Systematic Evaluation of the Effects of Voluntary Activation on Lower Extremity Motor Thresholds.

The purpose of this investigation was to elucidate the relationship between the resting motor threshold (rMT) and active motor threshold (aMT). A cross-sectional comparison of MTs measured at four states of lower extremity muscle activation was conducted: resting, 5% maximal voluntary contraction (MVC), 10%MVC, and standing. MTs were measured at the tibialis anterior in the ipsilesional and contralesional limbs in participants in the chronic phase (>6 months) of stroke ( = 11) and in the dominant limb of healthy controls ( = 11).

A novel biomechanical indicator for impaired ankle dorsiflexion function during walking in individuals with chronic stroke.

Ankle dorsiflexion function during swing phase of the gait cycle contributes to foot clearance and plays an important role in walking ability post-stroke. Commonly used biomechanical measures such as foot clearance and ankle joint excursion have limited ability to accurately evaluate dorsiflexor function in stroke gait. We retrospectively evaluated ankle angular velocity and ankle angular acceleration as direct measures for swing phase dorsiflexor function in post-stroke gait of 61 chronic stroke survivors.

Interhemispheric Asymmetries in Intracortical Facilitation Correlate With Fatigue Severity in Individuals With Poststroke Fatigue.

Purpose: Poststroke fatigue (PSF) contributes to increased mortality and reduces participation in rehabilitative therapy. Although PSF's negative influences are well known, there are currently no effective evidence-based treatments for PSF. The lack of treatments is in part because of a dearth of PSF pathophysiological knowledge.

Standing Neurophysiological Assessment of Lower Extremity Muscles Post-Stroke.

Transcranial magnetic stimulation (TMS) is a common tool used to measure the behavior of motor circuits in healthy and neurologically impaired populations. TMS is used extensively to study motor control and the response to neurorehabilitation of the upper extremities. However, TMS has been less utilized in the study of lower extremity postural and walking-specific motor control.

Transcranial Direct Current Stimulation Electrode Montages May Differentially Impact Variables of Walking Performance in Individuals Poststroke: A Preliminary Study.

Purpose: Transcranial direct current stimulation (tDCS) has mixed effects on walking performance in individuals poststroke. This is likely the result of variations in tDCS electrode montages and individualized responses. The purpose of this study was to quantify the effects of a single session of tDCS using various electrode montages on poststroke walking performance.

Individualized Responses to Ipsilesional High-Frequency and Contralesional Low-Frequency rTMS in Chronic Stroke: A Pilot Study to Support the Individualization of Neuromodulation for Rehabilitation.

: In this pilot study, we examined the effects of ipsilesional high-frequency rTMS (iHF-rTMS) and contralesional low-frequency rTMS (cLF-rTMS) applied a double-cone coil on neurophysiological and gait variables in patients with chronic stroke. : To determine the group and individual level effects of two types of stimulation to better individualize neuromodulation for rehabilitation. : Using a randomized, within-subject, double-blind, sham-controlled trial with 14 chronic stroke participants iHF-rTMS and cLF-rTMS were applied a double-cone coil to the tibialis anterior cortical representation.

The effects of chronic Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) use on cerebral glucose metabolism in multiple sclerosis: a pilot study.

This exploratory pilot study investigated the effects of chronic Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) on cerebral glucose metabolism in people with multiple sclerosis (PwMS). Compared with nonusers, THC users had hypermetabolism of 3 regions ( < 0.039, >1.

Single Sessions of High-Definition Transcranial Direct Current Stimulation Do Not Alter Lower Extremity Biomechanical or Corticomotor Response Variables Post-stroke.

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique used to modulate cortical activity. However, measured effects on clinically relevant assessments have been inconsistent, possibly due to the non-focal dispersion of current from traditional two electrode configurations. High-definition (HD)-tDCS uses a small array of electrodes ( = 5) to improve targeted current delivery.

Multiple Sclerosis, Cannabis Use, and Clinical Disability: A Preliminary [F]-Fluorodeoxyglucose Positron Emission Tomography Study.

Long-term consequences of medicinal cannabis use in people with multiple sclerosis (PwMS) are unknown. This study investigated whether PwMS using cannabis had lower resting brain glucose uptake (GU) and worse clinical test results compared with nonusers. Sixteen PwMS, eight users, underwent clinical testing followed by [F]-Fluorodeoxyglucose positron emission tomography/computed tomography imaging.

Cannabis use in people with Parkinson's disease and Multiple Sclerosis: A web-based investigation.

Objectives: Cannabis has been used for medicinal purpose for thousands of years; however the positive and negative effects of cannabis use in Parkinson's disease (PD) and Multiple Sclerosis (MS) are mostly unknown. Our aim was to assess cannabis use in PD and MS and compare results of self-reported assessments of neurological disability between current cannabis users and non-users.

Methods: An anonymous web-based survey was hosted on the Michael J.

Metabolic imaging in exercise physiology.

This minireview focuses on selected, noninvasive imaging techniques that have been used in the study of exercise physiology. These imaging modalities can be roughly divided into two categories: tracer based and nontracer based. Tracer-based methods use radiolabeled substrates whose location and quantity can subsequently be imaged once they are incorporated into metabolic processes.

FDG-PET detects nonuniform muscle activity in the lower body during human gait.

Introduction: Nonuniform muscle activity has been partially explained by anatomically defined neuromuscular compartments. The purpose of this study was to investigate the uniformity of skeletal muscle activity during walking.

Methods: Eight participants walked at a self-selected speed, and muscle activity was quantified using [ F]-fluorodeoxyglucose positron emission tomography imaging.

Fatigue in Multiple Sclerosis: Misconceptions and Future Research Directions.

Fatigue is one of the most disabling side effects in people with multiple sclerosis. While this fact is well known, there has been a remarkable lack of progress in determining the pathophysiological mechanisms behind fatigue and the establishment of effective treatments. The main barrier has been the lack of a unified definition of fatigue that can be objectively tested with validated experimental models.

Brown adipose and central nervous system glucose uptake is lower during cold exposure in older compared to young men: a preliminary PET study.

The purpose of this study was to determine the activity of brown adipose tissue (BAT) and the central nervous system (CNS) during cold exposure in young and older men. Two young, 24 and 21 years, and two older, 76 and 74 years, men participated in the study. Positron emission tomography images showed cold-induced BAT activity was absent in older men but clearly present in the clavicular region of the young men (Standardized Uptake Value: SUVmean: 3.

Core muscle characteristics during walking of patients with multiple sclerosis.

The purpose of this study was to investigate core muscle characteristics during walking in patients with multiple sclerosis (MS). Eight patients (4 men) with relapsing-remitting MS (aged 44.9 +/- 8.

Cognitive-Motor Related Brain Activity During Walking: Differences Between Men and Women With Multiple Sclerosis.

Objective: To determine if sex differences in glucose uptake, a marker of brain activity, are present in brain regions that facilitate walking performance in persons with multiple sclerosis (MS).

Design: Cross-sectional, observational pilot.

Setting: University laboratory.

Regional differences of [(18)F]-FDG uptake within the brain during fatiguing muscle contractions.

Background And Purpose: Many studies have shown that a position task is more difficult than a force task although both are performed at a similar net muscle force. Thus, the time to task failure is consistently shown to be briefer during the position task. The contributions of the central nervous system to these two types of fatiguing contractions are not completely understood.

[18F]-FDG positron emission tomography--an established clinical tool opening a new window into exercise physiology.

Positron emission tomography (PET) with [(18)F]-fluorodeoxyglucose (FDG) is an established clinical tool primarily used to diagnose and evaluate disease status in patients with cancer. PET imaging using FDG can be a highly valuable tool to investigate normal human physiology by providing a noninvasive, quantitative measure of glucose uptake into various cell types. Over the past years it has also been increasingly used in exercise physiology studies to identify changes in glucose uptake, metabolism, and muscle activity during different exercise modalities.

Walking Speed and Brain Glucose Uptake are Uncoupled in Patients with Multiple Sclerosis.

Motor impairments of the upper and lower extremities are common symptoms of multiple sclerosis (MS). While some peripheral effects like muscle weakness and loss of balance have been shown to influence these symptoms, central nervous system activity has not been fully elucidated. The purpose of this study was to determine if alterations in glucose uptake were associated with motor impairments in patients with multiple sclerosis.

Glucose uptake heterogeneity of the leg muscles is similar between patients with multiple sclerosis and healthy controls during walking.

Background: Difficulties in ambulation are one of the main problems reported by patients with multiple sclerosis. A previous study by our research group showed increased recruitment of muscle groups during walking, but the influence of skeletal muscle properties, such as muscle fiber activity, has not been fully elucidated. The purpose of this investigation was to use the novel method of calculating glucose uptake heterogeneity in the leg muscles of patients with multiple sclerosis and compare these results to healthy controls.

Greater glucose uptake heterogeneity in knee muscles of old compared to young men during isometric contractions detected by [(18)F]-FDG PET/CT.

We used positron emission tomography/computed tomography (PET/CT) and [(18)F]-FDG to test the hypothesis that glucose uptake (GU) heterogeneity in skeletal muscles as a measure of heterogeneity in muscle activity is greater in old than young men when they perform isometric contractions. Six young (26 ± 6 years) and six old (77 ± 6 years) men performed two types of submaximal isometric contractions that required either force or position control. [(18)F]-FDG was injected during the task and PET/CT scans were performed immediately after the task.