Different Error Size During Locomotor Adaptation Affects Transfer to Overground Walking Poststroke.

BACKGROUND: Studies in neurologically intact subjects suggest that the gradual presentation of small perturbations (errors) during learning results in better transfer of a newly learned walking pattern to overground walking. Whether the same result would be true after stroke is not known. OBJECTIVE: To determine whether introducing gradual perturbations, during locomotor learning using a split-belt treadmill influences learning the novel walking pattern or transfer to overground walking poststroke. METHODS: Twenty-six chronic stroke survivors participated and completed the following walking testing paradigm: baseline overground walking; baseline treadmill walking; split-belt treadmill/adaptation period (belts moving at different speeds); catch trial (belts at same speed); post overground walking. Subjects were randomly assigned to the Gradual group (gradual changes in treadmill belts speed during adaptation) or the Abrupt group (a single, large, abrupt change during adaptation). Step length asymmetry adaptation response on the treadmill and transfer of learning to overground walking was assessed. RESULTS: Step length asymmetry during the catch trial was the same between groups ( P = .195) confirming that both groups learned a similar amount. The magnitude of transfer to overground walking was greater in the Gradual than in the Abrupt group ( P = .041). CONCLUSIONS: The introduction of gradual perturbations (small errors), compared with abrupt (larger errors), during a locomotor adaptation task seems to improve transfer of the newly learned walking pattern to overground walking poststroke. However, given the limited magnitude of transfer, future studies should examine other factors that could impact locomotor learning and transfer poststroke.

Post-stroke BDNF Concentration Changes Following Physical Exercise: A Systematic Review.

Background: Research over the last two decades has highlighted the critical role of Brain-derived neurotrophic factor (BDNF) in brain neuroplasticity. Studies suggest that physical exercise may have a positive impact on the release of BDNF and therefore, brain plasticity. These results in animal and human studies have potential implications for the recovery from damage to the brain and for interventions that aim to facilitate neuroplasticity and, therefore, the rehabilitation process. Purpose: The aim of this study was to carry out a systematic review of the literature investigating how aerobic exercises and functional task training influence BDNF concentrations post-stroke in humans and animal models. Data Sources: Searches were conducted in PubMed (via National Library of Medicine), SCOPUS (Elsevier), CINAHL with Full Text (EBSCO), MEDLINE 1946-present with daily updates (Ovid) and Cochrane. Study Selection: All of the database searches were limited to the period from January, 2004 to May, 2017. Data Extraction: Two reviewers extracted study details and data. The methodological quality of the studies that used animal models was assessed using the ARRIVE Guidelines, and the study that evaluated human BDNF was assessed using the PEDro Scale. Data Synthesis: Twenty-one articles were included in this review. BDNF measurements were performed systemically (serum/plasma) or locally (central nervous system). Only one study evaluated human BDNF concentrations following physical exercise, while 20 studies were experimental studies using a stroke model in animals. A wide variation was observed in the training protocol between studies, although treadmill walking was the most common type of intervention among the studies. Studies were of variable quality: the studies that used animal models scored from 8/20 to 15/20 according to the ARRIVE Guidelines. The only study that evaluated human subjects scored 5/10 according to the PEDro scale and, which indicates a quality classified as "fair". Conclusions: The results of the current systematic review suggest that aerobic exercise promotes changes in central BDNF concentrations post-stroke. On the other hand, BDNF responses following functional exercises, such as reaching training and Constraint Induced Movement Therapy (CIMT), seem to be still controversial. Given the lack of studies evaluating post-stroke BDNF concentration following physical exercise in humans, these conclusions are based on animal work.

Midfemoral Bone Volume of Walking Subjects with Chronic Hemiparesis Post Stroke.

BACKGROUND AND PURPOSE: Muscle and bone form a functional unit. Residual physical poststroke impairments such as muscle weakness, spasticity, and decrease in function can promote metabolic bone changes. Moreover, muscle strength can influence this process. Thus, the purpose of the present study was to investigate bone volume and mobility performance in subjects with chronic hemiparesis post stroke. METHODS: A cross-sectional study was performed on 14 subjects post stroke who were paired with healthy controls. Bone volume, isometric muscle performance, and mobility levels were measured. Midfemoral bone volumes were determined using magnetic resonance imaging, and muscular performance was measured by dynamometry. Mobility was measured using the Timed Up and Go Test and the 10-Meter Walk Test. RESULTS: Regarding bone volume total, there was no difference in the medullary and cortical groups (P ≥ .05). During torque peak isometric flexion, the paretic group was significantly different compared with the other groups (P = .001). However, the control presented no difference compared with the nonparetic limb (P = .40). With regard to the extension isometric torque peak, the paretic limb was significantly different compared with the nonparetic (P = .033) and the control (P = .001) limbs, and the control was different from the nonparetic limb (P = .045). Bone volume variables correlated with the isometric torque peak. CONCLUSIONS: Chronic hemiparetic subjects maintain bone geometry compared with healthy volunteers matched by age, body mass index, and gender. The correlation between bone volume midfemoral structures and knee isometric torque was possible.

A single exercise bout and locomotor learning after stroke: physiological, behavioural, and computational outcomes.

KEY POINTS: Previous work demonstrated an effect of a single high-intensity exercise bout coupled with motor practice on the retention of a newly acquired skilled arm movement, in both neurologically intact and impaired adults. In the present study, using behavioural and computational analyses we demonstrated that a single exercise bout, regardless of its intensity and timing, did not increase the retention of a novel locomotor task after stroke. Considering both present and previous work, we postulate that the benefits of exercise effect may depend on the type of motor learning (e.g. skill learning, sensorimotor adaptation) and/or task (e.g. arm accuracy-tracking task, walking). ABSTRACT: Acute high-intensity exercise coupled with motor practice improves the retention of motor learning in neurologically intact adults. However, whether exercise could improve the retention of locomotor learning after stroke is still unknown. Here, we investigated the effect of exercise intensity and timing on the retention of a novel locomotor learning task (i.e. split-belt treadmill walking) after stroke. Thirty-seven people post stroke participated in two sessions, 24 h apart, and were allocated to active control (CON), treadmill walking (TMW), or total body exercise on a cycle ergometer (TBE). In session 1, all groups exercised for a short bout (∼5 min) at low (CON) or high (TMW and TBE) intensity and before (CON and TMW) or after (TBE) the locomotor learning task. In both sessions, the locomotor learning task was to walk on a split-belt treadmill in a 2:1 speed ratio (100% and 50% fast-comfortable walking speed) for 15 min. To test the effect of exercise on 24 h retention, we applied behavioural and computational analyses. Behavioural data showed that neither high-intensity group showed greater 24 h retention compared to CON, and computational data showed that 24 h retention was attributable to a slow learning process for sensorimotor adaptation. Our findings demonstrated that acute exercise coupled with a locomotor adaptation task, regardless of its intensity and timing, does not improve retention of the novel locomotor task after stroke. We postulate that exercise effects on motor learning may be context specific (e.g. type of motor learning and/or task) and interact with the presence of genetic variant (BDNF Val66Met).

The use of the Gait Deviation Index for the evaluation Post-stroke Hemiparetic Subjects / O uso do índice de desvio de marcha para a avaliação de pacientes hemiparéticos após acidente vascular cerebral

BACKGROUND: The Gait Deviation Index, initially conceived to evaluate the gait of children with cerebral palsy, has been used as a quantitative parameter of gait pattern changes of individuals with other conditions. However, there are no studies evaluating changes in the gait pattern of chronic hemiparetic post-stroke subjects based on this index. AIMS: To characterize the changes in gait pattern according to the Gait Deviation Index and gait spatiotemporal parameters of chronic hemiparetic subjects compared to healthy subjects. METHODS: Retrospective study. Data were obtained from the database of the Gait Laboratory of Hospital Israelita Albert Einstein. Thirty subjects were included in this study, with previous unilateral, ischemic or hemorrhagic chronic stroke (time post-lesion > 6 months) and ability of walking classified as 2, 3, 4 or 5 according to Functional Ambulation Category. Data from 87 healthy subjects were included in control group, obtained from a normality database. Statistical analysis was applied through the Kruskall Wallis test, followed by Mann-Whitney post-hoc test, considering a critical p value <0.05. RESULTS: The Gait Deviation Index scores were decreased for both paretic (64.69 ± 16.29) and non-paretic limbs (64.88 ± 15.00) compared to control (101.01 ± 10.12; p < 0.001). No differences were observed in Gait Deviation Index scores between paretic and non-paretic limbs (p > 0.99). CONCLUSION: The findings of the current study demonstrate that the Gait Deviation Index may be a sensitive parameter to identify changes in the gait pattern of chronic hemiparetic post-stroke subjects.

BASES: O Índice de Desvio da Marcha, inicialmente utilizado para avaliar a marcha de crianças com paralisia cerebral, tem sido utilizado como parâmetro quantitativo de alterações de marcha de indivíduos com outras condições. No entanto, não existem estudos que avaliem alterações no padrão de marcha de indivíduos hemiparéticos crônicos pós-AVC com base nesse índice. OBJETIVOS: Caracterizar as alterações no padrão de marcha de acordo com o Índice de Desvio da Marcha e parâmetros espácio-temporais da marcha de sujeitos hemiparéticos crônicos em relação a indivíduos saudáveis. MÉTODOS: Estudo retrospetivos. Os dados foram obtidos a partir da base de dados do Laboratório de Marcha do Hospital Israelita Albert Einstein. Trinta indivíduos foram incluídos neste estudo, com AVC unilateral, isquêmico ou hemorrágico, crônico (tempo pós-lesão> 6 meses) e habilidade de caminhada classificada como 2, 3, 4 ou 5 segundo a Categoria de Ambulação Funcional. Os dados de 87 indivíduos saudáveis foram incluídos no grupo controle, obtido a partir da base de dados de normalidade. A análise estatística foi aplicada através do teste de Kruskall Wallis, seguido do teste pós-hoc de Mann-Whitney, considerando um valor p crítico <0,05. RESULTADOS: Os valores observados para o Índice de Desvio da Marcha foram menores para os membros paréticos (64,69 ± 16,29) e não-paréticos (64,88 ± 15) em relação ao controle (101,01 ± 10,12; p <0,001). Não foram observadas diferenças nos escores do Índice de Desvio da Marcha entre os membros paréticos e não paréticos (p> 0,99). CONCLUSÃO: Os achados do presente estudo demonstram que o Índice de Desvio da Marcha pode ser um parâmetro sensível para identificar alterações no padrão de marcha de indivíduos hemiparéticos crônicos pós-AVC.

Effect of low-level laser therapy (LLLT) on acute neural recovery and inflammation-related gene expression after crush injury in rat sciatic nerve.

BACKGROUND AND OBJECTIVES: Peripheral nerve function can be debilitated by different kinds of injury. Low-level laser therapy (LLLT) has been used successfully during rehabilitation to stimulate recovery. The aim of this study was to evaluate the effects of LLLT (660 nm, 60 J/cm(2) , 40 mW/cm(2) ) on acute sciatic nerve injury. MATERIALS AND METHODS: Thirty Wistar male rats were divided into three groups: (1) Normal, intact nerves; (2) I3d, crushed nerves evaluated on Day-3 post-injury; (3) I + L3d, crushed nerves submitted to two sessions of LLLT and investigated at 3 days post-injury. Sciatic nerves were removed and processed for gene expression analysis (real-time PCR) of the pro-inflammatory factors TWEAK, Fn14 and TNF-α and extracellular matrix remodeling and axonal growth markers, such as TIMP-1, MMP-2, and MMP-9. Zymography was used to determine levels of MMP-2 and MMP-9 activity and Western blotting was used to evaluate TNF-α protein content. Shapiro-Wilk and Levene's tests were applied to evaluate data normality and homogeneity, respectively. One-way ANOVA followed by Tukey test was used for statistical analysis with a significance level set at 5%. RESULTS: An increase in TNF-α protein level was found in I + L3 compared to Normal and I3d (P < 0.05). Zymography showed an increase in proMMP-9 activity, in both I3d and I + L3d groups (P < 0.05). The increase was more evident in I + L3d (P = 0.02 compared to I3d). Active-MMP-9 isoform activity was increased in I + L3d compared to Normal and I3d groups (P < 0.05). Furthermore, the activity of active-MMP-2 isoform was increased in I3d and I + L3 (P < 0.05). An increase in TIMP-1 expression was observed in both I3d and I + L3d groups (P < 0.05). CONCLUSIONS: The current study showed that LLLT increased MMPs activity, mainly MMP-9, and TNF-α protein level during the acute phase of nerve injury, modulating inflammation. Based on these results, it is recommended that LLLT should be started as soon as possible after peripheral nerve injury.

Brazilian version of an assessment tool for the evaluation of work organizational aspects (AOT) by the NIOSH WMSD Research Consortium: translation and application in industrial sectors.

Work organization affects the production of a company as well as the health of employees. It is a challenge to create sustainable production systems with the least harm to the health. An observational assessment tool was developed by the NIOSH--WMSD Research Consortium and adapted by the SHARP study. The objectives were to translate this assessment tool into Brazilian Portuguese (as the Avaliação de Aspectos Organizacionais do Trabalho--AOT) and to evaluate its applicability in an industrial setting. The AOT final translated version was obtained after a consensus by the research team. Difficulties arose in applying the translated version due to technical terms with no direct equivalents in Portuguese, nonexcluding or similar alternatives, and questions that gave room for various interpretations, besides the great complexity of the tasks performed in the sectors. Despite that, the results suggest that AOT was sensitive for discriminating differences between sectors. Nevertheless, for better application of this tool in complex industrial environments, it is necessary: training and consensus among evaluators, familiarity with organizational aspects of the occupational settings evaluated. Also for assuring the internal validity of the analysis, might be necessary, the creation of subdivisions in the sectors evaluated if the tasks vary significantly intra-sector. The present report can help to understand the difficulties inherent to the evaluation of organizational aspects on a collective level and also the possible implications related to the translation of this assessment into other languages.