Skeletal muscle hypertrophy and muscle myostatin reduction after resistive training in stroke survivors

Relationship of serial muscle ultrasound of rectus femoris and ambulatory recovery in patients with acute incomplete spinal cord injury: A prospective observational study

CONTEXT/OBJECTIVE

To investigate the change in serial muscle ultrasound of rectus femoris of patients with incomplete spinal cord injury (SCI) performed within 2 months after SCI during acute rehabilitation, and the relationship with functional outcomes at 1 year post-injury.

DESIGN

Prospective observational study.

SETTING

Inpatient multi-speciality tertiary rehabilitation center in Singapore.

PARTICIPANTS

Fifty-four patients with incomplete SCI, defined as American Spinal Injury Association Impairment Scale B-D, with SCI above L2, were recruited from March 2020 to June 2021. Serial muscle ultrasound of the rectus femoris thickness and echo intensity were obtained at 1 week post-injury and after 2 months via standardized protocols.

OUTCOME MEASURES

Functional Independence Measure (FIM) motor score, Lower Extremity Motor Score (LEMS), Spinal Cord Independence Measure III (SCIM III) indoor mobility component and Walking Index for Spinal Cord Injury II (WISCI II) were assessed in the first week post-admission and at 1 year.

RESULTS

There was a significant positive correlation between change in rectus femoris muscle thickness over 2 months and FIM motor score (P < 0.001), LEMS (P < 0.001), SCIM III indoor mobility component (P < 0.001) and WISCI II (P < 0.001) at 1 year. For the change in echo intensity over 2 months, there was a significantly negative correlation with FIM motor score (P = 0.002), LEMS (P = 0.002), SCIM III indoor mobility component (P = 0.001) and WISCI II (P = 0.001) at 1 year.

CONCLUSION

The findings suggest that ultrasonographic serial assessment of rectus femoris muscle thickness and echo intensity during rehabilitation may be useful for determining the long-term functional outcomes in patients with incomplete SCI.

Effects of Multicomponent Home-Based Intervention on Muscle Composition, Fitness, and Bone Density After Hip Fracture

BACKGROUND

Mechanistic factors on the pathway to improving independent ambulatory ability among hip fracture patients by a multicomponent home-based physical therapy intervention that emphasized aerobic, strength, balance, and functional training are unknown. The aim of this study was to determine the effects of 2 different home-based physical therapy programs on muscle area and attenuation (reflects muscle density) of the lower extremities, bone mineral density (BMD), and aerobic capacity.

METHODS

Randomized controlled trial of home-based 16 weeks of strength, endurance, balance, and function exercises (PUSH, n = 19) compared to seated active range-of-motion exercises and transcutaneous electrical neurostimulation (PULSE, n = 18) in community-dwelling adults >60 years of age within 26 weeks of hip fracture.

RESULTS

In PUSH and PULSE groups combined, the fractured leg had lower muscle area and muscle attenuation and higher subcutaneous fat than the nonfractured leg (p < .001) at baseline. At 16 weeks, mean muscle area of the fractured leg was higher in the PUSH than PULSE group (p = .04). Changes in muscle area were not significantly different when compared to the comparative PULSE group. There was a clinically relevant difference in change in femoral neck BMD between groups (p = .05) that showed an increase after PULSE and decrease after PUSH. There were generally no between-group differences in mean VO2peak tests at 16-week follow-up, except the PUSH group reached a higher max incline (p = .04).

CONCLUSIONS

The treatment effects of a multicomponent home-based physical therapy intervention on muscle composition, BMD, and aerobic capacity were not significantly different than an active control intervention in older adults recovering from hip fracture.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01783704.

Effects of Exercise Training on Muscle Quality in Older Individuals: A Systematic Scoping Review with Meta-Analyses

BACKGROUND

The quantity and quality of skeletal muscle are important determinants of daily function and metabolic health. Various forms of physical exercise can improve muscle function, but this effect can be inconsistent and has not been systematically examined across the health-neurological disease continuum. The purpose of this systematic scoping review with meta-analyses was to determine the effects and potential moderators of exercise training on morphological and neuromuscular muscle quality (MMQ, NMQ) in healthy older individuals. In addition and in the form of a scoping review, we examined the effects of exercise training on NMQ and MMQ in individuals with neurological conditions.

METHODS

A systematic literature search was performed in the electronic databases Medline, Embase, and Web of Science. Randomized controlled trials were included that examined the effects of exercise training on muscle quality (MQ) in older individuals with and without neurological conditions. Risk of bias and study quality were assessed (Cochrane Risk of Bias Tool 2.0). We performed random-effects models using robust variance estimation and tested moderators using the approximate Hotelling-Zhang test.

RESULTS

Thirty studies (n = 1494, 34% females) in healthy older individuals and no studies in individuals with neurological conditions were eligible for inclusion. Exercise training had small effects on MMQ (g = 0.21, 95% confidence interval [CI]: 0.03-0.40, p = 0.029). Heterogeneity was low (median I² = 16%). Training and demographic variables did not moderate the effects of exercise on MMQ. There was no association between changes in MMQ and changes in functional outcomes. Exercise training improved NMQ (g = 0.68, 95% CI 0.35-1.01, p < 0.000) across all studies, in particular in higher-functioning older individuals (g = 0.72, 95% CI 0.38-1.06, p < 0.001), in lower extremity muscles (g = 0.74, 95% CI 0.35-1.13, p = 0.001), and after resistance training (g = 0.91; 95% CI 0.42-1.41, p = 0.001). Heterogeneity was very high (median I² = 79%). Of the training and demographic variables, only resistance training moderated the exercise-effects on NMQ. High- versus low-intensity exercise moderated the exercise-effects on NMQ, but these effects were considered unreliable due to a low number of studies at high intensity. There was no association between changes in NMQ and changes in functional outcomes.

CONCLUSION

Exercise training has small effects on MMQ and medium-large effects on NMQ in healthy older individuals. There was no association between improvements in MQ and increases in muscle strength, mobility, and balance. Information on dose-response relations following training is currently lacking. There is a critical gap in muscle quality data for older individuals with lower function and neurological conditions after exercise training. Health practitioners should use resistance training to improve muscle function in older individuals. Well-designed studies are needed to examine the relevance of exercise training-induced changes in MQ in daily function in older individuals, especially to those with lower function and neurological conditions.

Crosstalk between bone and muscle in chronic kidney disease

With increasing life expectancy, the related disorders of bone loss, metabolic dysregulation and sarcopenia have become major health threats to the elderly. Each of these conditions is prevalent in patients with chronic kidney disease (CKD), particularly in more advanced stages. Our current understanding of the bone-muscle interaction is beyond mechanical coupling, where bone and muscle have been identified as interrelated secretory organs, and regulation of both bone and muscle metabolism occurs through osteokines and myokines via autocrine, paracrine and endocrine systems. This review appraises the current knowledge regarding biochemical crosstalk between bone and muscle, and considers recent progress related to the role of osteokines and myokines in CKD, including modulatory effects of physical exercise and potential therapeutic targets to improve musculoskeletal health in CKD patients.

Effects of Creatine Supplementation and Progressive Resistance Training in Stroke Survivors

The purpose was to investigate the effects of progressive resistance training (PRT) and creatine supplementation in stroke survivors. Participants were randomized to one of two groups: creatine (n = 5; 51 ± 16y) or placebo (n = 3; 73 ± 8y) during 10 weeks of supervised PRT. Prior to and following PRT and supplementation, assessments were made for body composition (lean tissue and fat mass), muscle thickness, muscle strength (1-repetition maximum), functional exercise capacity (6-minute walk test, Berg Balance Scale; BBS), cognition (Montreal Cognitive Assessment; MoCA), and symptoms of anxiety (Generalized Anxiety Disorder Assessment-7; GAD-7) and depression (Center for Epidemiological Studies Depression Scale; CES-D). There were time main effects for leg press strength (increased; p = 0.001), chest press strength (increased; p = 0.003), elbow flexor muscle thickness (increased; p = 0.007), BBS (increased; p = 0.002), MoCA (increased; p = 0.031) and CES-D (decreased; p = 0.045). There was a group x time interaction for the 6 minute walk test (p = 0.039). The creatine group significantly increased walking distance over time (p = 0.002) with no change in the placebo group (p = 0.120). Ten weeks of PRT had some positive effects on measures of muscle strength and size, balance, cognition and depression. The addition of creatine to PRT significantly improved walking performance in stroke survivors.

Structural and passive mechanical properties of the medial gastrocnemius muscle in ambulatory individuals with chronic stroke

BACKGROUND

This study aimed to investigate the structural, morphological and passive mechanical properties of the medial gastrocnemius muscle among ambulating chronic stroke survivors using a computational model previously established in healthy individuals without stroke.

METHODS

Individuals with chronic stroke (n = 14, age = 63.4 ± 6.0 years) and healthy controls (n = 15, age = 59.6 ± 8.4 years) participated in the study. The mechanical properties of the medial gastrocnemius were measured during continuous passive ankle motion using ultrasound elastography and a corresponding muscle mechanical property-angle curve was estimated where slack angle and elasticity were determined. Muscle thickness, fascicle length, pennation angle, and echo intensity were also assessed using B-mode ultrasound.

FINDINGS

No significant differences in slack angle (paretic: -16.2° ± 6.13°, non-paretic: -16.93° ± 6.80°, p = 0.82), or slack elasticity (paretic: 4.36 ± 1.94 kPa, non-paretic: 4.54 ± 1.24 kPa, p = 0.64) were found between sides or groups. Lower muscle pennation angle (paretic: 13.6 ± 2.9°, non-paretic: 15.9 ± 2.0°, p = 0.019) and higher echo intensity (paretic: 80.5 ± 13.6, non-paretic: 63.4 ± 17.1, p = 0.003) were observed for paretic muscles. No significant between-sides differences were found for muscle thickness (paretic: 1.5 ± 0.3 cm, non-paretic: 1.6 ± 0.2 cm, p = 0.255) or fascicle length (paretic: 6.6 ± 1.9 cm, non-paretic: 7.1 ± 2.2 cm, p = 0.216). Significant between-groups difference was also observed for fascicle length [non-dominant side (control): 6.2 ± 0.8 cm, paretic side (stroke): 6.6 ± 1.9 cm, p = 0.017].

INTERPRETATION

Although muscle mechanical properties increased exponentially over the slack ankle, measures between paretic and non-paretic sides were similar in ambulating participants with chronic stroke. Side-to-side differences in structural and morphological measures suggest the impact of stroke was relatively more pronounced for these muscle parameters than for passive mechanical properties.

Effects of Citrus depressa Hayata Fruit Extract on Thigh Muscles Mass and Composition in Subacute Stroke Patients: A Double-Blind, Randomized, Controlled Pilot Trial

Objective: This pilot study evaluated the effects of Citrus depressa Hayata fruit extract (CFEx) on thigh muscle cross-sectional area (CSA) and composition in subacute stroke patients with hemiparesis who were undergoing rehabilitation. Design and Intervention: This double-blinded, placebo-controlled, randomized pilot trial included 40 subacute stroke patients with moderate-to-severe hemiparesis, and they were randomly assigned to receive CFEx or placebo supplements for 12 weeks. The thigh muscle CSA was measured by computed tomography as total muscle area defined by Hounsfield units (HU) values of -29 to 150 HU. The total muscle area was divided into muscle area with fat infiltration and normal muscle area to evaluate muscle composition (-29 to 29 and 30 to 150 HU, respectively). Results: At baseline, the total muscle area and normal muscle area in the paretic thigh were lower than those in the nonparetic thigh. The nonparetic normal muscle area was significantly higher in the CFEx group than in the placebo group at 12 weeks, whereas the total muscle area was not different. Conclusions: The thigh muscle CSA and composition in the paretic side have already deteriorated in patients with moderate-to-severe hemiparesis at the subacute stroke stage. CFEx supplementation during rehabilitation might improve the nonparetic thigh muscle composition in subacute stroke patients. Findings of this study are needed to be verified by a large-scale randomized trial since this study was a pilot study with a small sample size. Trial registration: UMIN Clinical Trial Registry (UMIN ID: UMIN000012902).

Muscle dysfunction in the long coronavirus disease 2019 syndrome: Pathogenesis and clinical approach

In long coronavirus disease 2019 (long COVID‐19), involvement of the musculoskeletal system is characterised by the persistence or appearance of symptoms such as fatigue, muscle weakness, myalgia, and decline in physical and functional performance, even at 4 weeks after the onset of acute symptoms of COVID‐19. Muscle injury biomarkers are altered during the acute phase of the disease. The cellular damage and hyperinflammatory state induced by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection may contribute to the persistence of symptoms, hypoxaemia, mitochondrial damage, and dysregulation of the renin‐angiotensin system. In addition, the occurrence of cerebrovascular diseases, involvement of the peripheral nervous system, and harmful effects of hospitalisation, such as the use of drugs, immobility, and weakness acquired in the intensive care unit, all aggravate muscle damage. Here, we review the multifactorial mechanisms of muscle tissue injury, aggravating conditions, and associated sequelae in long COVID‐19.

Changes in Muscle Thickness and Echo Intensity in Chronic Stroke Survivors: A 2-Year Longitudinal Study

Background and Purpose

The objective of this study was to identify 2-year longitudinal changes in the muscle thickness (MT) and echo intensity (EI) of the abdominal, thigh, and lower limb muscles in chronic stroke survivors.

Methods

This study included 15 chronic stroke survivors aged 74.1±9.9 years. The MT, EI, and subcutaneous fat thickness values of the following muscles on the paretic and nonparetic sides were assessed on transverse ultrasound images: rectus abdominis, external oblique, internal oblique, transversus abdominis, rectus femoris (RF), vastus intermedius, vastus lateralis (VL), vastus medialis, tibialis anterior, gastrocnemius, and soleus. The ultrasound measurements were performed both at baseline and 2 years later.

Results

After 2 years, the VL on the paretic side showed a significant decrease in MT (p=0.031) and increase in EI (p=0.002), whereas the RF on the nonparetic side showed a significant decrease in EI (p=0.046). Correlation coefficient analyses showed that changes in MT (r=0.668, p=0.012) and EI (r=0.597, p=0.018) of the VL on the paretic side were significantly associated with a change in the body mass index.

Conclusions

The findings of this longitudinal study suggest that the VL on the paretic side is subject to deteriorations in muscle quantity and quality, and conversely that the RF on the nonparetic side shows an improvement in muscle quality after 2 years in chronic stroke survivors.

How Does Stroke Affect Skeletal Muscle? State of the Art and Rehabilitation Perspective

Long-term disability caused by stroke is largely due to an impairment of motor function. The functional consequences after stroke are caused by central nervous system adaptations and modifications, but also by the peripheral skeletal muscle changes. The nervous and muscular systems work together and are strictly dependent in their structure and function, through afferent and efferent communication pathways with a reciprocal “modulation.” Knowing how altered interaction between these two important systems can modify the intrinsic properties of muscle tissue is essential in finding the best rehabilitative therapeutic approach. Traditionally, the rehabilitation effort has been oriented toward the treatment of the central nervous system damage with a central approach, overlooking the muscle tissue. However, to ensure greater effectiveness of treatments, it should not be forgotten that muscle can also be a target in the rehabilitation process. The purpose of this review is to summarize the current knowledge about the skeletal muscle changes, directly or indirectly induced by stroke, focusing on the changes induced by the treatments most applied in stroke rehabilitation. The results of this review highlight changes in several muscular features, suggesting specific treatments based on biological knowledge; on the other hand, in standard rehabilitative practice, a realist muscle function evaluation is rarely carried out. We provide some recommendations to improve a comprehensive muscle investigation, a specific rehabilitation approach, and to draw research protocol to solve the remaining conflicting data. Even if a complete multilevel muscular evaluation requires a great effort by a multidisciplinary team to optimize motor recovery after stroke.

Muscle Electrical Impedance Properties and Activation Alteration After Functional Electrical Stimulation-Assisted Cycling Training for Chronic Stroke Survivors: A Longitudinal Pilot Study

Electrical impedance myography (EIM) is a sensitive assessment for neuromuscular diseases to detect muscle inherent properties, whereas surface electromyography (sEMG) is a common technique for monitoring muscle activation. However, the application of EIM in detecting training effects on stroke survivors is relatively few. This study aimed to evaluate the muscle inherent properties and muscle activation alteration after functional electrical stimulation (FES)-assisted cycling training to chronic stroke survivors. Fifteen people with chronic stroke were recruited for 20 sessions of FES-assisted cycling training (40 min/session, 3–5 sessions/week). The periodically stimulated and assessed muscle groups were quadriceps (QC), tibialis anterior (TA), hamstrings (HS), and medial head of gastrocnemius (MG) on the paretic lower extremity. EIM parameters [resistance (R), reactance (X), phase angle (θ), and anisotropy ratio (AR)], clinical scales (Fugl-Meyer Lower Extremity (FMA-LE), Berg Balance Scale (BBS), and 6-min walking test (6MWT)] and sEMG parameters [including root-mean square (RMS) and co-contraction index (CI) value] were collected and computed before and after the training. Linear correlation analysis was conducted between EIM and clinical scales as well as between sEMG and clinical scales. The results showed that motor function of the lower extremity, balance, and walking performance of subjects improved after the training. After training, θ value of TA (P = 0.014) and MG (P = 0.017) significantly increased, and AR of X (P = 0.004) value and AR of θ value (P = 0.041) significantly increased on TA. The RMS value of TA decreased (P = 0.022) and a significant reduction of CI was revealed on TA/MG muscle pair (P < 0.001). Significant correlation was found between EIM and clinical assessments (AR of X value of TA and FMA-LE: r = 0.54, P = 0.046; X value of TA and BBS score: 0.628, P = 0.016), and between sEMG and clinical scores (RMS of TA and BBS score: r = −0.582, P = 0.029). This study demonstrated that FES-assisted cycling training improved lower limb function by developing coordinated muscle activation and facilitating an orderly myofiber arrangement. The current study also indicated that EIM can jointly evaluate lower extremity function alteration with sEMG after rehabilitation training.

Clinical Trail Registration: The study was registered on the Clinical Trial Registry (trial registration number: NCT 03208439, https://clinicaltrials.gov/ct2/show/NCT03208439).

Skeletal muscle myostatin gene expression and sarcopenia in overweight and obese middle‐aged and older adults

Background

Myostatin (MSTN) is a key negative regulator of muscle mass in humans and animals, having direct and indirect influences on molecular regulators of atrophy and hypertrophy, thus potentially impacting fitness and physical function. We have shown that myostatin is elevated in conditions of chronic disability (e.g. paretic limb of stroke). Our hypothesis is that myostatin would be elevated in older adults with sarcopenia. The purpose of this study was to examine the role of skeletal muscle myostatin in sarcopenia.

Methods

Sixty-four overweight to obese aged 45–81 years underwent a maximal aerobic capacity (VO₂max) test, dual-energy X-ray absorptiometry (DXA) scan to determine appendicular lean tissue (ALM), and vastus lateralis muscle biopsy to determine myostatin mRNA expression by quantitative real time PCR (Q-RT-PCR). Rates of sarcopenia were determined using (ALM/BMI), and sarcopenia was defined as <0.789 in men and <0.512 in women. Subjects had low fitness (VO₂max: 22.7 ± 0.7 mL/kg/min) and on average 40.9 ± 1% body fat.

Results

The prevalence of sarcopenia in this cohort was 16%. BMI, % body fat, and fat mass were higher in adults with sarcopenia than those without sarcopenia (all P < 0.001). Myostatin mRNA expression was lower in those without sarcopenia than those with sarcopenia (P < 0.05) and higher in men than women (P < 0.001). Myostatin expression was associated with BMI (r = 0.36, P < 0.01) and mid-thigh intramuscular fat (r = 0.29, P < 0.05).

Conclusion

Given that myostatin is important in muscle atrophy, fat accumulation, and sarcopenia, further work could address its implication in other aging cohorts of disability and chronic disease.

Elderly Patients after Stroke Increase Skeletal Muscle Mass by Exercise Therapy in Rehabilitation Wards

BACKGROUND

Loss of skeletal muscle is a critical health issue that frequently occurs due to aging and various pathologies. No studies have reported increases in appendicular skeletal muscle mass among elderly patients after stroke. Our hypothesis was that even older individuals after stroke could increase skeletal muscle mass by rehabilitation.

OBJECTIVES

This study aimed to evaluate changes to skeletal muscle mass in elderly patients after stroke rehabilitation and to assess factors associated with skeletal muscle mass increases.

MATERIALS AND METHODS

Participants in this case-control study were 159 patients ≥ 80 years old in rehabilitation wards after stroke. Body mass index (BMI), appendicular skeletal muscle index (SMI), Functional Independence Measure (FIM), interval from onset to transfer, presence of hemiplegia, National Institutes of Health Stroke Scale (NIHSS), length of hospital stay for rehabilitation, period of exercise therapy per day, and protein intake were examined. Multivariate logistic regression analysis was performed to identify association between these values and SMI increases.

RESULTS

SMI at discharge was significantly increased (5.30 kg/m²) compared to baseline (5.20kg/m²; p = 0.002). Multiple logistic regression analysis showed that length of hospital stay and protein intake were significantly associated with SMI increases, with odds ratios of 1.013 (95% confidence interval, 1.005-1.022) and 3.746 (95% confidence interval, 1.077-13.028), respectively.

CONCLUSIONS

The SMI of patients ≥ 80 years old increased significantly with rehabilitation after stroke. In addition, length of hospital stay and protein intake were independently associated with increases in SMI.

Increased intramuscular adipose tissue of the quadriceps is related to decreased activities of daily living in patients who have had a stroke

OBJECTIVE

This study examined the relationships between intramuscular adipose tissue of the quadriceps on the paretic and non-paretic sides at admission and activities of daily living (ADL) at discharge in patients who had a stroke.

METHODS

This prospective cohort study included 44 stroke inpatients. ADL were assessed at discharge using the Barthel index (BI) score. Ultrasound images were acquired at admission using B-mode ultrasound imaging. Intramuscular adipose tissue and muscle mass of the quadriceps were assessed based on echo intensity and muscle thickness, respectively. Relationships between BI score at discharge and quadriceps echo intensity or thickness on the paretic and non-paretic sides were assessed using partial correlation coefficients. Age, sex, days from onset of stroke, Fugl-Meyer assessment lower extremity score, and subcutaneous fat thickness of the thigh were used as the control variables in the partial correlation analysis.

RESULTS

BI score at discharge was significantly related to quadriceps echo intensity on the paretic (partial correlation coefficient = -0.377, P = 0.018) and non-paretic (partial correlation coefficient = -0.364, P = 0.023) sides. By contrast, quadriceps thickness on the paretic (partial correlation coefficient = 0.284, P = 0.075) and non-paretic (partial correlation coefficient = 0.278, P = 0.083) sides were not significantly related to BI score at discharge.

CONCLUSIONS

The present study revealed the negative relationship between intramuscular adipose tissue of the quadriceps on the paretic and non-paretic sides at admission and ADL at discharge. Assessments and interventions of intramuscular adipose tissue in the quadriceps may be essential for predicting and improving ADL of patients who have had a stroke.

Insulin Resistance in Skeletal Muscle of Chronic Stroke

A stroke can lead to reduced mobility affecting skeletal muscle mass and fatty infiltration which could lead to systemic insulin resistance, but this has not been examined and the mechanisms are currently unknown. The objective was to compare the effects of in vivo insulin on skeletal muscle glycogen synthase (GS) activity in paretic (P) and nonparetic (NP) skeletal muscle in chronic stroke, and to compare to nonstroke controls. Participants were mild to moderately disabled adults with chronic stroke (n = 30, 60 ± 8 years) and sedentary controls (n = 35, 62 ± 8 years). Insulin sensitivity (M) and bilateral GS activity were determined after an overnight fast and during a hyperinsulinemic-euglycemic clamp. Stroke subjects had lower aerobic capacity than controls, but M was not significantly different. Insulin-stimulated activities of GS (independent, total, fractional), as well as absolute differences (insulin minus basal) and the percent change (insulin minus basal, relative to basal) in GS activities, were all significantly lower in P versus NP muscle. Basal GS fractional activity was 3-fold higher, and the increase in GS fractional activity during the clamp was 2-fold higher in control versus P and NP muscle. Visceral fat and intermuscular fat were associated with lower M. The effect of in vivo insulin to increase GS fractional activity was associated with M in control and P muscle. A reduction in insulin action on GS in paretic muscle likely contributes to skeletal muscle-specific insulin resistance in chronic stroke.

Brain and Muscle: How Central Nervous System Disorders Can Modify the Skeletal Muscle

It is widely known that nervous and muscular systems work together and that they are strictly dependent in their structure and functions. Consequently, muscles undergo macro and microscopic changes with subsequent alterations after a central nervous system (CNS) disease. Despite this, only a few researchers have addressed the problem of skeletal muscle abnormalities following CNS diseases. The purpose of this review is to summarize the current knowledge on the potential mechanisms responsible for changes in skeletal muscle of patients suffering from some of the most common CSN disorders (Stroke, Multiple Sclerosis, Parkinson’s disease). With this purpose, we analyzed the studies published in the last decade. The published studies show an extreme heterogeneity of the assessment modality and examined population. Furthermore, it is evident that thanks to different evaluation methodologies, it is now possible to implement knowledge on muscle morphology, for a long time limited by the requirement of muscle biopsies. This could be the first step to amplify studies aimed to analyze muscle characteristics in CNS disease and developing rehabilitation protocols to prevent and treat the muscle, often neglected in CNS disease.

Muscle mass gain is positively associated with functional recovery in patients with sarcopenia after stroke

OBJECTIVE

Intervention for treating sarcopenia is of great concern in clinical settings. The aim of this study was to investigate the relationship between changes in skeletal muscle mass and functional outcomes in patients with sarcopenia after stroke.

METHODS

A retrospective cohort study of stroke patients with sarcopenia consecutively admitted to a single center's convalescent rehabilitation wards was conducted from 2015 to 2018. Sarcopenia was defined as a loss of skeletal muscle mass index (SMI) with bioelectrical impedance and decreased muscle strength as measured by handgrip strength; cut-off values were adopted from the 2019 Asian Working Group for Sarcopenia. Changes in SMI during hospitalization were measured. Outcomes included the motor domain of Functional Independence Measure at discharge and its gain. Multivariate analysis determined whether the changes in SMI were associated with these outcomes.

RESULTS

During the study period, 272 stroke patients were enrolled. Of those, 120 patients (44%) (mean age 79 years, 70 females) were diagnosed with sarcopenia. The mean (SD) for changes in SMI was 0.2 (0.5) kg/m². Multiple linear regression analysis showed that changes in SMI were significantly associated with Functional Independence Measure - motor at discharge (β=0.175, P=0.003) and Functional Independence Measure - motor gain (β=0.247, P=0.003).

CONCLUSIONS

Muscle mass gain may be positively associated with functional recovery in patients with sarcopenia after stroke. Exercise and nutritional therapy to increase skeletal muscle mass, in addition to conventional stroke rehabilitation, is needed for these patients.

Quadriceps Thickness and Echo Intensity Predict Gait Independence in Individuals with Severe and Mild Hemiparetic Stroke

INTRODUCTION

Smaller muscle size and higher adipose tissue ratio of the quadriceps femoris are often observed after stroke. However, it is unclear whether muscle size and the intramuscular fat ratio of the quadriceps measured with ultrasonography (US) reflect gait independence in individuals with mild or severe hemiparetic stroke.

OBJECTIVE

The present study was performed to examine the relationships of gait independence with muscle thickness (MT) and echo intensity (EI) of the quadriceps femoris in individuals with hemiparesis after stroke.

METHODS

We examined 43 individuals with hemiparetic stroke. We assessed functional independence measure (FIM) gait scores and measured thickness and EI of the quadriceps using US. The relationships of FIM gait scores with MT and EI were examined using Spearman's correlation coefficients in mild (n = 21) and severe (n = 22) hemiparetic stroke groups.

RESULTS

In the mild hemiparetic group, FIM gait scores were correlated with paretic limb MT (rho = 0.60, p < 0.01) and EI (rho = -0.57, p < 0.01). In the severe hemiparetic group, FIM gait scores were correlated with paretic limb MT (rho = 0.67, p < 0.01) and EI (rho = -0.43, p < 0.05), as well as non-paretic limb MT (rho = 0.86, p < 0.01) and EI (rho = -0.56, p < 0.01).

CONCLUSIONS

Quadriceps thickness and EI were associated with the degree of gait independence. Atrophy and increased intramuscular fat of the quadriceps may be limiting factors for achieving gait independence.

Beyond the Brain: The Systemic Pathophysiological Response to Acute Ischemic Stroke

Stroke research has traditionally focused on the cerebral processes following ischemic brain injury, where oxygen and glucose deprivation incite prolonged activation of excitatory neurotransmitter receptors, intracellular calcium accumulation, inflammation, reactive oxygen species proliferation, and ultimately neuronal death. A recent growing body of evidence, however, points to far-reaching pathophysiological consequences of acute ischemic stroke. Shortly after stroke onset, peripheral immunodepression in conjunction with hyperstimulation of autonomic and neuroendocrine pathways and motor pathway impairment result in dysfunction of the respiratory, urinary, cardiovascular, gastrointestinal, musculoskeletal, and endocrine systems. These end organ abnormalities play a major role in the morbidity and mortality of acute ischemic stroke. Using a pathophysiology-based approach, this current review discusses the pathophysiological mechanisms following ischemic brain insult that result in end organ dysfunction. By characterizing stroke as a systemic disease, future research must consider bidirectional interactions between the brain and peripheral organs to inform treatment paradigms and develop effective, comprehensive therapeutics for acute ischemic stroke.

[Modern aspects of the pathophysiology of walking disorders and their rehabilitation in post-stroke patients]

The problem of rehabilitation of post-stroke patients with motor deficit remains relevant with growing prevalence of disability and decreasing mortality, despite all measures aimed at stroke prevention and morbidity reduction. One of the most common consequences of stroke is gait impairment as a result of spastic paresis of the lower limb (decreased gait velocity, shortened step, excessive loading of intact limb etc.), which leads to significant maladaptation, increased risk of falls, decrease in quality of life. The article presents a detailed review of motor action in normal and pathologic conditions, analysis of neuronal structures involved into a movement act in healthy individuals and in stroke patients, current aspects of gait pathophysiology, characteristics of post-stroke gait (speed and asymmetry of gain, balance control impairment). A separate paragraph is devoted to gait recovery after stroke with analysis of existing and developing strategies of rehabilitation, aimed at the improvement of vertical posture, balance control and movement, condition, tone and functioning of skeletal muscles. Authors also analyze new research information on the efficacy of botulinum toxin preparations and programs of Guided Self-Rehabilitation Contracts (GSC), present the results of clinical trials demonstrating the efficacy of combination of these two methods.

Spinal Cord Injury as a Model of Bone-Muscle Interactions: Therapeutic Implications From in vitro and in vivo Studies

Spinal cord injuries (SCIs) represent a variety of conditions related to the damage of the spinal cord with consequent musculoskeletal repercussions. The bone and muscle tissues share several catabolic pathways that lead to variable degrees of disability in SCI patients. In this review article, we provide a comprehensive characterization of the available treatment options targeting the skeleton and the bone in the setting of SCI. Among the pharmacological intervention, bisphosphonates, anti-sclerostin monoclonal antibodies, hydrogen sulfide, parathyroid hormone, and RANKL pathway inhibitors represent valuable options for treating bone alterations. Loss phenomena at the level of the muscle can be counteracted with testosterone, anabolic-androgenic steroids, and selective androgen receptor modulators. Exercise and physical therapy are valuable strategies to increase bone and muscle mass. Nutritional interventions could enhance SCI treatment, particularly in the setting of synergistic and multidisciplinary interventions, but there are no specific guidelines available to date. The development of multidisciplinary recommendations is required for a proper clinical management of SCI patients.

Sarcopenia and myokines profile as risk factors in cardiovascular diseases?

Skeletal muscles and substances released during physical activity (myokines) have a beneficial influence on the functioning of the organism. Myokines (released also by myocardium) together with hepatokines and adipokines play an important role not only in energetic metabolism, but they also influence, among others, the function of the circulatory and nervous systems, modulation of inflammatory state and atherogenesis. Under pathological conditions connected with the presence of chronic diseases, chronic inflammatory state, low physical activity, long-term immobility the following consequences are observed: reduction of muscle mass and strength (sarcopenia) and changed profile of released myokines. The incidence of sarcopenia is connected with an unfavorable course of the aging process, often leading to disability and multiple morbidities. Sarcopenia can also lead to frailty syndrome, which not only worsens the prognosis of various diseases, but it can also increase the risk of medical procedures. Sarcopenia and adverse przymyokine profile are modifiable risk factors of cardiovascular diseases and affecting them may improve functional status and prognosis. An important intervention to improve muscles function and myokine profile, apart from nutritional treatment and pharmacotherapy, is regular physical activity as a component of cardiac rehabilitation. In our paper we focused on a review of the newest research regarding the association of sarcopenia and the profile of released myokines with incidence and course of cardiovascular diseases such as chronic heart failure, coronary artery disease, carotid artery atherosclerosis or ischemic cerebral stroke.

A secondary analysis of testosterone and electrically evoked resistance training versus testosterone only (TEREX-SCI) on untrained muscles after spinal cord injury: a pilot randomized clinical trial

STUDY DESIGN

Secondary analysis of a clinical trial.

OBJECTIVES

To perform a secondary analysis on the effects of neuromuscular electrical stimulation resistance training (RT) combined with testosterone replacement therapy (TRT) compared with TRT on the untrained muscles after spinal cord injury (SCI).

SETTING

Medical research center.

METHODS

Twenty-two men with chronic motor complete SCI were randomized into TRT + RT group (n = 11) or TRT group (n = 11). Both groups received 16 weeks of TRT (2-6 mg/day) via testosterone patches. The TRT + RT group received twice weekly progressive RT of the knee extensor muscles using electrical stimulation and ankle weights. Magnetic resonance images were captured to measure cross-sectional areas (CSAs) of trunk, glutei, and leg muscles.

RESULTS

Total and absolute gluteus maximus m. (14%, P = 0.003 and 16%, P = 0.001), gluteus medius m. (10%; P = 0.008 and 14%; P = 0.02), and total glutei m. (8%, P = 0.01 and 11%, P = 0.005) CSAs increased overtime for the TRT + RT group. Mean between-group differences of 2.86 (95% CI: 0.30, 5.4), 1.89 (95% CI: 0.23, 3.58) and 5.27 (95% CI: 0.90, 9.69) cm² were noted for absolute gluteus maximus, total gluteus medius and total glutei CSAs, respectively (P < 0.05). Trunk muscle CSAs showed a trend towards an interaction between groups.

CONCLUSIONS

RT combined with low-dose TRT results in significant hypertrophy compared with TRT only on the adjacent untrained glutei muscles. Trunk muscles may require direct stimulation to evoke hypertrophy. These exploratory findings may be of clinical relevance in the reduction of incidence and severity of pelvic pressure injuries.

Cross-sectional study of quadriceps properties and postural stability in patients with chronic stroke and limited vs. non-limited community ambulation

Background: Changes in the paretic-side metabolism post-stroke and quadriceps muscle mechanical properties favour muscle wasting, affecting postural instability and walking impairment. Further clarification is needed in subjects post-stroke who show limited or non-limited community ambulation. Objectives: To analyze between-limb differences in quadriceps muscle thickness, strength and thigh cutaneous temperature, as well as investigate postural stability in subjects with chronic stroke and limited vs. non-limited community ambulation and compared against healthy controls. Methods: In this controlled cross-sectional study, 26 participants with chronic hemiparesis post-stroke (divided in a slow gait group (SG<0.8 m/s) (n = 13) and a fast gait group with full community ambulation speed (FG≥0.8 m/s)) and 18 healthy people were recruited. Thigh surface temperature, rectus femoris (RF) and vastus intermedius (VI) muscles thickness, quadriceps' isometric maximal voluntary contraction and postural stability were measured. Results: The SG presented significantly lower RF (P = .019) and VI (P = .006) muscle thickness, less peak force (P < .001) and lower temperature (P = .002) in the paretic vs the non-paretic limb. The FG showed significantly lower VI thickness (P = .036) and peak force (P < .001) in the paretic vs the non-paretic limb. Regarding balance, all indices were worse in the SG versus the FG and CG. Conclusions: Subjects of the FG, despite showing full community ambulation speed, had less quadriceps strength and VI muscle thickness but not RF muscle wasting in the paretic limb. The paretic VI muscle wasting may be an important factor to reach normal walking. The SG showed between-limb differences in all the studied variables and the worst postural stability.

Brain-derived neurotrophic factor, epigenetics in stroke skeletal muscle, and exercise training

Objective

(1) To compare paretic (P) vs nonparetic (NP) skeletal muscle brain-derived neurotrophic factor (BDNF) and the effects of resistive training (RT) on systemic and skeletal muscle BDNF mRNA expression in stroke; and (2) to compare the DNA methylation profile for BDNF and BDNFAS (BDNF antisense RNA) between P and NP muscle and the effects of aerobic exercise training (AEX) on DNA methylation in stroke.

Methods

In this longitudinal investigation, participants (50-76 years) with chronic stroke underwent a fasting blood draw, a 12-week (3×/week) RT intervention (n = 16), and repeated bilateral vastus lateralis muscle tissue biopsies (n = 10) with BDNF expression determined by RT-PCR. Five stroke survivors completed 6 months of AEX (3×/week) and had bilateral muscle biopsies. DNA methylation status in gene BDNF and BDNFAS was assessed by Illumina 450k methylation array.

Results

P muscle had ∼45% lower BDNF mRNA expression than NP muscle (6.79 ± 1.30 vs 10.52 ± 2.06 arbitrary units [AU], p < 0.05), and P muscle exhibited differential methylation status in the DNA sequences of BDNF (3 CpG [5'-C-phosphate-G-3'] sites, p = 0.016-0.044) and BDNFAS (1 CpG site, p = 0.016) compared to NP. Plasma BDNF and muscle BDNF messenger RNA (mRNA) expression did not significantly change after RT. BDNFAS DNA methylation increased after AEX in P relative to NP muscle (p = 0.017).

Conclusions

This is the first evidence that stroke hemiparesis reduces BDNF skeletal muscle expression, with our findings identifying methylation alterations on the DNA sequence of BDNF and BDNFAS gene. Preliminary results further indicate that AEX increases methylation in BDNFAS gene, which presumably could regulate the expression of BDNF.

Low body mass index negatively affects muscle mass and intramuscular fat of chronic stroke survivors

Objective

Relationship between secondary changes in skeletal muscle and body weight in chronic stroke survivors has not yet been carefully examined. The objective of this study was to clarify the relationships between muscle mass, intramuscular fat, and body weight in chronic stroke survivors.

Methods

Seventy-two chronic stroke survivors participated in this study. Transverse ultrasound images were acquired using B-mode ultrasound imaging. Quadriceps muscle mass and intramuscular fat were assessed based on muscle thickness and echo intensity, respectively. We used a stepwise multiple regression analysis to identify the factors that were independently associated with the body mass index. We entered quadriceps thickness and echo intensity of the paretic and non-paretic sides into another stepwise multiple regression model to avoid multicollinearity. Age, sex, type of stroke, time since stroke, thigh length, number of medications, and an updated Charlson comorbidity index were included as the independent variables.

Results

The quadriceps thickness and echo intensity of the paretic and non-paretic sides were significantly independently associated with the body mass index: quadriceps thickness of the paretic side, β = 0.52; quadriceps thickness of the non-paretic side, β = 0.55; quadriceps echo intensity of the paretic side, β = −0.35; quadriceps echo intensity of the non-paretic side, β = −0.27).

Conclusions

Our results suggest that low body mass index is associated with loss of muscle mass and increased intramuscular fat on both the paretic and non-paretic sides of chronic stroke survivors. Further studies examining whether appropriate weight management, along with targeted rehabilitation programs aimed at increasing muscle mass and decreasing intramuscular fat, achieves good outcomes in chronic stroke survivors are warranted.

Structural muscular adaptations in upper limb after stroke: a systematic review

BACKGROUND

Stroke is a leading cause of disability in the adult population, impairing upper limb (UL) movements affecting activities of daily living. Muscle weakness has been associated to disabilities in this population, but much attention is given to central nervous system alterations and less to skeletal muscles.

OBJECTIVE

The objective of this review is to carry out a systematic literature review to identify structural muscle alterations in the UL of poststroke individuals.

METHOD

The search was performed in December, 2017. MEDLINE, PubMed, SCOPUS, CINAHL, and Science Direct were used as electronic databases. There was no restriction regarding language and publication dates. Studies conducted on poststroke subjects and results on UL skeletal muscle alterations identified by imaging tests were included.

RESULTS

Seven studies were included. The sample size and the variables varied among the studies. All the studies compared the paretic UL with the nonparetic UL and one of the studies also compared healthy subjects. Ultrasonography was the most used measurement tool to assess muscle adaptation.

CONCLUSIONS

This review demonstrated little evidence with poor to fair quality on the structural muscle adaptations in the poststroke subjects, showing muscle atrophy, a higher stiffness, and amount of fibrous and fat tissue without alterations in lean tissue of distal muscles of the paretic UL compared to the nonparetic limb. However, the nonparetic side also presented alterations, which makes it an inappropriate comparison. Thus, well-designed studies addressing this issue are required.

Prognostic impact of skeletal muscle volume derived from cross-sectional computed tomography images in breast cancer

PURPOSE

This study aimed to determine whether the prognosis of breast cancer is affected by muscle or fat volume as measured from computed tomography (CT) images.

METHODS

We identified 1460 patients with chest CT who were diagnosed as having breast cancer at the National Cancer Center, Korea, between January 2001 and December 2009. Using CT images of 10-mm slices, we measured the cross-sectional areas of skeletal muscle and adipose tissue at the 3rd lumbar vertebrae, and derived their volumes. The skeletal muscle volume, fat volume, and muscle-to-fat ratio were evaluated for association with overall survival (OS) and recurrence-free survival (RFS).

RESULTS

The median skeletal muscle and fat volumes among the patients were 93.3 cc (range 39.6-236.9) and 420.1 cc (range 19.5-1392.3), respectively. Patients with higher muscle volume had better prognosis than those with lower muscle volume [hazard ratio (HR) 0.56, 95% confidence interval (CI) 0.34-0.92, P = 0.022 for OS; HR 0.72, 95% CI 0.52-0.99, P = 0.046 for RFS]. However, body mass index (BMI) and fat volume were not associated with prognosis. In addition, muscle volume was a significant prognosticator for OS, regardless of BMI (HR 0.55, 95% CI 0.32-0.93, P = 0.034 in BMI < 25.0; HR 0.44, 95% CI 0.21-0.91, P = 0.026 in BMI ≥ 25.0). Among older patients (≥ 50), those with higher muscle volume showed better OS and RFS (HR 0.44, 95% CI 0.23-0.85, P = 0.015; HR 0.55, 95% CI 0.34-0.90, P = 0.017, respectively).

CONCLUSION

This study demonstrated that breast cancer patients with higher skeletal muscle volume showed more favorable prognosis.

Muscle mass and intramuscular fat of the quadriceps are related to muscle strength in non-ambulatory chronic stroke survivors: A cross-sectional study

Objective

Improving muscle mass and intramuscular fat in the mid-thigh increases the muscle strength of the paretic and non-paretic limbs in ambulatory chronic stroke survivors. There is a remarkable decrease in muscle mass and muscle strength and an increase in intramuscular fat in the quadriceps of both limbs of non-ambulatory compared with ambulatory survivors. Therefore, given that paretic lower extremity function does not recover sufficiently in the chronic phase, it may be helpful to improve muscle mass and intramuscular fat to increase muscle strength in the quadriceps of non-ambulatory chronic stroke survivors. However, these relationships remain unclear. The purpose of this study was to clarify the relationships between muscle strength, muscle mass, and intramuscular fat of the quadriceps in non-ambulatory chronic stroke survivors.

Methods

Study design: A cross-sectional study.

Participants: Fifty non-ambulatory chronic stroke survivors.

Main outcome measures: Quadriceps muscle strength was measured using a handheld dynamometer. Transverse ultrasound images were acquired using B-mode ultrasound imaging. Muscle mass and intramuscular fat of the quadriceps were assessed based on muscle thickness and echo intensity, respectively.

Data analysis: Stepwise multiple regression analyses were used to identify the factors independently associated with the quadriceps muscle strength of the paretic and non-paretic limbs. To avoid multicollinearity, muscle thickness and echo intensity were entered into separate multiple regression models. Muscle thickness or echo intensity of the paretic or non-paretic limbs and other confounding factors were set as the independent variables.

Results

Muscle thickness was positively related and echo intensity was negatively related to the quadriceps muscle strength of the paretic and non-paretic limbs.

Conclusions

Muscle mass and intramuscular fat of the quadriceps are related to muscle strength in non-ambulatory chronic stroke survivors. Increasing muscle mass and decreasing intramuscular fat of the quadriceps of both limbs may improve muscle strength.

Investigating Muscle Function After Stroke Rehabilitation with 31P-MRS: A Preliminary Study

BACKGROUND New evidence reveals significant metabolic changes in skeletal muscle after stroke. However, it is unknown if 31P magnetic resonance spectroscopy (31P-MRS) can evaluate these metabolic changes. Our objective here was to investigate: (a) if muscle energy metabolism changes in the affected side; (b) if muscle energy metabolism changes after rehabilitation; and (c) if energy metabolism measured by 31P-MRS can reflect changes in the Modified Modified Ashworth Scale (MMAS) and Fugl-Meyer assessment-lower extremity (FMA-LE) scores after rehabilitation. MATERIAL AND METHODS We enrolled 13 patients with stroke symptoms and hemiplegia. Lower-limb motor status on the affected side was evaluated by FMA-LE and MMAS. The 31P-MRS measures included phosphocreatine (PCr), inorganic phosphate (Pi), PCr/Pi, and pH. We statistically compared these measures in the affected and unaffected lower leg muscles before rehabilitation and after rehabilitation on the affected side. Spearman correlational analyses was performed to determine correlations between change in energy metabolism and change in FMA-LE score and MMAS score after rehabilitation. RESULTS PCr and PCr/Pi were significantly lower in the affected muscle compared to the unaffected muscle; however, there were no significant differences in Pi or pH. After rehabilitation, PCr, Pi, PCr/Pi, and pH did not significantly change. However, FMA-LE and MMAS score improved significantly after rehabilitation. Changes in energy metabolism measured by 31P-MRS had no correlation with FMA-LE change after rehabilitation. However, changes in PCr and PCr/Pi were correlated with change in MMAS score after rehabilitation. CONCLUSIONS 31P-MRS can evaluate changes in muscle energy metabolism in patients with stroke. PCr measured by 31P-MRS can reflect changes in MMAS after rehabilitation.

Aerobic With Resistance Training or Aerobic Training Alone Poststroke: A Secondary Analysis From a Randomized Clinical Trial

BACKGROUND

Stroke is associated with muscle atrophy and weakness, mobility deficits, and cardiorespiratory deconditioning. Aerobic and resistance training (AT and RT) each have the potential to improve deficits, yet there is limited evidence on the utility of combined training.

OBJECTIVE

To examine the effects of AT+RT versus AT on physiological outcomes in chronic stroke with motor impairments.

METHODS

Participants (n = 73) were randomized to 6 months of AT (5 d/wk) or AT+RT (3 and 2 d/wk, respectively). Outcomes included those related to body composition by dual-energy X-ray absorptiometry, mobility (6-minute walk distance [6MWD], sit-to-stand, and stair climb performance), cardiorespiratory fitness (VO_2peak, oxygen uptake at the ventilatory threshold [VO_2VT]), and muscular strength.

RESULTS

A total of 68 (93.2%) participants (age, mean ± SD = 63.7 ± 11.9) completed the study. AT+RT and AT yielded similar and significant improvements in 6MWD (39.9 ± 55.6 vs 36.5 ± 63.7 m, P = .8), VO_2peak (16.4% ± 43.8% vs 15.2% ± 24.7%, P = .9), sit-to-stand time (-2.3 ± 5.1 vs 1.02 ± 9.5 s, P = .05), and stair climb performance (8.2% ± 19.6% vs 7.5% ± 23%, P = .97), respectively. AT+RT produced greater improvements than AT alone for total body lean mass (1.23 ± 2.3 vs 0.27 ± 1.6 kg, P = .039), predominantly trunk ( P = .02) and affected-side limbs ( P = .04), VO_2VT (19.1% ± 26.8% vs 10.5% ± 28.9%, P = .046), and upper- and lower-limb muscular strength ( P < .03, all except affected-side leg).

CONCLUSION

Despite being prescribed 40% less AT, AT+RT resulted in similar and significant improvement in mobility and VO_2peak, superior improvements in VO_2VT and muscular strength, and an almost 5-fold greater increase in lean mass compared with AT. RT is the most neglected exercise component following stroke but should be prescribed with AT for metabolic, cardiorespiratory, and strength recovery.

Efficacy of neuromuscular electrical stimulation for preventing quadriceps muscle wasting in patients with moderate or severe acute stroke: A pilot study

BACKGROUND

Stroke-related muscle wasting is one of the factors leading to long-term disability and functional dependency. No study has reported an effective therapeutic intervention for such muscle wasting.

OBJECTIVE

The purpose of this study was to investigate the effects of neuromuscular electrical stimulation (NMES) on quadriceps muscle mass preservation in patients with acute moderate or severe stroke by using ultrasonography (US).

METHODS

Twenty patients with acute, moderate, or severe stroke (age: 68±11 years) were divided into usual care group (control group) and intervention groups (NMES group), respectively. Patients in the NMES group underwent NMES treatment for bilateral quadriceps muscles for 2 weeks in addition to the usual care. Quadriceps muscle thickness was measured on admission and 2 weeks after the first measurement.

RESULTS

The quadriceps muscle thickness on the paretic and non-paretic sides in the NMES group (-12.4% ±12.7%, -5.5% ±15.3%, respectively) significantly decreased to a lesser degree than that in the control group (-29.5% ±12.1%, P = 0.004; and -22.0% ±16.8%, P = 0.04, respectively).

CONCLUSIONS

NEMS seemed to have preserved the quadriceps muscle mass in patients with moderate or severe acute stroke.

Bilateral Transcutaneous Electrical Nerve Stimulation Improves Lower-Limb Motor Function in Subjects With Chronic Stroke: A Randomized Controlled Trial

BACKGROUND

Transcutaneous electrical nerve stimulation (TENS) has been used to augment the efficacy of task-oriented training (TOT) after stroke. Bilateral intervention approaches have also been shown to be effective in augmenting motor function after stroke. The purpose of this study was to compare the efficacy of bilateral TENS combined with TOT versus unilateral TENS combined with TOT in improving lower-limb motor function in subjects with chronic stroke.

METHODS AND RESULTS

Eighty subjects were randomly assigned to bilateral TENS+TOT or to unilateral TENS+TOT and underwent 20 sessions of training over a 10-week period. The outcome measures included the maximal strength of the lower-limb muscles and the results of the Lower Extremity Motor Coordination Test, Berg Balance Scale, Step Test, and Timed Up and Go test. Each participant was assessed at baseline, after 10 and 20 sessions of training and 3 months after the cessation of training. The subjects in the bilateral TENS+TOT group showed greater improvement in paretic ankle dorsiflexion strength (β=1.32; P=0.032) and in the completion time for the Timed Up and Go test (β=-1.54; P=0.004) than those in the unilateral TENS+TOT group. However, there were no significant between-group differences for other outcome measures.

CONCLUSIONS

The application of bilateral TENS over the common peroneal nerve combined with TOT was superior to the application of unilateral TENS combined with TOT in improving paretic ankle dorsiflexion strength after 10 sessions of training and in improving the completion time for the Timed Up and Go test after 20 sessions of training.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02152813.

Paradigms of Lower Extremity Electrical Stimulation Training After Spinal Cord Injury

Skeletal muscle atrophy, increased adiposity and reduced physical activity are key changes observed after spinal cord injury (SCI) and are associated with numerous cardiometabolic health consequences. These changes are likely to increase the risk of developing chronic secondary conditions and impact the quality of life in persons with SCI. Surface neuromuscular electrical stimulation evoked resistance training (NMES-RT) was developed as a strategy to attenuate the process of skeletal muscle atrophy, decrease ectopic adiposity, improve insulin sensitivity and enhance mitochondrial capacity. However, NMES-RT is limited to only a single muscle group. Involving multiple muscle groups of the lower extremities may maximize the health benefits of training. Functional electrical stimulation-lower extremity cycling (FES-LEC) allows for the activation of 6 muscle groups, which is likely to evoke greater metabolic and cardiovascular adaptation. Appropriate knowledge of the stimulation parameters is key to maximizing the outcomes of electrical stimulation training in persons with SCI. Adopting strategies for long-term use of NMES-RT and FES-LEC during rehabilitation may maintain the integrity of the musculoskeletal system, a pre-requisite for clinical trials aiming to restore walking after injury. The current manuscript presents a combined protocol using NMES-RT prior to FES-LEC. We hypothesize that muscles conditioned for 12 weeks prior to cycling will be capable of generating greater power, cycle against higher resistance and result in greater adaptation in persons with SCI.

Relationships between muscle mass, intramuscular adipose and fibrous tissues of the quadriceps, and gait independence in chronic stroke survivors: a cross-sectional study

OBJECTIVE

To examine the relationships between muscle mass, intramuscular adipose and fibrous tissues of the quadriceps, and gait independence in chronic stroke survivors.

DESIGN

Cross-sectional study.

SETTING

Hospital-based research.

PARTICIPANTS

Seventeen chronic stroke survivors who were unable to walk independently (non-independent walker group) and 11 chronic stroke survivors who were able to walk independently (independent walker group) participated in this study. In addition, 25 healthy older adults (healthy group) were enrolled.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

The muscle mass and intramuscular adipose and fibrous tissues of the rectus femoris and vastus intermedius were assessed based on muscle thickness and echo intensity of ultrasound images, respectively.

RESULTS

The thicknesses of the rectus femoris and vastus intermedius on the paretic and non-paretic sides in the non-independent walker group were significantly lower than those in the healthy group (mean difference -0.5 to -0.2cm; P<0.001-0.037). The paretic side in the non-independent walker group had significantly higher rectus femoris and vastus intermedius echo intensity compared with the healthy group (mean difference 15.8-17.4; P=0.007-0.025). The thickness of the rectus femoris on the non-paretic side was significantly lower in the independent walker group than in the healthy group (mean difference -0.3cm; P=0.001).

CONCLUSIONS

These results suggest that chronic stroke survivors who are unable to walk independently are likely to experience secondary changes in skeletal muscle on both the paretic and non-paretic sides.

Pharmacological inhibition of myostatin improves skeletal muscle mass and function in a mouse model of stroke

In stroke patients, loss of skeletal muscle mass leads to prolonged weakness and less efficient rehabilitation. We previously showed that expression of myostatin, a master negative regulator of skeletal muscle mass, was strongly increased in skeletal muscle in a mouse model of stroke. We therefore tested the hypothesis that myostatin inhibition would improve recovery of skeletal muscle mass and function after cerebral ischemia. Cerebral ischemia (45 minutes) was induced by intraluminal right middle cerebral artery occlusion (MCAO). Swiss male mice were randomly assigned to Sham-operated mice (n = 10), MCAO mice receiving the vehicle (n = 15) and MCAO mice receiving an anti-myostatin PINTA745 (n = 12; subcutaneous injection of 7.5 mg.kg^-1 PINTA745 immediately after surgery, 3, 7 and 10 days after MCAO). PINTA745 reduced body weight loss and improved body weight recovery after cerebral ischemia, as well as muscle strength and motor function. PINTA745 also increased muscle weight recovery 15 days after cerebral ischemia. Mechanistically, the better recovery of skeletal muscle mass in PINTA745-MCAO mice involved an increased expression of genes encoding myofibrillar proteins. Therefore, an anti-myostatin strategy can improve skeletal muscle recovery after cerebral ischemia and may thus represent an interesting strategy to combat skeletal muscle loss and weakness in stroke patients.

Clinical Applications of Iso-Inertial, Eccentric-Overload (YoYo™) Resistance Exercise

In the quest for a viable non-gravity dependent method to "lift weights" in space, our laboratory introduced iso-inertial resistance (YoYo™) exercise using spinning flywheel(s), more than 25 years ago. After being thoroughly tested in individuals subjected to various established spaceflight analogs, a multi-mode YoYo™ exercise apparatus was eventually installed on the International Space Station in 2009. The method, applicable to any muscle group, provides accommodated resistance and optimal muscle loading through the full range of motion of concentric actions, and brief episodes of eccentric overload. This exercise intervention has found terrestrial applications and shown success in enhancing sports performance and preventing injury and aiding neurological or orthopedic rehabilitation. Research has proven that this technique offers unique physiological responses not possible with other exercise hardware solutions. This paper provides a brief overview of research that has made use, and explored the efficacy, of this method in healthy sedentary or physically active individuals and populations suffering from muscle wasting, disease or injury. While the collective evidence to date suggests YoYo™ offers a potent stimulus to optimize the benefits of resistance exercise, systematic research to support clinical use of this method has only begun to emerge. Thus, we also offer perspectives on unresolved issues, unexplored applications for clinical conditions, and how this particular exercise paradigm could be implemented in future clinical research and eventually being prescribed. Fields of particular interest are those aimed at promoting muscle health by preventing injury or combating muscle wasting and neurological or metabolic dysfunction due to aging or illness, or those serving in rehabilitation following trauma and/or surgery.

Effects of Testosterone and Evoked Resistance Exercise after Spinal Cord Injury (TEREX-SCI): study protocol for a randomised controlled trial

INTRODUCTION

Individuals with spinal cord injury (SCI) are at a lifelong risk of obesity and chronic metabolic disorders including insulin resistance and dyslipidemia. Within a few weeks of injury, there is a significant decline in whole body fat-free mass, particularly lower extremity skeletal muscle mass, and subsequent increase in fat mass (FM). This is accompanied by a decrease in anabolic hormones including testosterone. Testosterone replacement therapy (TRT) has been shown to increase skeletal muscle mass and improve metabolic profile. Additionally, resistance training (RT) has been shown to increase lean mass and reduce metabolic disturbances in SCI and other clinical populations.

METHODS AND ANALYSIS

26 individuals with chronic, motor complete SCI between 18 and 50 years old were randomly assigned to a RT+TRT group (n=13) or a TRT group (n=13). 22 participants completed the initial 16-week training phase of the study and 4 participants withdrew. 12 participants of the 22 completed 16 weeks of detraining. The TRT was provided via transdermal testosterone patches (4-6 mg/day). The RT+TRT group had 16 weeks of supervised unilateral progressive RT using surface neuromuscular electrical stimulation with ankle weights. This study will investigate the effects of evoked RT+TRT or TRT alone on body composition (muscle cross-sectional area, visceral adipose tissue, %FM) and metabolic profile (glucose and lipid metabolism) in individuals with motor complete SCI. Findings from this study may help in designing exercise therapies to alleviate the deterioration in body composition after SCI and decrease the incidence of metabolic disorders in this clinical population.

ETHICS AND DISSEMINATION

The study is currently approved by the McGuire VA Medical Center and Virginia Commonwealth University. All participants read and signed approved consent forms. Results will be submitted to peer-reviewed journals and presented at national and international conferences.

TRIAL REGISTRATION NUMBER

Pre-result, NCT01652040.

Assessed and Emerging Biomarkers in Stroke and Training-Mediated Stroke Recovery: State of the Art

Since the increasing update of the biomolecular scientific literature, biomarkers in stroke have reached an outstanding and remarkable revision in the very recent years. Besides the diagnostic and prognostic role of some inflammatory markers, many further molecules and biological factors have been added to the list, including tissue derived cytokines, growth factor-like molecules, hormones, and microRNAs. The literatures on brain derived growth factor and other neuroimmune mediators, bone-skeletal muscle biomarkers, cellular and immunity biomarkers, and the role of microRNAs in stroke recovery were reviewed. To date, biomarkers represent a possible challenge in the diagnostic and prognostic evaluation of stroke onset, pathogenesis, and recovery. Many molecules are still under investigation and may become promising and encouraging biomarkers. Experimental and clinical research should increase this list and promote new discoveries in this field, to improve stroke diagnosis and treatment.

Skeletal muscle changes following stroke: a systematic review and comparison to healthy individuals

BACKGROUND

Despite extensive study of the impact of stroke on muscle and functional performance, questions remain regarding the extent to which changes are due to the neurological injury vs. age-related loss of morphology and force production.

OBJECTIVES

To synthesize available evidence describing post-stroke changes in lower extremity muscle size and strength compared to healthy adults.

METHODS

Scientific literature was searched up to April 2016 to identify studies that included lower extremity muscle size and strength measures in individuals with chronic stroke. Lower extremity muscle size and strength data from healthy controls were sought for comparison. Relative differences were calculated between paretic, nonparetic, and control limbs.

RESULTS

Fifteen studies with 375 participants (61% male; age = 62 ± 5 years; time since stroke = 60 ± 42 months) were included. The paretic limb exhibited deficits of ~13% in thigh muscle size, ~5% in lower leg muscle size, and ~8% in lean leg mass compared to the nonparetic limb. Paretic plantarflexor and knee extensor strength were 52 and 36% lower, respectively, compared to the nonparetic limb. When compared to age-matched control data, both paretic and nonparetic limbs showed deficits in muscle size and strength.

CONCLUSIONS

Age-related differences support the impact of stroke-related sarcopenia as a contributor to hemiparetic muscle dysfunction. Understanding these muscular changes is necessary for designing appropriate exercise interventions aimed at restoring muscle function.

Resistive Training and Molecular Regulators of Vascular-Metabolic Risk in Chronic Stroke

BACKGROUND

Peroxisome proliferator-activated receptor (PPAR)-γ coactivator (PGC-1α) gene and Sirtuin-1 (SIRT-1) respond to physiological stimuli and regulate insulin resistance. Inflammatory markers tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), and the soluble forms of intracellular adhesion molecule (sICAM-1) and vascular CAM-1 (sVCAM-1) are associated with increased risk of diabetes and coronary heart disease. Resistive training (RT) reduces hyperinsulinemia and improves insulin action in chronic stroke. Yet, the molecular mechanisms for this are unknown. This study will determine the effects of RT on skeletal muscle PGC-1α and SIRT-1 mRNA expression and inflammatory and vascular markers.

METHODS

Stroke survivors (50-76 years) underwent a fasting blood draw for measurement of TNF-α, IL-6, CRP, serum amyloid A, sICAM-1, sVCAM-1, and bilateral vastus lateralis biopsies before and after RT. Participants were also assessed using bilateral multislice thigh computed tomography scans from the knee to the hip, a total body scan by dual-energy X-ray absorptiometry, and 1-repetition maximum strength testing. Subjects performed 2 sets of 3 lower extremity RT exercises 3 times per week for 12 weeks.

RESULTS

Bilateral leg press and leg extension strength increased ~30-50% with RT (P < .001). Body weight, total body fat mass, and fat-free mass did not change. Thigh muscle area and volume increased in both legs (P < .05). Nonparetic muscle PGC-1α mRNA expression increased 14% (P < .05) after RT and SIRT-1 mRNA decreased 24% (P < .05) and 31% (P < .01) in paretic and nonparetic muscles. There were no significant changes in plasma inflammation with training.

DISCUSSION

RT in chronic stroke induces changes in key skeletal muscle regulators of metabolism, without effecting circulating inflammation.

Robot-assisted mechanical therapy attenuates stroke-induced limb skeletal muscle injury

The efficacy and optimization of poststroke physical therapy paradigms is challenged in part by a lack of objective tools available to researchers for systematic preclinical testing. This work represents a maiden effort to develop a robot-assisted mechanical therapy (RAMT) device to objectively address the significance of mechanical physiotherapy on poststroke outcomes. Wistar rats were subjected to right hemisphere middle-cerebral artery occlusion and reperfusion. After 24 h, rats were split into control (RAMT^-) or RAMT⁺ groups (30 min daily RAMT over the stroke-affected gastrocnemius) and were followed up to poststroke d 14. RAMT⁺ increased perfusion 1.5-fold in stroke-affected gastrocnemius as compared to RAMT^- controls. Furthermore, RAMT⁺ rats demonstrated improved poststroke track width (11% wider), stride length (21% longer), and travel distance (61% greater), as objectively measured using software-automated testing platforms. Stroke injury acutely increased myostatin (3-fold) and lowered brain-derived neurotrophic factor (BDNF) expression (0.6-fold) in the stroke-affected gastrocnemius, as compared to the contralateral one. RAMT attenuated the stroke-induced increase in myostatin and increased BDNF expression in skeletal muscle. Additional RAMT-sensitive myokine targets in skeletal muscle (IL-1ra and IP-10/CXCL10) were identified from a cytokine array. Taken together, outcomes suggest stroke acutely influences signal transduction in hindlimb skeletal muscle. Regimens based on mechanical therapy have the clear potential to protect hindlimb function from such adverse influence.-Sen, C. K., Khanna, S., Harris, H., Stewart, R., Balch, M., Heigel, M., Teplitsky, S., Gnyawali, S., Rink, C. Robot-assisted mechanical therapy attenuates stroke-induced limb skeletal muscle injury.

Strength Training for Skeletal Muscle Endurance after Stroke

BACKGROUND AND PURPOSE

Initial studies support the use of strength training (ST) as a safe and effective intervention after stroke. Our previous work shows that relatively aggressive, higher intensity ST translates into large effect sizes for paretic and non-paretic leg muscle volume, myostatin expression, and maximum strength post-stroke. An unanswered question pertains to how our unique ST model for stroke impacts skeletal muscle endurance (SME). Thus, we now report on ST-induced adaptation in the ability to sustain isotonic muscle contraction.

METHODS

Following screening and baseline testing, hemiparetic stroke participants were randomized to either ST or an attention-matched stretch control group (SC). Those in the ST group trained each leg individually to muscle failure (20 repetition sets, 3× per week for 3 months) on each of three pneumatic resistance machines (leg press, leg extension, and leg curl). Our primary outcome measure was SME, quantified as the number of submaximal weight leg press repetitions possible at a specified cadence. The secondary measures included one-repetition maximum strength, 6-minute walk distance (6MWD), 10-meter walk speeds, and peak aerobic capacity (VO₂ peak).

RESULTS

ST participants (N = 14) had significantly greater SME gains compared with SC participants (N = 16) in both the paretic (178% versus 12%, P < .01) and non-paretic legs (161% versus 12%, P < .01). These gains were accompanied by group differences for 6MWD (P < .05) and VO₂ peak (P < .05).

CONCLUSION

Our ST regimen had a large impact on the capacity to sustain submaximal muscle contraction, a metric that may carry more practical significance for stroke than the often reported measures of maximum strength.