[ARTICLE] Transcranial Direct Current Stimulation Does Not Affect Lower Extremity Muscle Strength Training in Healthy Individuals: A Triple-Blind, Sham-Controlled Study – Full Text

The present study investigated the effects of anodal transcranial direct current stimulation (tDCS) on lower extremity muscle strength training in 24 healthy participants. In this triple-blind, sham-controlled study, participants were randomly allocated to the anodal tDCS plus muscle strength training (anodal tDCS) group or sham tDCS plus muscle strength training (sham tDCS) group. Anodal tDCS (2 mA) was applied to the primary motor cortex of the lower extremity during muscle strength training of the knee extensors and flexors. Training was conducted once every 3 days for 3 weeks (7 sessions). Knee extensor and flexor peak torques were evaluated before and after the 3 weeks of training. After the 3-week intervention, peak torques of knee extension and flexion changed from 155.9 to 191.1 Nm and from 81.5 to 93.1 Nm in the anodal tDCS group. Peak torques changed from 164.1 to 194.8 Nm on extension and from 78.0 to 85.6 Nm on flexion in the sham tDCS group. In both groups, peak torques of knee extension and flexion significantly increased after the intervention, with no significant difference between the anodal tDCS and sham tDCS groups. In conclusion, although the administration of eccentric training increased knee extensor and flexor peak torques, anodal tDCS did not enhance the effects of lower extremity muscle strength training in healthy individuals. The present null results have crucial implications for selecting optimal stimulation parameters for clinical trials.

Introduction

Transcranial direct current stimulation (tDCS) is a non-invasive cortical stimulation procedure in which weak direct currents polarize target brain regions (Nitsche and Paulus, 2000). The application of anodal tDCS to the primary motor cortex of the lower extremity transiently increases corticospinal excitability in healthy individuals (Jeffery et al., 2007; Tatemoto et al., 2013) and improves motor function in healthy individuals and patients with stroke (Tanaka et al., 2009, 2011; Madhavan et al., 2011; Sriraman et al., 2014; Chang et al., 2015; Montenegro et al., 2015, 2016; Angius et al., 2016; Washabaugh et al., 2016). Thus, anodal tDCS has a potential to become a new adjunct therapeutic strategy for the rehabilitation of leg motor function and locomotion following a stroke.

Lower leg muscle strength is an important motor function required for patients who have had a stroke to regain activities of daily living (ADL). Lower leg muscle strength correlates with performance in activities, including sit-to-stand, gait, and stair ascent (Bohannon, 2007). Furthermore, lower leg muscle strength training increases muscle strength and improves ADL in patients with stroke (Ada et al., 2006). Therefore, lower leg muscle strength training is one of the important activities rehabilitating patients with stroke to regain their independence in ADL.

Several studies have examined the effect of a single session of tDCS on lower leg muscle strength, although the evidence is inconsistent (Tanaka et al., 2009, 2011; Montenegro et al., 2015, 2016; Angius et al., 2016; Washabaugh et al., 2016). Its effects seem dependent on tDCS protocols, training tasks, muscle groups, and subject populations. Although, most tDCS studies on lower leg muscle strength have focused on the acute effects of a single tDCS application, to the best of our knowledge, no study has examined how lower extremity strength training combined with repeated sessions of tDCS affects lower leg muscle strength. This type of investigation has strong clinical implications for the application of tDCS in rehabilitation for patients with lower leg muscle weakness.

Thus, to examine whether anodal tDCS can enhance the effects of lower extremity muscle strength training, the present study simultaneously applied anodal tDCS and lower extremity muscle strength training to healthy individuals and evaluated their effects on lower extremity muscle strength.

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Figure 1. Experimental setup of the muscle strength training and torque assessment.

[Abstract] Effects of sit-to-stand training combined with transcutaneous electrical stimulation on spasticity, muscle strength and balance ability in patients with stroke: a randomized controlled study

Highlights

• •The effect of sit-to-stand training combined with TENS was evaluated in stroke patients with spastic plantar flexor.
• •TENS followed by sit-to-stand training may improve spasticity, muscle strength and balance.
• •Clinician should consider TENS application prior to sit to stand training for stroke patients with spastic plantar flexor.

Abstract

Sit-to-stand is a fundamental movement of human being for performing mobility and independent activity. However, Stroke people symptoms experience difficulty in conducting the sit-to-stand due to paralysis and especially ankle spasticity. Recently, transcutaneous electrical- stimulation (TENS) is used to reduce pain but also to manage spasticity.

The purpose of this study was to determine

1. whether TENS would lead to ankle spasticity reduction and (
2. whether sit-to-stand training combined with TENS would improve spasticity, muscle strength and balance ability in stroke patients.

Forty-stroke patients were recruited and were randomly divided into two groups: TENS group (n = 20) and sham group (n = 20). All participants underwent 30-sessions of sit-to-stand training (for 15-minutes, five-times per week for 6-weeks). Prior to each training session, 30-minutes of TENS over the peroneal nerve was given in TENS group, whereas sham group received non-electrically stimulated TENS for the same amount of time. Composite-Spasticity-Score was used to assess spasticity level of ankle plantar-flexors. Isometric strength in the extensor of hip, knee and ankle were measured by handhelddynamometer. Postural-sway distance was measured using a force platform.

The spasticity score in the TENS group (2.6 ± 0.8) improved significantly greater than the sham group (0.7 ± 0.8, p < 0.05). The muscle strength of hip extensor in the TENS group (2.7 ± 1.1 kg) was significantly higher than the sham group (1.0 ± 0.8 kg, p < 0.05). Significant improvement in postural-sway was observed in the TENS group compared to the sham group (p < 0.05).

Thus, sit-to-stand training combined with TENS may be used to improve the spasticity, balance function and muscle strength in stroke patients.

Source: Effects of sit-to-stand training combined with transcutaneous electrical stimulation on spasticity, muscle strength and balance ability in patients with stroke: a randomized controlled study – Gait & Posture

[DOCTORAL DISSERTATION] Upper extremity disability after stroke. Psychometric properties of outcome measures and perceived ability to perform daily hand activities – Full Text

LUND UNIVERSITY

Department of Health Sciences, Physiotherapy, Lund University

DOCTORAL DISSERTATION

Date of issue 2016-10-08

Author(s) Elisabeth Ekstrand

Abstract

Disability of the upper extremity is common after stroke. To be able to evaluate recovery and effects of interventions there is a need for stable and precise outcome measures. In order to design and target efficient rehabilitation interventions it is important to know which factors that affect the ability to perform daily hand activities. At the time when the studies in this thesis were planned there was limited knowledge of the psychometric properties of outcome measures for persons with mild to moderate impairments of the upper extremity after stroke. There was also a lack of knowledge of which daily hand activities these persons perceive difficult to perform and which factors are associated with the performance.

The overall aim of this thesis was to evaluate the psychometric properties of outcome measures for upper extremity after stroke, and to describe which daily hand activities persons with mild to moderate impairments in upper extremity after stroke perceive difficult to perform and identify associated factors with their performance.

In paper I – IV, between 43 and 45 participants were included. Muscle strength in the upper extremity, somatosensation (active touch), dexterity and self-perceived ability to perform daily hand activities were assessed twice, one to two weeks apart. In paper V, 75 participants were included and the evaluated measures of the upper extremity were used together with other stroke specific outcomes to cover important aspects of functioning and disability according to the International Classification of Functioning, Disability and Health (ICF). Test-retest analyses for continuous data were made with the Intraclass Correlation Coefficient (ICC), the Change in Mean, the Standard Error of Measurement (SEM) and the Smallest Real Difference (SRD) (Paper I, III and IV). For ordinal data the Kappa coefficient and the Elisabeth Svensson rank-invariant method were used (Paper II and III). For analyses of convergent validity the Spearman’s correlation coefficient (rho) was calculated (Paper III). The ability to perform daily hand activities and the associations with potential factors were evaluated by univariate and multivariate linear regression models (Study V).

The results showed that outcome measures for isometric and isokinetic muscle strength, active touch, dexterity and self-perceived daily hand activities have high test-retest agreements and can be recommended for persons with mild to moderate impairments in the upper extremity after stroke (Paper I to IV). Isometric strength measurements had lower measurement errors than isokinetic measurements and might be preferred (Paper I). The outcomes of dexterity showed learning effects (Paper III) and the ratings of perceived daily hand activities (Paper IV) had relatively high random measurement errors which must be taken into account when recovery and effects of interventions are evaluated. The three evaluated dexterity measures were partly related and can complement each other (Paper IV). Daily hand activities that require bimanual dexterity were perceived most difficult to perform, and dexterity and participation were the strongest contributing factors for performing daily hand activities after stroke (Paper V).

In conclusion, this thesis has shown that outcome measures assessing functioning and disability of upper extremity after stroke are reliable and can be used in clinical settings and research. To increase the ability to perform daily hand activities, dexterity and perceived participation, in particular, should be considered in the assessments, goal-settings and rehabilitation after stroke.

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[Abstract] Lower Limb Strength Is Significantly Impaired in All Muscle Groups in Ambulatory People With Chronic Stroke: A Cross-Sectional Study – Archives of Physical Medicine and Rehabilitation

Abstract

Objective

To measure the strength of the major muscle groups of the affected and intact lower limbs in people with stroke compared with age-matched controls.

Design

Cross-sectional study.

Setting

University laboratory.

Participants

Ambulatory stroke survivors (n=60; mean age, 69±11y), who had had a stroke between 1 and 6 years previously, and age-matched controls (n=35; mean age, 65±9y) (N=95).

Interventions

Not applicable.

Main Outcome Measures

The maximum isometric strength of 12 muscle groups (hip flexors and extensors, hip adductors and abductors, hip internal rotators and external rotators, knee flexors and extensors, ankle dorsiflexors and plantarflexors, ankle invertors and evertors) of both lower limbs was measured using handheld dynamometry. All strength measurements were taken in standardized positions by 1 rater.

Results

The affected lower limb of the participants with stroke was significantly weaker than that of the control participants for all muscle groups (P<.01). Strength (adjusted for age, sex, and body weight) was 48% (range, 34%–62%) of that of the control participants. The most severely affected muscle groups were hip extensors (34% of controls), ankle dorsiflexors (35%), and hip adductors (38%), and the least severely affected muscle groups were ankle invertors (62%), ankle plantarflexors (57%), and hip flexors (55%). The intact lower limb of the participants with stroke was significantly weaker than that of the control participants for all muscle groups (P<.05) except for ankle invertors (P=.25). Strength (adjusted for age, sex, and body weight) was 66% (range, 44%–91%) of that of the control participants. The most severely affected muscle groups were hip extensors (44% of controls), ankle dorsiflexors (52%), and knee flexors (54%).

Conclusions

Ambulatory people with chronic stroke have a marked loss of strength in most of the major muscle groups of both lower limbs compared with age-matched controls.

Source: Lower Limb Strength Is Significantly Impaired in All Muscle Groups in Ambulatory People With Chronic Stroke: A Cross-Sectional Study – Archives of Physical Medicine and Rehabilitation

[Abstract] Transcranial direct current stimulation (tDCS) for improving activities of daily living, and physical and cognitive functioning, in people after stroke. – PubMed

Abstract

BACKGROUND:

Stroke is one of the leading causes of disability worldwide. Functional impairment, resulting in poor performance in activities of daily living (ADLs) among stroke survivors is common. Current rehabilitation approaches have limited effectiveness in improving ADL performance, function, muscle strength and cognitive abilities (including spatial neglect) after stroke, but a possible adjunct to stroke rehabilitation might be non-invasive brain stimulation by transcranial direct current stimulation (tDCS) to modulate cortical excitability, and hence to improve ADL performance, arm and leg function, muscle strength and cognitive abilities (including spatial neglect), dropouts and adverse events in people after stroke.

OBJECTIVES:

To assess the effects of tDCS on ADLs, arm and leg function, muscle strength and cognitive abilities (including spatial neglect), dropouts and adverse events in people after stroke.

SEARCH METHODS:

We searched the Cochrane Stroke Group Trials Register (February 2015), the Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library; 2015, Issue 2), MEDLINE (1948 to February 2015), EMBASE (1980 to February 2015), CINAHL (1982 to February 2015), AMED (1985 to February 2015), Science Citation Index (1899 to February 2015) and four additional databases. In an effort to identify further published, unpublished and ongoing trials, we searched trials registers and reference lists, handsearched conference proceedings and contacted authors and equipment manufacturers.

SELECTION CRITERIA:

This is the update of an existing review. In the previous version of this review we focused on the effects of tDCS on ADLs and function. In this update, we broadened our inclusion criteria to compare any kind of active tDCS for improving ADLs, function, muscle strength and cognitive abilities (including spatial neglect) versus any kind of placebo or control intervention.

DATA COLLECTION AND ANALYSIS:

Two review authors independently assessed trial quality and risk of bias (JM and MP) and extracted data (BE and JM). If necessary, we contacted study authors to ask for additional information. We collected information on dropouts and adverse events from the trial reports.

MAIN RESULTS:

We included 32 studies involving a total of 748 participants aged above 18 with acute, postacute or chronic ischaemic or haemorrhagic stroke. We also identified 55 ongoing studies. The risk of bias did not differ substantially for different comparisons and outcomes.We found nine studies with 396 participants examining the effects of tDCS versus sham tDCS (or any other passive intervention) on our primary outcome measure, ADLs after stroke. We found evidence of effect regarding ADL performance at the end of the intervention period (standardised mean difference (SMD) 0.24, 95% confidence interval (CI) 0.03 to 0.44; inverse variance method with random-effects model; moderate quality evidence). Six studies with 269 participants assessed the effects of tDCS on ADLs at the end of follow-up, and found improved ADL performance (SMD 0.31, 95% CI 0.01 to 0.62; inverse variance method with random-effects model; moderate quality evidence). However, the results did not persist in a sensitivity analysis including only trials of good methodological quality.One of our secondary outcome measures was upper extremity function: 12 trials with a total of 431 participants measured upper extremity function at the end of the intervention period, revealing no evidence of an effect in favour of tDCS (SMD 0.01, 95% CI -0.48 to 0.50 for studies presenting absolute values (low quality evidence) and SMD 0.32, 95% CI -0.51 to 1.15 (low quality evidence) for studies presenting change values; inverse variance method with random-effects model). Regarding the effects of tDCS on upper extremity function at the end of follow-up, we identified four studies with a total of 187 participants (absolute values) that showed no evidence of an effect (SMD 0.01, 95% CI -0.48 to 0.50; inverse variance method with random-effects model; low quality evidence). Ten studies with 313 participants reported outcome data for muscle strength at the end of the intervention period, but in the corresponding meta-analysis there was no evidence of an effect. Three studies with 156 participants reported outcome data on muscle strength at follow-up, but there was no evidence of an effect.In six of 23 studies (26%), dropouts, adverse events or deaths that occurred during the intervention period were reported, and the proportions of dropouts and adverse events were comparable between groups (risk difference (RD) 0.01, 95% CI -0.02 to 0.03; Mantel-Haenszel method with random-effects model; low quality evidence; analysis based only on studies that reported either on dropouts, or on adverse events, or on both). However, this effect may be underestimated due to reporting bias.

AUTHORS’ CONCLUSIONS:

At the moment, evidence of very low to moderate quality is available on the effectiveness of tDCS (anodal/cathodal/dual) versus control (sham/any other intervention) for improving ADL performance after stroke. However, there are many ongoing randomised trials that could change the quality of evidence in the future. Future studies should particularly engage those who may benefit most from tDCS after stroke and in the effects of tDCS on upper and lower limb function, muscle strength and cognitive abilities (including spatial neglect). Dropouts and adverse events should be routinely monitored and presented as secondary outcomes. They should also address methodological issues by adhering to the Consolidated Standards of Reporting Trials (CONSORT) statement.

Source: Transcranial direct current stimulation (tDCS) for improving activities of daily living, and physical and cognitive functioning, in people after st… – PubMed – NCBI

[ARTICLE] Associations between lower limb strength and gait velocity following stroke: A systematic review – Full Text HTML

Abstract

Objective: The aim of this systematic review was to identify literature examining associations between isometric strength and gait velocity following stroke.

Methods: An electronic search was performed using six online databases. Targeted searching of reference lists of included articles and three relevant journals was also performed. Two independent reviewers identified relevant articles, extracted data and assessed the methodological quality of included articles. Inclusion criteria involved studies that assessed univariate correlations between gait velocity and isometric strength of individual lower limb muscle groups in a stroke population.

Results: Twenty-one studies were included for review. The majority of included studies had a relatively small sample size. After accounting for sample size and methodological quality, the knee extensors showed poor-to-moderate correlations with gait velocity while the ankle dorsiflexors showed the strongest association with gait velocity.

Conclusions: Current evidence suggests that the strength of the ankle dorsiflexors has a stronger correlation to gait velocity compared with other lower limb muscle groups. Consequently, a focus on increasing ankle dorsiflexor strength to improve gait velocity following stroke may be beneficial. However, due to limitations of the research identified, further research is needed to determine the associations between lower limb strength and gait velocity following stroke.

Continue —>  Associations between lower limb strength and gait velocity following stroke: A systematic review, Brain Injury, Informa Healthcare.