Adaptive changes in foot placement for split-belt treadmill walking in individuals with stroke

The Detrimental Effect of Stroke on Motor Adaptation

BackgroundWhile it is evident that stroke impairs motor control, it remains unclear whether stroke impacts motor adaptation-the ability to flexibly modify movements in response to changes in the body and the environment. The mixed results in the literature may be due to differences in participants' brain lesions, sensorimotor tasks, or a combination of both.ObjectiveWe first sought to better understand the overall impact of stroke on motor adaptation and then to delineate the impact of lesion hemisphere and sensorimotor task on adaptation poststroke.MethodsFollowing the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, we conducted a systematic review and meta-analysis of 18 studies comparing individuals poststroke to neurotypical controls, with each group consisting of over 200 participants.ResultsWe found that stroke impairs motor adaptation (d = -0.63; 95% confidence interval [-1.02, -0.24]), and that the extent of this impairment did not differ across sensorimotor tasks but may vary with the lesioned hemisphere. Specifically, we observed greater evidence for impaired adaptation in individuals with left hemisphere lesions compared to those with right hemisphere lesions.ConclusionsThis review not only clarifies the detrimental effect of stroke on motor adaptation but also underscores the need for finer-grained studies to determine precisely how various sensorimotor learning mechanisms are impacted. The current findings may guide future mechanistic and applied research at the intersection of motor learning and neurorehabilitation.

Impact of unilateral knee restraint on symmetry adaptation and double-support phase dynamic stability during split-belt walking

The split-belt treadmill task is an effective tool for studying walking adaptation, particularly the symmetry adaptation of spatiotemporal parameters such as step length and double support time. This study aimed to evaluate the relationship between symmetry adaptation of spatiotemporal parameters and dynamic stability during the double-support phase in split-belt walking. We hypothesized that restraining fast-side knee extension, which is necessary for step lengthening during adaptation, would decrease dynamic stability during the double-support phase. Ten able-bodied male participants performed split-belt walking tasks under three conditions: control, fast-side knee restraint, and slow-side knee restraint. Our findings revealed that slow-side knee restraint disrupted symmetry in double support time and significantly decreased stability on the fast side during the early and late adaptation phases. Contrary to our hypothesis, fast-side knee restraint did not have a statistically significant effect on dynamic stability or symmetry. These results suggest that decreased dynamic stability during the double-support phase, particularly due to limitations in the movement of the trailing leg, may hinder the adaptation process. This study highlights the importance of dynamic stability control during the double-support phase for successful walking adaptation. Future studies with larger sample sizes and varying speed conditions are recommended to generalize these findings and develop targeted interventions to improve walking adaptability and dynamic stability.

Single-belt vs. split-belt treadmill symmetry training: is there a perfect choice for gait rehabilitation post-stroke?

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.

Habitual exercise evokes fast and persistent adaptation during split-belt walking

Changing movement patterns in response to environmental perturbations is a critical aspect of gait and is related to reducing the energetic cost of the movement. Exercise improves energetic capacity for submaximal exercise and may affect how people adapt movement to reach an energetic minimum. The purpose of this study was to determine whether self-reported exercise behavior influences gait adaptation in young adults. Young adults who met the optimal volume of exercise according to the Physical Activity Guidelines for Americans (MOVE; n = 19) and young adults who did not meet the optimal volume of exercise (notMOVE; n = 13) walked on a split-belt treadmill with one belt moving twice the speed of the other belt for 10 minutes. Step length asymmetry (SLA) and mechanical work done by each leg were measured. Nonlinear mixed effects models compared the time course of adaptation between MOVE and notMOVE, and t-tests compared net work at the end of adaptation between MOVE and notMOVE. Compared to notMOVE, MOVE had a faster initial response to the split belt treadmill, and continued to adapt over the duration of split-belt treadmill walking. Young adults who engage in sufficient amounts of exercise responded more quickly to the onset of a perturbation, and throughout the perturbation they continued to explore movement strategies, which might be related to reduction of energetic cost. Our findings provide insights into the multisystem positive effects of exercise, including walking adaptation.

Using robot-assisted stiffness perturbations to evoke aftereffects useful to post-stroke gait rehabilitation

Stroke is a major global issue, affecting millions every year. When a stroke occurs, survivors are often left with physical disabilities or difficulties, frequently marked by abnormal gait. Post-stroke gait normally presents as one of or a combination of unilaterally shortened step length, decreased dorsiflexion during swing phase, and decreased walking speed. These factors lead to an increased chance of falling and an overall decrease in quality of life due to a reduced ability to locomote quickly and safely under one's own power. Many current rehabilitation techniques fail to show lasting results that suggest the potential for producing permanent changes. As technology has advanced, robot-assisted rehabilitation appears to have a distinct advantage, as the precision and repeatability of such an intervention are not matched by conventional human-administered therapy. The possible role in gait rehabilitation of the Variable Stiffness Treadmill (VST), a unique, robotic treadmill, is further investigated in this paper. The VST is a split-belt treadmill that can reduce the vertical stiffness of one of the belts, while the other belt remains rigid. In this work, we show that the repeated unilateral stiffness perturbations created by this device elicit an aftereffect of increased step length that is seen for over 575 gait cycles with healthy subjects after a single 10-min intervention. These long aftereffects are currently unmatched in the literature according to our knowledge. This step length increase is accompanied by kinematics and muscle activity aftereffects that help explain functional changes and have their own independent value when considering the characteristics of post-stroke gait. These results suggest that repeated unilateral stiffness perturbations could possibly be a useful form of post-stroke gait rehabilitation.

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.