Anticipatory Postural Adjustments During Gait Initiation in Stroke Patients

Prior to gait initiation (GI), anticipatory postural adjustments (GI-APA) are activated in order to reorganize posture, favorably for gait. In healthy subjects, the center of pressure (CoP) is displaced backward during GI-APA, bilaterally by reducing soleus activities and activating the tibialis anterior (TA) muscles, and laterally in the direction of the leading leg, by activating hip abductors. In post-stroke hemiparetic patients, TA, soleus and hip abductor activities are impaired on the paretic side. Reduction in non-affected triceps surae activity can also be observed. These may result in a decreased ability to execute GI-APA and to generate propulsion forces during step execution. A systematic review was conducted to provide an overview of the reorganization which occurs in GI-APA following stroke as well as of the most effective strategies for tailoring gait-rehabilitation to these patients. Sixteen articles were included, providing gait data from a total of 220 patients. Stroke patients show a decrease in the TA activity associated with difficulties in silencing soleus muscle activity of the paretic leg, a decreased CoP shift, lower propulsive anterior forces and a longer preparatory phase. Regarding possible gait-rehabilitation strategies, the selected studies show that initiating gait with the paretic leg provides poor balance. The use of the non-paretic as the leading leg can be a useful exercise to stimulate the paretic postural muscles

Acute Effects of Whole-Body Vibration on the Postural Organization of Gait Initiation in Young Adults and Elderly: A Randomized Sham Intervention Study

Whole-body vibration (WBV) is a training method that exposes the entire body to mechanical oscillations while standing erect or seated on a vibrating platform. This method is nowadays commonly used by clinicians to improve specific motor outcomes in various sub-populations such as elderly and young healthy adults, either sedentary or well-trained. The present study investigated the effects of acute WBV application on the balance control mechanisms during gait initiation (GI) in young healthy adults and elderly. It was hypothesized that the balance control mechanisms at play during gait initiation may compensate each other in case one or several components are perturbed following acute WBV application, so that postural stability and/or motor performance can be maintained or even improved. It is further hypothesized that this capacity of adaptation is altered with aging. Main results showed that the effects of acute WBV application on the GI postural organization depended on the age of participants. Specifically, a positive effect was observed on dynamic stability in the young adults, while no effect was observed in the elderly. An increased stance leg stiffness was also observed in the young adults only. The positive effect of WBV on dynamic stability was ascribed to an increase in the mediolateral amplitude of ?anticipatory postural adjustments? following WBV application, which did overcompensate the potentially destabilizing effect of the increased stance leg stiffness. In elderly, no such anticipatory (nor corrective) postural adaptation was required since acute WBV application did not elicit any change in the stance leg stiffness. These results suggest that WBV application may be effective in improving dynamic stability but at the condition that participants are able to develop adaptive changes in balance control mechanisms, as did the young adults. Globally, these findings are thus in agreement with the hypothesis that balance control mechanisms are interdependent within the postural system, i.e., they may compensate each other in case one component (here the leg stiffness) is perturbed

Long-Term Effects of Whole-Body Vibration on Human Gait: A Systematic Review and Meta-Analysis

Background: Whole-body vibration is commonly used in physical medicine and neuro-rehabilitation as a clinical prevention and rehabilitation tool. The goal of this systematic review is to assess the long-term effects of whole-body vibration training on gait in different populations of patients.Methods: We conducted a literature search in PubMed, Science Direct, Springer, Sage and in study references for articles published prior to 7 December 2018. We used the keywords “vibration,” “gait” and “walk” in combination with their Medical Subject Headings (MeSH) terms. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was used. Only randomized controlled trials (RCT) published in English peer-reviewed journals were included. All patient categories were selected. The duration of Whole-Body Vibration (WBV) training had to be at least 4 weeks. The outcomes accepted could be clinical or biomechanical analysis. The selection procedure was conducted by two rehabilitation experts and disagreements were resolved by a third expert. Descriptive data regarding subjects, interventions, types of vibration, training parameters and main results on gait variables were collected and summarized in a descriptive table. The quality of selected studies was assessed using the PEDro scale. Statistical analysis was conducted to evaluate intergroup differences and changes after the WBV intervention compared to the pre-intervention status. The level of evidence was determined based on the results of meta-analysis (effect size), statistical heterogeneity (I2) and methodological quality (PEDro scale).Results: A total of 859 studies were initially identified through databases with 46 articles meeting all of the inclusion criteria and thus selected for qualitative assessment. Twenty-five studies were included in meta-analysis for quantitative synthesis. In elderly subjects, small but significant improvements in the TUG test (SMD = −0.18; 95% CI: −0.32, −0.04) and the 10MWT (SMD = −0.28; 95% CI: −0.56, −0.01) were found in the WBV groups with a strong level of evidence (I2 = 7%, p = 0.38 and I2 = 22%, p = 0.28, respectively; PEDro scores ≥5/10). However, WBV failed to improve the 6MWT (SMD = 0.37; 95% CI: −0.03, 0.78) and the Tinetti gait scores (SMD = 0.04; 95% CI: −0.23, 0.31) in older adults. In stroke patients, significant improvement in the 6MWT (SMD = 0.33; 95% CI: 0.06, 0.59) was found after WBV interventions, with a strong level of evidence (I2 = 0%, p = 0.58; PEDro score ≥5/10). On the other hand, there was no significant change in the TUG test despite a tendency toward improvement (SMD = −0.29; 95% CI: −0.60, 0.01). Results were inconsistent in COPD patients (I2 = 66%, p = 0.03), leading to a conflicting level of evidence despite a significant improvement with a large effect size (SMD = 0.92; 95% CI: 0.32, 1.51) after WBV treatment. Similarly, the heterogeneous results in the TUG test (I2 = 97%, p < 0.00001) in patients with knee osteoarthrosis make it impossible to draw a conclusion. Still, adding WBV treatment was effective in significantly improving the 6 MWT (SMD = 1.28; 95% CI: 0.57, 1.99), with a strong level of evidence (I2 = 64%, p = 0.06; PEDro score ≥5/10). As in stroke, WBV failed to improve the results of the TUG test in multiple sclerosis patients (SMD = −0.11; 95% CI: −0.64, 0.43). Other outcomes presented moderate or even limited levels of evidence due to the lack of data in some studies or because only one RCT was identified in the review.Conclusions: WBV training can be effective for improving balance and gait speed in the elderly. The intervention is also effective in improving walking performance following stroke and in patients with knee osteoarthrosis. However, no effect was found on gait quality in the elderly or on balance in stroke and multiple sclerosis patients. The results are too heterogenous in COPD to conclude on the effect of the treatment. The results must be taken with caution due to the lack of data in some studies and the methodological heterogeneity in the interventions. Further research is needed to explore the possibility of establishing a standardized protocol targeting gait ability in a wide range of populations

The SIB Swiss Institute of Bioinformatics' resources: focus on curated databases

The SIB Swiss Institute of Bioinformatics (www.isb-sib.ch) provides world-class bioinformatics databases, software tools, services and training to the international life science community in academia and industry. These solutions allow life scientists to turn the exponentially growing amount of data into knowledge. Here, we provide an overview of SIB's resources and competence areas, with a strong focus on curated databases and SIB's most popular and widely used resources. In particular, SIB's Bioinformatics resource portal ExPASy features over 150 resources, including UniProtKB/Swiss-Prot, ENZYME, PROSITE, neXtProt, STRING, UniCarbKB, SugarBindDB, SwissRegulon, EPD, arrayMap, Bgee, SWISS-MODEL Repository, OMA, OrthoDB and other databases, which are briefly described in this article

Unilateral biomechanical constraint versus bilateral biomechanical constraint : Rebalancing of functional capacities and improvement of performance on locomotive task

Dans la littérature, les résultats, dans le domaine de la rééducation neurologique des patients hémiplégiques, montraient que la performance motrice du membre atteint était améliorée lorsque les deux membres homolatéraux étaient mobilisés dans des mouvements symétriques. Il a alors été suggéré que le système nerveux avait plus de facilité à adapter une commande bilatérale symétrique, qu’une commande bilatérale asymétrique.L’objet des travaux dans cette thèse est de tester la généralité de ces résultats dans le cas du processus d’initiation de la marche (IM). Le handicap est simulé par une hypomobilité de la cheville, induite avec strapping et orthèse unilatéralement ou bilatéralement. Les résultats montrent que, dès la présence d’une contrainte, la biomécanique et les activités électromyographiques, des phases de préparation posturale et d’exécution du processus d’IM, sont modifiées. De plus, la performance motrice est également perturbée. Toutefois, il apparaît des différences « locales » selon où s'applique la contrainte. Un résultat est à souligner tout particulièrement : comme pour les patients hémi-handicapés, la performance motrice (i.e. vitesse du centre des masses à la fin du premier pas) est supérieure dans la condition « contrainte bilatérale i.e. hypomobilité des deux chevilles » versus « contrainte unilatérale i.e. hypomobilité du pied d’appui ». L’ensemble des résultats est discuté dans le cadre des processus d’adaptation de la commande motrice face aux contraintes biomécaniques unilatérales et bilatérales induites sur les appuis. En d'autres termes, tout se passe comme si un rééquilibrage des capacités fonctionnelles s’opère, permettant ainsi de générer une meilleure performance motrice. Enfin, les résultats permettent d’envisager des perspectives dans le domaine de la rééducation fonctionnelle.In the literature, the rehabilitation of hemiplegic patients showed that motor performance of the affected limb is improved when both limbs are mobilised in a symmetrical movement. It has been suggested that it was easier for the nervous system to adapt to symmetrical bilateral command. The aim of this dissertation is to test the validity of these results in gait initiation (GI). Handicap was simulated by means of blocking the ankle unilaterally or bilaterally with a strap or orthosis.Results showed that in the presence of a constraint, electromyographic activity and the kinematics of both postural preparation and step execution phase of GI declined. Furthermore, the motor performance was also perturbed.However, « Local » differences appeared according to the localisation of the constraint, reflecting the adaptation of the motor command. Nonetheless, a result needs to be particularly underlying.Like in hemi-handicapped patients, the motor performance (i.e. centre of mass velocity at the end of the first step) was higher in « bilateral constraint, hypomobility on both ankles » versus « unilateral constraint, hypomobility on stance ankle ».In the dissertation, the results are discussed in terms of the adaptation of the motor command of unilateral and bilateral induced biomechanical constraint. More specifically, we discuss how rebalancing the functional capacity of both legs should allow to increase motor performance. These results put forward new perspectives in the domain of functional rehabilitation

Vertical Center-of-Mass Braking and Motor Performance during Gait Initiation in Young Healthy Adults, Elderly Healthy Adults, and Patients with Parkinson’s Disease: A Comparison of Force-Plate and Markerless Motion Capture Systems

Background. This study tested the agreement between a markerless motion capture system and force-plate system (“gold standard”) to quantify stability control and motor performance during gait initiation. Methods. Healthy adults (young and elderly) and patients with Parkinson’s disease performed gait initiation series at spontaneous and maximal velocity on a system of two force-plates placed in series while being filmed by a markerless motion capture system. Signals from both systems were used to compute the peak of forward center-of-mass velocity (indicator of motor performance) and the braking index (indicator of stability control). Results. Descriptive statistics indicated that both systems detected between-group differences and velocity effects similarly, while a Bland–Altman plot analysis showed that mean biases of both biomechanical indicators were virtually zero in all groups and conditions. Bayes factor 01 indicated strong (braking index) and moderate (motor performance) evidence that both systems provided equivalent values. However, a trial-by-trial analysis of Bland–Altman plots revealed the possibility of differences >10% between the two systems. Conclusion. Although non-negligible differences do occur, a markerless motion capture system appears to be as efficient as a force-plate system in detecting Parkinson’s disease and velocity condition effects on the braking index and motor performance

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