After a cerebrovascular accident (CVA) aerobic deconditioning contributes to diminished physical function. Functional electrical stimulation (FES)-assisted cycling is a promising exercise paradigm ...designed to target both aerobic capacity and locomotor function. This pilot study aimed to evaluate the effects of an FES-assisted cycling intervention on aerobic capacity and locomotor function in individuals post-CVA.
Eleven individuals with chronic (>6 months) post-CVA hemiparesis completed an 8-wk (three times per week; 24 sessions) progressive FES-assisted cycling intervention. V˙O2peak, self-selected, and fastest comfortable walking speeds, gait, and pedaling symmetry, 6-min walk test (6MWT), balance, dynamic gait movements, and health status were measured at baseline and posttraining.
Functional electrical stimulation-assisted cycling significantly improved V˙O2peak (12%, P = 0.006), self-selected walking speed (SSWS, 0.05 ± 0.1 m·s, P = 0.04), Activities-specific Balance Confidence scale score (12.75 ± 17.4, P = 0.04), Berg Balance Scale score (3.91 ± 4.2, P = 0.016), Dynamic Gait Index score (1.64 ± 1.4, P = 0.016), and Stroke Impact Scale participation/role domain score (12.74 ± 16.7, P = 0.027). Additionally, pedal symmetry, represented by the paretic limb contribution to pedaling (paretic pedaling ratio PPR) significantly improved (10.09% ± 9.0%, P = 0.016). Although step length symmetry (paretic step ratio PSR) did improve, these changes were not statistically significant (-0.05% ± 0.1%, P = 0.09). Exploratory correlations showed moderate association between change in SSWS and 6-min walk test (r = 0.74), and moderate/strong negative association between change in PPR and PSR.
These results support FES-assisted cycling as a means to improve both aerobic capacity and locomotor function. Improvements in SSWS, balance, dynamic walking movements, and participation in familial and societal roles are important targets for rehabilitation of individuals after CVA. Interestingly, the correlation between PSR and PPR suggests that improvements in pedaling symmetry may translate to a more symmetric gait pattern.
People with chronic stroke (PwCS) are susceptible to mediolateral losses of balance while walking, possibly due in part to inaccurate control of mediolateral paretic foot placement. We hypothesized ...that mediolateral foot placement errors when stepping to stationary or shifting visual targets would be larger for paretic steps than for steps taken by neurologically-intact individuals, hereby referred to as controls. Secondarily, we hypothesized that paretic foot placement errors would be correlated with previously identified deficits in isolated paretic hip abduction accuracy. 34 PwCS and 12 controls walked overground on an instrumented mat used to quantify foot placement location relative to parallel lines separated by various widths (10, 20, 30 cm). With stationary step width targets, foot placement errors were larger for paretic steps than for either non-paretic or control steps, most notably for the narrowest prescribed step width (mean absolute errors of 3.9, 2.3, and 1.9 cm, respectively). However, no differences in foot placement accuracy were observed immediately following visual target shifts, as all groups required multiple steps to achieve the new prescribed step width. Paretic hip abduction accuracy was moderately correlated with mediolateral foot placement accuracy when stepping to stationary targets (r = 0.49), but not shifting targets (r = 0.16). The present results suggest that a reduced ability to accurately abduct the paretic leg contributes to inaccurate paretic foot placement. However, the need to ensure mediolateral walking balance through mechanically-appropriate foot placement may often override the prescribed goal of stepping to visual targets, a concern of particular importance for narrow steps.
•Dynamics-dependent adjustments in step width are important for a stable gait.•The link between paretic step width and pelvis dynamics is weakened post-stroke.•The mediolateral margin of stability is ...larger and more variable for paretic steps.•Increased step-by-step control of step width may improve post-stroke gait balance.
Humans partially maintain gait stability by actively controlling step width based on the dynamic state of the pelvis – hereby defined as the “dynamics-dependent control of step width”. Following a stroke, deficits in the accurate control of paretic leg motion may prevent use of this stabilization strategy.
Do chronic stroke survivors exhibit paretic-side deficits in the dynamics-dependent control of step width?
Twenty chronic stroke survivors participated in this cross-sectional study, walking on a treadmill at their self-selected (0.57 ± 0.25 m/s; mean ± s.d.) and fastest-comfortable (0.81 ± 0.30 m/s) speeds. To quantify the dynamics-dependent control of step width, we calculated the proportion of the step-by-step variance in step width that could be predicted from mediolateral pelvis dynamics, and used partial correlations to differentiate the relative effects of pelvis displacement and velocity. Secondarily, we calculated the mean and standard deviation of more traditional gait metrics: step width; lateral foot placement; and mediolateral margin of stability (MoS). We used repeated measures ANOVA to test for significant effects of leg (paretic vs. non-paretic) and speed (self-selected vs. fastest-comfortable) on these measures.
Relative to non-paretic steps, paretic steps exhibited a weaker (p ≤ 0.005) link between step width and pelvis dynamics, attributable to a decreased partial correlation between step width and pelvis displacement (p ≤ 0.001). Paretic steps were also placed more laterally (p < 0.0001), with a larger (p < 0.0001) and more variable (p = 0.003) MoS. The only effect of faster walking speeds was a narrower step width (p < 0.0001).
Pelvis displacement was less tightly linked to step width for paretic steps than for non-paretic steps, indicating a decrease in the step-by-step reactive control normally used to ensure mediolateral stability. Instead, stroke survivors placed their paretic leg farther laterally to ensure a larger MoS, behavior consistent with a greater reliance on a generalized feed-forward gait stabilization strategy.
Freezing of gait (FOG) is a debilitating feature of Parkinson's disease (PD). Evidence suggests patients with FOG have increased cortical control of gait. The supplementary motor area (SMA) may be a ...key structure due to its connectivity with locomotor and cognitive networks. The objectives of this study were to determine (1) if SMA connectivity is disrupted in patients with FOG and (2) if “inhibitory” repetitive transcranial magnetic stimulation can decrease maladaptive SMA connectivity.
Two experiments were performed. In experiment 1 resting-state (T2* BOLD imaging) was compared between 38 PD freezers and 17 PD controls. In experiment 2, twenty PD patients with FOG were randomized to either 10 sessions of real or sham rTMS to the SMA (1 Hz, 110% motor threshold, 1200 pulses/session) combined with daily gait training.
(Experiment 1) Freezers had increased connectivity between the left SMA and the vermis of the cerebellum and decreased connectivity between the SMA and the orbitofrontal cortex (pFDR-corr <0.05). (Experiment 2) 10 sessions of active TMS reduced SMA connectivity with the anterior cingulate, angular gyrus and the medial temporal cortex, whereas sham TMS did not reduce SMA connectivity. From a behavioral perspective, both groups showed nFOG-Q improvements (F(4, 25.7) = 3.87, p = 0.014).
The SMA in freezers is hyper-connected to the cerebellum, a key locomotor region which may represent maladaptive compensation. In this preliminary study, 1 Hz rTMS reduced SMA connectivity however, this was not specific to the locomotor regions. Intervention outcomes may be improved with subject specific targeting of SMA.
•Unknown if supplementary motor area is adaptive or maladaptive for freezing of gait.•The supplemental motor area is hyperconnected to the cerebellum in freezers.•Low frequency stimulation of the supplemental motor area and gait training reduces connectivity.•Low frequency stimulation and gait training has variable effects on freezing outcomes.
Transcranial direct current stimulation (tDCS) has mixed effects on walking performance in individuals poststroke. This is likely the result of variations in tDCS electrode montages and ...individualized responses. The purpose of this study was to quantify the effects of a single session of tDCS using various electrode montages on poststroke walking performance.
Individuals with chronic stroke ( n = 16) participated in a double-blind, randomized cross-over study with sham stimulation and three tDCS electrode montages. Gait speed, paretic step ratio, and paretic propulsion were assessed prestimulation and poststimulation at self-selected and fastest comfortable speeds. Changes in muscle activation patterns with self-selected walking were quantified by the number of modules derived from nonnegative matrix factorization of EMG signals for hypothesis generation.
There was no significant effect of active stimulation montages compared with sham. Comparisons between each participant's best response to tDCS and sham show personalized tDCS may have a positive effect on fastest comfortable overground gait speed ( P = 0.084), paretic step ratio ( P = 0.095) and paretic propulsion ( P = 0.090), and self-selected paretic step ratio ( P = 0.012). Participants with two or three modules at baseline increased module number in response to the all experimental montages and sham, but responses were highly variable.
A single session of tDCS may affect clinical and biomechanical walking performance, but effects seem to be dependent on individual response variability to different electrode montages. Findings of this study are consistent with responses to various tDCS electrode montages being the result of underlying neuropathology, and the authors recommend examining how individual factors affect responses to tDCS.
Many people with chronic stroke (PwCS) exhibit walking balance deficits linked to increased fall risk and decreased balance confidence. One potential contributor to these balance deficits is a ...decreased ability to modulate mediolateral stepping behavior based on pelvis motion. This behavior, hereby termed mediolateral step modulation, is thought to be an important balance strategy but can be disrupted in PwCS.
Are biomechanical metrics of mediolateral step modulation related to common clinical balance measures among PwCS?
In this cross-sectional study, 93 PwCS walked on a treadmill at their self-selected speed for 3-minutes. We quantified mediolateral step modulation for both paretic and non-paretic steps by calculating partial correlations between mediolateral pelvis displacement at the start of each step and step width (ρSW), mediolateral foot placement relative to the pelvis (ρFP), and final mediolateral location of the pelvis (ρPD) at the end of the step. We also assessed several common clinical balance measures (Functional Gait Assessment FGA, Activities-specific Balance Confidence scale ABC, self-reported fear of falling and fall history). We performed Spearman correlations to relate each biomechanical metric of step modulation to FGA and ABC scores. We performed Wilcoxon rank sum tests to compare each biomechanical metric between individuals with and without a fear of falling and a history of falls.
Only ρFP for paretic steps was significantly related to all four clinical balance measures; higher paretic ρFP values tended to be observed in participants with higher FGA scores, with higher ABC scores, without a fear of falling and without a history of falls. However, the strength of each of these relationships was only weak to moderate.
While the present results do not provide insight into causality, they justify future work investigating whether interventions designed to increase ρFP can improve clinical measures of post-stroke balance in parallel.
•Many people with chronic stroke have reduced walking balance and confidence.•Modulation of mediolateral foot placement may be an important balance strategy.•Paretic foot placement modulation was related to clinical balance measures.
Objective and importance Residual effects of stroke include well-documented functional limitations and high prevalence of depression. Repetitive transcranial magnetic stimulation (rTMS) and aerobic ...exercise (AEx) are established techniques that improve depressive symptoms, but a combination of the two has yet to be reported. The purpose of this case series is to examine the safety, feasibility, and impact of combined rTMS and AEx on post-stroke depression and functional mobility. Clinical presentation Three participants with a history of stroke and at least mild depressive symptoms (Patient Health Questionare-9 ≥5). Intervention Both rTMS and AEx were completed 3 times/week for 8-weeks. rTMS was applied to the left dorsolateral prefrontal cortex, 5000 pulses/session at 10 Hz, at an intensity of 120% of resting motor threshold. AEx consisted of 40 min of treadmill walking at 50-70% of heart rate reserve. Results Depressive symptoms improved in all three participants, with all demonstrating response (≥50% improvement in symptoms) and likely remission. All participants improved their Six Minute Walk Test distance and Participants 1 and 2 also improved Berg Balance Scale scores. Participants 1 and 3 improved overground walking speeds. No serious adverse events occurred with the application of rTMS or AEx and the participants' subjective reports indicated positive responses. Adherence rate for both rTMS and AEx was 98%. Conclusion Combined treatment of rTMS and AEx appears safe, feasible, and tolerable in individuals with a history of stroke and at least mild depressive symptoms. All participants had good compliance and demonstrated improvements in both depressive symptoms and walking capacity.
Background: Lower extremity muscle weakness is a primary contributor to post-stroke dysfunction. Resistance training is an effective treatment for hemiparetic weakness and improves walking ...performance. Post-stroke subject characteristics that do or do not improve walking speed following resistance training are unknown.
Objective: The purpose of this paper was to describe baseline characteristics, as well as responses to training, associated with achieving a minimal clinically important difference (MCID) in walking speed (≥0.16 m/s) following Post-stroke Optimization of Walking Using Explosive Resistance (POWER) training.
Methods: Seventeen participants completed 24 sessions of POWER training, which included intensive progressive leg presses, jump training, calf raises, sit-to-stands, step-ups, and over ground fast walking. Outcomes included SSWS, FCWS, DGI, FMA-LE, 6-MWT, paretic knee power, non-paretic knee power, and paretic step ratio.
Results: Specific to those who reached MCID in SSWS (e.g. "responders"), significant improvements in SSWS, FCWS, 6-MWT, paretic knee power, and non-paretic knee power was realized. Paretic knee power and non-paretic knee power significantly improved in those who did not achieve MCID for gait speed (e.g. "non-responders").
Conclusion: The potential for POWER training to enhance general locomotor function was confirmed. Baseline paretic knee strength/power may be an important factor in how an individual responds to this style of training. The lack of change within the non-responders emphasizes the contribution of factors other than lower extremity muscle power improvement to locomotor dysfunction.
Background. Approximately 35,000 strokes occur annually in adults below the age of 40, and there is disappointingly little data describing their responses to rehabilitation. The purpose of this ...analysis was to determine the effects of Poststroke Optimization of Walking using Explosive Resistance (POWER) training in young (<40 years) and older (>60 years) adults and to describe relationships between training-induced improvements in muscular and locomotor function. Methods. Data was analyzed from 16 individuals with chronic stroke who participated in 24 sessions of POWER training. Outcomes included muscle power generation, self-selected walking speed (SSWS), 6-minute walk test, Fugl-Meyer motor assessment, Berg Balance Scale, and Dynamic Gait Index. Results. There were no significant differences between groups at baseline. Within-group comparisons revealed significant improvements in paretic and nonparetic knee extensor muscle power generation in both groups. Additionally, young participants significantly improved SSWS. Improvements in SSWS were more strongly associated with improvements in power generation on both sides in young versus older participants. Conclusions. Younger adults after stroke seem to preferentially benefit from POWER training, particularly when increasing gait speed is a rehabilitation goal. Future research should aim to further understand age-related differences in response to training to provide optimal treatments for all individuals following stroke.
Abstract Background Gait instability often limits post-stroke function, although the mechanisms underlying this instability are not entirely clear. Our recent work has suggested that one possible ...factor contributing to post-stroke gait instability is a reduced ability to accurately control foot placement. The purpose of the present experiments was to investigate whether post-stroke gait function is related to the ability to accurately abduct and adduct the hip, as required for accurate foot placement. Methods 35 chronic stroke survivors and 12 age-matched controls participated in this experiment. Participants performed hip oscillation trials designed to quantify hip abduction/adduction accuracy, in which they lay supine and moved their leg through a prescribed range of motion in time with a metronome. Stroke survivors also performed overground walking trials at their self-selected speed. Findings 28 of the 35 stroke survivors had sufficient active range of motion to perform the prescribed hip oscillation task. In comparison to controls, these 28 stroke survivors were significantly less accurate at matching the abduction target, matching the adduction target, and moving in time with the metronome. Across these stroke survivors, a multiple regression revealed that only paretic hip abduction accuracy made a unique contribution to predicting paretic step width and paretic step period, metrics of gait performance. Interpretation The present results demonstrate that the ability to accurately abduct the hip is related to post-stroke gait performance, as predicted from a model-based gait stabilization strategy. Therefore, interventions designed to improve lower limb movement accuracy may hold promise for restoring post-stroke gait stability.
PDF
