Feasibility and preliminary efficacy of a combined virtual reality, robotics and electrical stimulation intervention in upper extremity stroke rehabilitation.

BACKGROUND: Approximately 80% of individuals with chronic stroke present with long lasting upper extremity (UE) impairments. We designed the perSonalized UPper Extremity Rehabilitation (SUPER) intervention, which combines robotics, virtual reality activities, and neuromuscular electrical stimulation (NMES). The objectives of our study were to determine the feasibility and the preliminary efficacy of the SUPER intervention in individuals with moderate/severe stroke. METHODS: Stroke participants (n = 28) received a 4-week intervention (3 × per week), tailored to their functional level. The functional integrity of the corticospinal tract was assessed using the Predict Recovery Potential algorithm, involving measurements of motor evoked potentials and manual muscle testing. Those with low potential for hand recovery (shoulder group; n = 18) received a robotic-rehabilitation intervention focusing on elbow and shoulder movements only. Those with a good potential for hand recovery (hand group; n = 10) received EMG-triggered NMES, in addition to robot therapy. The primary outcomes were the Fugl-Meyer UE assessment and the ABILHAND assessment. Secondary outcomes included the Motor Activity Log and the Stroke Impact Scale. RESULTS: Eighteen participants (64%), in either the hand or the shoulder group, showed changes in the Fugl-Meyer UE or in the ABILHAND assessment superior to the minimal clinically important difference. CONCLUSIONS: This indicates that our personalized approach is feasible and may be beneficial in improving UE function in individuals with moderate to severe impairments due to stroke. TRIAL REGISTRATION: ClinicalTrials.gov NCT03903770. Registered 4 April 2019. Registered retrospectively.

Neural circuits activated by error amplification and haptic guidance training techniques during performance of a timing-based motor task by healthy individuals.

To promote motor learning, robotic devices have been used to improve subjects' performance by guiding desired movements (haptic guidance-HG) or by artificially increasing movement errors to foster a more rapid learning (error amplification-EA). To better understand the neurophysiological basis of motor learning, a few studies have evaluated brain regions activated during EA/HG, but none has compared both approaches. The goal of this study was to investigate using fMRI which brain networks were activated during a single training session of HG/EA in healthy adults learning to play a computerized pinball-like timing task. Subjects had to trigger a robotic device by flexing their wrist at the correct timing to activate a virtual flipper and hit a falling ball towards randomly positioned targets. During training with HG/EA, subjects' timing errors were decreased/increased, respectively, by the robotic device to delay or accelerate their wrist movement. The results showed that at the beginning of the training period with HG/EA, an error-detection network, including cerebellum and angular gyrus, was activated, consistent with subjects recognizing discrepancies between their intended actions and the actual movement timing. At the end of the training period, an error-detection network was still present for EA, while a memory consolidation/automatization network (caudate head and parahippocampal gyrus) was activated for HG. The results indicate that training movement with various kinds of robotic input relies on different brain networks. Better understanding the neurophysiological underpinnings of brain processes during HG/EA could prove useful for optimizing rehabilitative movement training for people with different patterns of brain damage.

A crossover pilot study evaluating the functional outcomes of two different types of robotic movement training in chronic stroke survivors using the arm exoskeleton BONES.

BACKGROUND: To date, the limited degrees of freedom (DOF) of most robotic training devices hinders them from providing functional training following stroke. We developed a 6-DOF exoskeleton ("BONES") that allows movement of the upper limb to assist in rehabilitation. The objectives of this pilot study were to evaluate the impact of training with BONES on function of the affected upper limb, and to assess whether multijoint functional robotic training would translate into greater gains in arm function than single joint robotic training also conducted with BONES. METHODS: Twenty subjects with mild to moderate chronic stroke participated in this crossover study. Each subject experienced multijoint functional training and single joint training three sessions per week, for four weeks, with the order of presentation randomized. The primary outcome measure was the change in Box and Block Test (BBT). The secondary outcome measures were the changes in Fugl-Meyer Arm Motor Scale (FMA), Wolf Motor Function Test (WMFT), Motor Activity Log (MAL), and quantitative measures of strength and speed of reaching. These measures were assessed at baseline, after each training period, and at a 3-month follow-up evaluation session. RESULTS: Training with the robotic exoskeleton resulted in significant improvements in the BBT, FMA, WMFT, MAL, shoulder and elbow strength, and reaching speed (p < 0.05); these improvements were sustained at the 3 month follow-up. When comparing the effect of type of training on the gains obtained, no significant difference was noted between multijoint functional and single joint robotic training programs. However, for the BBT, WMFT and MAL, inequality of carryover effects were noted; subsequent analysis on the change in score between the baseline and first period of training again revealed no difference in the gains obtained between the types of training. CONCLUSIONS: Training with the 6 DOF arm exoskeleton improved motor function after chronic stroke, challenging the idea that robotic therapy is only useful for impairment reduction. The pilot results presented here also suggest that multijoint functional robotic training is not decisively superior to single joint robotic training. This challenges the idea that functionally-oriented games during training is a key element for improving behavioral outcomes. TRIAL REGISTRATION: NCT01050231.

Implementation of increased physical therapy intensity for improving walking after stroke: Walk 'n watch protocol for a multisite stepped-wedge cluster-randomized controlled trial.

RATIONALE: Clinical practice guidelines support structured, progressive protocols for improving walking after stroke. Yet, practice is slow to change, evidenced by the little amount of walking activity in stroke rehabilitation units. Our recent study (n = 75) found that a structured, progressive protocol integrated with typical daily physical therapy improved walking and quality-of-life measures over usual care. Research therapists progressed the intensity of exercise by using heart rate and step counters worn by the participants with stroke during therapy. To have the greatest impact, our next step is to undertake an implementation trial to change practice across stroke units where we enable the entire unit to use the protocol as part of standard of care. AIMS: What is the effect of introducing structured, progressive exercise (termed the Walk 'n Watch protocol) to the standard of care on the primary outcome of walking in adult participants with stroke over the hospital inpatient rehabilitation period? Secondary outcomes will be evaluated and include quality of life. METHODS AND SAMPLE SIZE ESTIMATES: This national, multisite clinical trial will randomize 12 sites using a stepped-wedge design where each site will be randomized to deliver Usual Care initially for 4, 8, 12, or 16 months (three sites for each duration). Then, each site will switch to the Walk 'n Watch phase for the remaining duration of a total 20-month enrolment period. Each participant will be exposed to either Usual Care or Walk 'n Watch. The trial will enroll a total of 195 participants with stroke to achieve a power of 80% with a Type I error rate of 5%, allowing for 20% dropout. Participants will be medically stable adults post-stroke and able to take five steps with a maximum physical assistance from one therapist. The Walk 'n Watch protocol focuses on completing a minimum of 30 min of weight-bearing, walking-related activities (at the physical therapists' discretion) that progressively increase in intensity informed by activity trackers measuring heart rate and step number. STUDY OUTCOME(S): The primary outcome will be the change in walking endurance, measured by the 6-Minute Walk Test, from baseline (T1) to 4 weeks (T2). This change will be compared across Usual Care and Walk 'n Watch phases using a linear mixed-effects model. Additional physical, cognitive, and quality of life outcomes will be measured at T1, T2, and 12 months post-stroke (T3) by a blinded assessor. DISCUSSION: The implementation of stepped-wedge cluster-randomized trial enables the protocol to be tested under real-world conditions, involving all clinicians on the unit. It will result in all sites and all clinicians on the unit to gain expertise in protocol delivery. Hence, a deliberate outcome of the trial is facilitating changes in best practice to improve outcomes for participants with stroke in the trial and for the many participants with stroke admitted after the trial ends.

Effect of a tailored upper extremity strength training intervention combined with direct current stimulation in chronic stroke survivors: A Randomized Controlled Trial.

Strengthening exercises are recommended for managing persisting upper limb (UL) weakness following a stroke. Yet, strengthening exercises often lead to variable gains because of their generic nature. For this randomized controlled trial (RCT), we aimed to determine whether tailoring strengthening exercises using a biomarker of corticospinal integrity, as reflected in the amplitude of motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS), could optimize training effects in the affected UL. A secondary aim was to determine whether applying anodal transcranial direct current stimulation (tDCS) could enhance exercise-induced training effects. For this multisite RCT, 90 adults at the chronic stage after stroke (>6 months) were recruited. Before training, participants underwent TMS to detect the presence of MEPs in the affected hand. The MEP amplitude was used to stratify participants into three training groups: (1) low-intensity, MEP <50 µV, (2) moderate-intensity, 50 µV < MEP < 120 µV, and (3) high-intensity, MEP>120 µV. Each group trained at a specific intensity based on the one-repetition maximum (1 RM): low-intensity, 35-50% 1RM; moderate-intensity, 50-65% 1RM; high-intensity, 70-85% 1RM. The strength training targeted the affected UL and was delivered 3X/week for four consecutive weeks. In each training group, participants were randomly assigned to receive either real or sham anodal tDCS (2 mA, 20 min) over the primary motor area of the affected hemisphere. Pre-/post-intervention, participants underwent a clinical evaluation of their UL to evaluate motor impairments (Fugl-Meyer Assessment), manual dexterity (Box and Blocks test) and grip strength. Post-intervention, all groups exhibited similar gains in terms of reduced impairments, improved dexterity, and grip strength, which was confirmed by multivariate and univariate analyses. However, no effect of interaction was found for tDCS or training group, indicating that tDCS had no significant impact on outcomes post-intervention. Collectively, these results indicate that adjusting training intensity based on the size of MEPs in the affected extremity provides a useful approach to optimize responses to strengthening exercises in chronic stroke survivors. Also, the lack of add-on effects of tDCS applied to the lesioned hemisphere on exercise-induced improvements in the affected UL raises questions about the relevance of combining such interventions in stroke. Clinical trial registry number: NCT02915185. https://www.clinicaltrials.gov/ct2/show/NCT02915185.

Effect of visual distraction and auditory feedback on patient effort during robot-assisted movement training after stroke.

BACKGROUND: Practicing arm and gait movements with robotic assistance after neurologic injury can help patients improve their movement ability, but patients sometimes reduce their effort during training in response to the assistance. Reduced effort has been hypothesized to diminish clinical outcomes of robotic training. To better understand patient slacking, we studied the role of visual distraction and auditory feedback in modulating patient effort during a common robot-assisted tracking task. METHODS: Fourteen participants with chronic left hemiparesis from stroke, five control participants with chronic right hemiparesis and fourteen non-impaired healthy control participants, tracked a visual target with their arms while receiving adaptive assistance from a robotic arm exoskeleton. We compared four practice conditions: the baseline tracking task alone; tracking while also performing a visual distracter task; tracking with the visual distracter and sound feedback; and tracking with sound feedback. For the distracter task, symbols were randomly displayed in the corners of the computer screen, and the participants were instructed to click a mouse button when a target symbol appeared. The sound feedback consisted of a repeating beep, with the frequency of repetition made to increase with increasing tracking error. RESULTS: Participants with stroke halved their effort and doubled their tracking error when performing the visual distracter task with their left hemiparetic arm. With sound feedback, however, these participants increased their effort and decreased their tracking error close to their baseline levels, while also performing the distracter task successfully. These effects were significantly smaller for the participants who used their non-paretic arm and for the participants without stroke. CONCLUSIONS: Visual distraction decreased participants effort during a standard robot-assisted movement training task. This effect was greater for the hemiparetic arm, suggesting that the increased demands associated with controlling an affected arm make the motor system more prone to slack when distracted. Providing an alternate sensory channel for feedback, i.e., auditory feedback of tracking error, enabled the participants to simultaneously perform the tracking task and distracter task effectively. Thus, incorporating real-time auditory feedback of performance errors might improve clinical outcomes of robotic therapy systems.

Comparison of error-amplification and haptic-guidance training techniques for learning of a timing-based motor task by healthy individuals.

Performance errors drive motor learning for many tasks. Some researchers have suggested that reducing performance errors with haptic guidance can benefit learning by demonstrating correct movements, while others have suggested that artificially increasing errors will force faster and more complete learning. This study compared the effect of these two techniques--haptic guidance and error amplification--as healthy subjects learned to play a computerized pinball-like game. The game required learning to press a button using wrist movement at the correct time to make a flipper hit a falling ball to a randomly positioned target. Errors were decreased or increased using a robotic device that retarded or accelerated wrist movement, based on sensed movement initiation timing errors. After training with either error amplification or haptic guidance, subjects significantly reduced their timing errors and generalized learning to untrained targets. However, for a subset of more skilled subjects, training with amplified errors produced significantly greater learning than training with the reduced errors associated with haptic guidance, while for a subset of less skilled subjects, training with haptic guidance seemed to benefit learning more. These results suggest that both techniques help enhanced performance of a timing task, but learning is optimized if training subjects with the appropriate technique based on their baseline skill level.

Using the Borg rating of perceived exertion scale to grade the intensity of a functional training program of the affected upper limb after a stroke: a feasibility study.

PURPOSE: Intensity of a training program is a critical variable in treatment gains poststroke, but there are no guidelines to adequately dose the intensity of functional training (FT); the recommended type of training to promote poststroke recovery. Such guidelines are made available for strength training (ST) using the 1 repetition maximum (1RM), which has been linked to individuals' self-rated level of exertion using the Borg rating of perceived exertion (BRPE) scale. The BRPE could be a valuable tool for clinicians to dose FT intensity after a stroke, but this remains to be tested. The main objective of the study was to evaluate the feasibility of the BRPE at grading FT intensity of the affected upper limb in older adults with a chronic stroke and secondarily to explore the clinical changes between FT and ST when the intensity is regulated with BRPE. PATIENTS AND METHODS: Twelve participants were randomized into a FT or ST group and trained their affected upper limb (3 times/week for 4 weeks) with the intensity standardized with BRPE. Feasibility was assessed by adherence, occurrence of adverse events, and comparison of BRPE ratings between groups. Clinical changes were defined as improvements on the Fugl-Meyer motor assessment (FMA) and Wolf motor function test (WMFT). RESULTS: All participants adhered to FT/ST without adverse effects, and comparable BRPE ratings were noted between groups throughout the training (P≥0.42). Both groups showed significant gains at the FMA (ST: 5±4 points/FT: 6±4 points; P=0.04) and WMFT (ST: 0.4±0.3 points/FT: 0.6±0.4 points; P=0.05), which were comparable between groups (P≥0.47). CONCLUSION: The results suggest that it is feasible to use the BRPE scale to adjust FT intensity. Gains in motor function in both groups suggest that undergoing therapy, regardless of its type, might be a sufficient stimulus to produce gains when intensity is adequately adjusted. Further studies are needed to validate the current observations.

Effects of a tailored strength training program of the upper limb combined with transcranial direct current stimulation (tDCS) in chronic stroke patients: study protocol for a randomised, double-blind, controlled trial.

BACKGROUND: A significant proportion of individuals are left with poor residual functioning of the affected arm after a stroke. This has a great impact on the quality of life and the ability for stroke survivors to live independently. While strengthening exercises have been recommended to improve arm function, their benefits are generally far from optimal due to the lack of appropriate dosing in terms of intensity. One way to address this problem is to develop better tools that could predict an individual's potential for recovery and then adjust the intensity of exercise accordingly. In this study, we aim at determining whether an individualized strengthening program based on the integrity of the corticospinal tract, as reflected in the amplitude of motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS), in conjunction with transcranial direct current stimulation (tDCS), could lead to more optimal outcomes in terms of arm function in chronic stroke patients. METHODS: This multicentre, double-blinded, randomised controlled trial will aim to recruit 84 chronic stroke patients. Before and after training, participants will undergo a clinical evaluation, assessing motor recovery of the affected arm (Fugl-Meyer Stroke Assessment-FMA) and a TMS evaluation to assess the integrity of the corticospinal tract, as reflected in MEP amplitude. Based on their baseline MEPs amplitude, participants will be stratified into three groups of training intensity levels determined by the one-repetition maximum (1RM); 1) low: 35-50% 1 RM (MEPs < 50 µV); 2) moderate: 50-65% 1RM (MEPs 50-120 µV); and 3) high: 70-80% 1RM (MEPs > 120 µV). Training will target the affected arm (3 times/week for 4 weeks). In addition, participants will be randomly allocated into two tDCS groups (real vs. sham) and tDCS will be applied in an anodal montage during the exercise. DISCUSSION: This study will determine whether an individualized strength training intervention in chronic stroke survivors can lead to improved arm function. In addition, we will also determine whether combining anodal tDCS over the lesioned hemisphere with strength training can lead to further improvement in arm function, when compared to sham tDCS. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02915185. Registered September 21 2016.

Efficacy, safety, and tolerability of bilateral transcranial direct current stimulation combined to a resistance training program in chronic stroke survivors: A double-blind, randomized, placebo-controlled pilot study.

BACKGROUND: Transcranial direct current stimulation (tDCS) is a promising tool for stroke rehabilitation. Yet, so far, results from the available clinical trials are inconclusive. OBJECTIVES: The primary objective of the present work was to test the efficacy of multiple sessions of tDCS combined with a highly standardized and progressive resistance training program of the affected upper limb in individuals in the chronic phase of recovery after a stroke. Secondary objectives were to test the safety and tolerability of these combined interventions. METHODS: This two-arm parallel pilot trial recruited participants that were ≥18 years old, community-dwelling, and had sustained a supratentorial stroke ≥6 months prior to the study. They were allocated using a stratified randomization into two groups: 1) real tDCS + resistance training and 2) sham tDCS + resistance training. The resistance training program targeted the affected upper limb and consisted in 60 minutes of exercises, 3 times/week over 4 weeks. During each session, participants received either real- or sham-tDCS, using a bi-hemispheric montage for the first 20 minutes, and were blinded to the tDCS intervention. Outcome measures of clinical efficacy (Fugl-Meyer Assessment, Box and Block Test, Wolf Motor Function Test, grip strength, modified Ashworth scale and Motor Activity Log) were assessed by a blinded evaluator before and after the 4-week training program. Safety and tolerability were evaluated, respectively, by the number and characteristics of tDCS adverse events and dropout rates with their reasons. RESULTS: From the 147 individuals screened for eligibility, 14 participants (68.9±10.0 years old; 70.9±57.6 months post-stroke) met the selection criteria and were allocated to real-tDCS (n = 7) or sham-tDCS (n = 7) groups. Both groups improved on the clinical outcome measures, but these changes were not significantly different between groups (p > 0.17). No dropout occurred throughout the study. Participants frequently reported mild skin tingling during the administration of both real- and sham-tDCS, and no group difference was noted for its frequency and intensity (p > 0.38). One participant having received real-tDCS complained about a mild skin burning sensation after two sessions. The a priori sample size analysis performed on the Fugl-Meyer Assessment scores revealed that 56 participants would be required in a future clinical trial to reach 80% power at a significance level of 0.05. CONCLUSIONS: In this pilot study, repeated sessions of bi-hemispheric tDCS coupled with resistance training were found safe and tolerable for individuals at the chronic phase post-stroke. However, the use of tDCS did not result in additional sensorimotor improvements when compared to sham-tDCS. Further research is needed to better assess the clinical benefits of combining non-invasive transcranial stimulation with rehabilitation after a stroke.

Effect of increases in plantarflexor and hip flexor muscle strength on the levels of effort during gait in individuals with hemiparesis.

BACKGROUND: Following a stroke, strength gain of the trained affected lower-limb muscles has been observed to result in a change in gait speed, but its effect on other variables related to gait performance has scarcely been studied. The aim of this study was to assess the effect of strength gain of the affected plantarflexors and hip flexors on bilateral levels of effort during gait, in the sagittal plane of movement. METHODS: The levels of effort of 24 chronic hemiparetic participants (mean (standard deviation (SD)): 57.3 (SD 15.5) years), who had strength gains in the ankle and hip muscles following a strengthening programme, were estimated with the muscular utilization ratio during self-selected and maximal speeds. The ratio relates the net moment in gait relative to the muscle's maximal capability. The peak value and the area under the curve of the ratio were used as main outcome measures. FINDINGS: Regardless of speed, strength gains have been noted to cause a significant 12-17% decrease in the peak value of the ratio of the affected plantarflexors and hip flexors with a reduction of the area under the curve of the affected hip flexors' ratio and a trend toward a decrease for the affected plantarflexors at maximal speed. A significant, albeit small increase in self-selected and maximal gait speeds (P<0.05) was also observed post-training. Regardless of assessment time, the peak value of the affected plantarflexors' ratio was greater than that of the affected hip flexors at self-selected speed (P=0.006) and the area under the curve of the affected hip flexors' ratio was greater than that of the affected plantarflexors (P=0.007) at maximal speed. Generally, negative associations (-0.32-0.83) were noted between the changes in the peak value of the ratio and strength but not between the changes in gait speed. INTERPRETATION: The decrease in the peak value of the ratio could be explained by the increase in strength. Becoming stronger, hemiparetic participants favoured a reduction of their levels of effort during walking instead of substantially increasing their gait speed.

Effects of cadence on energy generation and absorption at lower extremity joints during gait.

BACKGROUND: Information regarding kinetic changes associated with walking speed is important for identifying alterations in locomotor disorders caused by pathological processes, as opposed to those arising solely from altered speeds. METHODS: Fourteen healthy subjects were assessed walking at both natural and imposed cadences of 60, 80, and 120 steps/min. A 3D motion analysis system, force platforms, and related software were used to obtain kinematic and kinetic data. Net joint powers were calculated across cycles and the area under the positive and negative phases of the power curves provided the mechanical work generated and absorbed at the hip, knee, and ankle. The relative contributions to the total positive and negative work across the four cadences were calculated for each joint. ANOVAs followed by planned contrasts were used to assess the effects of laterality, joint, and cadence. FINDINGS: Power and mechanical work, as well as the contributions of individual joints to the total energy generated and absorbed, were shown to be influenced by walking cadence, independent of laterality. The ankle, knee, and hip contributions to the total limb generation and absorption at the lowest cadence were 53%, 21%, and 26%, and at the highest cadence, the corresponding values were 34%, 33%, and 33%, respectively. INTERPRETATION: Power and mechanical work, as well as the contributions of individual joints to the total energy generated and absorbed, were shown to be influenced by the walking cadence, independent of laterality. These findings will be helpful for identifying walking strategies and adaptations in populations with gait disorders.

Changes in transcranial magnetic stimulation outcome measures in response to upper-limb physical training in stroke: A systematic review of randomized controlled trials.

BACKGROUND: Physical training is known to be an effective intervention to improve sensorimotor impairments after stroke. However, the link between brain plastic changes, assessed by transcranial magnetic stimulation (TMS), and sensorimotor recovery in response to physical training is still misunderstood. We systematically reviewed reports of randomized controlled trials (RCTs) involving the use of TMS over the primary motor cortex (M1) to probe brain plasticity after upper-limb physical training interventions in people with stroke. METHODS: We searched 5 databases for articles published up to October 2016, with additional studies identified by hand-searching. RCTs had to investigate pre/post-intervention changes in at least one TMS outcome measure. Two independent raters assessed the eligibility of potential studies and reviewed the selected articles' quality by using 2 critical appraisal scales. RESULTS: In total, 14 reports of RCTs (pooled participants=358; mean 26±12 per study) met the selection criteria. Overall, 11 studies detected plastic changes with TMS in the presence of clinical improvements after training, and these changes were more often detected in the affected hemisphere by using map area and motor evoked potential (MEP) latency outcome measures. Plastic changes mostly pointed to increased M1/corticospinal excitability and potential interhemispheric rebalancing of M1 excitability, despite sometimes controversial results among studies. Also, the strength of the review observations was affected by heterogeneous TMS methods and upper-limb interventions across studies as well as several sources of bias within the selected studies. CONCLUSIONS: The current evidence encourages the use of TMS outcome measures, especially MEP latency and map area to investigate plastic changes in the brain after upper-limb physical training post-stroke. However, more studies involving rigorous and standardized TMS procedures are needed to validate these observations.

Muscular utilization of the plantarflexors, hip flexors and extensors in persons with hemiparesis walking at self-selected and maximal speeds.

Gait performance secondary to a stroke is partially dependent on residual muscle strength. However, to pinpoint more precisely the mechanism of this relationship, biomechanical models, such as the muscular utilization ratio (MUR) that integrates both muscle strength and gait parameters into the concept of level of effort, are warranted. The aim of the present study was to evaluate the MUR of plantarflexors, hip flexors and extensor muscles during their concentric action in 17 chronic hemiparetic participants walking at self-selected and maximal speeds. Results revealed that peak MUR increased with gait speed. At self-selected speed (0.73+/-0.27 m/s), peak MUR values on the paretic side were 64% (+/-18.7), 46% (+/-27.6) and 33% (+/-25.6) for the plantarflexors, hip flexors and extensor muscles, respectively. At maximal speed (1.26+/-0.39 m/s), corresponding values were 77% (+/-23.6), 72% (+/-33.0) and 58% (+/-32.1). Peak MUR showed negative associations (-0.33-0.68), although not all significant, with voluntary muscle strength. The results of this study indicated that the peak MUR increased with gait speed. The plantarflexors were the most used muscle group at self-selected speed, whereas at maximal speed the three muscle groups showed similar peak MUR values. This last finding suggested an important role of the hip muscles in reaching a faster speed. Lastly, because moderate associations were found between peak MUR values and the voluntary muscle strength of hip flexors and extensors, it can be concluded that the weakest paretic muscle groups show, in general, the highest level of effort during gait.

A single robotic session that guides or increases movement error in survivors post-chronic stroke: which intervention is best to boost the learning of a timing task?

PURPOSE: Timing deficits can have a negative impact on the lives of survivors post-chronic stroke. Studies evaluating ways to improve timing post stroke are scarce. The goal of the study was to evaluate the impact of a single session of haptic guidance (HG) and error amplification (EA) robotic training interventions on the improvement of post-stroke timing accuracy. MATERIALS AND METHODS: Thirty-four survivors post-chronic stroke were randomly assigned to HG or EA. Participants played a computerized pinball-like game with their affected hand positioned in a robot that either helped them perform better (HG) or worse (EA) during the task. A baseline and retention phase preceded and followed HG and EA, respectively, in order to assess their efficiency at improving absolute timing errors. The impact of the side of the stroke lesion on the participants' performance during the timing task was also explored for each training group. RESULTS: An improvement in timing performance was only noted following HG (8.9 ± 4.9 ms versus 7.8 ± 5.3 ms, p = 0.032). Moreover, for the EA group only, participants with a left-sided stroke lesion showed a worsening in performance as compared to those with a right-sided stroke lesion (p = 0.001). CONCLUSION: Helping survivors post-chronic stroke perform a timing-based task is beneficial to learning. Future studies should explore longer and more frequent HG training sessions in order to further promote post stroke motor recovery. Implications for Rehabilitation Timing is crucial for the accomplishment of daily tasks. The number of studies dedicated to improving timing is scarce in the literature, even though timing deficits are common post stroke. This innovative study evaluated the impact of a single session of haptic guidance-HG and error amplification-EA robotic training interventions on improvements in timing accuracy among survivors post chronic stroke. HG robotic training improves timing accuracy more than EA among survivors post chronic stroke.

Transcranial direct current stimulation over multiple days enhances motor performance of a grip task.

BACKGROUND: Recovery of handgrip is critical after stroke since it is positively related to upper limb function. To boost motor recovery, transcranial direct current stimulation (tDCS) is a promising, non-invasive brain stimulation technique for the rehabilitation of persons with stroke. When applied over the primary motor cortex (M1), tDCS has been shown to modulate neural processes involved in motor learning. However, no studies have looked at the impact of tDCS on the learning of a grip task in both stroke and healthy individuals. OBJECTIVE: To assess the use of tDCS over multiple days to promote motor learning of a grip task using a learning paradigm involving a speed-accuracy tradeoff in healthy individuals. METHODS: In a double-blinded experiment, 30 right-handed subjects (mean age: 22.1±3.3 years) participated in the study and were randomly assigned to an anodal (n=15) or sham (n=15) stimulation group. First, subjects performed the grip task with their dominant hand while following the pace of a metronome. Afterwards, subjects trained on the task, at their own pace, over 5 consecutive days while receiving sham or anodal tDCS over M1. After training, subjects performed de novo the metronome-assisted task. The change in performance between the pre and post metronome-assisted task was used to assess the impact of the grip task and tDCS on learning. RESULTS: Anodal tDCS over M1 had a significant effect on the speed-accuracy tradeoff function. The anodal tDCS group showed significantly greater improvement in performance (39.28±15.92%) than the sham tDCS group (24.06±16.35%) on the metronome-assisted task, t(28)=2.583, P=0.015 (effect size d=0.94). CONCLUSIONS: Anodal tDCS is effective in promoting grip motor learning in healthy individuals. Further studies are warranted to test its potential use for the rehabilitation of fine motor skills in stroke patients.

Bilateral level of effort of the plantar flexors, hip flexors, and extensors during gait in hemiparetic and healthy individuals.

BACKGROUND AND PURPOSE: Muscle weakness is recognized as a key factor in gait performance of poststroke individuals, but its impact on lower-limb muscular effort has been scarcely studied. The aims of this study were to compare the level of effort of the lower limbs of hemiparetic and able-bodied individuals and to assess the effect of side, cadence, and muscle group. METHODS: Seventeen chronic hemiparetic participants (7 females and 10 males) with a mean age of 60.5+/-13.4 years were assessed when walking. They were compared with a group of 14 able-bodied individuals. The level of effort was estimated from the muscular utilization ratio (MUR), which relates the walking moment of a given muscle group to its maximal potential moment. Peak MUR and MUR(area) were used as main outcome measures. RESULTS: Hemiparetic individuals showed greater peak MUR values (45% to 78%) than the able-bodied subjects matched for cadence (24% to 63%). For both groups, the peak MUR values were similar between sides and increased with cadence. At self-selected cadence, the plantar flexors showed greater peak MUR values, whereas at maximal cadence, levels of effort for all muscles were equivalent. The MUR(area) values at the hip joint were greater for the hemiparetic group, and both groups had values that increased with cadence. Differences between sides and muscle groups were noted for the hemiparetic and healthy individuals, respectively. Large peak MUR values were associated with high MUR(area) values. CONCLUSIONS: For a similar cadence, the levels of effort of hemiparetic individuals were greater than those of the able-bodied. In the presence of muscle weakness, similar bilateral levels of effort could mean that hemiparetic individuals relied on their sense of effort while walking.

Exerciser for rehabilitation of the Arm (ERA): Development and unique features of a 3D end-effector robot.

Stroke is one of the leading causes of disability worldwide. Consequently, many stroke survivors exhibit difficulties undergoing voluntary movement in their affected upper limb, compromising their functional performance and level of independence. To minimize the negative impact of stroke disabilities, exercises are recognized as a key element in post-stroke rehabilitation. In order to provide the practice of exercises in a uniform and controlled manner as well as increasing the efficiency of therapists' interventions, robotic training has been found, and continues to prove itself, as an innovative intervention for post-stroke rehabilitation. However, the complexity as well as the limited degrees of freedom and workspace of currently commercially available robots can limit their use in clinical settings. Up to now, user-friendly robots covering a sufficiently large workspace for training of the upper limb in its full range of motion are lacking. This paper presents the design and implementation of ERA, an upper-limb 3-DOF force-controlled exerciser robot, which presents a workspace covering the entire range of motion of the upper limb. The ERA robot provides 3D reaching movements in a haptic virtual environment. A description of the hardware and software components of the ERA robot is also presented along with a demonstration of its capabilities in one of the three operational modes that were developed.

Comparison of haptic guidance and error amplification robotic trainings for the learning of a timing-based motor task by healthy seniors.

With age, a decline in the temporal aspect of movement is observed such as a longer movement execution time and a decreased timing accuracy. Robotic training can represent an interesting approach to help improve movement timing among the elderly. Two types of robotic training-haptic guidance (HG; demonstrating the correct movement for a better movement planning and improved execution of movement) and error amplification (EA; exaggerating movement errors to have a more rapid and complete learning) have been positively used in young healthy subjects to boost timing accuracy. For healthy seniors, only HG training has been used so far where significant and positive timing gains have been obtained. The goal of the study was to evaluate and compare the impact of both HG and EA robotic trainings on the improvement of seniors' movement timing. Thirty-two healthy seniors (mean age 68 ± 4 years) learned to play a pinball-like game by triggering a one-degree-of-freedom hand robot at the proper time to make a flipper move and direct a falling ball toward a randomly positioned target. During HG and EA robotic trainings, the subjects' timing errors were decreased and increased, respectively, based on the subjects' timing errors in initiating a movement. Results showed that only HG training benefited learning, but the improvement did not generalize to untrained targets. Also, age had no influence on the efficacy of HG robotic training, meaning that the oldest subjects did not benefit more from HG training than the younger senior subjects. Using HG to teach the correct timing of movement seems to be a good strategy to improve motor learning for the elderly as for younger people. However, more studies are needed to assess the long-term impact of HG robotic training on improvement in movement timing.

Corticospinal excitability as a predictor of functional gains at the affected upper limb following robotic training in chronic stroke survivors.

BACKGROUND: Robotic training can help improve function of a paretic limb following a stroke, but individuals respond differently to the training. A predictor of functional gains might improve the ability to select those individuals more likely to benefit from robot-based therapy. Studies evaluating predictors of functional improvement after a robotic training are scarce. One study has found that white matter tract integrity predicts functional gains following a robotic training of the hand and wrist. Objective. To determine the predictive ability of behavioral and brain measures in order to improve selection of individuals for robotic training. METHODS: Twenty subjects with chronic stroke participated in an 8-week course of robotic exoskeletal training for the arm. Before training, a clinical evaluation, functional magnetic resonance imaging (fMRI), diffusion tensor imaging, and transcranial magnetic stimulation (TMS) were each measured as predictors. Final functional gain was defined as change in the Box and Block Test (BBT). Measures significant in bivariate analysis were fed into a multivariate linear regression model. RESULTS: Training was associated with an average gain of 6 ± 5 blocks on the BBT (P < .0001). Bivariate analysis revealed that lower baseline motor-evoked potential (MEP) amplitude on TMS, and lower laterality M1 index on fMRI each significantly correlated with greater BBT change. In the multivariate linear regression analysis, baseline MEP magnitude was the only measure that remained significant. CONCLUSION: Subjects with lower baseline MEP magnitude benefited the most from robotic training of the affected arm. These subjects might have reserve remaining for the training to boost corticospinal excitability, translating into functional gains.