Lower limb joint moments on the fast belt contribute to a reduction of step length asymmetry over ground after split-belt treadmill training in stroke: A pilot study

The influence of induced gait asymmetry on joint reaction forces

Chronic injury- or disease-induced joint impairments result in asymmetric gait deviations that may precipitate changes in joint loading associated with pain and osteoarthritis. Understanding the impact of gait deviations on joint reaction forces (JRFs) is challenging because of concurrent neurological and/or anatomical changes and because measuring JRFs requires medically invasive instrumented implants. Instead, we investigated the impact of joint motion limitations and induced asymmetry on JRFs by simulating data recorded as 8 unimpaired participants walked with bracing to unilaterally and bilaterally restrict ankle, knee, and simultaneous ankle + knee motion. Personalized models, calculated kinematics, and ground reaction forces (GRFs) were input into a computed muscle control tool to determine lower limb JRFs and simulated muscle activations guided by electromyography-driven timing constraints. Unilateral knee restriction increased GRF peak and loading rate ipsilaterally but peak values decreased contralaterally when compared to walking without joint restriction. GRF peak and loading rate increased with bilateral restriction compared to the contralateral limb of unilaterally restricted conditions. Despite changes in GRFs, JRFs were relatively unchanged due to reduced muscle forces during loading response. Thus, while joint restriction results in increased limb loading, reductions in muscle forces counteract changes in limb loading such that JRFs were relatively unchanged.

Modulation of the gait pattern during split-belt locomotion after lateral spinal cord hemisection in adult cats

Most previous studies investigated the recovery of locomotion in animals and people with incomplete spinal cord injury (SCI) during relatively simple tasks (e.g., walking in a straight line on a horizontal surface or a treadmill). We know less about the recovery of locomotion after incomplete SCI in left-right asymmetric conditions, such as turning or stepping along circular trajectories. To investigate this, we collected kinematic and electromyography data during split-belt locomotion at different left-right speed differences before and after a right thoracic lateral spinal cord hemisection in nine adult cats. After hemisection, although cats still performed split-belt locomotion, we observed several changes in the gait pattern compared with the intact state at early (1-2 wk) and late (7-8 wk) time points. Cats with larger lesions showed new coordination patterns between the fore- and hindlimbs, with the forelimbs taking more steps. Despite this change in fore-hind coordination, cats maintained consistent phasing between the fore- and hindlimbs. Adjustments in cycle and phase (stance and swing) durations between the slow and fast sides allowed animals to maintain 1:1 left-right coordination. Periods of triple support involving the right (ipsilesional) hindlimb decreased in favor of quad support and triple support involving the other limbs. Step and stride lengths decreased with concurrent changes in the right fore- and hindlimbs, possibly to avoid interference. The above adjustments in the gait pattern allowed cats to retain the ability to locomote in asymmetric conditions after incomplete SCI. We discuss potential plastic neuromechanical mechanisms involved in locomotor recovery in these conditions.NEW & NOTEWORTHY Everyday locomotion often involves left-right asymmetries, when turning, walking along circular paths, stepping on uneven terrains, etc. To show how incomplete spinal cord injury affects locomotor control in asymmetric conditions, we collected data before and after a thoracic lateral spinal hemisection on a split-belt treadmill with one side stepping faster than the other. We show that adjustments in kinematics and muscle activity allowed cats to retain the ability to perform asymmetric locomotion after hemisection.

Rehabilitation supported by technology: Protocol for an international co-creation and user experience study (Preprint)

Background

Living labs in the health and well-being domain have become increasingly common over the past decade but vary in available infrastructure, implemented study designs, and outcome measures. The Horizon 2020 Project Virtual Health and Wellbeing Living Lab Infrastructure aims to harmonize living lab procedures and open living lab infrastructures to facilitate and promote research activities in the health and well-being domain in Europe and beyond. This protocol will describe the design of a joint research activity, focusing on the use of innovative technology for both rehabilitation interventions and data collection in a rehabilitation context.

Objective

With this joint research activity, this study primarily aims to gain insight into each living lab’s infrastructure and procedures to harmonize health and well-being living lab procedures and infrastructures in Europe and beyond, particularly in the context of rehabilitation. Secondarily, this study aims to investigate the potential of innovative technologies for rehabilitation through living lab methodologies.

Methods

This study has a mixed methods design comprising multiple phases. There are two main phases of data collection: cocreation (phase 1) and small-scale pilot studies (phase 2), which are preceded by a preliminary harmonization of procedures among the different international living labs. An intermediate phase further allows the implementation of minor adjustments to the intervention or protocol depending on the input that was obtained in the cocreation phase. A total of 6 small-scale pilot studies using innovative technologies for intervention or data collection will be performed across 4 countries. The target study sample comprises patients with stroke and older adults with mild cognitive impairment. The third and final phases involve Delphi procedures to reach a consensus on harmonized procedures and protocols.

Results

Phase 1 data collection will begin in March 2022, and phase 2 data collection will begin in June 2022. Results will include the output of the cocreation sessions, small-scale pilot studies, and advice on harmonizing procedures and protocols for health and well-being living labs focusing on rehabilitation.

Conclusions

The knowledge gained by the execution of this research will lead to harmonized procedures and protocols in a rehabilitation context for health and well-being living labs in Europe and beyond. In addition to the harmonized procedures and protocols in rehabilitation, we will also be able to provide new insights for improving the implementation of innovative technologies in rehabilitation.

International Registered Report Identifier (IRRID)

PRR1-10.2196/34537

Dynamic Asymmetries Do Not Match Spatiotemporal Step Asymmetries during Split-Belt Walking

While walking on split-belt treadmills (two belts running at different speeds), the slower limb shows longer anterior steps than the limb dragged by the faster belt. After returning to basal conditions, the step length asymmetry is transiently reversed (after-effect). The lower limb joint dynamics, however, were not thoroughly investigated. In this study, 12 healthy adults walked on a force-sensorised split-belt treadmill for 15 min. Belts rotated at 0.4 m s−1 on both sides, or 0.4 and 1.2 m s−1 under the non-dominant and dominant legs, respectively. Spatiotemporal step parameters, ankle power and work, and the actual mean velocity of the body’s centre of mass (CoM) were computed. On the faster side, ankle power and work increased, while step length and stance time decreased. The mean velocity of the CoM slightly decreased. As an after-effect, modest converse asymmetries developed, fading within 2–5 min. These results may help to decide which belt should be assigned to the paretic and the unaffected lower limb when split-belt walking is applied for rehabilitation research in hemiparesis.

The Effect of Split-Belt Treadmill Interventions on Step Length Asymmetry in Individuals Poststroke: A Systematic Review With Meta-Analysis

BACKGROUND

Individuals poststroke experience gait asymmetries that result in decreased community ambulation and a lower quality of life. A variety of studies have utilized split-belt treadmill training to investigate its effect on gait asymmetry, but many employ various methodologies that report differing results.

OBJECTIVE

The purpose of this meta-analysis was to determine the effects of split-belt treadmill walking on step length symmetry in individuals poststroke both during and following training.

METHODS

A comprehensive search of PubMed/MEDLINE, CINAHL, Web of Science, and Scopus was conducted to find peer-reviewed journal articles that included individuals poststroke that participated in a split-belt treadmill walking intervention. Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) was used to assess risk of bias. Pooled Hedge's g with random effects models were used to estimate the effect of split-belt training on step length symmetry.

RESULTS

Twenty-one studies were assessed and included in the systematic review with 11 of them included in the meta-analysis. Included studies had an average STROBE score of 16.2 ± 2.5. The pooled effects for step length asymmetry from baseline to late adaptation were not significant (g = 0.060, P = .701). Large, significant effects were found at posttraining after a single session (g = 1.04, P < .01), posttraining after multiple sessions (g = -0.70, P = .01), and follow-up (g = -0.718, P = .023).

CONCLUSION

Results indicate split-belt treadmill training with the shorter step length on the fast belt has the potential to improve step length symmetry in individuals poststroke when long-term training is implemented, but randomized controlled trials are needed to confirm the efficacy of split-belt treadmill training.

A simple, clinically applicable motor learning protocol to increase push-off during gait: A proof-of-concept

OBJECTIVE

Task-specific training is often used in functional rehabilitation for its potential to improve performance at locomotor tasks in neurological populations. As push-off impairment are often seen with these patients, this functional approach shows potential to retrain gait overground to normalize the gait pattern and retrain the ability to improve gait speed. The main objective of this project was to validate, in healthy participants, a simple, low-cost push-off retraining protocol based on task-specific training that could be implemented during overground walking in the clinic.

METHODS

30 healthy participants walked in an 80-meter long corridor before, during, and after the application of an elastic resistance to the right ankle. Elastic tubing attached to the front of a modified ankle-foot orthosis delivered the resistance during push-off. Relative ankle joint angular displacements were recorded bilaterally and continuously during each walking condition.

RESULTS

On the resisted side, participants presented aftereffects (increased peak plantarflexion angle from 13.4±4.2° to 20.0±6.4°, p<0.0001 and increased peak plantarflexion angular velocity from 145.8±22.7°/s to 174.4±37.4°/s, p<0.0001). On the non-resisted side, aftereffects were much smaller than on the resisted side suggesting that the motor learning process was mainly specific to the trained leg.

CONCLUSION

This study shows the feasibility of modifying push-off kinematics using an elastic resistance applied at the ankle while walking overground. This approach represents an interesting venue for future gait rehabilitation.

Augmenting propulsion demands during split-belt walking increases locomotor adaptation of asymmetric step lengths

Background

Promising studies have shown that the gait symmetry of individuals with hemiparesis due to brain lesions, such as stroke, can improve through motor adaptation protocols forcing patients to use their affected limb more. However, little is known about how to facilitate this process. Here we asked if increasing propulsion demands during split-belt walking (i.e., legs moving at different speeds) leads to more motor adaptation and more symmetric gait in survivors of a stroke, as we previously observed in subjects without neurological disorders.

Methods

We investigated the effect of propulsion forces on locomotor adaptation during and after split-belt walking in the asymmetric motor system post-stroke. To test this, 12 subjects in the chronic phase post-stroke experienced a split-belt protocol in a flat and incline session so as to contrast the effects of two different propulsion demands. Step length asymmetry and propulsion forces were used to compare the motor behavior between the two sessions because these are clinically relevant measures that are altered by split-belt walking.

Results

The incline session resulted in more symmetric step lengths during late split-belt walking and larger after-effects following split-belt walking. In both testing sessions, subjects who have had a stroke adapted to regain speed and slope-specific leg orientations similarly to young, intact adults. Importantly, leg orientations, which were set by kinetic demands, during baseline walking were predictive of those achieved during split-belt walking, which in turn predicted each individual’s post-adaptation behavior. These results are relevant because they provide evidence that survivors of a stroke can generate the leg-specific forces to walk more symmetrically, but also because we provide insight into factors underlying the therapeutic effect of split-belt walking.

Conclusions

Individuals post-stroke at a chronic stage can adapt more during split-belt walking and have greater after-effects when propulsion demands are augmented by inclining the treadmill surface. Our results are promising since they suggest that increasing propulsion demands during paradigms that force patients to use their paretic side more could correct gait asymmetries post-stroke more effectively.

Effectiveness of rehabilitation interventions to improve paretic propulsion in individuals with stroke - A systematic review

BACKGROUND

Stroke survivors often show reduced walking velocity and gait asymmetry. These gait abnormalities are associated with reduced propulsion of the paretic leg. This review aimed to provide an overview of the potential effectiveness of post-stroke rehabilitation interventions to improve paretic propulsion, ankle kinetics and walking velocity.

METHODS

A systematic search was performed in Pubmed, Web of Science, Embase, and Pedro. Studies were eligible if they reported changes in propulsion measures (impulse, peak value and symmetry ratios) or ankle kinetics (moment and power) following intervention in stroke survivors (group size ≥10). Study selection, data extraction and quality assessment were performed independently by two authors.

FINDINGS

A total of 28 studies were included, of which 25 studies applied exercise interventions, two studies focused on surgical interventions, and one on non-invasive brain stimulation. The number of high-quality trials was limited (N = 6; score Downs and Black scale ≥19). Propulsion measures were the primary outcome in eight studies. In general, mixed results were reported with 14 interventions yielding improvements in propulsion and ankle kinetics. In contrast, gains in walking velocity were observed in the vast majority of studies (N = 20 out of 23).

INTERPRETATION

Interventions that yielded gains in propulsion appeared to have in common that they challenged and/or enabled the utilization of latent propulsive capacity of the paretic leg during walking. Walking speed generally increased, regardless of the observed change in propulsion, suggesting the use of compensatory mechanisms. Findings should, however, be interpreted with some caution, as the evidence base for this emerging focus of rehabilitation is limited.