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

Effects of an experimental modification of the posturo-kinetic capacity induced by two types of physical exercises on the biomechanical organization of walking and gait initiation : whole-body vibrations and muscle stretching

La « capacité posturo-cinétique » correspond à la capacité du système nerveux central à générer des ajustements posturaux en réponse à une perturbation de la posture et de l’équilibre. Cette capacité dépend étroitement de la mobilité articulaire. L’objectif de cette thèse était d’étudier les effets d’une modification de la capacité posturo-cinétique induite par deux types d’exercices physiques (les « vibrations corps entier » [VCE] et les étirements musculaires) sur l’organisation biomécanique de la marche et de l’initiation de la marche dans différents types de populations (saines et pathologiques). Pour chaque type d’exercice, nous avons réalisé, d’une part, une revue systématique de la littérature avec méta-analyse sur les effets à long terme sur la marche et, d’autre part, une étude expérimentale sur les effets à court terme sur l’initiation de la marche. Les populations inclues dans nos études expérimentales étaient des jeunes adultes et des personnes âgées saines (VCE) et des patients atteints de la maladie de Parkinson (étirements musculaires).Les résultats de notre première expérimentation ont montré qu’une séance de VCE suffisait à améliorer la stabilité des jeunes adultes, et ce, malgré une augmentation de la raideur du membre portant. Cette amélioration de la stabilité était rendue possible grâce à une augmentation de l’amplitude des « ajustements posturaux anticipateurs » (APA). Aucun effet à court terme des VCE n’a été observé sur la raideur et les paramètres de l’initiation de la marche chez les personnes âgées en bonne santé. Les résultats de notre méta-analyse ont cependant montré que l’exposition aux VCE améliorait la marche dans cette population sur le long terme. Les résultats de notre seconde expérimentation ont montré qu’une seule séance d’étirements du triceps sural permettait d’améliorer le développement des APA et la performance motrice chez des patients parkinsoniens. En revanche, notre méta- analyse n’a pu démontrer de bénéfice significatif des étirements sur le long terme dans cette population par manque de données dans la littérature. L’ensemble de ces résultats conforte le concept biomécanique de capacité posturo-cinétique et devrait avoir des répercussions pertinentes dans le domaine de la réhabilitation motrice."Posturo-kinetic capacity" refers to the central nervous system's ability to generate postural adjustments in response to a postural perturbation. This ability is known to depend on joint mobility. The objective of this thesis was to study the effects of a change in posturo-kinetic capacity induced by two types of physical exercise (whole-body vibrations [WBV] and muscle stretching) on the biomechanical organization of walking and gait initiation in different types of population (healthy and pathological). For each exercise, we conducted a systematic review of the literature with meta- analysis on long-term effects on walking, and an experimental study on short-term effects on gait initiation. The populations included in the experimental studies were healthy young adults and elderly (WBV) and patients with Parkinson's disease (muscle stretching). Results of the first experiment showed that a single WBV session was enough to improve stability in young adults, despite an increase in the supporting limb stiffness. This improvement was made possible by an increase in the amplitude of "anticipating postural adjustments" (APA). In healthy elderly, no short-term WBV effects were observed on leg stiffness and gait initiation parameters. However, results of the meta-analysis showed that exposure to WBV improved walking in this population over the long term. Results of our second experiment showed that a single session of triceps surae stretching improved APA development and motor performance in patients with Parkinson's disease. However, the meta-analysis could not demonstrate a significant benefit of long-term stretching on walking in this population due to a lack of data in the literature. Together, these results support the biomechanical concept of posturo-kinetic capacity and may have relevant applications in the field of motor rehabilitation

Analyse des effets d’une modification expérimentale de la capacité posturo-cinétique induite par deux types d’exercices physiques sur l’organisation biomécanique de la marche et de l’initiation de la marche : vibrations du corps entier et étirements musculaires

"Posturo-kinetic capacity" refers to the central nervous system's ability to generate postural adjustments in response to a postural perturbation. This ability is known to depend on joint mobility. The objective of this thesis was to study the effects of a change in posturo-kinetic capacity induced by two types of physical exercise (whole-body vibrations [WBV] and muscle stretching) on the biomechanical organization of walking and gait initiation in different types of population (healthy and pathological). For each exercise, we conducted a systematic review of the literature with meta- analysis on long-term effects on walking, and an experimental study on short-term effects on gait initiation. The populations included in the experimental studies were healthy young adults and elderly (WBV) and patients with Parkinson's disease (muscle stretching). Results of the first experiment showed that a single WBV session was enough to improve stability in young adults, despite an increase in the supporting limb stiffness. This improvement was made possible by an increase in the amplitude of "anticipating postural adjustments" (APA). In healthy elderly, no short-term WBV effects were observed on leg stiffness and gait initiation parameters. However, results of the meta-analysis showed that exposure to WBV improved walking in this population over the long term. Results of our second experiment showed that a single session of triceps surae stretching improved APA development and motor performance in patients with Parkinson's disease. However, the meta-analysis could not demonstrate a significant benefit of long-term stretching on walking in this population due to a lack of data in the literature. Together, these results support the biomechanical concept of posturo-kinetic capacity and may have relevant applications in the field of motor rehabilitation.La « capacité posturo-cinétique » correspond à la capacité du système nerveux central à générer des ajustements posturaux en réponse à une perturbation de la posture et de l’équilibre. Cette capacité dépend étroitement de la mobilité articulaire. L’objectif de cette thèse était d’étudier les effets d’une modification de la capacité posturo-cinétique induite par deux types d’exercices physiques (les « vibrations corps entier » [VCE] et les étirements musculaires) sur l’organisation biomécanique de la marche et de l’initiation de la marche dans différents types de populations (saines et pathologiques). Pour chaque type d’exercice, nous avons réalisé, d’une part, une revue systématique de la littérature avec méta-analyse sur les effets à long terme sur la marche et, d’autre part, une étude expérimentale sur les effets à court terme sur l’initiation de la marche. Les populations inclues dans nos études expérimentales étaient des jeunes adultes et des personnes âgées saines (VCE) et des patients atteints de la maladie de Parkinson (étirements musculaires).Les résultats de notre première expérimentation ont montré qu’une séance de VCE suffisait à améliorer la stabilité des jeunes adultes, et ce, malgré une augmentation de la raideur du membre portant. Cette amélioration de la stabilité était rendue possible grâce à une augmentation de l’amplitude des « ajustements posturaux anticipateurs » (APA). Aucun effet à court terme des VCE n’a été observé sur la raideur et les paramètres de l’initiation de la marche chez les personnes âgées en bonne santé. Les résultats de notre méta-analyse ont cependant montré que l’exposition aux VCE améliorait la marche dans cette population sur le long terme. Les résultats de notre seconde expérimentation ont montré qu’une seule séance d’étirements du triceps sural permettait d’améliorer le développement des APA et la performance motrice chez des patients parkinsoniens. En revanche, notre méta- analyse n’a pu démontrer de bénéfice significatif des étirements sur le long terme dans cette population par manque de données dans la littérature. L’ensemble de ces résultats conforte le concept biomécanique de capacité posturo-cinétique et devrait avoir des répercussions pertinentes dans le domaine de la réhabilitation motrice