigate the potential role of shear-wave elastography (SWE) in evaluating muscle quality and assess its association with muscle strength and mass. A total of 129 patients aged 18-87 years were included. Patients aged >65 years underwent comprehensive geriatric assessment. Anthropometric measurements, assessment of physical performance, muscle strength (handgrip strength [HGS]), muscle mass (B-mode muscle ultrasonography), and muscle quality (identified via SWE) were performed for all patients. The median (interquartile range) age of participants was 69 (59-76) years and 62% (n = 80) were female. According to HGS, patients were divided into normal and low HGS groups, and there were 85 (65.9%) and 44 (34.1%) patients in each group, respectively. The median average value of SWE measurement (Vmean ) of the rectus femoris (RF) in passive stretching was significantly lower in the low HGS group. In regression analyses, Vmean was significantly associated with HGS independently of age, sex, and body mass index. Optimal cutoff values of the Vmean value (m/s) of RF in passive stretching for predicting low HGS were ≤2.62 for male (area under the curve [AUC], 0.882; 95% CI, 0.705-0.938; P = <0.0001), and ≤2.52 for female (AUC, 0.719; 95% CI, 0.605-0.833; P = 0.002). To the best of our knowledge, this is the first study revealing SWE is a good predictor of muscle strength, and it could be a useful tool for evaluating muscle quality in clinical practice. Further randomized controlled studies are needed to confirm the presented cutoff values.

Sarcopenia in ovarian cancer: Identifying changes in muscle quantity and quality during treatment of advanced disease (214)

<b>Objectives:</b> Sarcopenia, a loss of muscle mass and function, is a risk factor for decreased survival in advanced epithelial ovarian cancer (EOC). Little is known about the effect of treatment for EOC on sarcopenia and how this relates to outcomes. We aimed to determine the change in sarcopenia measures over the course of primary EOC treatment and how this impacts overall survival. <b>Methods:</b> We utilized an institutional EOC surgical database to identify stage IIIC or IV EOC patients who received primary debulking surgery (PDS) and adjuvant platinum-based chemotherapy between 2006-2016. Patients were included if they underwent at least five cycles of adjuvant chemotherapy and had CT scans available both before PDS (pre) and near completion of six cycles of adjuvant chemotherapy (post). Patient CT scans were analyzed for body composition measures, including skeletal muscle area (SMA), skeletal muscle attenuation (SMD), and skeletal muscle index (SMI), defined as SMA normalized for patient height. Change in muscle quality (SMD) over muscle quantity (SMI) was evaluated by the ratio of SMD/SMI. The percent change ([post – pre] x100/pre) in body composition measures over time were analyzed for association with death. <b>Results:</b> Among 109 patients included in the analysis (mean age, 62.6 years), the majority of patients received 5-6 cycles of adjuvant chemotherapy (83%). The median time between pre- and post-CT scans was 188 days (IQR: 175 to 211 days). Based on SMI cutoff of <39 cm²/m², almost half of the patients (50/109; 45.9%) were sarcopenic at some point during their treatment, including 27 (24.8%) who were sarcopenic on both scans and 23 (21.1%) who became sarcopenic at post-treatment scan. We observed a statistically significant decrease in muscle quantity (mean±SD percent change in SMI, -4.4±9.2; p<0.001) and a non-significant increase in muscle quality (mean±SD percent change in SMD, 6.3±25.1; p=0.28) following treatment. Given these findings, the density of muscle per unit area (SMD/SMI) was analyzed. On average, SMD/SMI increased from pre- to post-treatment CT scans, from 0.83±0.26 to 0.89±0.25 HU*m²/cm², translating to a percent increase of 12.2±30.0 (p<0.001). An increase in the percent change of SMD/SMI over the course of treatment was significantly associated with an increased risk of death (Figure A). In particular, the median OS was 3.6 years in women with percent change in SMD/SMI >10%, 4.8 years in those with percent change between ±10%, and 6.2 years for those with > -10% change (Figure B, p=0.017). There was no significant association observed when evaluating SMI and SMD.Fig. 1 <b>Conclusions:</b> Patients who underwent curative-intent PDS and adjuvant chemotherapy had changes in sarcopenia measures following treatment. Those with an increase in muscle density per unit area following treatment had worse survival; this hypothesis-generating finding illustrates the need for continued research evaluating how patient factors and tumor biology influence sarcopenia and subsequent outcomes in this high-risk group.

Effects of Quercetin Glycoside Supplementation Combined With Low-Intensity Resistance Training on Muscle Quantity and Stiffness: A Randomized, Controlled Trial.

ObjectiveAging of skeletal muscle is characterized not only by a decrease of muscle quantity but also by changes in muscle quality, such as an increase in muscle stiffness. The present study aimed to investigate the effects of supplementation with quercetin glycosides (QGs), well-known polyphenolic flavonoids, combined with resistance exercise on muscle quantity and stiffness.Materials and MethodsA randomized, controlled trial was conducted in community-dwelling, Japanese people aged 50–74 years who were randomly allocated to exercise with placebo or 200 or 500 mg of QG supplementation. All participants performed low-intensity resistance training mainly targeting thigh muscles with 40% of 1-repetition maximum, 3 days per week for 24 weeks. Muscle cross-sectional area (CSA), lean mass, and vastus lateralis (VL) muscle stiffness were measured before and after the 24-week intervention.ResultsForty-eight subjects completed the 24-week intervention. There were no significant group × time interactions in thigh CSA for primary outcome, as well as lean mass. VL muscle stiffness in the stretched position was significantly lower in both the 200 mg and 500 mg QG groups than in the placebo group after the 24-week intervention (p < 0.05). No significant correlation was observed between changes of VL muscle CSA and stiffness during the 24-week intervention.ConclusionQuercetin glycoside supplementation combined with low-intensity resistance exercise improved passive muscle stiffness independently of muscle quantity.Clinical Trial Registration[www.umin.ac.jp/ctr/], identifier [UMIN000037633].

Changes in Muscle Quality after Physical Rehabilitation Reduce Blood Pressure in Weightlifters with Arterial Hypertension: Randomized Controlled Trial

Hypertension is a frequent diagnosis in power athletes. Aim. To assess the effect of increased muscle oxidative capacity on blood pressure in athletes with arterial hypertension from power sports, heavy weight categories. Material and methods. The study was conducted at the Department of Sports Medicine of the Russian State University of Physical Culture, Sports, Youth and Tourism and lasted 180 days. The study involved 65 representatives of strength sports (weightlifting), heavy weight categories with arterial hypertension. Athletes were randomized into two main groups: the HIIT (High Intensity Interval Training, n=23) group, the MICE (Moderate Intensity Continuous Exercise, n=22) group and the RT (Resistance Training, n=20) control group. The following methods were used to achieve the aim of the study: ergospirometry, muscle tissue oxygenation level measurement, blood pressure measurement and methods of mathematical statistics. Athletes in the main groups trained for 180 days (3 times per week) on a cycle ergometer using a high-intensity interval and uniform protocol, and participants in the control group trained for 180 days (3 times per week) according to their traditional strength protocol. Results. After 180 days of physical rehabilitation, participants of the main groups had increased oxygen consumption at the anaerobic threshold, decreased thigh muscle oxygenation and increased maximum oxygen consumption, resulting in an average decrease in systolic blood pressure of 11.1 mm Hg and diastolic blood pressure of 11.2 mm Hg in the intervention groups. Conclusion. The physical rehabilitation systems we have developed for power athletes allow us to effectively and safely influence the oxidative capacity of working muscles and blood pressure, but the time spent by athletes on non-specific training activities in the HIIT system is 38% less.

Changes in muscle quality and physicochemical characteristics of chicken breast subjected to ultrasound-assisted immersion freezing during long-term frozen storage

The influence of ultrasound-assisted immersion freezing (UF), immersion freezing (IF), and air freezing (AF) on the muscle quality and physicochemical properties of chicken breasts during frozen storage (0 –180 days) was investigated. The ice crystal size in UF samples was smaller than in IF and AF samples during frozen storage. UF significantly lowered the samples’ thawing and cooking losses during frozen storage compared to IF and AF (P < 0.05). While the cutting force values of all the samples gradually reduced with extension of storage period, the UF samples showed the least change in cutting force (P < 0.05), indicating that UF samples had the least muscle structure deterioration. UF samples also possessed the lower color deterioration and lipid oxidation compared to the IF and AF samples (P < 0.05). Low-field nuclear magnetic resonance analysis showed that UF treatment minimized water migration in samples during storage (P < 0.05). Hierarchical cluster analysis revealed that the quality of the UF samples after 180 days of storage was similar to the IF samples after 90 days and the AF samples after 60 days. In general, the UF treatment was beneficial to decrease muscle loss during frozen storage.

Single skeletal muscle fiber mechanical properties: a muscle quality biomarker of human aging.

Skeletal muscle strength, mass, and function should be carefully monitored for signs of decline with advanced adult age. An understanding of the pathophysiology and severity of sarcopenia can be improved with the exploration of changes in muscle fiber properties. Furthermore, although functional decline with increase age is a well-known phenomenon, the mechanisms underlying this decline, and the features that characterize it, are complex and variable. The age-related decline of muscle function is a result of not only a decrease of muscle mass but also a decline in the intrinsic properties of muscle fibers that are independent of size. We believe it is important to understand changes in muscle quality (force adjusted for size), and not to focus solely on muscle mass, because muscle quality is closely related to measurements of function and could potentially predict clinical outcomes such as morbidity, disability, and mortality. Neurological and metabolic mechanisms contribute to muscle quality, but the intrinsic properties of muscle cells are central to the maintenance of force-generating capacity. Muscle quality can be evaluated with the assessment of morphological, physiological, and mechanical properties in single permeabilized or skinned fibers. This approach excludes the influence of the nervous system, tendons, and the extracellular matrix. In this review, we summarized the changes in active and passive mechanical properties at the single muscle cell level in older skeletal muscles. We argue that intrinsic mechanical changes in human single muscle fibers are useful biomarkers and indicators of muscle quality.

STATIN USE IS ASSOCIATED WITH SUBTLE CHANGES IN MUSCLE COMPOSITION AND QUALITY: A QUANTITATIVE IMAGING ANALYSIS USING OAI DATA

Subjective statin-associated musculoskeletal symptoms such as myalgia are commonly reported and contribute to statins' non-adherence. Several trials have recently suggested that in the absence of rare myositis, such symptoms are probably a placebo effect. However, no longitudinal study has been conducted to investigate whether statin use can be associated with deterioration in muscle quality. Such an association can be of particular clinical concern in older patients with or at-risk of knee OA, in whom muscle changes can affect the knee OA clinical outcomes. To assess longitudinal changes of validated thigh muscle quality biomarkers associated with statin use in people with or at-risk of knee OA. OAI Statin users at baseline or any of the four annual follow-up visits and non-users were matched for confounding by indication using 1:1 propensity-score (PS) matching. Potential confounders as covariates of the PS-matching included a wide range of demographic variables, comorbid diseases, risk factors, and medications. After PS-matching, 3,772 thighs of 1,910 participants were included (1,886 thighs of statin-users: 1,886 of non-users; age: 62±9 years (average ± SD), range: 45-79; female/male ratio: 1). Participants were further stratified according to baseline radiographic knee OA status (with versus at-risk of knee OA). We trained, tested, and used an automated deep learning model with a 2D U-Net structure to segment thigh muscle MRIs, with similar results to manual segmentation and quantification. Longitudinal muscle quality biomarkers included cross-sectional area (CSA), intramuscular adipose tissue (intra-MAT), contractile percent, and knee extensors and flexors maximum contractile force and specific contractile force (contractile force/CSAs) at baseline, 2nd, and 4th-year follow up. Linear mixed-effects models were used. At baseline, there was no statistically significant imbalance in PS-matching variables or muscle quality biomarkers between PS-matched statin-users and non-users. During four years, statin use was associated with a slight decrease in muscle quality, indicated by decreased knee extensor (quadriceps) maximum and specific contractile forces (mean difference (% of baseline value), 95%CI: -1.85 Newton/year (0.5% of 355.15N at baseline), -3.23 – -0.47, and -0.04 N/cm2/year (0.6% of 6.96N/cm2 at baseline), -0.07 – -0.01), contractile percent of the thigh muscles (-0.03%/year (0.03% of 95.32% at baseline), -0.06 – -0.01), and increased thigh intra-MAT (3.06 mm2/year (0.7% of 461.45mm2 at baseline), 0.53–5.59). However, stratification analysis showed that these results were only present in participants at-risk of knee OA but not those with the existing radiographic knee OA at baseline. Statin use is associated with decreased muscle quality, indicated by reduced contractility of the extensor (quadriceps) muscle and increased intra-muscular fat deposition. However, considering the small size of changes in muscle quality compared to substantial favorable cardiovascular effects of statins in clinical practice, these muscle changes might be considered clinically negligible. NIH NIAMS, under Award Number R01AR079620-01. AG reported receiving funding from Merck Serono, AstraZeneca, Galapagos, Pfizer, Roche, TissueGene (for consultation), and Boston Imaging Core Lab (as the president and stockholder). SD reported that he received funding from Toshiba Medical Systems (for consultation) and grants from GERRAF and Carestream Health (for a clinical trial study). CORRESPONDENCE ADDRESS: sdemehri1@jhmi.edu

Differences in Muscle Quantity and Quality by HIV Serostatus and Sex.

People with HIV (PWH) experience greater declines in both muscle function and muscle mass with aging. Whether changes in muscle quality and quantity with aging differ between men and women with HIV and the implications on muscle function are not established. In coordinated substudies of the Multicenter AIDS Cohort Study and Women's Interagency HIV Study, participants completed physical function and falls assessments; total trunk/thigh density, inversely related to fatty infiltration, and area were quantified from computed tomography (CT) scans. Generalized linear models were used to explore variables affecting density/area, and associations between area/density and physical function and falls. CT scans were available on 387 men (198 PWH) and 184 women (118 PWH). HIV serostatus was associated with greater lateralis, paraspinal, and hamstring area, but lower psoas area and density. Older age and female sex were associated with smaller trunk muscle area and lower density. Both lower muscle area and muscle density were associated with several measures of impaired physical function. The odds of falling were lower with greater hamstring density, but not associated with other measurers of muscle area or density. In summary, older adults with HIV appear to have smaller and less dense (fattier) psoas, a key component in truncal stability and hip flexion that could have implications on physical function. The longitudinal associations of muscle area and density with physical function require careful investigation, with a particular focus on characteristics and interventions that can preserve muscle area, density, and function over time.

Seven months of aerobic intradialytic exercise training can prevent muscle loss in haemodialysis patients: an ultrasonography study.

This study aimed to evaluate the effects of 7-month intradialytic exercise training (IDE) on vastus lateralis (VL) muscle architecture, functional capacity and quality of life in stable haemodialysis (HD) patients. 44 HD patients were randomly assigned into an Exercise Group (EG = 21), which they received 7 months of IET, at 60% of pre-assessed maximum aerobic power, 3/week) or into a Control Group (CG = 23, no exercise). VL architecture was evaluated with ultrasonography, functional capacity was assessed using a series of functional tests (6min walking test, 5 repetitions sit-to-stand, sit-to-stand 60s, handgrip strength), and maximal aerobic power determined with a modified version of the Åstrand test. Quality of life and fatigue levels were evaluated using validated questionnaires. VL fascicle angle and length did not change significantly in both groups (P > 0.05). Muscle thickness decreased in CG (P = 0.02) while it was fully preserved in the EG. Functional capacity increased only in the EG (6min walking test 15.79 ± 12.35%, P < 0.001; max aerobic power 26.36 ± 1.24%, P < 0.001; STS-60rep: 10.23 ± 1.60%, P < 0.000; hand grip strength: 5.14 ± 28.30%, P < 0.02). Intradialytic aerobic exercise training, improves functional capacity and prevents thigh muscle mass loss in HD patients. It is evident that muscle ultrasonography could play a pivotal role in assessing muscle quality changes in haemodialysis patients. A higher level of training intensity or combination with resistance exercises may be required to further improve anabolism and influence muscle architecture in this patient population. NCT03905551.