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1.
Clin Biomech (Bristol, Avon) ; 71: 11-23, 2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31677546

RESUMO

BACKGROUND: Studies have demonstrated that ambulatory children and adolescents with cerebral palsy demonstrate atypical gait patterns. Out of numerous gait variables, identification of the most deteriorated gait parameters is important for targeted and effective gait rehabilitation. Therefore, this study aimed to identify the gait parameters with the most discriminating nature to distinguish cerebral palsy gait from normal gait. METHODS: Multiple databases were searched to include studies on ambulatory children and adolescents with cerebral palsy that included gait (spatio-temporal, kinematic, and kinetic) and dynamic stability variables. FINDINGS: Of 68 studies that met the inclusion criteria, 35 studies were included in the meta analysis. Effect size was used to assess the discriminative strength of each variable. A large effect (≥ 0.8) of cerebral palsy on double limb support time (Standardized Mean Difference = 0.98), step length (Standardized Mean Difference = 1.65), step width (Standardized Mean Difference = 1.21), stride length (Standardized Mean Difference = 1.75), and velocity (Standardized Mean Difference = 1.42) was observed at preferred-walking speed. At fast-walking speed, some gait variables (i.e. velocity and stride length) exhibited larger effect size compared to preferred-walking speed. For some kinematic variables (e.g. range of motion of pelvis), the effect size varied across the body planes. INTERPRETATION: Our systematic review detects the most discriminative features of cerebral palsy gait. Non-uniform effects on joint kinematics across the anatomical planes support the importance of 3D gait analysis. Differential effects at fast versus preferred speeds emphasize the importance of measuring gait at a range of speeds.

2.
Front Neurorobot ; 13: 80, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31632261

RESUMO

Stroke is a leading cause of long-term disability worldwide and often impairs walking ability. To improve recovery of walking function post-stroke, researchers have investigated the use of treatments such as fast functional electrical stimulation (FastFES). During FastFES treatments, individuals post-stroke walk on a treadmill at their fastest comfortable speed while electrical stimulation is delivered to two muscles of the paretic ankle, ideally to improve paretic leg propulsion and toe clearance. However, muscle selection and stimulation timing are currently standardized based on clinical intuition and a one-size-fits-all approach, which may explain in part why some patients respond to FastFES training while others do not. This study explores how personalized neuromusculoskeletal models could potentially be used to enable individual-specific selection of target muscles and stimulation timing to address unique functional limitations of individual patients post-stroke. Treadmill gait data, including EMG, surface marker positions, and ground reactions, were collected from an individual post-stroke who was a non-responder to FastFES treatment. The patient's gait data were used to personalize key aspects of a full-body neuromusculoskeletal walking model, including lower-body joint functional axes, lower-body muscle force generating properties, deformable foot-ground contact properties, and paretic and non-paretic leg neural control properties. The personalized model was utilized within a direct collocation optimal control framework to reproduce the patient's unstimulated treadmill gait data (verification problem) and to generate three stimulated walking predictions that sought to minimize inter-limb propulsive force asymmetry (prediction problems). The three predictions used: (1) Standard muscle selection (gastrocnemius and tibialis anterior) with standard stimulation timing, (2) Standard muscle selection with optimized stimulation timing, and (3) Optimized muscle selection (soleus and semimembranosus) with optimized stimulation timing. Relative to unstimulated walking, the optimal control problems predicted a 41% reduction in propulsive force asymmetry for scenario (1), a 45% reduction for scenario (2), and a 64% reduction for scenario (3), suggesting that non-standard muscle selection may be superior for this patient. Despite these predicted improvements, kinematic symmetry was not noticeably improved for any of the walking predictions. These results suggest that personalized neuromusculoskeletal models may be able to predict personalized FastFES training prescriptions that could improve propulsive force symmetry, though inclusion of kinematic requirements would be necessary to improve kinematic symmetry as well.

3.
Neural Plast ; 2019: 5190671, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31565049

RESUMO

Spinal pathways underlying reciprocal flexion-extension contractions have been well characterized, but the extent to which cortically evoked motor-evoked potentials (MEPs) are influenced by antagonist muscle activation remains unclear. A majority of studies using transcranial magnetic stimulation- (TMS-) evoked MEPs to evaluate the excitability of the corticospinal pathway focus on upper extremity muscles. Due to functional and neural control differences between lower and upper limb muscles, there is a need to evaluate methodological factors influencing TMS-evoked MEPs specifically in lower limb musculature. If and to what extent the activation of the nontargeted muscles, such as antagonists, affects TMS-evoked MEPs is poorly understood, and such gaps in our knowledge may limit the rigor and reproducibility of TMS studies. Here, we evaluated the effect of the activation state of the antagonist muscle on TMS-evoked MEPs obtained from the target (agonist) ankle muscle for both tibialis anterior (TA) and soleus muscles. Fourteen able-bodied participants (11 females, age: 26.1 ± 4.1 years) completed one experimental session; data from 12 individuals were included in the analysis. TMS was delivered during 4 conditions: rest, TA activated, soleus activated, and TA and soleus coactivation. Three pairwise comparisons were made for MEP amplitude and coefficient of variability (CV): rest versus coactivation, rest versus antagonist activation, and agonist activation versus coactivation. We demonstrated that agonist-antagonist coactivation enhanced MEP amplitude and reduced MEP CVs for both TA and soleus muscles. Our results provide methodological considerations for future TMS studies and pave the way for future exploration of coactivation-dependent modulation of corticomotor excitability in pathological cohorts such as stroke or spinal cord injury.

4.
NeuroRehabilitation ; 44(4): 587-597, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31256089

RESUMO

BACKGROUND: Downslope walking (DSW) is an eccentric-based exercise intervention that promotes neuroplasticity of spinal reflex circuitry by inducing depression of Soleus Hoffman (H)-reflexes in young, neurologically unimpaired adults. OBJECTIVE: The objective of the study was to evaluate the effects of DSW on spinal excitability (SE) and walking function (WF) in people with multiple sclerosis (PwMS). METHODS: Our study comprised two experiments on 12 PwMS (11 women; 45.3±11.8 years). Experiment 1 evaluated acute effects of a single 20-minute session of treadmill walking at three different walking grades on SE, 0% or level walking (LW), - 7.5% DSW, and - 15% DSW. Experiment 2 evaluated the effects of 6 sessions of DSW, at - 7.5% DSW (with second session being - 15% DSW) on SE and WF. RESULTS: Experiment 1 showed significantly greater acute % H-reflex depression following - 15% DSW compared to LW (p = 0.02) and - 7.5% DSW (p = 0.05). Experiment 2 demonstrated significant improvements in WF. PwMS who showed greater acute H-reflex depression during the - 15% DSW session also demonstrated greater physical activity, long-distance WF, and the ability to have greater H-reflex depression after DSW training. Significant changes were not observed in regards to SE. CONCLUSIONS: Though significant changes were not observed in SE after DSW training, we observed an improvement in WF which merits further investigation of DSW in PwMS.


Assuntos
Teste de Esforço/métodos , Reflexo H/fisiologia , Esclerose Múltipla/fisiopatologia , Esclerose Múltipla/terapia , Caminhada/fisiologia , Adulto , Idoso , Eletromiografia/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/diagnóstico , Músculo Esquelético/fisiopatologia , Plasticidade Neuronal/fisiologia , Resultado do Tratamento , Adulto Jovem
5.
J Neurophysiol ; 122(1): 277-289, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31066611

RESUMO

Muscle coordination is often impaired after stroke, leading to deficits in the control of walking and balance. In this study, we examined features of muscle coordination associated with reduced walking performance in chronic stroke survivors using motor module (a.k.a. muscle synergy) analysis. We identified differences between stroke survivors and age-similar neurotypical controls in the modular control of both overground walking and standing reactive balance. In contrast to previous studies that demonstrated reduced motor module number poststroke, our cohort of stroke survivors did not exhibit a reduction in motor module number compared with controls during either walking or reactive balance. Instead, the pool of motor modules common to walking and reactive balance was smaller, suggesting reduced generalizability of motor module function across behaviors. The motor modules common to walking and reactive balance tended to be less variable and more distinct, suggesting more reliable output compared with motor modules specific to either behavior. Greater motor module generalization in stroke survivors was associated with faster walking speed, more normal step length asymmetry, and narrower step widths. Our work is the first to show that motor module generalization across walking and balance may help to distinguish important and clinically relevant differences in walking performance across stroke survivors that would have been overlooked by examining only a single behavior. Finally, because similar relationships between motor module generalization and walking performance have been demonstrated in healthy young adults and individuals with Parkinson's disease, this suggests that motor module generalization across walking and balance may be important for well-coordinated walking. NEW & NOTEWORTHY This is the first work to simultaneously examine neuromuscular control of walking and standing reactive balance in stroke survivors. We show that motor module generalization across these behaviors (i.e., recruiting common motor modules) is reduced compared with controls and is associated with slower walking speeds, asymmetric step lengths, and larger step widths. This is true despite no between-group differences in module number, suggesting that motor module generalization across walking and balance is important for well-coordinated walking.

6.
Neuroscience ; 391: 73-80, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30223021

RESUMO

Downslope walking (DSW) causes H-reflex depression in healthy adults, and thus may hold promise for inducing spinal reflex plasticity in people with Multiple Sclerosis (PwMS). The study purpose was to test the hypothesis that DSW will cause acute depression of spinal excitability in PwMS. Soleus H-reflexes were measured in PwMS (n = 18) before and after 20 min of treadmill walking during three visits. Participants walked on a different slope each visit [level: 0% level walking (LW), upslope: +7.5% treadmill walking with an upslope (USW) or downslope: -7.5% (DSW)]. The soleus Hmax/Mmax ratio was used to measure spinal excitability. Heart rate and ratings of perceived exertion (RPE) were measured during walking. DSW induced the largest change in spinal excitability (a 26.7% reduction in soleus Hmax/Mmax (p = 0.001)), although LW also reduced Hmax/Mmax (-5.3%, p = 0.05). Heart rate (p < 0.001) was lowest for DSW, and RPE for DSW did not exceed "Fairly light". DSW evokes short-term spinal plasticity in PwMS, while requiring no greater effort than LW. Our results suggest that PwMS retain the capacity for DSW-induced short-term spinal reflex modulation previously found in healthy adults. These results may provide a foundation for further investigation of long-term effects of DSW on spinal reflex plasticity and functional ability in PwMS.


Assuntos
Reflexo H , Esclerose Múltipla/fisiopatologia , Músculo Esquelético/fisiopatologia , Caminhada , Adulto , Eletromiografia , Técnicas de Exercício e de Movimento/métodos , Teste de Esforço , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/reabilitação
7.
Restor Neurol Neurosci ; 36(3): 333-348, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29758954

RESUMO

Neuroplasticity is a fundamental yet relatively unexplored process that can impact rehabilitation of lower extremity (LE) movements. Transcranial magnetic stimulation (TMS) has gained widespread application as a non-invasive brain stimulation technique for evaluating neuroplasticity of the corticospinal pathway. However, a majority of TMS studies have been performed on hand muscles, with a paucity of TMS investigations focused on LE muscles. This perspective review paper proposes that there are unique methodological challenges associated with using TMS to evaluate corticospinal excitability of lower limb muscles. The challenges include: (1) the deeper location of the LE motor homunculus; (2) difficulty with targeting individual LE muscles during TMS; and (3) differences in corticospinal circuity controlling upper and lower limb muscles. We encourage future investigations that modify traditional methodological approaches to help address these challenges. Systematic TMS investigations are needed to determine the extent of overlap in corticomotor maps for different LE muscles. A simple, yet informative methodological solution involves simultaneous recordings from multiple LE muscles, which will provide the added benefit of observing how other relevant muscles co-vary in their responses during targeted TMS assessment directed toward a specific muscle. Furthermore, conventionally used TMS methods (e.g., determination of hot spot location and motor threshold) may need to be modified for TMS studies involving LE muscles. Additional investigations are necessary to determine the influence of testing posture as well as activation state of adjacent and distant LE muscles on TMS-elicited responses. An understanding of these challenges and solutions specific to LE TMS will improve the ability of neurorehabilitation clinicians to interpret TMS literature, and forge novel future directions for neuroscience research focused on elucidating neuroplasticity processes underlying locomotion and gait training.


Assuntos
Potencial Evocado Motor/fisiologia , Extremidade Inferior/fisiologia , Plasticidade Neuronal/fisiologia , Estimulação Magnética Transcraniana , Animais , Mãos/fisiologia , Humanos , Córtex Motor/fisiologia
8.
Top Stroke Rehabil ; 25(3): 186-193, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29457532

RESUMO

Objectives Gait training interventions that target paretic propulsion induce improvements in walking speed and function in individuals post-stroke. Previously, we demonstrated that able-bodied individuals increase propulsion unilaterally when provided real-time biofeedback targeting anterior ground reaction forces (AGRF). The purpose of this study was to, for the first time, investigate short-term effects of real-time AGRF gait biofeedback training on post-stroke gait. Methods Nine individuals with post-stroke hemiparesis (6 females, age = 54 ± 12.4 years 39.2 ± 24.4 months post-stroke) completed three 6-minute training bouts on an instrumented treadmill. During training, visual and auditory biofeedback were provided to increase paretic AGRF during terminal stance. Gait biomechanics were evaluated before training, and during retention tests conducted 2, 15, and 30 minutes post-training. Primary dependent variables were paretic and non-paretic peak AGRF; secondary variables included paretic and non-paretic peak trailing limb angle, plantarflexor moment, and step length. In addition to evaluating the effects of biofeedback training on these dependent variables, we compared effects of a 6-minute biofeedback training bout to a non-biofeedback control condition. Results Compared to pre-training, significantly greater paretic peak AGRFs were generated during the 2, 15, and 30-minute retention tests conducted after the 18-minute biofeedback training session. Biofeedback training induced no significant effects on the non-paretic leg. Comparison of a 6-minute biofeedback training bout with a speed-matched control bout without biofeedback demonstrated a main effect for training type, with greater peak AGRF generation during biofeedback. Discussion Our results suggest that AGRF biofeedback may be a feasible and promising gait training strategy to target propulsive deficits in individuals post-stroke.


Assuntos
Biorretroalimentação Psicológica/métodos , Terapia por Exercício/métodos , Transtornos Neurológicos da Marcha/terapia , Paresia/terapia , Reabilitação do Acidente Vascular Cerebral/métodos , Acidente Vascular Cerebral/terapia , Adulto , Idoso , Fenômenos Biomecânicos , Feminino , Transtornos Neurológicos da Marcha/etiologia , Humanos , Masculino , Pessoa de Meia-Idade , Paresia/etiologia , Acidente Vascular Cerebral/complicações
9.
Restor Neurol Neurosci ; 36(1): 131-146, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29439363

RESUMO

BACKGROUND: The use of transcranial magnetic stimulation (TMS) to evaluate corticomotor excitability of lower limb (LL) muscles can provide insights about neuroplasticity mechanisms underlying LL rehabilitation. However, to date, a majority of TMS studies have focused on upper limb muscles. Posture-related activation is an important under-investigated factor influencing corticomotor excitability of LL muscles. OBJECTIVE: The purpose of this study was to evaluate effects of posture and background activation on corticomotor excitability of ankle muscles. METHODS: Fourteen young neurologically-unimpaired participants (26.1±4.1 years) completed the study. TMS-evoked motor evoked potentials (MEPs) were recorded from the tibialis anterior (TA) and soleus during 4 conditions - standing, standing coactivation, sitting, and sitting coactivation. TA and soleus MEP amplitudes were compared during: (1) standing versus sitting;(2) standing coactivation (standing while activating both TA and soleus) versus sitting coactivation; and (3) standing coactivation versus standing. For each comparison, background EMG for TA and soleus were matched. Trial-to-trial coefficient of variation of MEP amplitude and coil-positioning errors were additional dependent variables. RESULTS: No differences were observed in TA or soleus MEP amplitudes during standing versus sitting. Compared to sitting coactivation, larger MEPs were observed during standing coactivation for soleus but not TA. Compared to standing, the standing coactivation task demonstrated larger MEPs and reduced trial-to-trial MEP variability. CONCLUSION: Our findings suggest that incorporation of measurements in standing in future TMS studies may provide novel insights into neural circuits controlling LL muscles. Standing and standing coactivation tasks may be beneficial for obtaining functionally-relevant neuroplasticity assessments of LL musculature.


Assuntos
Tornozelo/inervação , Potencial Evocado Motor/fisiologia , Músculo Esquelético/fisiologia , Estimulação Magnética Transcraniana/métodos , Adulto , Análise de Variância , Eletromiografia , Feminino , Humanos , Masculino , Contração Muscular/fisiologia , Neurorretroalimentação , Postura , Adulto Jovem
10.
Front Neurol ; 9: 1127, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30619077

RESUMO

Background: Previous studies have demonstrated that post-stroke gait rehabilitation combining functional electrical stimulation (FES) applied to the ankle muscles during fast treadmill walking (FastFES) improves gait biomechanics and clinical walking function. However, there is considerable inter-individual variability in response to FastFES. Although FastFES aims to sculpt ankle muscle coordination, whether changes in ankle muscle activity underlie observed gait improvements is unknown. The aim of this study was to investigate three cases illustrating how FastFES modulates ankle muscle recruitment during walking. Methods: We conducted a preliminary case series study on three individuals (53-70 y; 2 M; 35-60 months post-stroke; 19-22 lower extremity Fugl-Meyer) who participated in 18 sessions of FastFES (3 sessions/week; ClinicalTrials.gov: NCT01668602). Clinical walking function (speed, 6-min walk test, and Timed-Up-and-Go test), gait biomechanics (paretic propulsion and ankle angle at initial-contact), and plantarflexor (soleus)/dorsiflexor (tibialis anterior) muscle recruitment were assessed pre- and post-FastFES while walking without stimulation. Results:Two participants (R1, R2) were categorized as responders based on improvements in clinical walking function. Consistent with heterogeneity of clinical and biomechanical changes commonly observed following gait rehabilitation, how muscle activity was altered with FastFES differed between responders. R1 exhibited improved plantarflexor recruitment during stance accompanied by increased paretic propulsion. R2 exhibited improved dorsiflexor recruitment during swing accompanied by improved paretic ankle angle at initial-contact. In contrast, the third participant (NR1), classified as a non-responder, demonstrated increased ankle muscle activity during inappropriate phases of the gait cycle. Across all participants, there was a positive relationship between increased walking speeds after FastFES and reduced SOL/TA muscle coactivation. Conclusion:Our preliminary case series study is the first to demonstrate that improvements in ankle plantarflexor and dorsiflexor muscle recruitment (muscles targeted by FastFES) accompanied improvements in gait biomechanics and walking function following FastFES in individuals post-stroke. Our results also suggest that inducing more appropriate (i.e., reduced) ankle plantar/dorsi-flexor muscle coactivation may be an important neuromuscular mechanism underlying improvements in gait function after FastFES training, suggesting that pre-treatment ankle muscle status could be used for inclusion into FastFES. The findings of this case-series study, albeit preliminary, provide the rationale and foundations for larger-sample studies using similar methodology.

11.
Neurology (ECronicon) ; 10(8): 761-770, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31032493

RESUMO

Objectives: The Hoffman-reflex (H-reflex) is an electrophysiological technique used to evaluate the excitability of the monosynaptic spinal reflex arc. In individuals with upper motor neuron lesions who show elevated spinal excitability, a depression of spinal excitability may indicate adaptive spinal plasticity. Downslope walking (DSW), an exercise intervention comprising repetitive eccentric muscle activity, has been shown to induce depression of soleus H-reflex amplitudes while seated, however, the dose-response time-course of H-reflex modulation during DSW has not been characterized. The objectives of this study were twofold: (1) to evaluate DSW-induced soleus H-reflex depression in the standing posture and during walking, and (2) to investigate the effect of walking duration (20 minutes and 40 minutes) of DSW (-15% decline) on soleus H-reflexes, (with level walking (LW) as a control intervention). Methods: Soleus H-reflexes were collected Pre, Post-20 minutes, and Post-40 minutes of walking in the standing position; and H-reflexes were also measured at 4 different time points during the terminal stance phase of walking. Results: Our results showed that soleus H-reflexes evaluated in standing showed a greater % depression after DSW compared to LW, with a statistical trend for greater depression with longer durations (40-minutes). H-reflexes measured during walking showed greater depression after 40 minutes of walking compared to 20- or 30-minutes for both DSW and LW. Conclusions: Longer duration treadmill walking (40-minutes) may induce a greater acute depressive effect on soleus H-reflex excitability compared to shorter durations (20-minutes) of treadmill walking. Future work will investigate the potential for DSW as a gait training intervention in people with upper motor neuron lesions such as multiple sclerosis and stroke.

12.
Brain Res ; 1670: 106-117, 2017 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-28633996

RESUMO

Primary motor cortex (M1) plasticity is involved in motor learning and stroke motor recovery, and enhanced by increasing monoaminergic transmission. Age impacts these processes but there is a paucity of systematic studies on the effects of monoaminergic drugs in older adults. Here, in ten older adults (age 61+4years, 4 males), we determine the effects of a single oral dose of carbidopa/levodopa (DOPA), d-amphetamine (AMPH), methylphenidate (MEPH) and placebo (PLAC) on M1 excitability and motor training-induced M1 plasticity. M1 plasticity is defined as training related long lasting changes in M1 excitability and kinematics of the trained movement. At peak plasma level of the drugs, subjects trained wrist extension movements for 30min. Outcome measures were motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation at increasing intensity (stimulus response curve, SRC) and peak acceleration of the trained wrist extension movements. Measures were obtained before and after completion of training. The curve parameters plateau (MEPmax), inflection point, and slope were extracted from SRC. At baseline drugs had a differential effect on curve parameters, while kinematics remained unchanged. Training alone (PLAC) increased MEPmax but did not improve kinematics. Drugs affected training-related changes of the curve parameters differently, but did not enhance them or kinematics when compared to PLAC. The results demonstrate that in the older adults, MEPH, DOPA, or AMPH have differential effects on baseline M1 excitability and training-related M1 plasticity but fail to enhance them above the naïve level.


Assuntos
Monoaminas Biogênicas/farmacologia , Córtex Motor/efeitos dos fármacos , Plasticidade Neuronal/efeitos dos fármacos , Idoso , Fenômenos Biomecânicos/efeitos dos fármacos , Carbidopa/farmacologia , Estudos Cross-Over , Dextroanfetamina/farmacologia , Método Duplo-Cego , Combinação de Medicamentos , Eletromiografia , Potencial Evocado Motor/efeitos dos fármacos , Potencial Evocado Motor/fisiologia , Feminino , Humanos , Levodopa/farmacologia , Masculino , Metilfenidato/farmacologia , Pessoa de Meia-Idade , Córtex Motor/fisiologia , Destreza Motora/fisiologia , Movimento/fisiologia , Músculo Esquelético/fisiologia , Estimulação Magnética Transcraniana/métodos , Punho
13.
J Neuroeng Rehabil ; 14(1): 52, 2017 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-28583196

RESUMO

BACKGROUND: In individuals with post-stroke hemiparesis, reduced push-off force generation in the paretic leg negatively impacts walking function. Gait training interventions that increase paretic push-off can improve walking function in individuals with neurologic impairment. During normal locomotion, push-off forces are modulated with variations in gait speed and slope. However, it is unknown whether able-bodied individuals can selectively modulate push-off forces from one leg in response to biofeedback. Here, in a group of young, neurologically-unimpaired individuals, we determined the effects of a real-time visual and auditory biofeedback gait training paradigm aimed at unilaterally increasing anteriorly-directed ground reaction force (AGRF) in the targeted leg. METHODS: Ground reaction force data during were collected from 7 able-bodied individuals as they walked at a self-selected pace on a dual-belt treadmill instrumented with force platforms. During 11-min of gait training, study participants were provided real-time AGRF biofeedback encouraging a 20-30% increase in peak AGRF generated by their right (targeted) leg compared to their baseline (pre-training) AGRF. AGRF data were collected before, during, and after the biofeedback training period, as well as during two retention tests performed without biofeedback and after standing breaks. RESULTS: Compared to AGRFs generated during the pre-training gait trials, participants demonstrated a significantly greater AGRF in the targeted leg during and immediately after training, indicating that biofeedback training was successful at inducing increased AGRF production in the targeted leg. Additionally, participants continued to demonstrate greater AGRF production in the targeted leg after two standing breaks, showing short-term recall of the gait pattern learned during the biofeedback training. No significant effects of training were observed on the AGRF in the non-targeted limb, showing the specificity of the effects of biofeedback toward the targeted limb. CONCLUSIONS: These results demonstrate the short-term effects of using unilateral AGRF biofeedback to target propulsion in a specific leg, which may have utility as a training tool for individuals with gait deficits such as post-stroke hemiparesis. Future studies are needed to investigate the effects of real-time AGRF biofeedback as a gait training tool in neurologically-impaired individuals.


Assuntos
Biorretroalimentação Psicológica/métodos , Marcha/fisiologia , Reabilitação do Acidente Vascular Cerebral/métodos , Adulto , Feminino , Voluntários Saudáveis , Humanos , Masculino , Paresia/reabilitação , Caminhada/fisiologia , Velocidade de Caminhada
14.
J Neurophysiol ; 117(4): 1615-1624, 2017 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-28077661

RESUMO

Imbalance of corticomotor excitability between the paretic and nonparetic limbs has been associated with the extent of upper extremity motor recovery poststroke, is greatly influenced by specific testing conditions such as the presence or absence of volitional muscle activation, and may vary across muscle groups. However, despite its clinical importance, poststroke corticomotor drive to lower extremity muscles has not been thoroughly investigated. Additionally, whereas conventional gait rehabilitation strategies for stroke survivors focus on paretic limb foot drop and dorsiflexion impairments, most contemporary literature has indicated that paretic limb propulsion and plantarflexion impairments are the most significant limiters to poststroke walking function. The purpose of this study was to compare corticomotor excitability of the dorsi- and plantarflexor muscles during resting and active conditions in individuals with good and poor poststroke walking recovery and in neurologically intact controls. We found that plantarflexor muscles showed reduced corticomotor symmetry between paretic and nonparetic limbs compared with dorsiflexor muscles in individuals with poor poststroke walking recovery during active muscle contraction but not during rest. Reduced plantarflexor corticomotor symmetry during active muscle contraction was a result of reduced corticomotor drive to the paretic muscles and enhanced corticomotor drive to the nonparetic muscles compared with the neurologically intact controls. These results demonstrate that atypical corticomotor drive exists in both the paretic and nonparetic lower limbs and implicate greater severity of corticomotor impairments to plantarflexor vs. dorsiflexor muscles during muscle activation in stroke survivors with poor walking recovery.NEW & NOTEWORTHY The present study observed that lower-limb corticomotor asymmetry resulted from both reduced paretic and enhanced nonparetic limb corticomotor excitability compared with neurologically intact controls. The most asymmetrical corticomotor drive was observed in the plantarflexor muscles of individuals with poor poststroke walking recovery. This suggests that neural function of dorsi- and plantarflexor muscles in both paretic and nonparetic limbs may play a role in poststroke walking function, which may have important implications when developing targeted poststroke rehabilitation programs to improve walking ability.


Assuntos
Potencial Evocado Motor/fisiologia , Extremidade Inferior/fisiopatologia , Músculo Esquelético/fisiopatologia , Descanso/fisiologia , Acidente Vascular Cerebral/patologia , Idoso , Análise de Variância , Estudos Transversais , Eletromiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Paresia/etiologia , Acidente Vascular Cerebral/complicações , Estimulação Magnética Transcraniana , Adulto Jovem
16.
Neuron ; 86(1): 38-54, 2015 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-25856485

RESUMO

Neuromechanical principles define the properties and problems that shape neural solutions for movement. Although the theoretical and experimental evidence is debated, we present arguments for consistent structures in motor patterns, i.e., motor modules, that are neuromechanical solutions for movement particular to an individual and shaped by evolutionary, developmental, and learning processes. As a consequence, motor modules may be useful in assessing sensorimotor deficits specific to an individual and define targets for the rational development of novel rehabilitation therapies that enhance neural plasticity and sculpt motor recovery. We propose that motor module organization is disrupted and may be improved by therapy in spinal cord injury, stroke, and Parkinson's disease. Recent studies provide insights into the yet-unknown underlying neural mechanisms of motor modules, motor impairment, and motor learning and may lead to better understanding of the causal nature of modularity and its underlying neural substrates.


Assuntos
Encéfalo/fisiologia , Transtornos dos Movimentos/reabilitação , Movimento/fisiologia , Plasticidade Neuronal/fisiologia , Fenômenos Biomecânicos , Humanos
17.
J Neurol Phys Ther ; 38(3): 183-9, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24933501

RESUMO

INTRODUCTION: To develop more effective gait rehabilitation strategies, it is important to understand the time course of motor learning that underlies improvements achieved with gait training. The purpose of this case study was to evaluate motor learning through the measurement of within-session and across-session changes in gait biomechanics during the first and sixth weeks of a 6-week clinical gait training program. CASE DESCRIPTION: A 47-year-old man with poststroke left hemiparesis participated in the study (15.5 months poststroke, lower extremity Fugl-Meyer score of 12). INTERVENTION: The subject participated in 6 weeks of training with 3 sessions per week, comprising fast treadmill walking and functional electrical stimulation to plantar and dorsiflexors. In one training session during the first and sixth weeks, paretic propulsion and swing phase knee flexion were measured during a pretest (before the training session), posttest (after the training session), and retention test (48 hours after training). OUTCOMES: After 6 week of training, the subject's gait speed increased from 0.38 to 0.57 m/s; there was a 55.4% improvement in paretic propulsion and 25% increase in swing phase knee flexion. Examination of change scores revealed greater within-session gains and greater retention during the first versus sixth weeks of gait training for both paretic propulsion and knee flexion. DISCUSSION: We demonstrate the feasibility and advantage of using within- and across-session changes for evaluating motor learning during clinical gait rehabilitation. An understanding of the time course of motor learning that underlies gait training can guide the development of novel strategies and dosing regimens to increase the efficacy of each session of gait rehabilitation. VIDEO ABSTRACT AVAILABLE: (See Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A72, for more insights from the authors.).


Assuntos
Transtornos Neurológicos da Marcha/reabilitação , Aprendizagem , Paresia/reabilitação , Modalidades de Fisioterapia , Reabilitação do Acidente Vascular Cerebral , Fenômenos Biomecânicos , Terapia por Estimulação Elétrica , Transtornos Neurológicos da Marcha/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Paresia/fisiopatologia , Recuperação de Função Fisiológica/fisiologia , Acidente Vascular Cerebral/fisiopatologia
18.
Arch Phys Med Rehabil ; 95(5): 840-8, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24378803

RESUMO

OBJECTIVES: To determine the feasibility and safety of implementing a 12-week locomotor intervention targeting paretic propulsion deficits during walking through the joining of 2 independent interventions, walking at maximal speed on a treadmill and functional electrical stimulation of the paretic ankle musculature (FastFES); to determine the effects of FastFES training on individual subjects; and to determine the influence of baseline impairment severity on treatment outcomes. DESIGN: Single group pre-post preliminary study investigating a novel locomotor intervention. SETTING: Research laboratory. PARTICIPANTS: Individuals (N=13) with locomotor deficits after stroke. INTERVENTION: FastFES training was provided for 12 weeks at a frequency of 3 sessions per week and 30 minutes per session. MAIN OUTCOME MEASURES: Measures of gait mechanics, functional balance, short- and long-distance walking function, and self-perceived participation were collected at baseline, posttraining, and 3-month follow-up evaluations. Changes after treatment were assessed using pairwise comparisons and compared with known minimal clinically important differences or minimal detectable changes. Correlation analyses were run to determine the correlation between baseline clinical and biomechanical performance versus improvements in walking speed. RESULTS: Twelve of the 13 subjects that were recruited completed the training. Improvements in paretic propulsion were accompanied by improvements in functional balance, walking function, and self-perceived participation (each P<.02)-all of which were maintained at 3-month follow-up. Eleven of the 12 subjects achieved meaningful functional improvements. Baseline impairment was predictive of absolute, but not relative, functional change after training. CONCLUSIONS: This report demonstrates the safety and feasibility of the FastFES intervention and supports further study of this promising locomotor intervention for persons poststroke.


Assuntos
Terapia por Exercício/instrumentação , Transtornos Neurológicos da Marcha/reabilitação , Marcha/fisiologia , Locomoção/fisiologia , Recuperação de Função Fisiológica , Reabilitação do Acidente Vascular Cerebral , Caminhada/fisiologia , Idoso , Teste de Esforço , Feminino , Seguimentos , Transtornos Neurológicos da Marcha/etiologia , Transtornos Neurológicos da Marcha/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Aparelhos Ortopédicos , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/fisiopatologia , Resultado do Tratamento
19.
J Neurol Phys Ther ; 37(4): 159-65, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24189337

RESUMO

BACKGROUND AND PURPOSE: In rehabilitation, examining how variables change over time can help define the minimal number of training sessions required to produce a desired change. The purpose of this study was to identify the time course of changes in gait biomechanics and walking function in persons with chronic stroke. METHODS: Thirteen persons who were more than 6 months poststroke participated in 12 weeks of fast treadmill training combined with plantar- and dorsiflexor muscle functional electrical stimulation (FastFES). All participants completed testing before the start of intervention, after 4, 8, and 12 weeks of FastFES locomotor training. RESULTS: Peak limb paretic propulsion, paretic limb propulsive integral, peak paretic limb knee flexion (P < 0.05 for all), and peak paretic trailing limb angle (P < 0.01) improved from pretraining to 4 weeks but not between 4 and 12 weeks. Self-selected walking speed and 6-minute walk test distance improved from pretraining to 4 weeks and from 4 to 12 weeks (P < 0.01 and P < 0.05, respectively for both). Timed Up & Go test time did not improve between pretraining and 4 weeks, but improved by 12 weeks (P = 0.24 and P < 0.01, respectively). DISCUSSION AND CONCLUSIONS: The results demonstrate that walking function improves with a different time course compared with gait biomechanics in response to a locomotor training intervention in persons with chronic stroke. Thirty-six training sessions were necessary to achieve an increase in walking speed that exceeded the minimally clinically important difference. These findings should be considered when designing locomotor training interventions after stroke.Video Abstract available (see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A63) for more insights from the authors.


Assuntos
Terapia por Exercício/métodos , Transtornos Neurológicos da Marcha/reabilitação , Marcha/fisiologia , Recuperação de Função Fisiológica/fisiologia , Reabilitação do Acidente Vascular Cerebral , Caminhada/fisiologia , Adulto , Fenômenos Biomecânicos/fisiologia , Feminino , Transtornos Neurológicos da Marcha/etiologia , Transtornos Neurológicos da Marcha/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/fisiopatologia , Fatores de Tempo , Resultado do Tratamento
20.
J Sport Rehabil ; 22(3): 202-11, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23579401

RESUMO

CONTEXT: Current research into the etiology of joint instability has yielded inconsistent results, limiting our understanding of how to prevent and treat ligamentous injury effectively. Recently, cortical reorganization was demonstrated in patients with ligamentous injury; however, these neural changes have not been assessed relative to joint laxity. OBJECTIVE: The purpose of the current study was to determine if changes in cortical excitability and inhibition occur in subjects with functional ankle instability, as well as to investigate the relationship between these measures and joint laxity. DESIGN: Posttest only with control group. SETTING: University laboratory. SUBJECTS: 12 subjects with no history of ankle sprain (CON) and 12 subjects with a history of unilateral functional ankle instability (UNS). INTERVENTIONS: Subjects were tested for joint laxity using an instrumented ankle arthrometer. Cortical excitability and inhibition were assessed using transcranial magnetic stimulation (TMS) to obtain motor-evoked potentials and the cortical silent period from the lower leg muscles. MAIN OUTCOME MEASURES: Joint laxity was quantified as peak anterior displacement and inversion rotation. Active motor threshold, slope, and intensity at 50% of peak slope of TMS-derived recruitment curves were used to quantify cortical excitability from lower leg muscles, while the cortical silent period from the peroneus longus was used to represent intracortical inhibition. RESULTS: No significant differences were observed between groups for laxity or cortical measures. CON demonstrated a significant relationship between laxity and tibialis anterior excitability, as well as laxity and silent period, while UNS ankles demonstrated significant relationships between peroneal and soleus excitability and laxity measures. CONCLUSION: Our results support relationships between laxity and measures of excitability and inhibition that differ between healthy and unstable subjects. Future research should further investigate the mechanisms behind these findings and consider cortical influences when investigating altered joint laxity.


Assuntos
Articulação do Tornozelo/fisiopatologia , Encéfalo/fisiopatologia , Instabilidade Articular/fisiopatologia , Tono Muscular/fisiologia , Músculo Esquelético/fisiopatologia , Adulto , Artrometria Articular , Fenômenos Biomecânicos , Potencial Evocado Motor , Feminino , Humanos , Masculino , Estimulação Magnética Transcraniana , Adulto Jovem
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