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Post-stroke gait asymmetry leads to inefficient gait and a higher fall risk, often causing limited home and community ambulation. Two types of treadmills are typically used for training focused on symmetry: split-belt and single belt treadmills, but there is no consensus on which treadmill is superior to improve gait symmetry in individuals with stroke. To comprehensively determine which intervention is superior, we considered multiple spatial and temporal gait parameters (step length, stride time, swing time, and stance time) and their symmetries. Ten individuals with stroke underwent a single session of split-belt treadmill training and single belt treadmill training on separate days. The changes in step length, stride time, swing time, stance time and their respective symmetries were compared to investigate which training improves both spatiotemporal gait parameters and symmetries immediately after the intervention and after 5 min of rest. Both types of treadmill training immediately increased gait velocity (0.08 m/s faster) and shorter step length (4.15 cm longer). However, split-belt treadmill training was more effective at improving step length symmetry (improved by 27.3%) without sacrificing gait velocity or step length. However, this step length symmetry effect diminished after a 5-min rest period. Split-belt treadmill training may have some advantages over single belt treadmill training, when targeting step length symmetry. Future research should focus on comparing the long-term effects of these two types of training and examining the duration of the observed effects to provide clinically applicable information. [ABSTRACT FROM AUTHOR]

Background: Multiple sclerosis is a neurodegenerative disease that damages the myelin sheath within the central nervous system. Axonal demyelination, particularly in the corpus callosum, impacts communication between the brain's hemispheres in persons with multiple sclerosis (PwMS). Changes in interhemispheric communication may impair gait coordination which is modulated by communication across the corpus callosum to excite and inhibit specific muscle groups. To further evaluate the functional role of interhemispheric communication in gait and mobility, this study assessed the ipsilateral silent period (iSP), an indirect marker of interhemispheric inhibition and how it relates to gait adaptation in PwMS. Methods: Using transcranial magnetic stimulation (TMS), we assessed interhemispheric inhibition differences between the more affected and less affected hemisphere in the primary motor cortices in 29 PwMS. In addition, these same PwMS underwent a split-belt treadmill walking paradigm, with the faster paced belt moving under their more affected limb. Step length asymmetry (SLA) was the primary outcome measure used to assess gait adaptability during split-belt treadmill walking. We hypothesized that PwMS would exhibit differences in iSP inhibitory metrics between the more affected and less affected hemispheres and that increased interhemispheric inhibition would be associated with greater gait adaptability in PwMS. Results: No statistically significant differences in interhemispheric inhibition or conduction time were found between the more affected and less affected hemisphere. Furthermore, SLA aftereffect was negatively correlated with both average percent depth of silent period (dSP%AVE) (r = -0.40, p = 0.07) and max percent depth of silent period (dSP%MAX) r = -0.40, p = 0.07), indicating that reduced interhemispheric inhibition was associated with greater gait adaptability in PwMS. Conclusion: The lack of differences between the more affected and less affected hemisphere indicates that PwMS have similar interhemispheric inhibitory capacity irrespective of the more affected hemisphere. Additionally, we identified a moderate correlation between reduced interhemispheric inhibition and greater gait adaptability. These findings may indicate that interhemispheric inhibition may in part influence responsiveness to motor adaptation paradigms and the need for further research evaluating the neural mechanisms underlying the relationship between interhemispheric inhibition and motor adaptability. [ABSTRACT FROM AUTHOR]

Perthes disease is a condition that affects walking patterns in young children due to poor blood circulation in the hip joint. Understanding the gait strategies of affected children is of great importance for an objective assessment and better management of this condition. The aim of this systematic review was to evaluate the current literature to identify gait compensation patterns in non-operative children with Perthes disease. Methods: A systematic electronic search was performed using MEDLINE, CINAHL, Embase, BIOSIS, and the Cochrane Library to identify studies published from inception up until December 2023. An adapted Downs and Black checklist was utilised to assess methodological quality and project risk of bias. Percentage agreement and nominal kappa statistics with bootstrapped bias-corrected 95% confidence intervals (CIs) were used. Result: A comprehensive literature search revealed 277 citations for review, of which 210 studies entered full-text screening. In total, eight studies met the inclusion criteria for quality assessment by two independent reviewers. The results revealed variations in data quality, with scores ranging from 12 to 17 due to missing information related to subject characteristics, biomechanical model, and power calculation. Conclusions: This review reveals common compensation strategies associated with walking among non-operative children with Perthes disease such as Trendelenburg gait due to weakness of the hip abductor muscle. [ABSTRACT FROM AUTHOR]

Background: Patients often sustain prolonged neuromuscular dysfunction after anterior cruciate ligament reconstruction (ACLR). This dysfunction can present as interlimb loading rate asymmetries linked to reinjury and knee osteoarthritis progression. Purpose/Hypothesis: To evaluate how asymmetric walking protocols can reduce interlimb loading rate asymmetry in patients after ACLR. It was hypothesized that asymmetric walking perturbations would (1) produce a short-term adaptation of interlimb gait symmetry and (2) induce the temporary storage of these new gait patterns after the perturbations were removed. Study Design: Descriptive laboratory study. Methods: Fifteen patients who had undergone ACLR were asked to perform an asymmetric walking protocol during the study period (2022-2023). First, to classify each limb as overloaded or underloaded based on the vertical ground-reaction force loading rate for each limb, participants were asked to perform baseline symmetric walking trials. Participants then performed an asymmetric walking trial for 10 minutes, where one limb was moving 0.5 m/s faster than the other limb (1 vs 1.5 m/s), followed by a 2-minute 1 m/s symmetric deadaptation walking trial. This process was repeated with the limb speeds switched for a second asymmetric trial. Results: Participants adopted a new, symmetric interlimb loading rate gait pattern over time in response to the asymmetric trial, where the overloaded limb was set at 1 m/s. A linear mixed-effects model detected a significant change in gait dynamics (P <.001). The participants exhibited negative aftereffects after this asymmetric perturbation, indicating the temporary storage of the new gait pattern. No positive short-term gait adaptation or storage was observed when the overloaded limb was set to a faster speed. Conclusion: Asymmetric walking successfully produced the short-term adaptation of interlimb loading rate symmetry in patients after ACLR and induced the temporary storage of these gait patterns in the initial period when the perturbation was removed. Clinical Relevance: These findings are promising, as they suggest that asymmetric walking could serve as an effective gait retraining protocol that has the potential to improve long-term outcomes in patients after ACLR. [ABSTRACT FROM AUTHOR]

Walking requires constant adjustments to the changing environment. An asymmetrical perturbation can affect the gait symmetry, cause gait adaptations, and potentially induce retention of the adapted gait after removal of the perturbation. A unilateral ankle load has the potential to create asymmetry and facilitate the emergence of new gait patterns. However, few studies have examined the effect of unilateral loading on muscular adjustments during walking. The purpose of this study was to investigate gait adaptations and muscular adjustments after unilaterally loading or unloading the ankle. What are the effects of unilateral loading and unloading on gait spatiotemporal parameters and muscle activation in young adults? Twenty young adults (10 M/10 F) walked on a treadmill at their preferred walking speeds in 3 conditions: 1) a 2-minute baseline trial; 2) three 5-minute trials with a load (3 % of bodyweight) on the dominant ankle (Loading); and 3) one 5-minute trial with the load removed (Unloading). Inertial measurement units (IMUs) and electromyography sensors (EMGs) were used for data collection. Early and late adaptation and post-adaptation were assessed using the first 5 strides and the last 30 strides of loading and unloading conditions. Outcome measures included symmetry index (SI) of spatiotemporal parameters, range-of-motion (ROM) of the lower body joints, and EMG integrals of leg muscles. Repeated measures ANOVA was conducted for statistical analysis (α = 0.05). SI of swing phase percentage demonstrated rapid adaptation after unilateral loading or unloading. Stride length demonstrated an aftereffect following unloading. Young adults reduced ankle ROMs bilaterally in early adaptation and increased loaded-side knee and hip ROMs in late adaptation. Additionally, they increased the tibialis anterior activity bilaterally immediately after unilateral loading. Young adults showed an aftereffect in some variables after unilateral unloading, signifying that unilateral ankle loading can induce short term learning of a new gait pattern. • Unilateral ankle loading can cause gait asymmetry in young adults. • Young adults demonstrated asymmetrical gait after removal of the unilateral load. • Young adults adjusted their step length gradually after unilateral loading. • Temporal gait parameters showed instant adjustments after unilateral loading. • There were small increases in ankle muscle activities after unilateral loading. [ABSTRACT FROM AUTHOR]

As the population ages, the number of elderly people suffering from systemic diseases such as stroke increases. To address this problem, various wearable walking assistive robots have been developed to promote physical exercise for stroke prevention. Wearable assistive robots have shown the ability to improve human mobility. However, most of these robots are heavy, bulky, and impractical. In this study, we developed a compact ankle assistive robot for elderly users to promote walking exercise. By informing the user of correct motion and timing, the robot can guide the user to achieve a healthy gait by only assisting their ankle joint. The robot provides faster-than-ankle motion to allow the user to feel supported while walking. Users can adjust the robot's assistance parameters through a graphical user interface (GUI) according to their needs. Furthermore, we proposed a gait-adaptive method for ankle assistive robots to adapt to the user's changing gait. Hence, the robot can automatically adjust the parameters to provide more accurate walking assistance. Finally, the results of an evaluation experiment demonstrated the feasibility of human gait adaptation. The proposed methods have the advantages of low cost and easy implementation. [ABSTRACT FROM AUTHOR]

Background: Gait deficits in people with Parkinson's disease (PD) are triggered by circumstances requiring gait adaptation. The effects of gait adaptation training on a split‐belt treadmill (SBT) are unknown in PD. Objective: We investigated the effects of repeated SBT versus tied‐belt treadmill (TBT) training on retention and automaticity of gait adaptation and its transfer to over‐ground walking and turning. Methods: We recruited 52 individuals with PD, of whom 22 were freezers, in a multi‐center randomized single‐blind controlled study. Training consisted of 4 weeks of supervised treadmill training delivered three times per week. Tests were conducted pre‐ and post‐training and at 4‐weeks follow‐up. Turning (primary outcome) and gait were assessed over‐ground and during a gait adaptation protocol on the treadmill. All tasks were performed with and without a cognitive task. Results: We found that SBT‐training improved gait adaptation with moderate to large effects sizes (P < 0.02) compared to TBT, effects that were sustained at follow‐up and during dual tasking. However, better gait adaptation did not transfer to over‐ground turning speed. In both SBT‐ and TBT‐arms, over‐ground walking and Movement Disorder Society‐Unified Parkinson's Disease Rating Scale III (MDS‐UPDRS‐III scores were improved, the latter of which reached clinically meaningful effects in the SBT‐group only. No impact was found on freezing of gait. Conclusion: People with PD are able to learn and retain the ability to overcome asymmetric gait‐speed perturbations on a treadmill remarkably well, but seem unable to generalize these skills to asymmetric gait off‐treadmill. Future study is warranted into gait adaptation training to boost the transfer of complex walking skills. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

Since the mid-2000s, perturbation-based balance training has been gaining interest as an efficient and effective way to prevent falls in older adults. It has been suggested that this task-specific training approach may present a paradigm shift in fall prevention. In this review, we discuss key concepts and common issues and questions regarding perturbation-based balance training. In doing so, we aim to provide a comprehensive synthesis of the current evidence on the mechanisms, feasibility and efficacy of perturbation-based balance training for researchers and practitioners. We address this in two sections: “Principles and Mechanisms” and “Implementation in Practice.” In the first section, definitions, task-specificity, adaptation and retention mechanisms and the dose-response relationship are discussed. In the second section, issues related to safety, anxiety, evidence in clinical populations (e.g., Parkinson's disease, stroke), technology and training devices are discussed. Perturbation-based balance training is a promising approach to fall prevention. However, several fundamental and applied aspects of the approach need to be further investigated before it can be widely implemented in clinical practice.

Post-stroke gait asymmetry leads to inefficient gait and a higher fall risk, often causing limited home and community ambulation. Two types of treadmills are typically used for training focused on symmetry: split-belt and single belt treadmills, but there is no consensus on which treadmill is superior to improve gait symmetry in individuals with stroke. To comprehensively determine which intervention is superior, we considered multiple spatial and temporal gait parameters (step length, stride time, swing time, and stance time) and their symmetries. Ten individuals with stroke underwent a single session of split-belt treadmill training and single belt treadmill training on separate days. The changes in step length, stride time, swing time, stance time and their respective symmetries were compared to investigate which training improves both spatiotemporal gait parameters and symmetries immediately after the intervention and after 5 min of rest. Both types of treadmill training immediately increased gait velocity (0.08 m/s faster) and shorter step length (4.15 cm longer). However, split-belt treadmill training was more effective at improving step length symmetry (improved by 27.3%) without sacrificing gait velocity or step length. However, this step length symmetry effect diminished after a 5-min rest period. Split-belt treadmill training may have some advantages over single belt treadmill training, when targeting step length symmetry. Future research should focus on comparing the long-term effects of these two types of training and examining the duration of the observed effects to provide clinically applicable information., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Yang, Veit, McKenzie, Aalla, Embry, Kishta, Roth and Jayaraman.)

The ability to safely negotiate the world on foot takes humans years to develop, reflecting the extensive cognitive demands associated with real‐time planning and control of walking. Despite the importance of walking, methodological limitations mean that surprisingly little is known about the neural and cognitive processes that support ambulatory motor control. Here, we report mobile EEG data recorded from 32 healthy young adults during real‐world ambulatory obstacle avoidance. Participants walked along a path while stepping over expected and unexpected obstacles projected on the floor, allowing us to capture the dynamic oscillatory response to changes in environmental demands. Compared to obstacle‐free walking, time–frequency analysis of the EEG data revealed clear neural markers of proactive and reactive forms of movement control (occurring before and after crossing an obstacle), visible as increases in frontal theta and centro‐parietal beta power respectively. Critically, the temporal profile of changes in frontal theta allowed us to arbitrate between early selection and late adaptation mechanisms of proactive control. Our data show that motor plans are updated as soon as an upcoming obstacle appears, rather than when the obstacle is reached. In addition, regardless of whether motor plans required updating, a clear beta rebound was present after obstacles were crossed, reflecting the resetting of the motor system. Overall, mobile EEG recorded during real‐world walking provides novel insight into the cognitive and neural basis of dynamic motor control in humans, suggesting new routes to the monitoring and rehabilitation of motor disorders such as dyspraxia and Parkinson's disease. [ABSTRACT FROM AUTHOR]

Background: Gait impairments are common in healthy older adults (HOA) and people with Parkinson's disease (PwPD), especially when adaptations to the environment are required. Traditional rehabilitation programs do not typically address these adaptive gait demands in contrast to repeated gait perturbation training (RGPT). RGPT is a novel reactive form of gait training with potential for both short and long-term consolidation in HOA and PwPD. The aim of this systematic review with meta-analysis is to determine whether RGPT is more effective than non-RGPT gait training in improving gait and balance in HOA and PwPD in the short and longer term. Methods: This review was conducted according to the PRISMA-guidelines and pre-registered in the PROSPERO database (CRD42020183273). Included studies tested the effects of any form of repeated perturbations during gait in HOA and PwPD on gait speed, step or stride length. Studies using balance scales or sway measures as outcomes were included in a secondary analysis. Effects of randomized controlled trials (RCT) on RGPT were pooled using a meta-analysis of final measures. Results: Of the 4421 studies, eight studies were deemed eligible for review, of which six could be included in the meta-analysis, totaling 209 participants (159 PwPD and 50 HOA). The studies were all of moderate quality. The meta-analysis revealed no significant effects of RGPT over non-RGPT training on gait performance (SMD = 0.16; 95% CI = −0.18, 0.49; Z = 0.92; P = 0.36). Yet, in some individual studies, favorable effects on gait speed, step length and stride length were observed immediately after the intervention as well as after a retention period. Gait variability and asymmetry, signifying more direct outcomes of gait adaptation, also indicated favorable RGPT effects in some individual studies. Conclusion: Despite some promising results, the pooled effects of RGPT on gait and balance were not significantly greater as compared to non-RGPT gait training in PwPD and HOA. However, these findings could have been driven by low statistical power. Therefore, the present review points to the imperative to conduct sufficiently powered RCT's to verify the true effects of RGPT on gait and balance in HOA and PwPD. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display%5frecord.php? Identifier: CRD42020183273. [ABSTRACT FROM AUTHOR]

Background: Gait impairments are common in healthy older adults (HOA) and people with Parkinson's disease (PwPD), especially when adaptations to the environment are required. Traditional rehabilitation programs do not typically address these adaptive gait demands in contrast to repeated gait perturbation training (RGPT). RGPT is a novel reactive form of gait training with potential for both short and long-term consolidation in HOA and PwPD. The aim of this systematic review with meta-analysis is to determine whether RGPT is more effective than non-RGPT gait training in improving gait and balance in HOA and PwPD in the short and longer term.Methods: This review was conducted according to the PRISMA-guidelines and pre-registered in the PROSPERO database (CRD42020183273). Included studies tested the effects of any form of repeated perturbations during gait in HOA and PwPD on gait speed, step or stride length. Studies using balance scales or sway measures as outcomes were included in a secondary analysis. Effects of randomized controlled trials (RCT) on RGPT were pooled using a meta-analysis of final measures.Results: Of the 4421 studies, eight studies were deemed eligible for review, of which six could be included in the meta-analysis, totaling 209 participants (159 PwPD and 50 HOA). The studies were all of moderate quality. The meta-analysis revealed no significant effects of RGPT over non-RGPT training on gait performance (SMD = 0.16; 95% CI = −0.18, 0.49; Z = 0.92; P = 0.36). Yet, in some individual studies, favorable effects on gait speed, step length and stride length were observed immediately after the intervention as well as after a retention period. Gait variability and asymmetry, signifying more direct outcomes of gait adaptation, also indicated favorable RGPT effects in some individual studies.Conclusion: Despite some promising results, the pooled effects of RGPT on gait and balance were not significantly greater as compared to non-RGPT gait training in PwPD and HOA. However, these findings could have been driven by low statistical power. Therefore, the present review points to the imperative to conduct sufficiently powered RCT's to verify the true effects of RGPT on gait and balance in HOA and PwPD.Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php? Identifier: CRD42020183273.

The present article demonstrates split-belt treadmill training, but not cerebellar transcranial direct current stimulation (tDCS), reduces fall risk for people with multiple sclerosis. Concerns regarding the implementation of the split-belt paradigm, coupled with insensitive outcome measures and a nonoptimal neural target for tDCS may have contributed to the limited gait improvements observed. A more fitting stimulation may be to target nervous system structures in the periphery to improve sensorimotor transduction and elicit more accurate proprioception. [ABSTRACT FROM AUTHOR]

In this study, we present a novel neural control architecture for gait adaptation and obstacle avoidance of a tailless gecko robot. The control architecture is based on a hierarchical modular structure, consisting of several neural layers and modules. The first layer contains three sensory preprocessing modules which filter sensory noise and generate appropriate descending commands to activate corresponding behaviors through the second and third layers. The second and third layers contain a central pattern generator (CPG) module and CPG postprocessing modules, respectively. The CPG module generates basic rhythmic locomotion patterns, shaped by the CPG postprocessing modules to achieve different gaits (i.e., wave, intermediate, and trot) as well as different climbing directions (i.e., forward and sideways). We use a body inclination sensor to adapt the robot gait while climbing on different slope angles, with infrared sensors to detect an obstacle on its climbing path and activate obstacle avoidance behavior. We successfully tested our control approach on a real tailless gecko robot. As a result, the robot can efficiently climb forward on different slope angles (including 90∘) and automatically adapt its climbing gait accordingly, to maximize climbing speed and ensure stability. It can also avoid an obstacle by changing its climbing direction from forward to sideways. [ABSTRACT FROM AUTHOR]

• We propose a model describing the roles of the human CNS during split-belt treadmill gait adaptation. • Initial adjustments to split-belts rely on proprioceptive feedback to spinal circuits. • Adaptation requires cognitive and cerebellar influence to learn a new gait pattern. • However, despite altered neural control, clinical populations can adapt the gait pattern. Many studies of split-belt treadmill adaptation have been focused on the biomechanical changes that occur in response to walking on belts at different speeds. This process of adaptation, and the ensuing aftereffects that are present when participants return to typical treadmill walking, have inspired the potential use of the split-belt treadmill as a rehabilitation tool. However, a full systematic review of the current split-belt treadmill literature has not yet been published to consolidate what is known about how the human central nervous system (CNS) controls adaptation to this type of symmetry perturbation. A systematic literature search identified 55 studies that investigated the neural control of human gait adaptation to a split-belt treadmill. Studies of infants and manipulated sensory feedback in healthy adults suggest that the initial gait adjustments to split-belt walking are reliant on proprioceptive feedback to inform central pattern generators to modify lower limb muscle activation patterns appropriately. Simultaneously, this literature suggested that proprioceptive and visual feedback inform supraspinal centres for motor planning and motor output to adapt and store a new and efficient gait pattern to walk on belts at different speeds. However, evidence from participants with brain injury (post-stroke, cerebellar lesions) suggest that injury impedes, but does not completely take away, the ability to adjust and adapt aspects of the gait pattern to split-belts. The model proposed from this review provides the overarching roles of the CNS in the adaptation process, specifically in short-term, and potential sites of focus within the human CNS for future rehabilitation-based work. [ABSTRACT FROM AUTHOR]

Background: Dual tasking during prolonged split-belt adaptation (10-15 min) has shown to slow the adaptation process and prolong aftereffects. Therefore, dual tasks during split-belt adaptation are being explored for their potential in gait symmetry rehabilitation. However, the ideal paradigm configuration it is still not clear.Research Question: To determine whether split-belt adaptation and ensuing aftereffects are altered by dual task placement, specifically looking at onset of split-belt adaptation or later part way through Adaptation (Experiment 1) and dual task duration (Experiment 2).Methods: Healthy young adults (n = 40) performed 5 min of tied-belt walking, followed by 14 min of split-belts (Adaptation, 1:3 ratio) and 5 min of de-adaptation (both belts at same speed) to assess after effects (Post-Adaptation). Experiment 1: To assess the effects of dual task placement, an auditory version of an n-back task was presented during the first 8 min or last 8 min of Adaptation. Experiment 2: To assess the effects of dual task duration, the cognitive task was presented during the entire split-belt Adaptation phase (14 min) or during four 2-minute bouts (8 min). Cognitive task accuracy, dual support symmetry, and rates of adaptation and de-adaptation were compared.Results: When both the onset of the auditory cognitive task and the onset of Adaptation (split-belts) occurred simultaneously, participants prioritized split-belt adaptation and in doing so, cognitive task accuracy was reduced (Experiment 1). By prioritizing gait symmetry over cognitive performance, there were no differences in dual support symmetry adaptation (magnitude, variability or rate of Adaptation/De-adaptation) regardless of cognitive task placement or duration (Experiment 2).Significance: We believe the early portion of split-belt treadmill adaptation to be a cognitive interference period. These results support future work exploring the use of dual task in a rehabilitation setting with more complicated motor-cognitive dual task paradigms during this key period. [ABSTRACT FROM AUTHOR]

When humans make errors in stepping during walking due to a perturbation, they may adapt their gait as a way to correct for discrepancies between predicted and actual sensory feedback. This study sought to determine if increased contextual interference during acquisition of a novel asymmetric gait pattern would change lower-limb mechanical strategies generalized to different walking contexts. Such knowledge could help to clarify the role of contextual interference in locomotor adaptation, and demonstrate potential use in future gait rehabilitation paradigms. One belt on a split-belt treadmill was driven at a constant velocity while the other was driven at changing velocities according to one of three practice paradigms: serial, random blocked, or random training. Subjects returned to complete one of two different transfer tests. Results indicate that during acquisition, random practice requires unique gait mechanics to adapt to a challenging walking environment. Also, results from one transfer test close to that of the acquisition experience did not seem to demonstrate any contextual interference effect. Finally, random blocked practice resulted in highly unique changes in step length symmetry on a second, more challenging, transfer test. This perhaps indicates that a moderate level of contextual interference causes unique locomotor generalization strategies.

Previous research indicates the correlation structure of gait parameters (i.e., fractal dynamics) decreases with age. This decrease is suggested to reflect a reduced capacity for locomotor adaptation in older adults. The purpose of this study was to investigate potential differences between physical activity-matched young and older adults’ fractal dynamics and gait adaptability during unperturbed and asymmetric walking, and to determine if fractal dynamics predict adaptive capacity. Fifteen young (28.9 ± 5.6 years, nine women) and 15 older (64.7 ± 2.7, nine women) adults with similar habitual physical activity levels walked at preferred speed, half of preferred speed, and asymmetrically whereby their dominant and non-dominant legs moved at preferred and half-preferred speed, respectively. Fractal correlations (scaling exponent α) of stride times were assessed through detrended fluctuation analysis, and gait adaptation to asymmetric walking on the basis of lower limb relative phase. Both cohorts displayed similar fractal dynamics at preferred speed and asymmetric walking, while older adults exhibited greater α during slow walking. Both groups exhibited comparable gait adaptation to split-belt walking based on analysis of lower limb relative phase. Fractal dynamics during preferred speed and asymmetric walking was moderately associated with gait adaptation in the young and older adult cohorts, respectively. In these activity-matched groups, there were no age-based reductions in fractal dynamics or gait adaptation, and fractal scaling α was moderately associated with gait adaptation. These findings suggest that stride time fractal dynamics and gait adaptation may be preserved in older adults who habitually perform moderate intensity physical activity.

Modifications in load-related sensory input during unloaded walking can lead to recalibration of the body schema and result in aftereffects. The main objective of this study was to identify the adaptive changes in gait and body-weight perception produced by unloaded walking. Gait performance during treadmill walking was assessed in 12 young participants before and after 30 min of unloaded walking (38% body weight) by measuring lower limb kinematics, temporal gait measures, and electromyography (EMG). A customized weight-perception scale was used to assess perception of body weight. Participants perceived their body weight to be significantly heavier than normal after unloading while walking. Angular displacement about ankle and knee was significantly reduced immediately after unloaded walking, while temporal gait parameters remained unchanged. The EMG activity in some muscles was significantly reduced after unloading. These findings indicate that walking at reduced body weight results in alterations in segmental kinematics, neuromuscular activity, and perception of body weight, which are the aftereffects of motor adaptation to altered load-related afferent information produced by unloading. Understanding the adaptive responses of gait to unloading and the time course of the aftereffects will be useful for practitioners who use body-weight unloading for rehabilitation. [ABSTRACT FROM AUTHOR]

Previous research indicates the correlation structure of gait parameters (i.e., fractal dynamics) decreases with age. This decrease is suggested to reflect a reduced capacity for locomotor adaptation in older adults. The purpose of this study was to investigate potential differences between physical activity-matched young and older adults’ fractal dynamics and gait adaptability during unperturbed and asymmetric walking, and to determine if fractal dynamics predict adaptive capacity. Fifteen young (28.9 ± 5.6 years, nine women) and 15 older (64.7 ± 2.7, nine women) adults with similar habitual physical activity levels walked at preferred speed, half of preferred speed, and asymmetrically whereby their dominant and non-dominant legs moved at preferred and half-preferred speed, respectively. Fractal correlations (scaling exponent α) of stride times were assessed through detrended fluctuation analysis, and gait adaptation to asymmetric walking on the basis of lower limb relative phase. Both cohorts displayed similar fractal dynamics at preferred speed and asymmetric walking, while older adults exhibited greater α during slow walking. Both groups exhibited comparable gait adaptation to split-belt walking based on analysis of lower limb relative phase. Fractal dynamics during preferred speed and asymmetric walking was moderately associated with gait adaptation in the young and older adult cohorts, respectively. In these activity-matched groups, there were no age-based reductions in fractal dynamics or gait adaptation, and fractal scaling α was moderately associated with gait adaptation. These findings suggest that stride time fractal dynamics and gait adaptation may be preserved in older adults who habitually perform moderate intensity physical activity. [ABSTRACT FROM AUTHOR]

Background: Walking on a split-belt treadmill (SBT) can help to modulate an asymmetric gait, particularly for people with neurological conditions, such as Parkinson's disease (PD), where asymmetry plays a role due to the laterality of the disease.Research Question: This systematic review critically evaluates the literature on SBT in PD. First, different SBT paradigms and methodological approaches were evaluated. Second, the review explored how people with PD adapt their gait to different SBT conditions compared to healthy controls (HC).Methods: We conducted a systematic search of the PubMED, PsychINFO, and Web of Knowledge databases. Original research articles, published in English and investigating SBT walking in people with PD, were included.Results: From the 925 studies originally identified, seven met the inclusion criteria and were selected for evaluation (n = 118 individuals with PD of whom 44 had freezing of gait (FOG)). The SBT paradigms varied across studies regarding the SBT settings, definitions of gait variables, and criteria for determining dominance of body side. Gait variability and bilateral coordination were found to adapt to the SBT condition similarly in people with PD and healthy controls (HC). Inconsistent results were found with respect to the adaptation of gait asymmetry, for the differences between PD and HC participants. The subgroup of people with PD and FOG showed reduced accuracy in detecting belt speed differences and slower adaptation to SBT conditions.Conclusion: Individuals with mild to moderately severe PD adapted similarly to HCs to SBT walking for gait variability and bilateral gait coordination. However, those with FOG had impaired perception of belt speed differences and did not adapt their gait so readily. Although SBT can be useful for modulating gait asymmetry in some people with PD, it was not beneficial for all. We recommend standardization of SBT protocols for clinical practice in future studies. [ABSTRACT FROM AUTHOR]

In this study, the authors focus on the structural design of and recovery methods for a damaged quadruped robot with a limited number of functional legs. Because the pre-designed controller cannot be executed when the robot is damaged, a control strategy to avoid task failures in such a scenario should be developed. Not only the control method but also the shape and structure of the robot itself are significant for the robot to be able to move again after damage. We present a caterpillar-inspired quadruped robot (CIQR) and a self-learning mudskipper inspired crawling (SLMIC) algorithm in this research. The CIQR is realized by imitating the prolegs of caterpillars and by using a numerical optimization technique. A reinforcement learning method called Q-learning is employed to improve the adaptability of locomotion based on the crawling behavior of mudskipper. The results show that the proposed robotic platform and recovery method can improve the moving ability of the damaged quadruped robot with a few active legs in both simulations and experiments. Moreover, we obtained satisfactory results showing that a damaged multi-legged robot with at least one leg could travel properly along the required direction. Furthermore, the presented algorithm can successfully be employed in a damaged quadruped robot with fewer than four legs. [ABSTRACT FROM AUTHOR]

A method is presented for detecting changes in the axial peak tibial acceleration while adapting to self-discovered lower-impact running. Ten runners with high peak tibial acceleration were equipped with a wearable auditory biofeedback system. They ran on an athletic track without and with real-time auditory biofeedback at the instructed speed of 3.2 m·s−1. Because inter-subject variation may underline the importance of individualized retraining, a change-point analysis was used for each subject. The tuned change-point application detected major and subtle changes in the time series. No changes were found in the no-biofeedback condition. In the biofeedback condition, a first change in the axial peak tibial acceleration occurred on average after 309 running gait cycles (3′40″). The major change was a mean reduction of 2.45 g which occurred after 699 running gait cycles (8′04″) in this group. The time needed to achieve the major reduction varied considerably between subjects. Because of the individualized approach to gait retraining and its relatively quick response due to a strong sensorimotor coupling, we want to highlight the potential of a stand-alone biofeedback system that provides real-time, continuous, and auditory feedback in response to the axial peak tibial acceleration for lower-impact running.

The use of visual feedback in gait rehabilitation has been suggested to promote recovery of locomotor function by incorporating interactive visual components. Our prior work demonstrated that visual feedback distortion of changes in step length symmetry entails an implicit or unconscious adaptive process in the subjects’ spatial gait patterns. We investigated whether the effect of the implicit visual feedback distortion would persist at three different walking speeds (slow, self-preferred and fast speeds) and how different walking speeds would affect the amount of adaption. In the visual feedback distortion paradigm, visual vertical bars portraying subjects’ step lengths were distorted so that subjects perceived their step lengths to be asymmetric during testing. Measuring the adjustments in step length during the experiment showed that healthy subjects made spontaneous modulations away from actual symmetry in response to the implicit visual distortion, no matter the walking speed. In all walking scenarios, the effects of implicit distortion became more significant at higher distortion levels. In addition, the amount of adaptation induced by the visual distortion was significantly greater during walking at preferred or slow speed than at the fast speed. These findings indicate that although a link exists between supraspinal function through visual system and human locomotion, sensory feedback control for locomotion is speed-dependent. Ultimately, our results support the concept that implicit visual feedback can act as a dominant form of feedback in gait modulation, regardless of speed.

The use of visual feedback in gait rehabilitation has been suggested to promote recovery of locomotor function by incorporating interactive visual components. Our prior work demonstrated that visual feedback distortion of changes in step length symmetry entails an implicit or unconscious adaptive process in the subjects' spatial gait patterns. We investigated whether the effect of the implicit visual feedback distortion would persist at three different walking speeds (slow, self-preferred and fast speeds) and how different walking speeds would affect the amount of adaption. In the visual feedback distortion paradigm, visual vertical bars portraying subjects' step lengths were distorted so that subjects perceived their step lengths to be asymmetric during testing. Measuring the adjustments in step length during the experiment showed that healthy subjects made spontaneous modulations away from actual symmetry in response to the implicit visual distortion, no matter the walking speed. In all walking scenarios, the effects of implicit distortion became more significant at higher distortion levels. In addition, the amount of adaptation induced by the visual distortion was significantly greater during walking at preferred or slow speed than at the fast speed. These findings indicate that although a link exists between supraspinal function through visual system and human locomotion, sensory feedback control for locomotion is speed-dependent. Ultimately, our results support the concept that implicit visual feedback can act as a dominant form of feedback in gait modulation, regardless of speed. [ABSTRACT FROM AUTHOR]

Previous studies showed the existence of implicit interaction rules shared by human walkers when crossing each other. Especially, each walker contributes to the collision avoidance task and the crossing order, as set at the beginning, is preserved along the interaction. This order determines the adaptation strategy: the first arrived increases his/her advance by slightly accelerating and changing his/her heading, whereas the second one slows down and moves in the opposite direction. In this study, we analyzed the behavior of human walkers crossing the trajectory of a mobile robot that was programmed to reproduce this human avoidance strategy. In contrast with a previous study, which showed that humans mostly prefer to give the way to a non-reactive robot, we observed similar behaviors between human-human avoidance and human-robot avoidance when the robot replicates the human interaction rules. We discuss this result in relation with the importance of controlling robots in a human-like way in order to ease their cohabitation with humans. [ABSTRACT FROM AUTHOR]

Our prior work provides evidence that visual feedback distortion drives an implicit adaptation; a gradual distortion of visual representation of step length modulated subjects' step lengths away from symmetry. To further explore the effect of the visual feedback distortion on unconscious change in step symmetry, we investigated whether such adaptation would occur even in the presence of altered limb mechanics by adding mass to one side of the leg. 26 subjects performed three 8-min trials (weight only, weight plus visual feedback, and weight plus visual feedback distortion) of treadmill walking. During the weight only trial, the subjects wore a 5 lb mass around the right ankle. The modification of limb inertia caused asymmetric gait. The visual feedback showing right and left step length information as bar graphs was displayed on a computer screen. To add visual feedback distortion, we increased the length of one side of the visual bars by 10% above the actual step length, and the visual distortion was implemented for the side that took longer in response to the added mass. We found that even when adjustments were made to unilateral loading, the subjects spontaneously changed their step symmetry in response to the visual distortion, which resulted in a more symmetric gait. This change may be characterized by sensory prediction errors, and our results suggest that visual feedback distortion has a significant impact on gait symmetry regardless of other conditions affecting limb mechanics. A rehabilitation program employing visual feedback distortion may provide an effective way to restore gait symmetry. [ABSTRACT FROM AUTHOR]

Modifications in load-related sensory input during unloaded walking can lead to recalibration of the body schema and result in aftereffects. The main objective of this study was to identify the adaptive changes in gait and body-weight perception produced by unloaded walking. Gait performance during treadmill walking was assessed in 12 young participants before and after 30 min of unloaded walking (38% body weight) by measuring lower limb kinematics, temporal gait measures, and electromyography (EMG). A customized weight-perception scale was used to assess perception of body weight. Participants perceived their body weight to be significantly heavier than normal after unloading while walking. Angular displacement about ankle and knee was significantly reduced immediately after unloaded walking, while temporal gait parameters remained unchanged. The EMG activity in some muscles was significantly reduced after unloading. These findings indicate that walking at reduced body weight results in alterations in segmental kinematics, neuromuscular activity, and perception of body weight, which are the aftereffects of motor adaptation to altered load-related afferent information produced by unloading. Understanding the adaptive responses of gait to unloading and the time course of the aftereffects will be useful for practitioners who use body-weight unloading for rehabilitation.

In this study, the authors focus on the structural design of and recovery methods for a damaged quadruped robot with a limited number of functional legs. Because the pre-designed controller cannot be executed when the robot is damaged, a control strategy to avoid task failures in such a scenario should be developed. Not only the control method but also the shape and structure of the robot itself are significant for the robot to be able to move again after damage. We present a caterpillar-inspired quadruped robot (CIQR) and a self-learning mudskipper inspired crawling (SLMIC) algorithm in this research. The CIQR is realized by imitating the prolegs of caterpillars and by using a numerical optimization technique. A reinforcement learning method called Q-learning is employed to improve the adaptability of locomotion based on the crawling behavior of mudskipper. The results show that the proposed robotic platform and recovery method can improve the moving ability of the damaged quadruped robot with a few active legs in both simulations and experiments. Moreover, we obtained satisfactory results showing that a damaged multi-legged robot with at least one leg could travel properly along the required direction. Furthermore, the presented algorithm can successfully be employed in a damaged quadruped robot with fewer than four legs.

Background Walking in the real-world involves negotiating challenging or uneven surfaces, including sand. This can be challenging for people with Multiple Sclerosis (PWMS) due to motor deficits affecting the lower extremities. The study objective was to characterise kinematic gait adaptations made by PWMS when walking on sand and describe any immediate post-adaptation effects. Methods 17 PWMS (mean age 51.4 ± 5.5, Disease Steps 2.4 ± 1.0), and 14 age-and gender matched healthy adults (HA) took part in a case-control study. 3D gait analysis was conducted using an eight-camera Vicon motion capture system. Each participant completed walking trials over level ground (baseline), sand (gait adaptation response), and again level ground (post-adaptation). Spatiotemporal data and kinematic data for the hip knee and ankle were recorded. Results At baseline PWMS showed significantly less total lower limb flexion (p<0.05) compared to HA. PWMS adapted to walking on sand by significantly increasing hip and knee flexion and ankle dorsiflexion (p<0.05) during swing, resulting in an overall 23° greater total lower limb flexion (p<0.05), reaching values within normal range. During the return to level ground walking values of temporal-spatial and kinematic parameters returned towards baseline values. Conclusions PWMS adapted to walking on sand by increasing lower limb flexion during swing, and returned to their gait pattern to near baseline levels, in a manner similar to but with values not equalling HA. Further work is required to determine whether this mode of walking has potential to act as a gait retraining strategy to increase flexion of the lower limb. [ABSTRACT FROM AUTHOR]

Gait adaptation to employ different ways to avoid a potential slip is needed to continue walking safely on a new surface, especially when transitioning to a slippery surface. In this experiment, participants walked back and forth five times (trials) on surfaces with different degrees of slipperiness. The results show that trial 1 was significantly different from other trials for most of the dependent variables, especially for the low and high friction conditions. Kinematics on high and medium friction surfaces were very similar, but more adjustments were needed for low friction surfaces. The data for the first trial reflect gait after walking for 2.4 m on the walkway, not the first step onto the walkway. The current data show that gait adaptation continued beyond the first trial. Since participants in this experiment were aware of the floor conditions, the results could have important safety implications that user awareness alone might be insufficient for safe floor designs. [ABSTRACT FROM AUTHOR]

Minimum-toe-clearance (MTC) above the walking surface is a critical representation of toe-trajectory control due to its association with tripping risk. Not all gait cycles exhibit a clearly defined MTC within the swing phase but there have been few previous accounts of the biomechanical characteristics of non-MTC gait cycles. The present report investigated the within-subject non-MTC gait cycle characteristics of 15 older adults (mean 73.1 years) and 15 young controls (mean 26.1 years). Participants performed the following tasks on a motorized treadmill: preferred speed walking, dual task walking (carrying a glass of water) and a dual-task speed-matched control. Toe position-time coordinates were acquired using a 3 dimensional motion capture system. When MTC was present, toe height at MTC (MTCheight) was extracted. The proportion of non-MTC gait cycles was computed for the age groups and individuals. For non-MTC gait cycles an 'indicative' toe height at the individual's average swing phase time (MTCtime) for observed MTC cycles was averaged across multiple non-MTC gait cycles. In preferred-speed walking Young demonstrated 2.9% non-MTC gait cycles and Older 18.7%. In constrained walking conditions both groups increased non-MTC gait cycles and some older adults revealed over 90%, confirming non-MTC gait cycles as an ageing-related phenomenon in lower limb trajectory control. For all participants median indicative toe-height on non-MTC gait cycles was greater than median MTCheight. This result suggests that eliminating the biomechanically hazardous MTC event by adopting more of the higher-clearance non-MTC gait cycles, is adaptive in reducing the likelihood of toe-ground contact. [ABSTRACT FROM AUTHOR]

Robots and Humans have to share the same environment more and more often. In the aim of steering robots in a safe and convenient manner among humans it is required to understand how humans interact with them. This work focuses on collision avoidance between a human and a robot during locomotion. Having in mind previous results on human obstacle avoidance, as well as the description of the main principles which guide collision avoidance strategies, we observe how humans adapt a goal-directed locomotion task when they have to interfere with a mobile robot. Our results show differences in the strategy set by humans to avoid a robot in comparison with avoiding another human. Humans prefer to give the way to the robot even when they are likely to pass first at the beginning of the interaction. [ABSTRACT FROM AUTHOR]

Everyday locomotion and obstacle avoidance requires effective gait adaptation in response to sensory cues. Many studies have shown that efficient motor actions are associated with ji rhythm (8-13 Hz) and (3 band (13-35 Hz) local field desynchronizations in sensorimotor and parietal cortex, whereas a number of cognitive task studies have reported higher behavioral accuracy to be associated with increases in β band power in prefrontal and sensory cortex. How these two distinct patterns of J3 band oscillations interplay during gait adaptation, however, has not been established. Here we recorded 108 channel EEG activity from 18 participants (10 males, 22-35 years old) attempting to walk on a treadmill in synchrony with a series of pacing cue tones, and quickly adapting their step rate and length to sudden shifts in pacing cue tempo. Independent component analysis parsed each participant's EEG data into maximally independent component (IC) source processes, which were then grouped across participants into distinct spatial/spectral clusters. Following cue tempo shifts, mean β band power was suppressed for IC sources in central midline and parietal regions, whereas mean β band power increased in IC sources in or near medial prefrontal and dorsolateral prefrontal cortex. In the right dorsolateral prefrontal cortex IC cluster, the)3 band power increase was stronger during (more effortful) step shortening than during step lengthening. These results thus show that two distinct patterns of J3 band activity modulation accompany gait adaptations: one likely serving movement initiation and execution; and the other, motor control and inhibition. [ABSTRACT FROM AUTHOR]

Spatiotemporal gait cycle characteristics were assessed at early (P1), and late (P2) pregnancy, as well as at 2 months (PP1) and 6 months (PP2) postpartum. A substantial decrease in walking speed was observed throughout the pregnancy, with the slowest speed (1±0.2m/s) being during the third trimester. Walking at slower velocity resulted in complex adaptive adjustments to their spatiotemporal gait pattern, including a shorter step length and an increased duration of both their stance and double-support phases. Duration of the swing phase remained the least susceptible to changes. Habitual walking velocity (1.13±0.2m/s) and the optimal gait pattern were fully recovered 6 months after childbirth. Documented here adaptive changes in the preferred gait pattern seem to result mainly from the altered body anthropometry leading to temporary balance impairments. All the observed changes within stride cycle aimed to improve gait safety by focusing on its dynamic stability. The pregnant women preferred to walk at a slower velocity which allowed them to spend more time in double-support compared with their habitual pattern. Such changes provided pregnant women with a safer and more tentative ambulation that reduced the single-support period and, hence, the possibility of instability. As pregnancy progressed a significant increase in stance width and a decrease in step length was observed. Both factors allow also for gait stability improvement. [ABSTRACT FROM AUTHOR]

Visuomotor adaptation with prism glasses is a paradigm often used to understand how the motor system responds to visual perturbations. Both reaching and walking adaptation have been documented, but not directly compared. Because the sensorimotor environment and demands are different between reaching and walking, we hypothesized that characteristics of prism adaptation, namely rates and aftereffects, would be different during walking compared to reaching. Furthermore, we aimed to determine the impact of age on motor adaptation. We studied healthy younger and older adults who performed visually guided reaching and walking tasks with and without prism glasses. We noted age effects on visuomotor adaptation, such that older adults adapted and re-adapted slower compared to younger adults, in accord with previous studies of adaptation in older adults. Interestingly, we also noted that both groups adapted slower and showed smaller aftereffects during walking prism adaptation compared to reaching. We propose that walking adaptation is slower because of the complex multi-effector and multi-sensory demands associated with walking. Altogether, these data suggest that humans can adapt various movement types but the rate and extent of adaptation is not the same across movement types nor across ages. [ABSTRACT FROM AUTHOR]

Goal: Visual feedback can be used during gait rehabilitation to improve the efficacy of training. We presented a paradigm called visual feedback distortion; the visual representation of step length was manipulated during treadmill walking. Our prior work demonstrated that an implicit distortion of visual feedback of step length entails an unintentional adaptive process in the subjects’ spatial gait pattern. Here, we investigated whether the implicit visual feedback distortion, versus conscious correction, promotes efficient locomotor adaptation that relates to greater retention of a task. Methods: Thirteen healthy subjects were studied under two conditions: (1) we implicitly distorted the visual representation of their gait symmetry over 14 min, and (2) with help of visual feedback, subjects were told to walk on the treadmill with the intent of attaining the gait asymmetry observed during the first implicit trial. After adaptation, the visual feedback was removed while subjects continued walking normally. Over this 6-min period, retention of preserved asymmetric pattern was assessed. Results: We found that there was a greater retention rate during the implicit distortion trial than that of the visually guided conscious modulation trial. Conclusion: This study highlights the important role of implicit learning in the context of gait rehabilitation by demonstrating that training with implicit visual feedback distortion may produce longer lasting effects. Significance: This suggests that using visual feedback distortion could improve the effectiveness of treadmill rehabilitation processes by influencing the retention of motor skills. [ABSTRACT FROM AUTHOR]

Humans generally prefer gait patterns with a low metabolic cost, but it is unclear how such patterns are chosen. We have previously proposed that humans may use proprioceptive feedback to identify economical movement patterns. The purpose of the present experiments was to investigate the role of plantarflexor proprioception in the adaptation toward an economical gait pattern. To disrupt proprioception in some trials, we applied noisy vibration (randomly varying between 40–120 Hz) over the bilateral Achilles tendons while participants stood quietly or walked on a treadmill. For all 10 min walking trials, the treadmill surface was initially level before slowly increasing to a 2.5% incline midway through the trial without participant knowledge. During standing posture, noisy vibration increased sway, indicating decreased proprioception accuracy. While walking on a level surface, vibration did not significantly influence stride period or metabolic rate. However, vibration had clear effects for the first 2–3 min after the incline increase; vibration caused participants to walk with shorter stride periods, reduced medial gastrocnemius (MG) activity during mid-stance (30–65% stance), and increased MG activity during late-stance (65–100% stance). Over time, these metrics gradually converged toward the gait pattern without vibration. Likely as a result of this delayed adaptation to the new mechanical context, the metabolic rate when walking uphill was significantly higher in the presence of noisy vibration. These results may be explained by the disruption of proprioception preventing rapid identification of muscle activation patterns which allow the muscles to operate under favorable mechanical conditions with low metabolic demand. [ABSTRACT FROM AUTHOR]

Background: The current study aimed to investigate the immediate and long-term effects of laterally-wedged (LW) insoles on the knee loadings, the knee abductor moment (KAM) in particular, and the compensatory changes at other lower limb joints in patients with bilateral medial knee osteoarthritis during level walking with and without LW insoles. Methods: Older adults with bilateral medial knee OA (age 66 ± 5.3 years; height 156 ± 4.9 cm; mass 60 ± 5.1 kg; leg length 83.72 ± 3.64 cm) were studied using computerized gait analysis initially (Baseline) and 6 weeks after using LW insoles (Follow-up) during barefoot walking and walking with LW insoles (7° of lateral inclination, with medial arch support). The three-dimensional angles and internal moments at the lower limb joints, as well as the ground reaction forces, were obtained using a motion analysis system and twoforceplates. Key features of all the variables were compared using paired t tests for immediate effects (barefoot vs. LW) and for long-term effects (Baseline vs. Follow-up). The symptomatic severity (WOMAC Index) was also evaluated (Baseline vs. Follow-up). Results: The KAM with LW insoles at Baseline was significantly reduced when compared to the barefoot condition (p < 0.05), suggesting that the LW insoles were effective in reducing unfavorable loadings at the knee immediately upon wearing the insoles. After 6 weeks of wearing LW insoles (Follow-up), no significant changes were found in most of the biomechanical variables, including KAM (p > 0.05), when compared to Baseline with LW insoles. However, a specific gait adaptation with reduced knee loading was revealed when walking without LW insoles, i.e., for the barefoot condition (p < 0.05). Conclusions: After long-term use of LW insoles, the pain and physical function were improved with decreased peak KAM. A specific gait adaptation with reduced KAM was alsofound when walking without LW insoles. These results indicate a positive long-term effect in persons with bilateral medial knee OA, both as an orthosis to assist walking, and as a treatment intervention to facilitate gait adaptations in favor of reduced KAM. [ABSTRACT FROM AUTHOR]

Unilateral peripheral vestibular disorder ( UPVD) causes deficient locomotor responses to novel environments due to a lack of accurate vestibular sensory information, increasing fall risk. This study aimed to examine recovery response (stability recovery actions) and adaptive feedback potential in dynamic stability of UPVD-patients and healthy control subjects during perturbed walking. 17 UPVD-patients (>6 months since onset) and 17 matched healthy control participants walked on a treadmill and were subjected to eight unexpected perturbations during the swing phase of the right leg. For each perturbation, the margin of stability ( MS; state of body's centre of mass in relation to the base of support), was determined at touchdown of the perturbed leg and during the following six recovery steps. The first perturbation caused a reduced MS at touchdown for the perturbed leg compared to baseline, indicating an unstable position, with controls requiring five recovery steps to return to MS baseline and UPVD-patients not returning to baseline level within the analyzed six recovery steps. By the eighth perturbation, control subjects needed two steps, and UPVD-patients required three recovery steps, both thereby improving their recovery response with practice. However, MS at touchdown of the perturbed leg increased only for the controls after repeated perturbations, indicating adaptive feedback-driven locomotor improvements for the controls, but not for the UPVD-patients. We concluded that UPVD-patients have a diminished ability to control dynamic gait stability during unexpected perturbations, increasing their fall risk, and that vestibular dysfunction may inhibit the neuromotor system adapting the reactive motor response to perturbations. [ABSTRACT FROM AUTHOR]

Several studies have demonstrated how cerebellar ataxia (CA) affects gait, resulting in deficits in multijoint coordination and stability. Nevertheless, how lesions of cerebellum influence the locomotor muscle pattern generation is still unclear. To better understand the effects of CA on locomotor output, here we investigated the idiosyncratic features of the spatiotemporal structure of leg muscle activity and impairments in the biomechanics of CA gait. To this end, we recorded the electromyographic (EMG) activity of 12 unilateral lower limb muscles and analyzed kinematic and kinetic parameters of 19 ataxic patients and 20 age-matched healthy subjects during overground walking. Neuromuscular control of gait in CA was characterized by a considerable widening of EMG bursts and significant temporal shifts in the center of activity due to overall enhanced muscle activation between late swing and mid-stance. Patients also demonstrated significant changes in the intersegmental coordination, an abnormal transient in the vertical ground reaction force and instability of limb loading at heel strike. The observed abnormalities in EMG patterns and foot loading correlated with the severity of pathology [International Cooperative Ataxia Rating Scale (ICARS), a clinical ataxia scale] and the changes in the biomechanical output. The findings provide new insights into the physiological role of cerebellum in optimizing the duration of muscle activity bursts and the control of appropriate foot loading during locomotion. [ABSTRACT FROM AUTHOR]

Abstract: Background: Individuals with incomplete spinal cord injury need to be assessed in different environments. The objective of this study was to compare lower-limb power generation in subjects with spinal cord injury and healthy subjects while walking on an inclined pathway. Methods: Eleven subjects with spinal cord injury and eleven healthy subjects walked on an inclined pathway at their natural gait speed and at slow gait speed (healthy subjects only). Ground reaction forces were recorded by force plates embedded in the inclined pathway and a 3-D motion analysis system recorded lower-limb motions. Data analysis included gait cycle parameters and joint peak powers. Differences were identified by student t-tests. Findings: Gait cycle parameters were lower in spinal cord injury subjects compared to healthy subjects at natural speed but similar at slow gait speed. Subjects with spinal cord injury presented lower power at the ankle, knee and hip compared to healthy subjects at natural gait speed while only the power generation at push-off remained lower when the two groups performed at similar speed. Interpretation: The most important differences are associated with the fact that individuals with spinal cord injury walk at a slower speed, except for the ankle power generation. This study demonstrated that, even with a good motor recovery, distal deficits remain and may limit the ability to adapt to uphill and downhill walking. Inclined pathways are indicated to train patients with spinal cord injury. Clinicians should focus on the speed of uphill and downhill walking and on the use of plantar flexors. [Copyright &y& Elsevier]