Assessment Of Muscle Function Research Articles

Wearable ultrasound system for assessing muscle function during physical activity

Conventional ultrasound transducers, which are meant for hand-held operation, are not ideally suited for MSK-US during dynamic physical activity. We have developed a custom wearable ultrasound system for Motion-mode (M-mode) MSK-US, which enables multi-site hands-free sensing of tissue movement during physical activity such as that encountered during rehabilitation exercises. Participants performed a jumping task on a force plate with a sensor attached to their right vastus lateralis (VL). Mean pixel value (MPV) and normalized pixel differences (NPDs) were acquired from the images during the jumping task. Signals were filtered and normalized to root-mean square baseline and percent change was calculated for peaks of jump take-off and landing. The correlation coefficient was calculated to determine a relationship between metrics. Concurrently acquired force-plate data showed that the percent change during take-off and landing was 0.28% ± 0.09 and 0.66% ± 0.17 relative to baseline for each peak, respectively. MPV values changed 0.42% ± 0.29 and 0.81% ± 0.17, and NPD changed 0.41% ± 0.32 and 0.84% ± 0.12 for corresponding peaks. Overall results indicated significant correlation between force data and MSK-US (p < 0.05). Our system can maintain acoustic coupling during complex movements providing real-time feedback and expanding the potential for wearable MSK-US sensors.

The Adiponectin Receptor Agonist, ALY688: A Promising Therapeutic for Fibrosis in the Dystrophic Muscle.

Duchenne muscular dystrophy (DMD) is one of the most devastating myopathies, where severe inflammation exacerbates disease progression. Previously, we demonstrated that adiponectin (ApN), a hormone with powerful pleiotropic effects, can efficiently improve the dystrophic phenotype. However, its practical therapeutic application is limited. In this study, we investigated ALY688, a small peptide ApN receptor agonist, as a potential novel treatment for DMD. Four-week-old mdx mice were subcutaneously treated for two months with ALY688 and then compared to untreated mdx and wild-type mice. In vivo and ex vivo tests were performed to assess muscle function and pathophysiology. Additionally, in vitro tests were conducted on human DMD myotubes. Our results showed that ALY688 significantly improved the physical performance of mice and exerted potent anti-inflammatory, anti-oxidative and anti-fibrotic actions on the dystrophic muscle. Additionally, ALY688 hampered myonecrosis, partly mediated by necroptosis, and enhanced the myogenic program. Some of these effects were also recapitulated in human DMD myotubes. ALY688's protective and beneficial properties were mainly mediated by the AMPK-PGC-1α axis, which led to suppression of NF-κβ and TGF-β. Our results demonstrate that an ApN mimic may be a promising and effective therapeutic prospect for a better management of DMD.

Screening data from 19 patients with late-onset Pompe disease for a phase I clinical trial of AAV8 vector-mediated gene therapy.

Late-onset Pompe disease (LOPD) is a multisystem disorder with significant myopathy. The standard treatment is enzyme replacement therapy (ERT), a therapy that is lifesaving, yet with limitations. Clinical trials have emerged for other potential treatment options, including adeno-associated virus (AAV) gene therapy. We present clinical parameters and AAV antibody titers for 19 individuals with LOPD undergoing screening for a Phase I clinical trial with an AAV serotype 8 vector targeting hepatic transduction (AAV2/8-LSPhGAA). Reported clinical parameters included GAA genotype, assessments of muscle function, upright and supine spirometry, anti-recombinant human GAA antibody titers, and biomarkers. Variability in measured parameters and phenotypes of screened individuals was evident. Eligibility criteria required that all participants have six-minute walk test (6MWT) and upright forced vital capacity (FVC) below the expected range for normal individuals, and were stably treated with ERT for >2 years. All participants had Pompe disease diagnosed by enzyme deficiency, and all had the common c.-32-13T>G LOPD pathogenic variant. Screening identified 14 patients (74%) with no or minimal detectable neutralizing antibodies against AAV8 (titer ≤1:5). 6MWT distance varied significantly (percent of expected distance ranging from 24% to 91% with an average of 60 and standard deviation of 21). Upright FVC percent predicted ranged from 35% predicted to 91% predicted with an average of 66 and standard deviation of 18. None of the participants had significantly elevated alanine transaminase, which has been associated with LOPD and could complicate screening for hepatitis related to AAV gene therapy. We review the parameters considered in screening for eligibility for a clinical trial of AAV8 vector-mediated gene therapy.

SEMPAI: a Self-Enhancing Multi-Photon Artificial Intelligence for Prior-Informed Assessment of Muscle Function and Pathology.

Deep learning (DL) shows notable success in biomedical studies. However, most DL algorithms work as black boxes, exclude biomedical experts, and need extensive data. This is especially problematic for fundamental research in the laboratory, where often only small and sparse data are available and the objective is knowledge discovery rather than automation. Furthermore, basic research is usually hypothesis-driven and extensive prior knowledge (priors) exists. To address this, the Self-Enhancing Multi-Photon Artificial Intelligence (SEMPAI) that is designed for multiphoton microscopy (MPM)-based laboratory research is presented. It utilizes meta-learning to optimize prior (and hypothesis) integration, data representation, and neural network architecture simultaneously. By this, the method allows hypothesis testing with DL and provides interpretable feedback about the origin of biological information in 3D images. SEMPAI performs multi-task learning of several related tasks to enable prediction for small datasets. SEMPAI is applied on an extensive MPM database of single muscle fibers from a decade of experiments, resulting in the largest joint analysis of pathologies and function for single muscle fibers to date. It outperforms state-of-the-art biomarkers in six of seven prediction tasks, including those with scarce data. SEMPAI's DL models with integrated priors are superior to those without priors and to prior-only approaches.

Factors affecting real‐time evaluation of muscle function in smart rehab systems

AbstractAdvancements in remote medical technologies and smart devices have led to expectations of contactless rehabilitation. Conventionally, rehabilitation requires clinicians to perform routine muscle function assessments with patients. However, assessment results are difficult to cross‐reference owing to the lack of a gold standard. Thus, the application of remote smart rehabilitation systems is significantly hindered. This study analyzes the factors affecting the real‐time evaluation of muscle function based on biometric sensor data so that we can provide a basis for a remote system. We acquired real clinical stroke patient data to identify the meaningful features associated with normal and abnormal musculature. We provide a system based on these emerging features that assesses muscle functionality in real time via streamed biometric signal data. A system view based on the amount of data, data processing speed, and feature proportions is provided to support the production of a rudimentary remote smart rehabilitation system.

Nonsurgical hypoparathyroidism is associated with skeletal muscle dysfunction and restrictive lung disease.

Systematic assessment of skeletal muscle function is lacking in patients with nonsurgical hypoparathyroidism (HP). Whether muscle dysfunction involves respiratory muscles and results in restrictive lung disease (RLD) is not studied. To assess skeletal muscle and pulmonary functions in patients with HP. Observational case-control study. Thirty patients with HP (mean age 37.7 years, 60% males) and age, sex, and body mass index-matched forty healthy-controls were assessed for skeletal muscle function by hand-grip strength, short physical performance battery (SPPB) test, dual-energy x-ray absorptiometry, and electromyography. Pulmonary function was assessed by spirometry, body plethysmography, diffusion lung capacity for carbon monoxide and diaphragmatic ultrasound. Patients with HP had lower serum calcium (2.25±0.15 vs 2.4±0.12 mmol/L, p<0.001), serum magnesium [median (interquartile-range) 0.74 (0.69-0.82) vs 0.78 (0.69-0.90) mmol/L, p=0.04], hand-grip strength (18.08±8.36 vs 22.90±7.77 kg, p=0.01) and composite SPPB score (9.5 [7-10] vs 12 [12-12], p< 0.001) compared to healthy-controls. Electromyographic evidence of myopathy was seen in 23% (5 of 22) patients with HP, but in none of the controls (p=0.08). The prevalence of RLD was higher in the HP cohort compared to that in controls (24% vs 0%, p=0.01). Diaphragmatic excursion (4.22±1.38 vs 5.18±1.53 cm, p=0.01) and thickness (3.79±1.18 vs 4.28±0.94 mm, p=0.05) on deep inspiration were reduced in patients with HP. Detailed testing of patients with HP without overt muscle and lung diseases revealed significant impairment in parameters of skeletal muscle function. Myopathy and RLD were observed in a considerable proportion of patients with HP.

THE EFFECTS OF MYOFASCIAL SELF-RELEASE METHOD AND TOOL APPLICATION ON ATHLETE STRENGTH INDICATORS IN TIBIA EXTENSOR MUSCLES IN FITNESS

The aim of the present study was to analyse the effectiveness of myofascial self-release methods and the use of the tool in the development of strength indicators in the tibia extensor muscles. Instrumental assessment of muscle function was performed on a REV 9000, Technogymᴿ, Italy. The subjects of our study were twenty healthy fitness athletes aged between 20 and 23 years. A set of strength exercises was developed, consisting of 10 exercises focused on increasing the muscle strength of tibia extensor muscles. For the experimental group self-massage with a roller was applied. When applying strength-development exercises with a set of self-release, the dynamics of maximum strength results are as follows: the force balance of the dominant and the non-dominant leg in the control group before (p=0.001) and after (p=0.02) the experiment, and in the experimental group before (p=0.01) and after (p=0.02) the experiment remained unchanged – no significant changes were observed in the results between the groups; - positive dynamics in strength changes were observed for the dominant leg between the control group (p=0.08) and the experimental group (p=0.37) before and after the experiment. The positive increase in the results is in favour of the experimental group, although there are no significant statistical differences in the results of the control group. On the other hand, no differences in the strength dynamics of the non-dominant leg were found.

Pelvic Floor Muscle Function and Its Relationship with Post-Prostatectomy Incontinence

ObjectivesPost-prostatectomy incontinence (PPI) is a common condition, but the underlying mechanisms are not completely understood. Transperineal ultrasound (TPUS) assessment of voluntary pelvic floor muscle (PFM) function may be associated with PPI. This study investigates the relationship between PPI and pre- and postoperative displacement of anatomical landmarks related to PFM function.MethodsThis was a prospective longitudinal cohort study of 40 patients undergoing robotic-assisted radical prostatectomy (RARP) by a high-volume single surgeon. All patients underwent PFM training pre- and postoperatively. TPUS was used to obtain sagittal images of pelvic structures during maximal voluntary PFM contractions: (1) preoperatively, (2) 3 weeks postoperatively, and (3) 6 weeks postoperatively. TPUS images were analyzed to calculate displacement of anatomical landmarks associated with activation of striated urethral sphincter (SUS), bulbocavernosus muscle (BC), and puborectalis muscle (PR). Continence was assessed at 3 and 6 weeks postoperatively, defined as use of ≤ 1 pad/day. The relationship of continence to the displacement of SUS, BC, and PR was analyzed.ResultsSUS, BC, and PR displacement decreased significantly 3 weeks postoperatively (P = 0.042, P = 0.002, P &lt; 0.001, respectively). Continent men exhibited significantly greater SUS displacement (median, 5.13 mm) than incontinent men (median, 3.90 mm) 3 weeks postoperatively (P = 0.029). Between 3 and 6 weeks following RARP, there was significant increase in SUS, BC, and PR displacement (P = 0.003, P = 0.030, P &lt; 0.001, respectively).ConclusionsA significant decrease in PFM function occurs following RARP, with a subsequent recovery of postoperative PFM function between 3 and 6 weeks post-procedure in men who undergo PFM training. SUS activation was significantly greater in continent patients compared to incontinent patients at 3 weeks following RARP.

Respiratory muscle ultrasonography evaluation and its clinical application in stroke patients: A review.

Respiratory muscle ultrasound is a widely available, highly feasible technique that can be used to study the contribution of the individual respiratory muscles related to respiratory dysfunction. Stroke disrupts multiple functions, and the respiratory function is often significantly decreased in stroke patients. A search of the MEDLINE, Web of Science, and PubMed databases was conducted. We identified studies measuring respiratory muscles in healthy and patients by ultrasonography. Two reviewers independently extracted and documented data regarding to the criteria. Data were extracted including participant demographics, ultrasonography evaluation protocol, subject population, reference values, etc. A total of 1954 participants from 39 studies were included. Among them, there were 1,135 participants from 19 studies on diaphragm, 259 participants from 6 studies on extra-diaphragmatic inspiratory muscles, and 560 participants from 14 studies on abdominal expiratory muscles. The ultrasonic evaluation of diaphragm and abdominal expiratory muscle thickness had a relatively typically approach, while, extra-diaphragmatic inspiratory muscles were mainly used in ICU that lack of a consistent paradigm. Diaphragm and expiratory muscle ultrasound has been widely used in the assessment of respiratory muscle function. On the contrary, there is not enough evidence to assess extra-diaphragmatic inspiratory muscles by ultrasound. In addition, the thickness of the diaphragm on the hemiplegic side was lower than that on the non-hemiplegic side in stroke patients. For internal oblique muscle (IO), rectus abdominis muscle (RA), transversus abdominis muscle (TrA), and external oblique muscle (EO), most studies showed that the thickness on the hemiplegic side was lower than that on the non-hemiplegic side.Clinical Trial Registration: The protocol of this review was registered in the PROSPERO database (CRD42022352901).

Electrical impedance myography combined with quantitative assessment techniques in paretic muscle of stroke survivors: Insights and challenges.

Aging is a non-modifiable risk factor for stroke and the global burden of stroke is continuing to increase due to the aging society. Muscle dysfunction, common sequela of stroke, has long been of research interests. Therefore, how to accurately assess muscle function is particularly important. Electrical impedance myography (EIM) has proven to be feasible to assess muscle impairment in patients with stroke in terms of micro structures, such as muscle membrane integrity, extracellular and intracellular fluids. However, EIM alone is not sufficient to assess muscle function comprehensively given the complex contributors to paretic muscle after an insult. This article discusses the potential to combine EIM and other common quantitative methods as ways to improve the assessment of muscle function in stroke survivors. Clinically, these combined assessments provide not only a distinct advantage for greater accuracy of muscle assessment through cross-validation, but also the physiological explanation on muscle dysfunction at the micro level. Different combinations of assessments are discussed with insights for different purposes. The assessments of morphological, mechanical and contractile properties combined with EIM are focused since changes in muscle structures, tone and strength directly reflect the muscle function of stroke survivors. With advances in computational technology, finite element model and machine learning model that incorporate multi-modal evaluation parameters to enable the establishment of predictive or diagnostic model will be the next step forward to assess muscle function for individual with stroke.

In vivo estimation of anisotropic mechanical properties of the gastrocnemius during functional loading with MR elastography

Objective. In vivo imaging assessments of skeletal muscle structure and function allow for longitudinal quantification of tissue health. Magnetic resonance elastography (MRE) non-invasively quantifies tissue mechanical properties, allowing for evaluation of skeletal muscle biomechanics in response to loading, creating a better understanding of muscle functional health. Approach. In this study, we analyze the anisotropic mechanical response of calf muscles using MRE with a transversely isotropic, nonlinear inversion algorithm (TI-NLI) to investigate the role of muscle fiber stiffening under load. We estimate anisotropic material parameters including fiber shear stiffness (), substrate shear stiffness (), shear anisotropy (), and tensile anisotropy () of the gastrocnemius muscle in response to both passive and active tension. Main results. In passive tension, we found a significant increase in and with increasing muscle length. While in active tension, we observed increasing and decreasing and during active dorsiflexion and plantarflexion—indicating less anisotropy—with greater effects when the muscles act as agonist. Significance. The study demonstrates the ability of this anisotropic MRE method to capture the multifaceted mechanical response of skeletal muscle to tissue loading from muscle lengthening and contraction.

The "Mother Load" and Return to Sport: A Case Report of Returning to Professional Netball Following Cesarean Section.

Increasing numbers of elite female athletes are competing in professional sport, and many wish to become pregnant and return to competitive sport after childbirth. Athletes have a higher risk of pelvic floor dysfunction (PFD) than non-athletes (54% versus 7%) and there is also an increased prevalence in post-partum women compared to nulliparous women (35% versus 2.8-7.9%). Additionally, PFD has been shown to influence athletic performance. High quality evidence for elite athletes is lacking, and there are no exercise guidelines specifically for these women to prepare or effectively guide their safe return to sport (RTS). The purpose of this case report is to detail the management of an elite athlete who presented following cesarean section (CS) with the goal of RTS within 16 weeks. A 27-year-old primiparous Caucasian professional netballer presented at four weeks post- caesarean section (CS) for RTS screening and assessment of pelvic floor muscle (PFM) function. Assessment included readiness and fear of movement screening, dynamic pelvic floor muscle function, structural integrity of the CS wound, levator hiatal dimensions, bladder neck descent, and early global neuromuscular screening. Measures were collected at four weeks, eight weeks, and six months post-partum. The post-partum athlete demonstrated alterations in pelvic floor muscle function, reduced lower limb power and psychological readiness. A functionally staged dynamic and sport specific pelvic floor muscle training program was implemented and adapted to the patient for her early post-partum timeline. Rehabilitation strategies were effective in achieving the primary outcome of RTS at 16 weeks post-partum with no adverse events reported at 6 months follow-up. This case highlights the need for a holistic and individualised RTS management approach that includes women's and pelvic health risk factors in a professional athlete. 5.

Non-invasive methods to assess muscle function in dogs: A scoping review.

Skeletal muscle function can be affected by multiple disorders in dogs of which cranial cruciate ligament rupture or disease (CCLD) is one of the most common. Despite the significance of this condition only sparse research exists regarding assessment of muscle function in dogs. This scoping review aimed to identify the non-invasive methods for canine muscle function assessments that have been reported in the literature in the past 10 years. A systematic literature search was conducted 1st March 2022 across six databases. After screening, 139 studies were considered eligible for inclusion. Among the included studies, 18 different muscle function assessment categories were identified, and the most frequently reported disease state was CCLD. We included an attempt to elucidate the clinical applicability of the 18 reported methods, as experts were asked to subjectively assess the methods for their clinical relevance as well as their practical applicability in dogs with CCLD.

Value of conventional ultrasound and shear wave elastography in the assessment of muscle mass and function in elderly people with type 2 diabetes.

We assessed muscle mass and function using ultrasound (US) and shear wave elastography (SWE) for sarcopenia in elderly patients with type 2 diabetes. There were 84 patients with type 2 diabetes enrolled in this study; of these, 30 had sarcopenia and 54 did not. We measured appendicular skeletal muscle mass index (ASMI), handgrip strength, calf circumference, 6-m walking speed, and 5-time chair stand test. All patients were in the supine position with their knees in straight and bent poses in turn. The US-derived thickness (Tstraight, Tbent), cross-sectional area (CSAstraight, CSAbent), and SWE (SWEstraight, SWEbent) of the rectus femoris muscle (RFM) were measured and the differences (ΔT, ΔCSA, ΔSWE) were calculated. We assessed the correlations of clinical indicators with US and SWE features. We then compared the clinical indicators and US and SWE features between patients with and without sarcopenia to determine independent predictors. Diagnostic models were established based on these independent predictors. The ASMI was correlated with Tbent (r = 0.57, p < 0.001) and CSAbent (r = 0.50, p < 0.001). Handgrip strength was correlated with Tbent (r = 0.53, p < 0.001) and CSAbent (r = 0.51, p < 0.001). Between patients with and without sarcopenia, the indicators of age, ΔCSA, and ΔSWE were statically different (all p ≤ 0.001). Based on these results, a diagnostic model for sarcopenia was established with 83.3% sensitivity, 83.3% specificity, and 83.3% accuracy. In elderly people with type 2 diabetes, sarcopenia patients had smaller muscle CSA and less stiffness than non-sarcopenia patients. US and SWE might be useful to screen them. • Sarcopenia is common in elderly people with type 2 diabetes. • Ultrasound and shear wave elastography might be useful methods for quantitatively assessing muscle mass and strength. • Ultrasound and shear wave elastography might be useful methods for screening sarcopenia in elderly patients with type 2 diabetes.

Hip abductor dysfunction following total hip arthroplasty by modified direct lateral approach: Assessment by quantitative electromyography

Abstract Background The use of the direct lateral approach and its modifications for total hip arthroplasty (THA) may lead to postoperative abductor weakness. Assessment of abductor muscle function by the use of quantitative electromyography (EMG) aims to investigate the nature of abductor muscle dysfunction. Methods We conducted a study on 40 patients who had hip replacement through the modified direct lateral approach. EMG was performed before surgery on the affected and normal sides and repeated on the operated side after surgery by 6 and 12 weeks. Analysis of EMG of the three abductor muscles was done in all patients. Results EMG evidence of acute denervation of hip abductors was present in 15 hips (37.5%) after 6 weeks. Improvement of EMG findings occurred in 8 out of 15 patients. Quantitative electromyography (QEMG) showed early significant increase in amplitude in all muscles and decrease in duration in gluteus medius (G. Med) with a pattern of acute nerve injury. At 12 weeks, the values of duration, amplitude, and phase were insignificantly different from the preoperative values signifying the return of near normal muscle activity. Conclusion The use of modified direct lateral approach can cause denervation of hip abductors. It is common in the early postoperative weeks. However, it tends to improve and the residual weakness in some patients is not marked. Quantitative electromyography showed that partial denervation is related to superior gluteal nerve stretching and not to direct injury of the terminal branches of the nerve through the incision.

Associations of phase angle obtained by bioelectrical impedance analysis with muscle mass and strength in Japanese patients with type 2 diabetes.

The age-dependent decrease in muscle mass and function is known as sarcopenia. The risk of sarcopenia is higher in patients with diabetes, and assessment of muscle mass and function is especially important in patients with diabetes. Recent reports suggest that the phase angle (PhA), which is obtained from bioelectrical impedance analysis (BIA), may be a good marker of not only muscle mass but also muscle function in healthy people. However, the clinical significance of PhA in patients with diabetes has not been fully investigated. Therefore, we evaluated the association of PhA with muscle mass, muscle strength, and physical performance in 159 patients with type 2 diabetes (male 102; female 57) aged 40 to 89 years. We measured PhA and appendicular skeletal muscle index (SMI) by BIA and handgrip and leg extension strength and performed the Short Physical Performance Battery (SPPB). In a simple correlation analysis, both right and left PhA correlated with SMI, handgrip and leg extension strength, and SPPB score, and in multiple regression analysis, PhA on each side correlated with SMI and ipsilateral handgrip strength. These data suggest that PhA may be a useful marker of muscle mass, muscle strength, and physical performance in patients with type 2 diabetes. A large-scale prospective study should be performed to confirm the results and clarify the clinical usefulness of PhA in patients with diabetes.

Comprehensive Analyses of Muscle Function, Lean and Muscle Mass, and Myofiber Typing in Mice.

Skeletal muscle disorders commonly affect the function and integrity of muscles. Novel interventions bring new potential to rescue or alleviate the symptoms associated with these disorders. In vivo and in vitro testing in mouse models allows quantitative evaluation of the degree of muscle dysfunction, and therefore, the level of potential rescue/restoration by the target intervention. Several resources and methods are available to assess muscle function and lean and muscle mass, as well as myofiber typing as separate concepts; however, a technical resource unifying these methods is missing. Here, we provide detailed procedures for analyzing muscle function, lean and muscle mass, and myofiber typing in a comprehensive technical resource paper. Graphical abstract.

Muscle Function, Body Composition, Insulin Sensitivity and Physical Activity in Adolescents Born Preterm: Impact of Gestation and Vitamin D Status.

Whilst several studies have explored adolescent metabolic and cognitive function after preterm birth, few have explored muscle function and physical activity. We set out to examine the relationship between gestational age and muscle metabolism in a cohort of adolescents who were born preterm. Participants were recruited from the Newcastle preterm birth growth study cohort. They did not have severe neurological disease and were not on daily medication. Participants underwent an assessment of oxidative muscle function using phosphorus magnetic resonance spectroscopy that included the half-time for recovery of equilibrium of phosphocreatine, τ½PCr. In addition, we measured key variables that might affect muscle function including physical activity levels determined by 3-day accelerometry, body composition using air displacement plethysmography, insulin sensitivity using the homeostatic model assessment/Matsuda index and serum vitamin D concentrations. 60 adolescents (35F) median age 15.6 years (range 12.1−18.8) with a median gestation of 31 weeks (range 24 to 34 weeks) underwent a single assessment. Males were more active and spent less time in sedentary mode. Time spent in light activity was associated with insulin sensitivity (IS) (Matsuda Index; p < 0.05) but there were no strong correlations between activity levels and gestational age. Greater fat mass, waist circumference and body mass index were all associated with lower IS. Gestational age was negatively associated with adjusted measures of oxidative muscle function (τ½PCr). In a stepwise multivariate linear regression model, gestational age at birth was the most significant predictor of oxidative muscle function (p = 0.005). Higher serum vitamin D levels were also associated with faster phosphocreatine recovery time (p = 0.045). Oxidative function in the skeletal muscle of adolescents born preterm is associated with gestational age and vitamin D concentrations. Our study suggests that being born preterm may have a long-term impact on muscle metabolism.

Physiological Assessment of Muscle, Heart, and Whole Body Function in the Canine Model of Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) is a lethal muscle disease caused by dystrophin deficiency. Patients gradually lose motor function, become wheelchair-bound, and die from respiratory and/or cardiac muscle failure. Dystrophin-null dogs have been used as a large animal model for DMD since 1988 and are considered an excellent bridge between rodent models and human patients. While numerous protocols have been published for studying muscle and heart physiology in mice, few such protocols exist for studying skeletal muscle contractility, heart function, and whole-body activity in dogs. Over the last 20 years, we have developed and adapted an array of assays to evaluate whole-body movement, gait, single muscle force, whole limb torque, cardiac electrophysiology, and hemodynamic function in normal and dystrophic dogs. In this chapter, we present detailed working protocols for these assays and lessons we learned during the development and use of these protocols.

Association of serum 25-hydroxy vitamin D with gait speed and handgrip strength in patients on hemodialysis

BackgroundMuscle dysfunction is prevalent in dialysis patients. Gait speed and handgrip strength are simple and reliable methods of assessing muscle function. Numerous observational studies have linked 25-hydroxy vitamin D[25(OH)D] status with gait speed and handgrip strength in populations without kidney diseases. This study aimed to evaluate the potential associations of 25(OH)D status with gait speed and handgrip strength in patients on hemodialysis.MethodsIn this observational cross-sectional study, demographic data, biological data, and dialysis parameters were collected. Gait speed and handgrip strength were measured. Multiple linear regression and logistic regression analysis were used to investigate the relationship of 25(OH)D status with gait speed and handgrip strength after adjusting for potential confounders.ResultsOverall, a total of 118 participants undergoing hemodialysis were included. Seventy-one (60.2%) participants were male. The median 25(OH)D status in participants was 11.58 (interquartile range: 8.51 to 15.41) ng/ml. When controlling for age, gender, dialysis vintage, and other confounders with a p-value < 0.15 in univariate analyses, 25(OH)D was significantly positively associated with gait speed (β = 0.16, 95% CI 0.05 to 0.28, p = 0.006) and handgrip strength (β = 3.83, 95% CI 1.09 to 6.56, p = 0.007).ConclusionOur study showed that 25(OH)D status seemed to be associated with gait speed and handgrip strength in patients on hemodialysis. However, these results were not robust. The relationships between 25(OH)D status and gait speed and handgrip should be further explored.