Dorsiflexion Specific Ankle Robotics to Enhance Motor Learning After Stroke: A Preliminary Report.

Background: Robotics has emerged as a promising avenue for gait retraining of persons with chronic hemiparetic gait and footdrop, yet there is a gap regarding the biomechanical adaptations that occur with locomotor learning. We developed an ankle exoskeleton (AMBLE) enabling dorsiflexion assist-as-needed across gait cycle sub-events to train and study the biomechanics of motor learning stroke. This single-armed, non-controlled study investigates effects of nine hours (9 weeks × 2 sessions/week) locomotor task-specific ankle robotics training on gait biomechanics and functional mobility in persons with chronic hemiparetic gait and foot drop.

Randomization to Treadmill Training Improves Physical and Metabolic Health in Association With Declines in Oxidative Stress in Stroke.

Objective: To investigate the effect of aerobic exercise vs control (stretching/balance) on inflammatory and oxidative stress biomarkers in stroke survivors and whether these changes are associated with improvements in physical and metabolic health.

Design: Randomized controlled trial.

Setting: The general communities of Baltimore, Maryland, and Atlanta, Georgia.

CD31+ Circulating Angiogenic Cell Number and Subtypes are Reduced in Individuals with Chronic Stroke.

Background And Purpose: Reduced number and function of CD31+ circulating angiogenic cells (CACs) may explain vascular complications associated with the chronic phase stroke. The purpose of this study was to quantify CD31+ CAC paracrine function, total number and number of various subtypes of CD31+ CACs in individuals with chronic stroke compared with controls.

Methods: Peripheral blood mononuclear cells were isolated from chronic stroke participants and controls.

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 ( = 30, 60 ± 8 years) and sedentary controls ( = 35, 62 ± 8 years).

Vitamin K Intake in Chronic Stroke: Implications for Dietary Recommendations.

Previous research has identified a possible association between vitamin K intake and cardiometabolic disease. This could mean that the assessment of vitamin K intake is a meaningful tool when monitoring individuals with preexisting cardiovascular disease. Sixty chronic stroke survivors (men and women, body mass index (BMI) 30.

Dietary and Serum Omega-6/Omega-3 Fatty Acids Are Associated with Physical and Metabolic Function in Stroke Survivors.

The purpose of this study was to quantify habitual dietary and systemic omega-6 and omega-3 fatty acids and their ratios and to determine their relationship with physical and metabolic function in a cohort of chronic adult stroke survivors. Twenty-five older chronic stroke survivors (age: 63 ± 8 years; BMI: 31 ± 7 kg/m; mean ± SD) were assessed for fitness (VOpeak), gait speed (GS), 3 m timed up and go (TUG), and six-minute walk distance (6MWD). Plasma lipid and glucose profiles were measured, and HOMA-IR calculated.

Metabolomics of Aerobic Exercise in Chronic Stroke Survivors: A Pilot Study.

Background: Understanding the metabolic response to exercise may aid in optimizing stroke management. Therefore, the purpose of this pilot study was to evaluate plasma metabolomic profiles in chronic stroke survivors following aerobic exercise training.

Methods: Participants (age: 62 ± 1 years, body mass index: 31 ± 1 kg/m, mean ± standard error of the mean) were randomized to 6 months of treadmill exercise (N = 17) or whole-body stretching (N = 8) with preintervention and postintervention measurement of aerobic capacity (VOpeak).

Aerobic Exercise Recommendations to Optimize Best Practices in Care After Stroke: AEROBICS 2019 Update.

Most stroke survivors have very low levels of cardiovascular fitness, which limits mobility and leads to further physical deconditioning, increased sedentary behavior, and heightened risk of recurrent stroke. Although clinical guidelines recommend that aerobic exercise be a part of routine stroke rehabilitation, clinical uptake has been suboptimal. In 2013, an international group of stroke rehabilitation experts developed a user-friendly set of recommendations to guide screening and prescription-the Aerobic Exercise Recommendations to Optimize Best Practices in Care after Stroke (AEROBICS 2013).

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.

Type 2 diabetes and older age contribute to elevated plasma microparticle concentrations independent of chronic stroke.

New Findings: What is the central question of this study? What is the effect of chronic stroke on circulating microparticle populations, accounting for potential effects of age and type 2 diabetes? What is the main finding and its importance? Elevated concentrations of CD31 /CD42b and CD62E microparticles appear to be driven by type 2 diabetes but not chronic stroke and are associated with fasting glucose and triglyceride levels. Older age results in elevations in CD62E and CD34 microparticle concentrations. These microparticles have been proposed as potential targets for diagnosing, treating and identifying the clinical progression and complications of type 2 diabetes.

Increased Energy Cost of Mobility in Chronic Stroke.

The purpose of this study was to compare the energy cost of completing mobility-related activities in chronic stroke to the estimated energy cost found in the compendium of physical activities, a resource that estimates and classifies energy cost of various human physical activities. Men (n=18) and women (n=10) with chronic hemiparetic gait (stroke latency: 4 ± 2 years, age: 60.4 ± 1.

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.

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).

Dynamic Balanced Reach: A Temporal and Spectral Analysis Across Increasing Performance Demands.

Standing balanced reach is a fundamental task involved in many activities of daily living that has not been well analyzed quantitatively to assess and characterize the multisegmental nature of the body's movements. We developed a dynamic balanced reach test (BRT) to analyze performance in this activity; in which a standing subject is required to maintain balance while reaching and pointing to a target disk moving across a large projection screen according to a sum-of-sines function. This tracking and balance task is made progressively more difficult by increasing the disk's overall excursion amplitude.

Sarcopenia and Physical Function in Middle-Aged and Older Stroke Survivors.

Objectives: To determine the prevalence of sarcopenia in stroke survivors using different methodologies, and compare a subset of the stroke group to age-, sex-, and body mass index (BMI)-matched nonstroke control counterparts.

Design: Cohort study.

Setting: A Veterans Affairs medical center and a university hospital.

Validating accelerometry as a measure of physical activity and energy expenditure in chronic stroke.

Background: Accelerometers can objectively measure steps taken per day in individuals without gait deficits, but accelerometers also have the ability to estimate frequency, intensity, and duration of physical activity. However, thresholds to distinguish varying levels of activity intensity using the Actical brand accelerometer are standardized only for the general population and may underestimate intensity in stroke.

Objective: To derive Actical activity count thresholds specific to stroke disability for use in more accurately gauging time spent at differing activity levels.

Task-specific ankle robotics gait training after stroke: a randomized pilot study.

Background: An unsettled question in the use of robotics for post-stroke gait rehabilitation is whether task-specific locomotor training is more effective than targeting individual joint impairments to improve walking function. The paretic ankle is implicated in gait instability and fall risk, but is difficult to therapeutically isolate and refractory to recovery. We hypothesize that in chronic stroke, treadmill-integrated ankle robotics training is more effective to improve gait function than robotics focused on paretic ankle impairments.

Skeletal muscle cellular metabolism in older HIV-infected men.

Skeletal muscle mitochondrial dysfunction may contribute to low aerobic capacity. We previously reported 40% lower aerobic capacity in HIV-infected men compared to noninfected age-matched men. The objective of this study was to compare skeletal muscle mitochondrial enzyme activities in HIV-infected men on antiretroviral therapy (55 ± 1 years of age, n = 10 African American men) with age-matched controls (55 ± 1 years of age, n = 8 Caucasian men), and determine their relationship with aerobic capacity.

Reduced Resting Metabolic Rate in Adults with Hemiparetic Chronic Stroke.

Objective: Resting metabolic rate (RMR) is the component of energy expenditure that explains the largest proportion of total daily energy requirements. Since RMR is determined largely by fat-free mass and a low RMR predicts weight gain in healthy adults, identifying the role of muscle atrophy following stroke on RMR may help identify ways to mitigate the development of obesity post-stroke.

Methods: Thirty-nine stroke survivors with chronic hemiparesis (mean ± SEM: age: 61 ± 1 years, latency from stroke: 107 ± 40 months, BMI: 31 ± 3 kg/m2) underwent DXA scans for measurement of body composition, including total, paretic, and non-paretic leg lean mass and fasted, 30-min indirect calorimetry for measurement of RMR.

Higher Treadmill Training Intensity to Address Functional Aerobic Impairment after Stroke.

Background: Peak aerobic capacity (VO2 peak) is severely worsened after disabling stroke, having serious implications for function, metabolism, and ongoing cardiovascular risk. Work from our laboratory and others has previously shown that modest improvements in VO2 peak are possible in stroke participants with aerobic exercise training. The purpose of the current investigation was to test the extent to which greater enhancements in VO2 peak after stroke are possible using a treadmill protocol with far greater emphasis on intensity progression compared with a protocol without such emphasis.

Impact of serum nutritional status on physical function in african american and caucasian stroke survivors.

Background. The purpose of this study is to compare serum nutritional profiles in chronic stroke survivors to a representative sample of US Adults (NHANESIII) and determine whether these serum markers differed by race and impact physical function in stroke. Methods.

Atrophy and intramuscular fat in specific muscles of the thigh: associated weakness and hyperinsulinemia in stroke survivors.

Purpose: Sarcopenia and increased fat infiltration in muscle may play a role in the functional impairment and high risk for diabetes in stroke. Our purpose was to compare muscle volume and muscle attenuation across 6 muscles of the paretic and nonparetic thigh and examine the relationships between intramuscular fat and insulin resistance and between muscle volume and strength in stroke patients.

Methods: Stroke participants (70; 39 men, 31 women) aged 40 to 84 years, BMI = 16 to 45 kg/m(2) underwent multiple thigh CT scans, total body scan by DXA (dual-energy X-ray absorptiometry), peak oxygen intake (VO(2peak)) graded treadmill test, 6-minute walk, fasting blood draws, and isokinetic strength testing.

Improved cerebral vasomotor reactivity after exercise training in hemiparetic stroke survivors.

Background And Purpose: Animal studies provide strong evidence that aerobic exercise training positively influences cerebral blood flow, but no human studies support the use of exercise for improving cerebral hemodynamics. This randomized study in stroke survivors assessed the effects of treadmill aerobic exercise training (TM) on cerebral blood flow parameters compared to a control intervention of nonaerobic stretching.

Methods: Thirty-eight participants (19 in TM group and 19 in control group) with remote stroke (>6 months) and mild to moderate gait deficits completed middle cerebral artery blood flow velocity measurements by transcranial Doppler ultrasonography before and after a 6-month intervention period.

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

Background And Purpose: Stroke survivors experience disproportionate muscle atrophy and other detrimental tissue composition changes on the paretic side. The purpose was to determine whether myostatin levels are higher in paretic vs nonparetic muscle and the effects of resistive training (RT) on paretic and nonparetic mid-thigh muscle composition and myostatin mRNA expression in stroke survivors.

Methods: Fifteen stroke survivors (50-76 years) underwent bilateral multi-slice thigh CT scanning from the knee to the hip, bilateral vastus lateralis skeletal muscle tissue biopsies, a total body scan by dual-energy X-ray absorptiometry, and 1-repetition maximum strength test before and after a 12-week, (3 times/week) RT intervention.

Impaired leg vasodilatory function after stroke: adaptations with treadmill exercise training.

Background And Purpose: Resting and reactive hyperemic leg blood flows are significantly reduced in the paretic compared with the nonparetic limb after disabling stroke. Our objective was to compare the effects of regular treadmill exercise (TM) with an active control regimen of supervised stretching (CONTROL) on peripheral hemodynamic function.

Methods: This intervention study used a randomized, controlled design, in which participants were randomized with stratification according to age and baseline walking capacity to ensure approximate balance between the 2 groups.