Effects of Gait Training With Body Weight Support on a Treadmill Versus Overground in Individuals With Stroke.

OBJECTIVE: To investigate the effects of gait training with body weight support (BWS) on a treadmill versus overground in individuals with chronic stroke. DESIGN: Randomized controlled trial. SETTING: University research laboratory. PARTICIPANTS: Individuals (N=28) with chronic stroke (>6mo from the stroke event). INTERVENTIONS: Participants were randomly assigned to receive gait training with BWS on a treadmill (n=14) or overground (n=14) 3 times a week for 6 weeks. MAIN OUTCOME MEASURES: Gait speed measured using the 10-meter walk test, endurance measured using the 6-minute walk test, functional independence measured using the motor domain of the FIM, lower limb recovery measured using the lower extremity domain of the Fugl-Meyer assessment, step length, step length symmetry ratio, and single-limb support duration. Measurements were obtained at baseline, immediately after the training session, and 6 weeks after the training session. RESULTS: At 1 week after the last training session, both groups improved in all outcome measures except paretic step length and step length symmetry ratio, which were improved only in the overground group (P=.01 and P=.01, respectively). At 6 weeks after the last training session, all improvements remained and the treadmill group also improved paretic step length (P<.001) but not step length symmetry ratio (P>.05). CONCLUSIONS: Individuals with chronic stroke equally improve gait speed and other gait parameters after 18 sessions of BWS gait training on either a treadmill or overground. Only the overground group improved step length symmetry ratio, suggesting a role of integrating overground walking into BWS interventions poststroke.

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. FINDINGS: Participants with chronic hemiparetic gait were randomized to either six weeks of treadmill-integrated ankle robotics (n = 14) or dose-matched seated ankle robotics (n = 12) videogame training. Selected gait measures were collected at baseline, post-training, and six-week retention. Friedman, and Wilcoxon Sign Rank and Fisher's exact tests evaluated within and between group differences across time, respectively. Six weeks post-training, treadmill robotics proved more effective than seated robotics to increase walking velocity, paretic single support, paretic push-off impulse, and active dorsiflexion range of motion. Treadmill robotics durably improved gait dorsiflexion swing angle leading 6/7 initially requiring ankle braces to self-discarded them, while their unassisted paretic heel-first contacts increased from 44 % to 99.6 %, versus no change in assistive device usage (0/9) following seated robotics. CONCLUSIONS: Treadmill-integrated, but not seated ankle robotics training, durably improves gait biomechanics, reversing foot drop, restoring walking propulsion, and establishing safer foot landing in chronic stroke that may reduce reliance on assistive devices. These findings support a task-specific approach integrating adaptive ankle robotics with locomotor training to optimize mobility recovery. CLINICAL TRIAL IDENTIFIER: NCT01337960. https://clinicaltrials.gov/ct2/show/NCT01337960?term=NCT01337960&rank=1.

Neural decoding of treadmill walking from noninvasive electroencephalographic signals.

Chronic recordings from ensembles of cortical neurons in primary motor and somatosensory areas in rhesus macaques provide accurate information about bipedal locomotion (Fitzsimmons NA, Lebedev MA, Peikon ID, Nicolelis MA. Front Integr Neurosci 3: 3, 2009). Here we show that the linear and angular kinematics of the ankle, knee, and hip joints during both normal and precision (attentive) human treadmill walking can be inferred from noninvasive scalp electroencephalography (EEG) with decoding accuracies comparable to those from neural decoders based on multiple single-unit activities (SUAs) recorded in nonhuman primates. Six healthy adults were recorded. Participants were asked to walk on a treadmill at their self-selected comfortable speed while receiving visual feedback of their lower limbs (i.e., precision walking), to repeatedly avoid stepping on a strip drawn on the treadmill belt. Angular and linear kinematics of the left and right hip, knee, and ankle joints and EEG were recorded, and neural decoders were designed and optimized with cross-validation procedures. Of note, the optimal set of electrodes of these decoders were also used to accurately infer gait trajectories in a normal walking task that did not require subjects to control and monitor their foot placement. Our results indicate a high involvement of a fronto-posterior cortical network in the control of both precision and normal walking and suggest that EEG signals can be used to study in real time the cortical dynamics of walking and to develop brain-machine interfaces aimed at restoring human gait function.

Measurement of passive ankle stiffness in subjects with chronic hemiparesis using a novel ankle robot.

Our objective in this study was to assess passive mechanical stiffness in the ankle of chronic hemiparetic stroke survivors and to compare it with those of healthy young and older (age-matched) individuals. Given the importance of the ankle during locomotion, an accurate estimate of passive ankle stiffness would be valuable for locomotor rehabilitation, potentially providing a measure of recovery and a quantitative basis to design treatment protocols. Using a novel ankle robot, we characterized passive ankle stiffness both in sagittal and in frontal planes by applying perturbations to the ankle joint over the entire range of motion with subjects in a relaxed state. We found that passive stiffness of the affected ankle joint was significantly higher in chronic stroke survivors than in healthy adults of a similar cohort, both in the sagittal as well as frontal plane of movement, in three out of four directions tested with indistinguishable stiffness values in plantarflexion direction. Our findings are comparable to the literature, thus indicating its plausibility, and, to our knowledge, report for the first time passive stiffness in the frontal plane for persons with chronic stroke and older healthy adults.

Electroencephalographic reactivity to unimodal and bimodal visual and proprioceptive demands in sensorimotor integration.

We used electroencephalography to see how the brain deals with altered sensory processing demands in lower extremity movements. In unimodal conditions, sensory processing demands were altered with subjects performing movement to a small or large visual target, or with a small or large weight to modify proprioception. In bimodal conditions, both weight and targets needed to be met. We assessed activity over primary sensorimotor, premotor and parietal areas before and during knee movements. In unimodal conditions, the primary sensorimotor area showed the least sensitivity to the maximally increased sensory demand in both vision and proprioception, while the premotor region was most sensitive to proprioceptive demands, and the parietal region showed greatest sensitivity to visual demands. In bimodal conditions, intermediate levels of sensory processing demand maximally increased activation at premotor and parietal regions. However, when visual and proprioceptive demands were both maximal, activation decreased and was similar to that seen with the lowest level of sensory processing demand. As behavior was consistent across conditions while activation at these regions decreased, we suggest that additional brain areas, possibly high order cognitive and attentional regions, may be required to augment the function of the traditional sensorimotor network in lower extremity movements with increasingly difficult sensory processing demands.

Theta frequency band activity and attentional mechanisms in visual and proprioceptive demand.

In a companion manuscript we reported reduced electroencephalographic (EEG) activation at traditional sensorimotor areas in knee movements with high levels of task difficulty modulated by varying visual and proprioceptive sensory demands. Given that reduced cortical activity with more complex tasks is counter-intuitive, we suggested that high order cognitive-motor areas may show increased EEG activation to compensate for the observed decrease in sensorimotor regions. To test this hypothesis, we evaluated theta band activation at anterior frontal regions in a secondary analysis of our previous data. Unlike activation at sensorimotor areas, anterior frontal responses increased with each level of task difficulty as modulated by precision of visual targeting and/or proprioceptive demands from adding masses to the leg. Activity was increased as both unimodal visual and proprioceptive requirements became more demanding, but showed greater sensitivity to visual over proprioceptive processing requirements. Each level of bimodal task demands showed increasing activation, which was consistently greater when modulated through visual demands. These results are consistent with our hypothesis of increased contribution of anterior frontal regions for motor control in lower extremity movements with increasing sensory demands and further support different mechanisms for internally and externally guided movement.

The effect of claudication pain on temporal and spatial gait measures during self-paced ambulation.

We determined the effect of claudication pain on temporal and spatial gait characteristics, and on ambulatory symmetry at preferred and rapid self-selected walking paces in patients with unilateral peripheral arterial disease (PAD). Twenty-eight patients with PAD limited by intermittent claudication were studied. Patients ambulated at their preferred and rapid paces over a 7.3-meter portable gait mat system while they were pain-free and after experiencing claudication pain. The order of the pain-free and painful walking trials was randomized, and the following gait parameters were obtained: velocity, cadence, stride length, swing time, stance time, single-support time, and double-support time. During the self-selected rapid pace, patients walked 3% slower (p = 0.020) while in pain due to a 3% shorter stride length (p < 0.001), and they were in double-stance longer (p = 0.024). Claudication pain in the symptomatic leg resulted in an increase in single-stance (p = 0.007). Furthermore, gait became asymmetrical with pain, as the symptomatic leg spent a higher percentage of the gait cycle in the swing phase (p < 0.01) and lower percentages in stance (p < 0.01) and single-stance (p < 0.01) than the asymptomatic leg. Ambulation was symmetrical for all measures during the pain-free trial. In conclusion, claudication pain slows ambulatory velocity at preferred and rapid paces, and increases asymmetry when ambulatory function is challenged with rapid walking. The reduced ambulatory speed with the development of claudication pain may be an adaptation to elicit a safer and less destabilizing gait pattern.

Effects of unilateral robotic limb loading on gait characteristics in subjects with chronic stroke.

BACKGROUND: Hemiparesis after stroke often leads to impaired ankle motor control that impacts gait function. In recent studies, robotic devices have been developed to address this impairment. While capable of imparting forces to assist during training and gait, these devices add mass to the paretic leg which might encumber patients' gait pattern. The purpose of this study was to assess the effects of the added mass of one of these robots, the MIT's Anklebot, while unpowered, on gait of chronic stroke survivors during overground and treadmill walking. METHODS: Nine chronic stroke survivors walked overground and on a treadmill with and without the anklebot mounted on the paretic leg. Gait parameters, interlimb symmetry, and joint kinematics were collected for the four conditions. Repeated-measures analysis of variance (ANOVA) tests were conducted to examine for possible differences across four conditions for the paretic and nonparetic leg. RESULTS: The added inertia and friction of the unpowered anklebot had no statistically significant effect on spatio-temporal parameters of gait, including paretic and nonparetic step time and stance percentage, in both overground and treadmill conditions. Noteworthy, interlimb symmetry as characterized by relative stance duration was greater on the treadmill than overground regardless of loading conditions. The presence of the unpowered robot loading reduced the nonparetic knee peak flexion on the treadmill and paretic peak dorsiflexion overground (p < 0.05). CONCLUSIONS: Our results suggest that for these subjects the added inertia and friction of this backdriveable robot did not significantly alter their gait pattern.

Reliability of TMS motor evoked potentials in quadriceps of subjects with chronic hemiparesis after stroke.

Transcranial magnetic stimulation (TMS) non-invasively measures excitability of central motor pathways in humans and is used to characterize neuroplasticity after stroke. Using TMS to index lower extremity neuroplasticity after gait rehabilitation requires test-retest reliability. This study assesses the reliability of TMS-derived variables measured at bilateral quadriceps of chronic hemiparetic stroke survivors. Results support using measures of both paretic and nonparetic motor threshold, motor evoked potential (MEP) latencies; and nonparetic MEP amplitudes. Implications for longitudinal research are discussed.

Treadmill exercise activates subcortical neural networks and improves walking after stroke: a randomized controlled trial.

BACKGROUND AND PURPOSE: Stroke often impairs gait thereby reducing mobility and fitness and promoting chronic disability. Gait is a complex sensorimotor function controlled by integrated cortical, subcortical, and spinal networks. The mechanisms of gait recovery after stroke are not well understood. This study examines the hypothesis that progressive task-repetitive treadmill exercise (T-EX) improves fitness and gait function in subjects with chronic hemiparetic stroke by inducing adaptations in the brain (plasticity). METHODS: A randomized controlled trial determined the effects of 6-month T-EX (n=37) versus comparable duration stretching (CON, n=34) on walking, aerobic fitness and in a subset (n=15/17) on brain activation measured by functional MRI. RESULTS: T-EX significantly improved treadmill-walking velocity by 51% and cardiovascular fitness by 18% (11% and -3% for CON, respectively; P<0.05). T-EX but not CON affected brain activation during paretic, but not during nonparetic limb movement, showing 72% increased activation in posterior cerebellar lobe and 18% in midbrain (P<0.005). Exercise-mediated improvements in walking velocity correlated with increased activation in cerebellum and midbrain. CONCLUSIONS: T-EX improves walking, fitness and recruits cerebellum-midbrain circuits, likely reflecting neural network plasticity. This neural recruitment is associated with better walking. These findings demonstrate the effectiveness of T-EX rehabilitation in promoting gait recovery of stroke survivors with long-term mobility impairment and provide evidence of neuroplastic mechanisms that could lead to further refinements in these paradigms to improve functional outcomes.

Intracortical inhibition and facilitation with unilateral dominant, unilateral nondominant and bilateral movement tasks in left- and right-handed adults.

PURPOSE: To investigate intracortical inhibition and facilitation in response to unilateral dominant, nondominant and bilateral biceps activation and short-term upper extremity training in right- and left-handed adults. METHODS: Paired-pulse transcranial magnetic stimulation was used to measure intracortical excitability in motor dominant and nondominant cortices of 26 nondisabled adults. Neural facilitation and inhibition were measured in each hemisphere during unilateral dominant, nondominant and bilateral arm activation and after training in each condition. RESULTS: No differences were seen between right- and left-handed subjects. Intracortical facilitation and decreased inhibition were seen in each hemisphere with unilateral activation/training of contralateral muscles and bilateral muscle activation/training. Persistent intracortical inhibition was seen in each hemisphere with ipsilateral muscle activation/training. Inhibition was greater in the nondominant hemisphere during dominant hemisphere activation (dominant arm contraction). CONCLUSION: Strongly dominant individuals show no difference in intracortical responses given handedness. Intracortical activity with unilateral and bilateral arm activation and short-term training differs based on hemispheric dominance, with the motor dominant hemisphere exerting a larger inhibitory influence over the nondominant hemisphere. Bilateral activation and training have a disinhibitory effect in both dominant and nondominant hemispheres.

Preparatory band specific premotor cortical activity differentiates upper and lower extremity movement.

Event related desynchronization (ERD) allows evaluation of brain signals in multiple frequency dimensions. The purpose of this study was to determine left hemispheric non-primary motor cortex differences at varying frequencies of premovement ERD for similar movements by end-effectors of the upper and lower extremities. We recorded 32-channel electroencephalography (EEG) while subjects performed self-paced right ankle dorsiflexion and wrist extension. Electromyography (EMG) was recorded over the tibialis anterior and extensor carpi ulnaris. EEG was analyzed for premovement ERD within the alpha (8-12 Hz), low beta (13-18 Hz) and high beta (18-22 Hz) frequencies over the premotor, motor, and sensory areas of the left and mesial cortex from -1.5 to 0 s before movement. Within the alpha and high beta bands, wrist movements showed limited topography, but greater ERD over posterior premotor cortex areas. Alpha ERD was also significantly greater over the lateral motor cortex for wrist movements. In the low beta band, wrist movements provided extensive ERD differences to include the left motor and mesial/lateral premotor areas, whereas ankle movements showed only limited ERD activity. Overall, alpha and high beta activity demonstrated distinctions that are consistent with mapping of wrist and ankle representations over the sensorimotor strip, whereas the low beta representation demonstrated the clearest distinctions between the limbs over widespread brain areas, particularly the lateral premotor cortex. This suggests limited leg premovement activity at the dorsolateral premotor cortex. Low beta ERD may be reflect joint or limb specific preparatory activity in the premotor area. Further work is required to better evaluate the extent of this low beta activity for multiple comparative joints.

Post-stroke exercise rehabilitation: what we know about retraining the motor system and how it may apply to retraining the heart.

A plateau in recovery within the first few months of rehabilitative therapy was assumed to be the norm in stroke survivors. Recent studies in our laboratory examined the effect of 6 months of treadmill exercise training in chronically disabled stroke survivors. Treadmill exercise improves fitness and walking ability in patients when initiated 6 months or more following their index stroke. Functional imaging studies show that such exercise also induces subcortical reorganization in these patients. Future investigations will explore the relationship between these functional and structural effects and characterize the therapeutic mechanisms of post-stroke rehabilitation. Nonetheless, treadmill exercise appears to have motor, cardiac, and daily functional benefits in stroke survivors.

Bilateral foot center of pressure measures predict hemiparetic gait velocity.

Stroke is a major cause of disability in the US, leaving most survivors with abnormal motor function, often resulting in hemiparetic gait. Quality of gait in this population has been well characterized by measures of velocity, though velocity alone provides only a general index of functional mobility. Researchers and clinicians should continue to develop a complete characterization of behavioral alterations, but should also work to identify the neuromechanical processes underlying the loss and recovery of locomotor function. We hypothesized that selected foot center of pressure (CoP) measures would show a predictive relationship with hemiparetic gait velocity, a standard clinical metric of locomotor capability, thus providing insight into the relationship between neuromotor control and function. Thirty-three chronic stroke survivors (67+/-10 years) were evaluated during walking at a self-selected speed. Patients wore pressure sensitive shoe insoles and completed 15 steady-state gait cycles over an instrumented gait mat. CoP parameters and walking velocity were measured during each cycle. Multiple regression analyses were used to model all combinations of CoP and interlimb symmetry parameters as predictor variables of gait velocity. Eleven CoP and symmetry parameters were selected in a final regression model, and provided a robust prediction of hemiparetic gait velocity (R(adj)(2)=0.90) in this group of chronic stroke patients. These results indicate that bilateral foot CoP measures, especially those representing variability of foot CoP control, not only index locomotor function, but may also have the potential to provide information about the underlying control properties of the stroke-injured neuromuscular system.

A note on time-frequency analysis of finger tapping.

Finger tapping involves 3 important features: time, spatial amplitude, and frequency. In classical analysis, investigators examine timing parameters; in spectral analysis, they examine frequency parameters. Both types of analysis are based on stationary tap information. The authors propose that time-frequency analysis is a useful tool for analyzing nonstationary finger tapping. They describe the method and give examples of frequency modulation, age difference, and speed transition that demonstrate additional insights one can gain by using this analysis.

Treadmill exercise rehabilitation improves ambulatory function and cardiovascular fitness in patients with chronic stroke: a randomized, controlled trial.

BACKGROUND AND PURPOSE: Physical inactivity propagates disability after stroke through physical deconditioning and learned nonuse. We investigated whether treadmill aerobic training (T-AEX) is more effective than conventional rehabilitation to improve ambulatory function and cardiovascular fitness in patients with chronic stroke. METHODS: Sixty-one adults with chronic hemiparetic gait after ischemic stroke (>6 months) were randomized to 6 months (3x/week) progressive T-AEX or a reference rehabilitation program of stretching plus low-intensity walking (R-CONTROL). Peak exercise capacity (Vo2 peak), o2 consumption during submaximal effort walking (economy of gait), timed walks, Walking Impairment Questionnaire (WIQ), and Rivermead Mobility Index (RMI) were measured before and after 3 and 6 months of training. RESULTS: Twenty-five patients completed T-AEX and 20 completed R-CONTROL. Only T-AEX increased cardiovascular fitness (17% versus 3%, delta% T-AEX versus R-CONTROL, P<0.005). Group-by-time analyses revealed T-AEX improved ambulatory performance on 6-minute walks (30% versus 11%, P<0.02) and mobility function indexed by WIQ distance scores (56% versus 12%, P<0.05). In the T-AEX group, increasing training velocity predicted improved Vo2 peak (r=0.43, P<0.05), but not walking function. In contrast, increasing training session duration predicted improved 6-minute walk (r=0.41, P<0.05), but not fitness gains. CONCLUSIONS: T-AEX improves both functional mobility and cardiovascular fitness in patients with chronic stroke and is more effective than reference rehabilitation common to conventional care. Specific characteristics of training may determine the nature of exercise-mediated adaptations.

Improved hemiparetic muscle activation in treadmill versus overground walking.

OBJECTIVE: Treadmill training is a promising tool for retraining gait after stroke. The treadmill induces an immediate shift toward symmetry and longer paretic stance times due to altered muscle activation (active) or the motorized belt (passive). The authors investigated vastus lateralis and medial hamstrings activation differences between treadmill and overground walking in participants with stroke. METHODS: Vastus lateralis and medial hamstrings surface electromyography was recorded during velocity-matched overground and treadmill walking in 19 chronically hemiparetic subjects. Variables from ensemble averages of electromyography included burst onset and offset times (% cycle), duration (% cycle), integrated amplitude (mV.% cycle), and onset relative to foot strike (% cycle). Conditions were compared using paired t-tests (alpha = 0.05). RESULTS: Paretic vastus lateralis onset occurred earlier in the treadmill condition (overground: 47.1%, treadmill: 41.9%, P = 0.01). For nonparetic vastus lateralis in the treadmill condition, onset occurred later (overground: 85.2%, treadmill: 87.6%, P = 0.09), offset occurred earlier (overground: 54.7%, treadmill: 47.8%, P = 0.03), duration was shorter (overground: 69.1%, treadmill: 61.2%, P = 0.01), and integrated amplitude was lower (overground: 14.1, treadmill: 10.6, P = 0.05). Within limbs, paretic vastus lateralis onset occurred earlier relative to paretic foot strike. Nonparetic vastus lateralis onset occurred later relative to nonparetic foot strike. CONCLUSIONS: Treadmill walking induces immediate changes in vastus lateralis, but not medial ham-strings, activation patterns. These alterations (earlier paretic vastus lateralis onset and later nonparetic vastus lateralis onset) during treadmill versus overground walking parallel the increased symmetry in gait patterning.

Repetitive bilateral arm training and motor cortex activation in chronic stroke: a randomized controlled trial.

CONTEXT: Reorganization in central motor networks occurs during early recovery from hemiparetic stroke. In chronic stroke survivors, specific rehabilitation therapy can improve upper extremity function. OBJECTIVE: To test the hypothesis that in patients who have chronic motor impairment following stroke, specific rehabilitation therapy that improves arm function is associated with reorganization of cortical networks. DESIGN, SETTING, AND PATIENTS: A randomized controlled clinical trial conducted in a US ambulatory rehabilitation program with 21 patients (median [IQR], 50.3 [34.8-77.3] months after unilateral stroke). Data were collected between 2001 and 2004. INTERVENTIONS: Patients were randomly assigned to bilateral arm training with rhythmic auditory cueing (BATRAC) (n = 9) or standardized dose-matched therapeutic exercises (DMTE) (n = 12). Both were conducted for 1 hour, 3 times a week, for 6 weeks. MAIN OUTCOME MEASURES: Within 2 weeks before and after the intervention, brain activation during elbow movement assessed by functional magnetic resonance imaging (fMRI) and functional outcome assessed using arm function scores. RESULTS: Patients in the BATRAC group but not in the DMTE group increased hemispheric activation during paretic arm movement (P = .03). Changes in activation were observed in the contralesional cerebrum and ipsilesional cerebellum (P = .009). BATRAC was associated with significant increases in activation in precentral (P<.001) and postcentral gyri (P = .03) and the cerebellum (P<.001), although 3 BATRAC patients showed no fMRI changes. Considering all patients, there were no differences in functional outcome between groups. When only BATRAC patients with fMRI response were included (n = 6), BATRAC improved arm function more than DMTE did (P = .02). CONCLUSIONS: These preliminary findings suggest that BATRAC induces reorganization in contralesional motor networks and provide biological plausibility for repetitive bilateral training as a potential therapy for upper extremity rehabilitation in hemiparetic stroke.

Modular ankle robotics training in early subacute stroke: a randomized controlled pilot study.

UNLABELLED: BACKGROUND. Modular lower extremity robotics may offer a valuable avenue for restoring neuromotor control after hemiparetic stroke. Prior studies show that visually guided and visually evoked practice with an ankle robot (anklebot) improves paretic ankle motor control that translates into improved overground walking. OBJECTIVE: To assess the feasibility and efficacy of daily anklebot training during early subacute hospitalization poststroke. METHODS: Thirty-four inpatients from a stroke unit were randomly assigned to anklebot (n = 18) or passive manual stretching (n = 16) treatments. All suffered a first stroke with residual hemiparesis (ankle manual muscle test grade 1/5 to 4/5), and at least trace muscle activation in plantar- or dorsiflexion. Anklebot training employed an "assist-as-needed" approach during >200 volitional targeted paretic ankle movements, with difficulty adjusted to active range of motion and success rate. Stretching included >200 daily mobilizations in these same ranges. All sessions lasted 1 hour and assessments were not blinded. RESULTS: Both groups walked faster at discharge; however, the robot group improved more in percentage change of temporal symmetry (P = .032) and also of step length symmetry (P = .038), with longer nonparetic step lengths in the robot (133%) versus stretching (31%) groups. Paretic ankle control improved in the robot group, with increased peak (P ≤ .001) and mean (P ≤ .01) angular speeds, and increased movement smoothness (P ≤ .01). There were no adverse events. CONCLUSION: Though limited by small sample size and restricted entry criteria, our findings suggest that modular lower extremity robotics during early subacute hospitalization is well tolerated and improves ankle motor control and gait patterning.

Increased reward in ankle robotics training enhances motor control and cortical efficiency in stroke.

Robotics is rapidly emerging as a viable approach to enhance motor recovery after disabling stroke. Current principles of cognitive motor learning recognize a positive relationship between reward and motor learning. Yet no prior studies have established explicitly whether reward improves the rate or efficacy of robotics-assisted rehabilitation or produces neurophysiologic adaptations associated with motor learning. We conducted a 3 wk, 9-session clinical pilot with 10 people with chronic hemiparetic stroke, randomly assigned to train with an impedance-controlled ankle robot (anklebot) under either high reward (HR) or low reward conditions. The 1 h training sessions entailed playing a seated video game by moving the paretic ankle to hit moving onscreen targets with the anklebot only providing assistance as needed. Assessments included paretic ankle motor control, learning curves, electroencephalograpy (EEG) coherence and spectral power during unassisted trials, and gait function. While both groups exhibited changes in EEG, the HR group had faster learning curves (p = 0.05), smoother movements (p