Relationship between step length asymmetry and walking performance in subjects with chronic hemiparesis

Biomechanical mechanism of peak braking force modulation during increased walking speed in healthy young adults

Walking speed is an important indicator of health and function across a variety of populations. Faster walking requires both larger propulsive and braking forces, thoughof the two, propulsive force generation has been far more extensively investigated. This study seeks to develop and validatea quasi-static biomechanical model of braking forcein healthy individualsacrossself-selected and fast walking speeds. Additionally, the model was used to quantify the relative contribution of knee extension torque versus leading limb angle (LLA) to changes in braking force across walking speeds. Kinetic and kinematic data from 44 young healthy participants walking overground at 2 different speeds were analyzed. The model prediction correlated strongly with actual braking force production at the self-selected speed (r = 0.9; p < 0.01), the fast speed (r = 0.97; p < 0.01) andthe change between speeds (r = 0.95, p < 0.01). On average, increases in knee extension torque and the LLA contributed 132 % and 12 %, respectively, to increases in peak braking force (PBF). Increases in the external lever arm length operated to reduce predicted braking force by 56 %. The results highlight the importance of rapid eccentric contraction of the knee extensors during braking force modulation in healthy gait.

Therapeutic effect of gait training with two types of ankle-foot orthoses on the gait of the stroke patients in the recovery phase

Objectives

This study aimed to demonstrate the therapeutic effect of gait training using ankle-foot orthoses (AFOs) on the gait of stroke patients when not wearing AFOs with two different types of AFO, an AFO with an oil damper (AFO-OD) that resists plantarflexion and an AFO with a plantarflexion stop (AFO-PS), and to display the possible differences between the AFO types.

Patients and methods

Forty-two patients (38 males, 4 males, mean age: 59.7±10.9; range, 38 to 81 years) with subacute stroke were randomized to either an AFO-PS or an AFO-OD group. Participants were given gait training in a two-week period by physiotherapists wearing their allocated AFO. Nineteen patients were assigned to the AFO-PS group and 20 to the AFO-OD group. Patients' gait without an AFO before gait training and then after two weeks of training wearing allocated AFOs was recorded through a three-dimensional movement capture system.

Results

A therapeutic effect through two weeks of continuous use of AFOs and gait training was found in both AFO groups (main effect of time) in the spatiotemporal factors, ankle joint moments, ankle power generation, shank-to-vertical angle, and center of gravity velocity throughout the stance phase, pre-swing knee angular velocity, and hip flexion moment in pre-swing. The results did not show a large interaction between two AFOs group.

Conclusion

These findings reveal that both AFOs had significant therapeutic effects on stroke gait. There was no significant difference between the two AFO groups. Further studies with a control group representing the effects of gait training without wearing an AFO are needed.

Ankle-foot orthosis with an oil damper versus nonarticulated ankle-foot orthosis in the gait of patients with subacute stroke: a randomized controlled trial

BACKGROUND

Gait improvement in patients with stroke has been examined in terms of use or non-use of an ankle-foot orthosis (AFO), but the effects of different kinds of AFOs remain unclear. In this study, the effect on gait of using an AFO with an oil damper (AFO-OD), which has plantarflexion stiffness without dorsiflexion resistance, was compared with a nonarticulated AFO, which has both dorsiflexion and plantarflexion stiffness, in a randomized controlled trial.

METHODS

Forty-one patients (31 men, 10 women; mean age 58.4 ± 11.3 years) in the subacute phase of stroke were randomly allocated to two groups to undergo gait training for 1 h daily over 2 weeks by physiotherapists while wearing an AFO-OD or a nonarticulated AFO. A motion capture system was utilized to measure shod gait without orthosis at baseline and after training with the allocated AFO. Data analysis focused on the joint kinematics and kinetics, spatial and temporal parameters, ground reaction force, and shank-to-vertical angle. Unpaired t-test or Mann-Whitney U test was performed to clarify the difference in gait with an AFO between the two AFO groups after training, with a significance level of p = 0.05.

RESULTS

Thirty-six patients completed the study (17 in the AFO-OD group and 19 in the nonarticulated AFO group). The ankle joint was more dorsiflexed in single stance (p = 0.008, effect size r = 0.46) and peak ankle power absorption was larger in stance (p = 0.007, r = 0.55) in the AFO-OD group compared with the nonarticulated AFO group. Peak power absorption varied among patients in the AFO-OD group. Increased dorsiflexion angles were also found at initial contact (p = 0.008, r = 1.51), pre-swing (p = 0.045, r = 0.91), and the swing phase (p = 0.045, r = 0.91) in the AFO-OD group. There was no difference in peak plantarflexion moment, ankle power generation, spatial or temporal parameters, ground reaction force, or shank-to-vertical angle between the two groups.

CONCLUSIONS

The results of this study showed that an AFO with plantarflexion stiffness but without dorsiflexion resistance produced greater improvement in ankle joint kinematics and kinetics compared with the nonarticulated AFO, but the results of peak power absorption varied greatly among patients. Trial registration UMIN000028126, Registered 1 August 2017, https://upload.umin.ac.jp/cgi-bin/icdr/ctr_menu_form_reg.cgi?recptno=R000032197.

Gait Adaptation Is Different between the Affected and Unaffected Legs in Children with Spastic Hemiplegic Cerebral Palsy While Walking on a Changing Slope

Walking on sloped surfaces requires additional effort; how individuals with spastic hemiplegic cerebral palsy (CP) manage their gait on slopes remains unknown. Herein, we analyzed the difference in gait adaptation between the affected and unaffected legs according to changes in the incline by measuring spatiotemporal and kinematic data in children with spastic hemiplegic CP. Seventeen children underwent instrumented three-dimensional gait analysis on a dynamic pitch treadmill at an incline of +10° to −10° (intervals of 5°). While the step length of the affected legs increased during uphill gait and decreased during downhill gait, the unaffected legs showed no significance. During uphill gait, the hip, knee, and ankle joints of the affected and unaffected legs showed increased flexion, while the unaffected leg showed increased knee flexion throughout most of the stance phase compared with the affected leg. During downhill gait, hip and knee flexion increased in the affected leg, and knee flexion increased in the unaffected leg during the early swing phase. However, the ankle plantar flexion increased during the stance phase only in the unaffected leg. Although alterations in temporospatial variables and joint kinematics occurred in both legs as the slope angle changed, they showed different adaptation mechanisms.

Bilateral vs. Paretic-Limb-Only Ankle Exoskeleton Assistance for Improving Hemiparetic Gait: A Case Series

People with lower-limb hemiparesis have impaired function on one side of the body that affects their walking ability. Wearable robotic assistance has been investigated to treat hemiparetic gait by applying assistance to the paretic limb. In this exploratory case series, we sought to compare the effects of bilateral vs. paretic-limb-only ankle exoskeleton assistance on walking performance in a case series of three heterogeneous presentations of lower-limb hemiparesis. A secondary goal was to validate the use of a real-time ankle-moment-adaptive exoskeleton control system for effectively assisting hemiparetic gait; the ankle moment controller accuracy ranged from 72 - 90% across all conditions and participants. Compared to walking without the device, both paretic-limb-only and bilateral assistance resulted in greater average total ankle power (up to 72%), improved treadmill walking efficiency (up to 28%), and increased over-ground walking distance (up to 41%). All participants achieved a more symmetrical, efficient gait pattern with bilateral assistance, indicating that assisting both limbs may be more beneficial than assisting only the paretic side in people with hemiparetic gait. The results of this case series are intended to inform future clinical studies and exoskeleton designs in a wide range of patient populations.

Two-Month Individually Supervised Exercise Therapy Improves Walking Speed, Step Length, and Temporal Gait Symmetry in Chronic Stroke Patients: A before-after Trial

Gait asymmetry is common after stroke and is a major risk factor for falls. In particular, temporal gait asymmetry often remains in the chronic stage of stroke. However, health insurance does not cover rehabilitation for patients with chronic stroke in many countries. Accordingly, it is undetermined whether individually supervised exercise therapy has beneficial effects on chronic hemiparetic gait. Patients with stroke (n = 25) more than 6 months after onset performed 70 min of individually supervised exercise twice weekly for 2 months in 16 sessions with qualified personnel. The intervention significantly reduced the pre-swing phase on the paretic side (mean = 91.8%, 95%CI, 84.8−98.8). In addition, there was a significant improvement in pre-swing phase symmetry in those with great asymmetry prior to the intervention (p = 0.022). Step length significantly increased after the intervention on both sides (non-paretic, p = 0.029; paretic, p = 0.0055). Walking time at both comfortable and maximum speeds was significantly shortened (comfortable, p = 0.0041; maximum, p < 0.0001). Our findings suggest that there remains scope to improve gait ability with individually supervised exercise therapy in patients with chronic stroke, whose functional recovery is often considered unlikely. This type of intervention may be a simple and effective option to improve gait parameters, including temporal asymmetry, even in patients with chronic stroke.

Adjunct Non-Elastic Hip Taping Improves Gait Stability in Cane-Assisted Individuals with Chronic Stroke: A Randomized Controlled Trial

Cane-assisted individuals with chronic stroke may perform with an abnormal gait pattern. One of the important factors of gait training for cane-assisted individuals is inducing improvement in lower limb muscle activity of the paretic side. Non-elastic taping on the hip may be used as an adjunct therapy for improving gait. The objective of this study was to investigate effects of non-elastic hip taping combined with exercise on gait in cane-assisted individuals with chronic stroke. This study is a single-blinded, randomized controlled trial. A total of 21 cane-assisted ambulators with chronic stroke were enrolled. Participants in both groups received a therapeutic exercise program, with the experimental and control groups having adjunct non-elastic taping and sham taping on the hip, respectively. The gait, Berg Balance Scale, 6-min walk test, and Fall Efficacy Scale–International were measured at pre-intervention, post-intervention, and 1-month follow-up. The experimental group resulted in significantly better performance in double-support time compared with the control group. Furthermore, the experimental group showed a significant improvement in double-support time and spatial symmetry at post-intervention and 1-month follow-up compared with pre-intervention. This study demonstrated that non-elastic hip taping combined with exercise could improve gait stability in cane-assisted ambulators. Non-elastic hip taping would be a useful adjunct to rehabilitation strategies for individuals with chronic stroke.

Methodological Considerations in Assessing Interlimb Coordination on Poststroke Gait: A Scoping Review of Biomechanical Approaches and Outcomes

Objective: To identify and summarize biomechanical assessment approaches in interlimb coordination on poststroke gait. Introduction: Interlimb coordination involves complex neurophysiological mechanisms that can be expressed through the biomechanical output. The deepening of this concept would have a significant contribution in gait rehabilitation in patients with an asymmetric neurological impairment as poststroke adults. Inclusion criteria: Poststroke adults (>19 years old), with assessment of interlimb coordination during gait, in an open context, according to the Population, Concept, Context framework. Methods: A literature search was performed in PubMed, Web of Science™, Scopus, and gray literature in Google Scholar™, according to the PRISMA-ScR recommendations. Studies written in Portuguese or English language and published between database inception and 14 November 2021 were included. Qualitative studies, conference proceedings, letters, and editorials were excluded. The main conceptual categories were “author/year”, “study design”, “participant’s characteristics”, “walking conditions”, “instruments” and “outcomes”. Results: The search identified 827 potentially relevant studies, with a remaining seven fulfilling the established criteria. Interlimb coordination was assessed during walking in treadmill (n = 3), overground (n = 3) and both (n = 1). The instruments used monitored electromyography (n = 2), kinetics (n = 2), and kinematics (n = 4) to assess spatiotemporal parameters (n = 4), joint kinematics (n = 2), anteroposterior ground reaction forces (n = 2), and electromyography root mean square (n = 2) outcomes. These outcomes were mostly used to analyze symmetry indices or ratios, to calculate propulsive impulse and external mechanical power produced on the CoM, as well as antagonist coactivation. Conclusions: Assessment of interlimb coordination during gait is important for consideration of natural auto-selected overground walking, using kinematic, kinetic, and EMG instruments. These allow for the collection of the main biomechanical outcomes that could contribute to improve better knowledge of interlimb coordination assessment in poststroke patients.

Merged swing-muscle synergies and their relation to walking characteristics in subacute post-stroke patients: An observational study

In post-stroke patients, muscle synergy (the coordination of motor modules during walking) is impaired. In some patients, the muscle synergy termed module 1 (hip/knee extensors) is merged with module 2 (ankle plantar flexors), and in other cases, module 1 is merged with module 4 (knee flexors). However, post-stroke individuals with a merging pattern of module 3 (hip flexor and ankle dorsiflexor) and module 4, which is the swing-muscle synergy, have not been reported. This study aimed to determine the muscle-synergy merging subtypes of post-stroke during comfortable walking speed (cws). We also examined the effect of experimental lower-limb angle modulation on the muscle synergy patterns of walking in each subtype. Forty-one participants were assessed under three conditions: cws, long stepping on the paretic side (p-long), and long stepping on the non-paretic side (np-long). Lower-limb flexion and extension angles and the electromyogram were measured during walking. Subtype classification was based on the merging pattern of the muscle synergies, and we examined the effect of different lower-limb angles on the muscle synergies. We identified three merging subtypes: module 1 with module 2 (subtype 1), module 1 with module 4 (subtype 2), and module 3 with module 4 (subtype 3). In the cws condition, the lower-limb flexion angle was reduced in subtype 3, and the lower-limb extension angle was decreased in subtype 1. A more complex muscle synergy was observed only in subtype 3 in the p-long condition versus cws (p = 0.036). This subtype classification of walking impairments based on the merging pattern of the muscle synergies could be useful for the selection of a rehabilitation strategy according to the individual's particular neurological condition. Rehabilitation with increased lower-limb flexion may be effective for the training of patients with merging of modules 3 and 4 in comfortable walking.

Lower Limb Kinematic Coordination during the Running Motion of Stroke Patient: A Single Case Study

The purpose of this study was to clarify the lower limb joint motor coordination of para-athletes during running motion from frequency characteristics and to propose this as a method for evaluating their performance. The subject used was a 43-year-old male para-athlete who had suffered a left cerebral infarction. Using a three-dimensional motion analysis system, the angles of the hip, knee, and ankle joints were measured during 1 min of running at a speed of 8 km/h on a treadmill. Nine inter- and intra-limb joint angle pairs were analyzed by coherence and phase analyses. The main characteristic of the stroke patient was that there were joint pairs with absent or increased coherence peaks in the high-frequency band above 4 Hz that were not found in healthy subjects. Interestingly, these features were also observed on the non-paralyzed side. Furthermore, a phase analysis showed different phase differences between the joint motions of the stroke patient and healthy subjects in some joint pairs. Thus, we concluded there was a widespread functional impairment of joint motion in the stroke patient that has not been revealed by conventional methods. The coherence analysis of joint motion may be useful for identifying joint motion problems in para-athletes.

The centre of pressure position determined by capacity of weight-shifting in stride stances in individuals with post-stroke

BACKGROUND

The dynamics of shifting the centre-of-pressure in stride stances are essential for postural control during the double-limb support phase of gait. Impaired loading onto a paretic limb following stroke causes a biased self-centred position (defined as the centre-of-pressure position in a static stride stance) between legs, which may be related to the capacity of the centre-of-pressure movements. This study investigated anteroposterior centre-of-pressure movements relative to two different positions in stride stances and determine their relationship with the self-centred position and clinical measures after stroke.

METHODS

Sixteen chronic post-stroke individuals performed anteroposterior weight-shifting in stride stances with the anterior and posterior paretic foot on a plantar pressure platform. The maximum anterior and posterior centre-of-pressure movements in stride stances were quantified relative to the self-centred position and the origin of the platform.

FINDINGS

The self-centred position was biased towards the non-paretic limb to maintain identical anterior and posterior centre-of-pressure movements between stride stances with the anterior and posterior paretic foot. Furthermore, the self-centred position was related to the capacity of anteroposterior centre-of-pressure movements in stride stances. Especially, impaired balance function was associated with the self-centred position and decreased posterior centre-of-pressure movement in stride stance with the posterior paretic foot.

INTERPRETATIONS

The assessment of the self-centred position in stride stances can be beneficial in understanding the capability to control weight-shifting. In particular, the improvement of balance control in stride stance with the posterior paretic foot would help to improve postural control during the double-limb support phase following stroke.

Investigating the Effect of Real-Time Center of Pressure (CoP) Feedback Training on the Swing Phase of Lower Limb Kinematics in Transfemoral Prostheses with SACH foot

Transfemoral amputee often encounters reduced toe clearance resulting in trip-related falls. Swing phase joint angles have been shown to influence the toe clearance therefore, training intervention that targets shaping the swing phase joint angles can potentially enhance toe clearance. The focus of this study was to investigate the effect of the shift in the location of the center of pressure (CoP) during heel strike on modulation of the swing phase joint angles in able-bodied participants (n=6) and transfemoral amputees (n=3). We first developed a real-time CoP-based visual feedback system such that participants could shift the CoP during treadmill walking. Next, the kinematic data were collected during two different walking sessions- baseline (without feedback) and feedback (shifting the CoP anteriorly/posteriorly at heel strike to match the target CoP location). Primary swing phase joint angle adaptations were observed with feedback such that during the mid-swing phase, posterior CoP shift feedback significantly increases (p<0.05) the average hip and knee flexion angle by 11.55 degrees and 11.86 degrees respectively in amputees, whereas a significant increase (p<0.05) in ankle dorsiflexion, hip and knee flexion angle by 3.60 degrees, 3.22 degrees, and 1.27 degrees respectively compared to baseline was observed in able-bodied participants. Moreover, an opposite kinematic adaptation was seen during anterior CoP shift feedback. Overall, results confirm a direct correlation between the CoP shift and the modulation in the swing phase lower limb joint angles.

Gait and Axial Spondyloarthritis: Comparative Gait Analysis Study Using Foot-Worn Inertial Sensors

Background

Axial spondyloarthritis (axSpA) can lead to spinal mobility restrictions associated with restricted lower limb ranges of motion, thoracic kyphosis, spinopelvic ankylosis, or decrease in muscle strength. It is well known that these factors can have consequences on spatiotemporal gait parameters during walking. However, no study has assessed spatiotemporal gait parameters in patients with axSpA. Divergent results have been obtained in the studies assessing spatiotemporal gait parameters in ankylosing spondylitis, a subgroup of axSpA, which could be partly explained by self-reported pain intensity scores at time of assessment. Inertial measurement units (IMUs) are increasingly popular and may facilitate gait assessment in clinical practice.

Objective

This study compared spatiotemporal gait parameters assessed with foot-worn IMUs in patients with axSpA and matched healthy individuals without and with pain intensity score as a covariate.

Methods

A total of 30 patients with axSpA and 30 age- and sex-matched healthy controls performed a 10-m walk test at comfortable speed. Various spatiotemporal gait parameters were computed from foot-worn inertial sensors including gait speed in ms^–1 (mean walking velocity), cadence in steps/minute (number of steps in a minute), stride length in m (distance between 2 consecutive footprints of the same foot on the ground), swing time in percentage (portion of the cycle during which the foot is in the air), stance time in percentage (portion of the cycle during which part of the foot touches the ground), and double support time in percentage (portion of the cycle where both feet touch the ground).

Results

Age, height, and weight were not significantly different between groups. Self-reported pain intensity was significantly higher in patients with axSpA than healthy controls (P<.001). Independent sample t tests indicated that patients with axSpA presented lower gait speed (P<.001) and cadence (P=.004), shorter stride length (P<.001) and swing time (P<.001), and longer double support time (P<.001) and stance time (P<.001) than healthy controls. When using pain intensity as a covariate, spatiotemporal gait parameters were still significant with patients with axSpA exhibiting lower gait speed (P<.001), shorter stride length (P=.001) and swing time (P<.001), and longer double support time (P<.001) and stance time (P<.001) than matched healthy controls. Interestingly, there were no longer statistically significant between-group differences observed for the cadence (P=.17).

Conclusions

Gait was significantly altered in patients with axSpA with reduced speed, cadence, stride length, and swing time and increased double support and stance time. Taken together, these changes in spatiotemporal gait parameters could be interpreted as the adoption of a so-called cautious gait pattern in patients with axSpA. Among factors that may influence gait in patients with axSpA, patient self-reported pain intensity could play a role. Finally, IMUs allowed computation of spatiotemporal gait parameters and are usable to assess gait in patients with axSpA in clinical routine.

Trial Registration

ClinicalTrials.gov NCT03761212; https://clinicaltrials.gov/ct2/show/NCT03761212

International Registered Report Identifier (IRRID)

RR2-10.1007/s00296-019-04396-4

Effects of limited knee flexion movement in intra-limb gait coordination

This study aimed to investigate intra-limb coordination in non-disabled individuals walking with and without a constrained knee and in individuals with stroke. We hypothesized that a constrained knee would modify the intra-limb coordination of non-disabled individuals and that non-disabled individuals walking with a constrained knee would present coordination patterns similar to those presented by individuals with stroke. Twelve individuals with chronic stroke (age: 54.1 ± 9.9 years) and 12 age- and sex-matched individuals (age: 54.8 ± 9.2 years) with no known gait impairment (non-disabled individuals) participated in this study. Non-disabled individuals walked with and without an orthosis on one of their knees, limiting flexion to 40°, which was the average maximum knee flexion presented by the participants with stroke. Lower limb coordination was assessed on the basis of vector coding for the thigh-shank and shank-foot couplings during stance and swing periods of gait. Constrained knee flexion in non-disabled individuals mainly affected the thigh-shank coupling but not the shank-foot coupling of the constrained limb. There was reduced anti-phase coordination during the stance and swing periods and a marked increase in in-phase coordination during the swing period. Non-disabled individuals presented most changes toward the coordination pattern presented by individuals with stroke, except for the thigh-phase mode during the swing period, which was lower than that in individuals with stroke. Reduced knee flexion movement caused similar alterations in the intra-limb coordination pattern in non-disabled individuals compared to those observed in individuals with stroke. Therefore, diminished knee flexion movement, which is presented by individuals with stroke, can be considered a key disturbance that leads to impairment in lower extremity intra-limb coordination.

Predictive simulation of post-stroke gait with functional electrical stimulation

Post-stroke patients present various gait abnormalities such as drop foot, stiff-knee gait (SKG), and knee hyperextension. Functional electrical stimulation (FES) improves drop foot gait although the mechanistic basis for this effect is not well understood. To answer this question, we evaluated the gait of a post-stroke patient walking with and without FES by inverse dynamics analysis and compared the results to an optimal control framework. The effect of FES and cause-effect relationship of changes in knee and ankle muscle strength were investigated; personalized muscle–tendon parameters allowed the prediction of pathologic gait. We also predicted healthy gait patterns at different speeds to simulate the subject walking without impairment. The passive moment of the knee played an important role in the estimation of muscle force with knee hyperextension, which was decreased during FES and knee extensor strengthening. Weakening the knee extensors and strengthening the flexors improved SKG. During FES, weak ankle plantarflexors and strong ankle dorsiflexors resulted in increased ankle dorsiflexion, which reduced drop foot. FES also improved gait speed and reduced circumduction. These findings provide insight into compensatory strategies adopted by post-stroke patients that can guide the design of individualized rehabilitation and treatment programs.

A principal component analysis (PCA) based assessment of the gait performance

The gait assessment is instrumental for evaluating the efficiency of rehabilitation of persons with a motor impairment of the lower extremities. The protocol for quantifying the gait performance needs to be simple and easy to implement; therefore, a wearable system and user-friendly computer program are preferable. We used the Gait Master (instrumented insoles) with the industrial quality ground reaction forces (GRF) sensors and 6D inertial measurement units (IMU). WiFi transmitted 10 signals from the GRF sensors and 12 signals from the accelerometers and gyroscopes to the host computer. The clinician was following in real-time the acquired data to be assured that the WiFi operated correctly. We developed a method that uses principal component analysis (PCA) to provide a clinician with easy to interpret cyclograms showing the difference between the recorded and healthy-like gait performance. The cyclograms formed by the first two principal components in the PCA space show the step-to-step reproducibility. We suggest that a cyclogram and its orientation to the coordinate system PC1 vs. PC2 allow a simple assessment of the gait. We show results for six healthy persons and five patients with hemiplegia.

The Effects of Auditory Feedback Gait Training Using Smart Insole on Stroke Patients

This study aimed to assess the effect of the auditory feedback gait training (AFGT) using smart insole on the gait variables, dynamic balance, and activities of daily living (ADL) of stroke patients. In this case, 45 chronic stroke patients who were diagnosed with a stroke before 6 months and could walk more than 10 m were included in this study. Participants were randomly allocated to the smart insole training group (n = 23), in which the AFGT system was used, or to the general gait training group (GGTG) (n = 22). Both groups completed conventional rehabilitation, including conventional physiotherapy and gait training, lasting 60 min per session, five times per week for 4 weeks. Instead of gait training, the smart insole training group received smart insole training twice per week for 4 weeks. Participants were assessed using the GAITRite for gait variables and Timed Up and Go test (TUG), Berg Balance Scale (BBS) for dynamic balance, and Modified Barthel Index (MBI) for ADL. The spatiotemporal gait parameters, symmetry of gait, TUG, BBS, and MBI in the smart insole training group were significantly improved compared to those in the GGTG (p < 0.05). The AFGT system approach is a helpful method for improving gait variables, dynamic balance, and ADL in chronic stroke patients.

Comparative Study on Overground Gait of Stroke Survivors With a Conventional Cane and a Haptic Cane

The conventional cane (single cane) is widely used to promote gait ability of stroke survivors as it provides postural stability by extending the base of support. However, its use can reduce muscle activity in the user's paretic side and cause upper limb neuropathies due to the intermittent and excessive loading of the upper limb. The provision of low magnitude support and speed regulation may result in collective improvement of gait parameters such as symmetry, balance and muscle activation. In this paper, we developed a robotic Haptic Cane (HC) that is composed of a tilted structure with motorized wheels and sensors to allow continuous haptic contact with the ground while moving at a regulated speed, and carried out gait experiments to compare the HC with an Instrumented conventional Cane (IC). The results show that use of the HC involved more continuous ground support force of a comparatively lesser magnitude than the IC, and resulted in greater improvements in the swing symmetry ratio and significant improvements in the step length symmetry ratio. Percentage of Non-Paretic Activity (%NPA) of paretic muscles (vastus medialis obliquus (VMO), semitendinosus (SMT), tibialis anterior (TBA) and gastrocnemius medialis (GCM)) in swing phase was significantly improved by the use of either device at fast speed. However, the use of HC improved %NPA of paretic VMO and SMT more than the use of IC at both preferred and fast speeds. It also significantly improved %NPA of paretic GCM in stance phase. Furthermore, comfortable speed with the HC was higher than with the IC and exhibited better RMS of anteroposterior (AP) tilt. Thus, the developed device with a simple and intuitive mechanism can provide efficient assistance for overground gait of stroke patients with a high possibility of widespread use.

Utilization of Robotic Exoskeleton for Overground Walking in Acute and Chronic Stroke

Stroke commonly results in gait deficits which impacts functional ambulation and quality of life. Robotic exoskeletons (RE) for overground walking are devices that are programmable to provide high dose and movement-impairment specific assistance thus offering new rehabilitation possibilities for recovery progression in individuals post stroke. The purpose of this investigation is to present preliminary utilization data in individuals with acute and chronic stroke after walking overground with an RE. Secondary analysis on a subset of individuals is presented to understand the mechanistic changes due to RE overground walking. Thirty-eight participants with hemiplegia secondary to stroke were enrolled in a clinical trial conducted at eight rehabilitation centers. Data is presented for four sessions of overground walking in the RE over the course of 2 weeks. Participants continued their standard of care if they had any ongoing therapy at the time of study enrollment. Gait speed during the 10 Meter Walk Test, Gait deviations and the Functional Ambulation Category (FAC) data were collected before (baseline) and after (follow-up) the RE walking sessions. Walking speed significantly increased between baseline and follow-up for participants in the chronic (p <0.01) and acute (p < 0.05) stage of stroke recovery. FAC level significantly improved (p < 0.05) and there were significantly fewer (p < 0.05) gait deviations observed for participants in the acute stages of stroke recovery between baseline and follow-up. Secondary analysis on a subset of eight participants indicated that after four sessions of overground walking with the RE, the participants significantly improved their spatial symmetry. The walk time, step count and ratio of walk time to up time increased from first session to the last session for participants in the chronic and acute stages of stroke. The RE was effectively utilized for overground walking for individuals with acute and chronic stroke with varying severity levels. The results demonstrated an increase in walking speed, improvement in FAC and a decrease in gait deviations (from baseline to follow-up) after four sessions of overground walking in the RE for participants. In addition, preliminary data indicated that spatial symmetry and step length also improved after utilization of an RE for overground walking.

Compensatory Strategies Due to Knee Flexion Constraint during Gait of Non-Disabled Adults

Constraining knee flexion of non-disabled individuals could further our understanding regarding the importance of knee joint during gait, which is a common disturbance in individuals with gait impairment. In this study we investigated whether a mechanical constraint of knee flexion in non-disabled adults would lead to compensatory strategies. Eleven non-disabled male adults walked without and with an orthosis that permitted full extension and limited knee flexion up to either 45° or 30°. We analyzed the temporal organization of lower limb kinematics and electromyograms of the rectus femoris, vastus medialis and lateralis, tibialis anterior, semitendinosus, biceps femoris, and gastrocnemius medialis and lateralis. Non-disabled adults compensated for the reduced knee flexion by increasing hip and ankle joint excursions and ankle flexor activation amplitude. Also, these adults shortened pre-swing and lengthened swing duration in the constrained limb and increased the activity of bifunctional hip extensor and knee flexor muscles in the constrained limb in relation to the unconstrained limb. The use of an orthosis that limited knee flexion in non-disabled adults leaded to compensatory strategies in the temporal organization of joint excursions and muscle activations in the constrained limb. The compensatory effects were correlated with the extent of knee flexion constraint.

Different Biomechanical Variables Explain Within-Subjects Versus Between-Subjects Variance in Step Length Asymmetry Post-Stroke

Step length asymmetry (SLA) is common in most stroke survivors. Several studies have shown that factors such as paretic propulsion can explain between-subjects differences in SLA. However, whether the factors that account for between-subjects variance in SLA are consistent with those that account for within-subjects, stride-by-stride variance in SLA has not been determined. SLA direction is heterogeneous, and different impairments likely contribute to differences in SLA direction. Here, we identified common predictors between-subjects that explain within-subjects variance in SLA using sparse partial least squares regression (sPLSR). We determined whether the SLA predictors differ based on SLA direction and whether predictors obtained from within-subjects analyses were the same as those obtained from between-subjects analyses. We found that for participants who walked with longer paretic steps paretic double support time, braking impulse, peak vertical ground reaction force, and peak plantarflexion moment explained 59% of the within-subjects variance in SLA. However the within-subjects variance accounted for by each individual predictor was less than 10%. Peak paretic plantarflexion moment accounted for 4% of the within-subjects variance and 42% of the between-subjects variance in SLA. In participants who walked with shorter paretic steps, paretic and non-paretic braking impulse explained 18% of the within-subjects variance in SLA. Conversely, paretic braking impulse explained 68% of the between-subjects variance in SLA, but the association between SLA and paretic braking impulse was in the opposite direction for within-subjects vs. between-subjects analyses. Thus, the relationships that explain between-subjects variance might not account for within-subjects stride-by-stride variance in SLA.

Comparison of the Immediate Effects of Audio, Visual, or Audiovisual Gait Biofeedback on Propulsive Force Generation in Able-Bodied and Post-stroke Individuals

Real-time biofeedback is a promising post-stroke gait rehabilitation strategy that can target specific gait deficits preferentially in the paretic leg. Our previous work demonstrated that the use of an audiovisual biofeedback interface designed to increase paretic leg propulsion, measured via anterior ground reaction force (AGRF) generation during late stance phase of gait, can induce improvements in peak AGRF production of the targeted and paretic limb of able-bodied and post-stroke individuals, respectively. However, whether different modes of biofeedback, such as visual, auditory, or a combination of both, have differential effects on AGRF generation is unknown. The present study investigated the effects of audio only, visual only, or audiovisual AGRF biofeedback in able-bodied and post-stroke individuals. Seven able-bodied (6 females, 27 ± 2 years) and nine post-stroke individuals (6 females, 54 ± 12 years, 42 ± 26 months post-stroke) completed four 30-s walking trials on a treadmill under 4 conditions: no biofeedback, audio biofeedback, visual biofeedback, or audiovisual biofeedback. Compared to walking without biofeedback, all three biofeedback modes significantly increased peak AGRF in the targeted and paretic leg. There was no significant difference in peak AGRF between the three biofeedback modes. Able-bodied individuals demonstrated greater feedback-induced increase in stride-to-stride variation of AGRF generation during audio biofeedback compared to visual biofeedback; however, similar results were not observed in the post-stroke group. The present findings may inform future development of real-time gait biofeedback interfaces for use in clinical or community environments.

The effects of unilateral step training and conventional treadmill training on gait asymmetry in patients with chronic stroke

BACKGROUND

Step length asymmetry is common after stroke. Unilateral step training (UST) can improve step length asymmetry for patients who take a longer step with their paretic leg (P-long). UST has not been tested with patients who take a shorter step with their paretic leg (P-short).

RESEARCH QUESTION

Does training patients according to the direction of their asymmetry improve step length asymmetry?

METHODS

Adults 18 years and older with asymmetrical gait at least 6 months post-stroke completed three 20 min treadmill training sessions at least 48 h apart: Conventional treadmill; UST with the non-paretic leg stationary on the side of the treadmill and the paretic leg stepping on the moving treadmill belt (P-stepping); and UST with the paretic leg stationary on the side of the treadmill and the non-paretic leg stepping on the moving belt (NP-stepping). Spatiotemporal gait parameters before, immediately, 10 min and 30 min after training were recorded at self-selected and fastest walking pace. Asymmetry values for each parameter were calculated. RmANOVAs were used to investigate the effects of training type on spatiotemporal parameters and paired-samples t-tests used to investigate potential contributors to training effects on asymmetry.

RESULTS

Twenty participants (16 male, median age 65 (43-80) years; 11 P-long, 9 P-short) were included. Improvements in step length asymmetry were observed immediately after both Conventional (9.1 %; 95 % CI 2.7-15.4%) and P-stepping (11.6 %; 95 % CI 5.3-17.8 %) treadmill training in participants who take a shorter step with their paretic leg, however effects were only sustained after Conventional training. Step length asymmetry did not improve for P-long participants with any training type.

SIGNIFICANCE

The effectiveness of unilateral step training may be related to the direction of step length asymmetry. Further investigation is required before considering using unilateral step training as a rehabilitation tool for gait asymmetry after stroke.

Using Biofeedback to Reduce Step Length Asymmetry Impairs Dynamic Balance in People Poststroke

BACKGROUND

People poststroke often walk with a spatiotemporally asymmetric gait, due in part to sensorimotor impairments in the paretic lower extremity. Although reducing asymmetry is a common objective of rehabilitation, the effects of improving symmetry on balance are yet to be determined.

OBJECTIVE

We established the concurrent validity of whole-body angular momentum as a measure of balance, and we determined if reducing step length asymmetry would improve balance by decreasing whole-body angular momentum.

METHODS

We performed clinical balance assessments and measured whole-body angular momentum during walking using a full-body marker set in a sample of 36 people with chronic stroke. We then used a biofeedback-based approach to modify step length asymmetry in a subset of 15 of these individuals who had marked asymmetry and we measured the resulting changes in whole-body angular momentum.

RESULTS

When participants walked without biofeedback, whole-body angular momentum in the sagittal and frontal plane was negatively correlated with scores on the Berg Balance Scale and Functional Gait Assessment supporting the validity of whole-body angular momentum as an objective measure of dynamic balance. We also observed that when participants walked more symmetrically, their whole-body angular momentum in the sagittal plane increased rather than decreased.

CONCLUSIONS

Voluntary reductions of step length asymmetry in people poststroke resulted in reduced measures of dynamic balance. This is consistent with the idea that after stroke, individuals might have an implicit preference not to deviate from their natural asymmetry while walking because it could compromise their balance. Clinical Trials Number: NCT03916562.

Asymmetric Gait Analysis Using a DTW Algorithm with Combined Gyroscope and Pressure Sensor

Walking is one of the most basic human activities. Various diseases may be caused by abnormal walking, and abnormal walking is mostly caused by disease. There are various characteristics of abnormal walking, but in general, it can be judged as asymmetric walking. Generally, spatiotemporal parameters can be used to determine asymmetric walking. The spatiotemporal parameter has the disadvantage that it does not consider the influence of the diversity of patterns and the walking speed. Therefore, in this paper, we propose a method to analyze asymmetric walking using Dynamic Time Warping (DTW) distance, a time series analysis method. The DTW distance was obtained by combining gyroscope data and pressure data. The experiment was carried out by performing symmetrical walking and asymmetrical walking, and asymmetric walking was performed as a simulation of hemiplegic walking by fixing one ankle using an auxiliary device. The proposed method was compared with the existing asymmetric gait analysis method. As a result of the experiment, a p-value lower than 0.05 was obtained, which proved that there was a statistically significant difference.

Targeted verbal cues can immediately alter gait following stroke

Background: Physical therapists use verbal cueing extensively during gait rehabilitation. Nevertheless, little is known about the ability of individuals post-stroke to make immediate changes to targeted spatiotemporal gait parameters from verbal commands. Additionally, adequate muscle strength may be necessary to promote positive alterations in gait.Objectives: To determine the influence of targeted verbal cues on spatiotemporal gait parameters for individuals with chronic stroke. Further, we assessed the potential of a relationship between cue-induced gait modifications and paretic lower limb strength.Methods: Using a within-subjects design, twenty-seven adults with chronic stroke walked over a pressure mat with verbal cues to walk at (1) comfortable and (2) fast speeds, with increased (3) arm swing, (4) foot height, (5) step length, (6) push off, and (7) cadence. We also assessed lower extremity strength using a hand-held dynamometer. We measured gait speed, step length, stance time, and cadence for comparisons between conditions and performed correlational analyses to assess the influence of strength on gait alterations.Results: Specific cues elicited increased walking speed, cadence, step lengths and paretic limb stance time. Only greater paretic hip and knee flexion strength was related to the ability to increase cadence when cued to do so (r > 0.41).Conclusion: With targeted verbal cueing, clinicians can improve step length, gait speed, stance time and cadence for individuals with chronic stroke. Lower extremity strength does not appear to be related to the ability to alter gait with verbal cueing in individuals with chronic stroke.

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.

Exploiting telerobotics for sensorimotor rehabilitation: a locomotor embodiment

Background

Manual treadmill training is used for rehabilitating locomotor impairments but can be physically demanding for trainers. This has been addressed by enlisting robots, but in doing so, the ability of trainers to use their experience and judgment to modulate locomotor assistance on the fly has been lost. This paper explores the feasibility of a telerobotics approach for locomotor training that allows patients to receive remote physical assistance from trainers.

Methods

In the approach, a trainer holds a small robotic manipulandum that shadows the motion of a large robotic arm magnetically attached to a locomoting patient's leg. When the trainer deflects the manipulandum, the robotic arm applies a proportional force to the patient. An initial evaluation of the telerobotic system’s transparency (ability to follow the leg during unassisted locomotion) was performed with two unimpaired participants. Transparency was quantified by the magnitude of unwanted robot interaction forces. In a small six-session feasibility study, six individuals who had prior strokes telerobotically interacted with two trainers (separately), who assisted in altering a targeted gait feature: an increase in the affected leg’s swing length.

Results

During unassisted walking, unwanted robot interaction forces averaged 3−4 N (swing–stance) for unimpaired individuals and 2−3 N for the patients who survived strokes. Transients averaging about 10 N were sometimes present at heel-strike/toe-off. For five of six patients, these forces increased with treadmill speed during stance (R² = .99; p < 0.001) and increased with patient height during swing (R² = .71; p = 0.073). During assisted walking, the trainers applied 3.0 ± 2.8 N (mean ± standard deviation across patients) and 14.1 ± 3.4 N of force anteriorly and upwards, respectively. The patients exhibited a 20 ± 21% increase in unassisted swing length between Days 1−6 (p = 0.058).

Conclusions

The results support the feasibility of locomotor assistance with a telerobotics approach. Simultaneous measurement of trainer manipulative actions, patient motor responses, and the forces associated with these interactions may prove useful for testing sensorimotor rehabilitation hypotheses. Further research with clinicians as operators and randomized controlled trials are needed before conclusions regarding efficacy can be made.

Lesion-based structural and functional networks in patients with step length asymmetry after stroke

OBJECTIVE

The aim of this study was to determine common structural and functional networks associated with asymmetric step length after unilateral ischemic stroke.

METHODS

Thirty-nine chronic stroke patients were divided into two groups, based on the presence or absence of asymmetric step length. In each group, each lesion was mapped onto a brain magnetic resonance image. The structural and functional networks of brain regions connected to each lesion were identified using a public diffusion tensor and resting state function magnetic resonance image dataset. To identify brain regions associated with asymmetric step length, we conducted voxel-wise independent sample t-tests for structural and function lesion network maps.

RESULTS

At least 85% of lesions showed functional network overlap in the bilateral frontal lobe. Functional connectivity of the dorsolateral prefrontal cortex in the contralesional hemisphere was significantly decreased in group 1 compared to that in group 2.

CONCLUSIONS

The dorsolateral prefrontal cortex may have an important role in compensating for an asymmetric step length after a unilateral stroke.

Changes in Walking Speed After High-Intensity Treadmill Training Are Independent of Changes in Spatiotemporal Symmetry After Stroke

Objectives: Decreased walking speeds and spatiotemporal asymmetry both occur after stroke, but it is unclear whether and how they are related. It is also unclear whether rehabilitation-induced improvements in walking speed are associated with improvements in symmetry or greater asymmetry. High-intensity speed-based treadmill training (HISTT) is a recent rehabilitative strategy whose effects on symmetry are unclear. The purpose of this study was to: (1) assess whether walking speed is cross-sectionally associated with spatiotemporal symmetry in chronic stroke, (2) determine whether HISTT leads to changes in the spatiotemporal symmetry of walking, and (3) evaluate whether HISTT-induced changes in walking speed are associated with changes in spatiotemporal symmetry.

Methods: Eighty-one participants with chronic stroke performed 4 weeks of HISTT. At pre, post, and 3-month follow-up assessments, comfortable and maximal walking speed were measured with the 10-meter walk test, and spatiotemporal characteristics of walking were measured with the GAITRite mat. Step length and swing time were expressed as symmetry ratios (paretic/non-paretic). Changes in walking speed and symmetry were calculated and the association was determined.

Results: At pre-assessment, step length and swing time asymmetries were present (p < 0.001). Greater temporal symmetry was associated with faster walking speeds (p ≤ 0.001). After HISTT, walking speeds increased from pre-assessment to post-assessment and follow-up (p ≤ 0.002). There were no changes in spatiotemporal symmetry (p ≥ 0.10). Change in walking speed was not associated with change in spatial or temporal symmetry from pre- to post-assessment or from post-assessment to follow-up (R² ≤ 0.01, p ≥ 0.37).

Conclusions: HISTT improves walking speed but does not systematically improve or worsen spatiotemporal symmetry. Clinicians may need to pair walking interventions like HISTT with another intervention designed to improve walking symmetry simultaneously. The cross-sectional relation between temporal symmetry and walking speed may be mediated by other factors, and not be causative.

Comparing the effects of multicomponent exercise with or without power training on the cardiorespiratory fitness, physical function, and muscular strength of patients with stroke: a randomized controlled trial

BACKGROUND

Literature studies concerning the effect of implementing a multicomponent program with different individual exercise intensities are insufficient. This study aimed to examine the effects of performing a multicomponent exercise program incorporating high-speed power training on cardiorespiratory fitness, physical function, and muscular strength in post-stroke patients. We compared the results of two different exercise regimens: high-speed power training and traditional low-speed strength training.

METHODS

Forty-five post-stroke patients were randomly assigned to the high-speed, low-speed, and control groups. A 60-min multicomponent exercise program was conducted three times per week for 8 weeks in the two exercise groups, whereas static stretching was performed in the control group. Cardiorespiratory fitness, physical function, and muscular strength were assessed before and after the intervention.

RESULTS

Significant improvements were observed in the peak oxygen consumption values and results of the Berg balance scale, Korean version of the Trunk Impairment Scale, and Timed Up-and-Go test. The aforementioned were evaluated as a measure of cardiorespiratory function and functional ability in the exercise groups and compared to those obtained in the control group. High-speed power training led to greater improvement in patients compared with low-speed strength training.

CONCLUSIONS

Multicomponent exercise involving high-speed power training was beneficial in helping patients with stroke regain cardiorespiratory fitness, physical function, and muscular strength.

Effect of ankle joint fixation on tibialis anterior muscle activity during split-belt treadmill walking in healthy subjects: A pilot study

Objectives

This study aims to examine the characteristics of muscle activity change of the tibialis anterior (TA) muscle in healthy adults while they walked on a split-belt treadmill with one fixed ankle.

Patients and methods

This randomized controlled trial was conducted between November 2017 and July 2018. Fourteen healthy male individuals (mean age 31.4 years; range, 23 to 50 years) were divided into two groups: right ankle joint fixed by ankle-foot orthosis (fixation group) and no orthosis (control group). Both groups were asked to walk on a treadmill with the same belt speed. After familiarizing with walking on both belts at 5.0 km/h, they walked for 6 min with the right belt slower (2.5 km/h) and the left faster (5.0 km/h). For analysis, the 6 min were divided equally among three time periods. The TA muscle activity was calculated at first and last time periods. We compared muscle activities in time periods (early and late phase) and in groups (fixation and control) using two-way mixed analysis of variance.

Results

The TA muscle activity decreased in the late phase regardless of ankle joint fixation, and also decreased in the fixation group regardless of the time periods. There was an interaction between these factors.

Conclusion

These data show that changes in the TA muscle activity were smaller in the fixation group, suggesting that the ankle joint fixation reduces the adaptation.

Novel velocity estimation for symmetric and asymmetric self-paced treadmill training

Background

Self-paced treadmills (SPT) can provide an engaging setting for gait rehabilitation by responding directly to the user’s intent to modulate the external environment and internal effort. They also can improve gait analyses by allowing scientists and clinicians to directly measure the effect of an intervention on walking velocity. Unfortunately, many common SPT algorithms are not suitable for individuals with gait impairment because they are designed for symmetric gait patterns. When the user’s gait is asymmetric due to paresis or if it contains large accelerations, the performance is diminished. Creating and validating an SPT that is suitable for asymmetric gait will improve our ability to study rehabilitation interventions in populations with gait impairment. The objective of this study was to test and validate a novel self-paced treadmill on both symmetric and asymmetric gait patterns and evaluate differences in gait kinematics, kinetics, and muscle activity between fixed-speed and self-paced treadmill walking.

Methods

We collected motion capture, ground reaction force data, and muscle activity from 6 muscles in the dominant leg during walking from 8 unimpaired subjects. In the baseline condition, the subjects walked at 3 fixed-speeds normalized to their leg length as Froude numbers. We developed a novel kinematic method for increasing the accuracy of the user’s estimated walking velocity and compared our method against other published algorithms at each speed. Afterward, subjects walked on the SPT while matching their walking speed to a given target velocity using visual feedback of the treadmill speed. We evaluated the SPT by measuring steady-state error and the number of steps to reach the desired speed. We split the gait cycle into 7 phases and compared the kinematic, kinetic, and muscle activity between the fixed speed and self-paced mode in each phase. Then, we validated the performance of the SPT for asymmetric gait by having subjects walk on the SPT while wearing a locked-knee brace set to 0° on the non-dominant leg.

Results

Our SPT enabled controlled walking for both symmetric and asymmetric gait patterns. Starting from rest, subjects were able to control the SPT to reach the targeted speeds using visual feedback in 13–21 steps. With the locked knee brace, subjects controlled the treadmill with substantial step length and step velocity asymmetry. One subject was able to execute a step-to gait and halt the treadmill on heel-strikes with the braced leg. Our kinematic correction for step-length outperformed the competing algorithms by significantly reducing the velocity estimation error at the tested velocities. The joint kinematics, joint torques, and muscle activity were generally similar between fixed-speed and self-paced walking. Statistically significant differences were found in 5 of 63 tests for joint kinematics, 2 of 63 tests for joint torques, and 9 of 126 tests for muscle activity. The differences that were statistically significant were not found across all speeds and were generally small enough to be of limited clinical relevance.

Conclusions

We present a validated method for implementing a self-paced treadmill for asymmetric and symmetric gaits. As a result of the increased accuracy of our estimation algorithm, our SPT produced controlled walking without including a position feedback controller, thereby reducing the influence of the controller on measurements of the user’s true walking speed. Our method relies only on a kinematic correction to step length and step time which can support transfer to systems outside of the laboratory for symmetric and asymmetric gaits in clinical populations.

Comparison of the effects of real-time propulsive force versus limb angle gait biofeedback on gait biomechanics

BACKGROUND

Reduced forward propulsion during gait, measured as the anterior component of the ground reaction force (AGRF), may contribute to slower walking speeds in older adults and gait dysfunction in individuals with neurological impairments. Trailing limb angle (TLA) is a clinically important gait parameter that is associated with AGRF generation. Real-time gait biofeedback can induce modifications in targeted gait parameters, with potential to modulate AGRF and TLA. However, the effects of real-time TLA biofeedback on gait biomechanics have not been studied thus far.

RESEARCH QUESTION

What are the effects of unilateral, real-time, audiovisual trailing limb angle biofeedback on gait biomechanics in able-bodied individuals?

METHODS

Ten able-bodied adults participated in one session of treadmill-based gait analyses comprising 60-second walking trials under three conditions: no biofeedback, AGRF biofeedback, and TLA biofeedback. Biofeedback was provided unilaterally to the right leg. Dependent variables included AGRF, TLA, ankle moment, and ankle power. One-way repeated measures ANOVA with post-hoc tests were conducted to determine the effect of the biofeedback conditions on gait parameters.

RESULTS

Compared to no biofeedback, both AGRF and TLA biofeedback induced significant increases in targeted leg AGRF without concomitant changes to the non-targeted leg AGRF. Targeted leg TLA was significantly larger during TLA biofeedback compared to AGRF biofeedback. Only AGRF biofeedback induced significant increases in ankle power; and only the TLA biofeedback condition induced increases in the non-targeted leg TLA.

SIGNIFICANCE

Our novel findings provide support for the feasibility and promise of TLA as a gait biofeedback target. Our study demonstrates that comparable magnitudes of feedback-induced increases in AGRF in response to AGRF and TLA biofeedback may be achieved through divergent biomechanical strategies. Further investigation is needed to uncover the effects of TLA biofeedback on gait parameters in individuals with neuro-pathologies such as spinal cord injury or stroke.

Cerebellar Transcranial Direct Current Stimulation for Motor Learning in People with Chronic Stroke: A Pilot Randomized Controlled Trial

Cerebellar transcranial direct current stimulation (ctDCS) is a non-invasive brain stimulation technique that alters neural plasticity through weak, continuous, direct currents delivered to the cerebellum. This study aimed to evaluate the feasibility of conducting a randomized controlled trial (RCT) delivering three consecutive days of ctDCS during split-belt treadmill training (SBTT) in people with chronic stroke. Using a double-blinded, parallel-group RCT design, eligible participants were randomly allocated to receive either active anodal ctDCS or sham ctDCS combined with SBTT on three consecutive days. Outcomes were assessed at one-week follow-up, using step length symmetry as a measure of motor learning and comfortable over-ground walking speed as a measure of walking capacity. The feasibility of the RCT protocol was evaluated based on recruitment, retention, protocol deviations and data completeness. The feasibility of the intervention was assessed based on safety, adherence and intervention fidelity. Of the 26 potential participants identified over four months, only four were enrolled in the study (active anodal ctDCS n = 1, sham ctDCS n = 3). Both the inclusion criteria and the fidelity of the SBTT relied upon the accurate estimation of step length asymmetry. The method used to determine the side of the step length asymmetry was unreliable and led to deviations in the protocol. The ctDCS intervention was well adhered to, safe, and delivered as per the planned protocol. Motor learning outcomes for individual participants revealed that treadmill step length symmetry remained unchanged for three participants but improved for one participant (sham ctDCS). Comfortable over-ground walking speed improved for two participants (sham ctDCS). The feasibility of the planned protocol and intervention was limited by intra-individual variability in the magnitude and side of the step length asymmetry. This limited the sample and compromised the fidelity of the SBTT intervention. To feasibly conduct a full RCT investigating the effect of ctDCS on locomotor adaptation, a reliable method of identifying and defining step length asymmetry in people with stroke is required. Future ctDCS research should either optimize the methods for SBTT delivery or utilize an alternative motor adaptation task.

Characterizing gait pattern dynamics during symmetric and asymmetric walking using autoregressive modeling

Gait asymmetry is often observed in populations with varying degrees of neuromuscular control. While changes in vertical ground reaction force (vGRF) peak magnitude are associated with altered limb loading that can be observed during asymmetric gait, the challenge is identifying techniques with the sensitivity to detect these altered movement patterns. Autoregressive (AR) modeling has successfully delineated between healthy and pathological gait during running; but has been little explored in walking. Thus, AR modeling was implemented to assess differences in vGRF pattern dynamics during symmetric and asymmetric walking. We hypothesized that the AR model coefficients would better detect differences amongst the symmetric and asymmetric walking conditions than the vGRF peak magnitude mean. Seventeen healthy individuals performed a protocol that involved walking on a split-belt instrumented treadmill at different symmetric (0.75m/s, 1.0 m/s, 1.5 m/s) and asymmetric (Side 1: 0.75m/s-Side 2:1.0 m/s; Side 1:1.0m/s-Side 2:1.5 m/s) gait conditions. Vertical ground reaction force peaks extracted during the weight-acceptance and propulsive phase of each step were used to construct a vGRF peak time series. Then, a second order AR model was fit to the vGRF peak waveform data to determine the AR model coefficients. The resulting AR coefficients were plotted on a stationarity triangle and their distance from the triangle centroid was computed. Significant differences in vGRF patterns were detected amongst the symmetric and asymmetric conditions using the AR modeling coefficients (p = 0.01); however, no differences were found when comparing vGRF peak magnitude means. These findings suggest that AR modeling has the sensitivity to identify differences in gait asymmetry that could aid in monitoring rehabilitation progression.

Maintaining sagittal plane balance compromises frontal plane balance during reactive stepping in people post-stroke

BACKGROUND

Maintaining balance in response to perturbations during walking often requires the use of corrective responses to keep the center of mass within the base of support. The relationship between the center of mass and base of support is often quantified using the margin of stability. Although people post-stroke increase the margin of stability following perturbations, control deficits may lead to asymmetries in regulation of margins of stability, which may also cause maladaptive coupling between the sagittal and frontal planes during balance-correcting responses.

METHODS

We assessed how paretic and non-paretic margins of stability are controlled during recovery from forward perturbations and determined how stroke-related impairments influence the coupling between the anteroposterior and mediolateral margins of stability. Twenty-one participants with post-stroke hemiparesis walked on a treadmill while receiving slip-like perturbations on both limbs at foot-strike. We assessed anteroposterior and mediolateral margins of stability before perturbations and during perturbation recovery.

FINDINGS

Participants walked with smaller anteroposterior and larger mediolateral margins of stability on the paretic versus non-paretic sides. When responding to perturbations, participants increased the anteroposterior margin of stability bilaterally by extending the base of support and reducing the excursion of the extrapolated center of mass. The anteroposterior and mediolateral margins of stability in the paretic limb negatively covaried during reactive steps such that increases in anteroposterior were associated with reductions in mediolateral margins of stability.

INTERPRETATION

Balance training interventions to reduce fall risk post-stroke may benefit from incorporating strategies to reduce maladaptive coupling of frontal and sagittal plane stability.

Motor Impairment and Its Influence in Gait Velocity and Asymmetry in Community Ambulating Hemiplegic Individuals

Objectives

To determine the most important motor impairments that are predictors of gait velocity and spatiotemporal symmetrical ratio in patients with stroke.

Design

Cross-sectional, descriptive analysis study.

Setting

Human performance laboratory of the University of Santo Tomas.

Participants

Individuals with chronic stroke (N=55; 34 men, 21 women) who are community dwellers.

Interventions

Not applicable.

Main Outcome Measures

The gait velocity and spatiotemporal symmetrical ratio (step length; step, stance, swing, single-leg support, and double-leg support stance times) was determined using Vicon motion capture. We also calculated motor impairment of the leg and foot using Brunnstrom’s stages of motor recovery, evaluated muscle strength using the scoring system described by Collin and Wade, and assessed spasticity using by the modified Ashworth Scale.

Results

Regression analysis showed that plantarflexor strength is a predictor of gait velocity and all temporospatial symmetry ratio. Knee flexor and extensor strength are predictors in single-leg support time and double-leg support time symmetry ratio, respectively. On the other hand, hip adductor and quadriceps spasticity are predictors of swing time and step length symmetry ratio.

Conclusion

Different motor impairments are predictors of stroke gait abnormality. Interventions should be focused on these motor impairments to allow for optimal gait rehabilitation results.

Influence of leg length discrepancy on balance and gait in post-stroke patients: a correlational study

Background

A frequent complaint by stroke patients presenting for physiotherapy was perceived shortness of the affected lower limb and inability to weight bear onto the affected side. So, the present study aimed to evaluate influence of limb length discrepancy (LLD) on balance and gait parameters in patients with stroke.

Subjects and methods

Twenty participants were recruited based on the inclusion and exclusion criteria and were divided into two groups group A (LLD ≤ 1 cm) and group B (LLD > 1 cm). Postural sway was measured under wide base eyes open, wide base eyes closed, narrow base eyes open, and narrow base eyes closed conditions. Weight-bearing asymmetry and functional balance were assessed using the percentage body weight asymmetry and Berg balance scale. Also, step leg ratio and 10-M walk test was used to assess gait parameters.

Results

Intergroup comparison of postural sway exhibited a significant difference between groups in the AP direction in wide-based eyes open (WBEO), wide-based eyes closed (WBEC), narrow-based eyes open (NBEO), and narrow-based eyes closed (NBEC) conditions whereas only in NBEC condition in mediolateral direction; with group B (LLD > 1 cm) displaying a greater mean postural sway in all the conditions. The correlation of LLD with postural sway showed a significant positive correlation within AP direction under all the conditions and in WBEC and NBEC conditions in mediolateral direction. Intergroup comparison of step length ratio (SLR) showed a statistical difference between groups, and a negative correlation was found between LLD and SLR. A negative correlation was also seen between percentage weight-bearing asymmetry (PWBA) and speed as well as Berg’s balance scale (BBS), and a positive correlation was observed between BBS and speed.

Conclusion

Leg length discrepancy results in a significant decrease in balance control in the sagittal and frontal planes in patients with stroke. It also adds to the asymmetries in their gait. Therefore, LLD should be considered as a factor for balance and gait asymmetries in post-stroke patients.

The Effect of Exercise Training on Gait, Balance, and Physical Fitness Asymmetries in Persons With Chronic Neurological Conditions: A Systematic Review of Randomized Controlled Trials

Background: Persons with chronic neurological conditions (CNCs) often present with asymmetrical impairments, creating significant differences between contralateral limbs in body functions. These asymmetries have been associated with reduced mobility and balance, and are often targeted for reduction during rehabilitation. Exercise training has established benefits for persons with CNCs, and may have positive effects on asymmetry outcomes.

Objectives: The purpose of this review was to summarize the current evidence for the effects exercise training on gait, balance, and physical fitness asymmetry in randomized control trials (RCTs) of persons with CNCs.

Methods: A search of four electronic databases (EMBASE, CINAHL, SPORTdiscus, and ovidMEDLINE) was conducted following the structured Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Results: The search retrieved 3,493 articles, with 465 articles assessed for eligibly, and nine articles meeting the criteria for inclusion. Of the included articles, five incorporated resistance exercise, three incorporated aerobic exercise, and one incorporated combined exercise (i.e., resistance and aerobic exercise). Gait asymmetry improved significantly in four studies after resistance, aerobic, and combined exercise. Significant improvements in weight bearing asymmetry were reported in three studies after resistance exercise. One study reported significant improvements in both gait and balance asymmetry after resistance exercise.

Conclusions: Preliminary evidence suggests that exercise training, as a component of rehabilitation, may have positive effects on gait and balance asymmetry in persons with CNCs. Several limitations of the current literature were noted, including a limited number of studies, combination of exercise with other rehabilitation modalities, a lack of reporting on exercise prescriptions (e.g., number of repetitions, intensity), and variability in the calculation of asymmetry outcomes. These limitations prevent definitive conclusions on the effects of exercise training on asymmetry outcomes. Future trials are needed to determine the potential of exercise training for reducing asymmetry in persons with CNCs.

A Novel User Control for Lower Extremity Rehabilitation Exoskeletons

Lower extremity exoskeletons offer the potential to restore ambulation to individuals with paraplegia due to spinal cord injury. However, they often rely on preprogrammed gait, initiated by switches, sensors, and/or EEG triggers. Users can exercise only limited independent control over the trajectory of the feet, the speed of walking, and the placement of feet to avoid obstacles. In this paper, we introduce and evaluate a novel approach that naturally decodes a neuromuscular surrogate for a user's neutrally planned foot control, uses the exoskeleton's motors to move the user's legs in real-time, and provides sensory feedback to the user allowing real-time sensation and path correction resulting in gait similar to biological ambulation. Users express their desired gait by applying Cartesian forces via their hands to rigid trekking poles that are connected to the exoskeleton feet through multi-axis force sensors. Using admittance control, the forces applied by the hands are converted into desired foot positions, every 10 milliseconds (ms), to which the exoskeleton is moved by its motors. As the trekking poles reflect the resulting foot movement, users receive sensory feedback of foot kinematics and ground contact that allows on-the-fly force corrections to maintain the desired foot behavior. We present preliminary results showing that our novel control can allow users to produce biologically similar exoskeleton gait.

Effects of Varying Plantarflexion Stiffness of Ankle-Foot Orthosis on Achilles Tendon and Propulsion Force During Gait

An ankle-foot orthosis (AFO) with a plantarflexion resistance function, improves post-stroke gait. An AFO with a plantarflexion resistance function not only affects the first rocker function and the weight acceptance but also the late stance phase. Achilles tendon extension is important for ankle joint function and for forward propulsion during the late stance phase; however, the effect of an AFO with a plantarflexion resistance function on the Achilles tendon is unclear. The purpose of this study was to investigate the effect of plantarflexion resistance on the extension of the Achilles tendon and the forward-propulsive force. Herein, 10 healthy adult males participated who walked under three different conditions: a no-AFO condition and two AFO conditions that had different levels of plantarflexion resistance (P1 and P2). The stiffness value of the P1 and P2 conditions was 0.56 and 1.47 Nm/°, respectively. A three-dimensional (3D) motion analysis system and a musculoskeletal model were used to assess the tendon-length change, the ground reaction force, kinematics, and kinetics data. The change in Achilles tendon length was significantly lower in the P1 and P2 conditions than the no-AFO condition. Furthermore, changes in the length of the Achilles tendon significantly decreased in the P2 condition when compared with that in the P1 condition. The peak anterior ground reaction force was significantly lower in the P2 condition than the no-AFO condition. These results suggest that excessive assist provided by an AFO prevents efficient gait by decreasing both the forward-propulsive force and tendon function.

Effect of Ankle Plantar Flexor Spasticity Level on Balance in Patients With Stroke: Protocol for a Cross-Sectional Study

BACKGROUND

The lower limb spasticity after stroke can affect the balance and gait of patients with stroke.

OBJECTIVE

The aim of this study is to assess the effects of ankle plantar flexor spasticity level on balance in patients with stroke.

METHODS

Patients with stroke were recruited from neurology and physiotherapy clinics in Tehran, Iran. Based on the level of ankle plantar flexor spasticity according to the Modified Modified Ashworth Scale (MMAS), the eligible patients with stroke were divided into 2 groups: high spasticity (MMAS score≥2) and low spasticity (MMAS score<2). The primary outcome measures were the MMAS scores, Activities-Specific Balance Confidence questionnaire scores, eyes-open and eyes-closed posturography measures, and Timed Up and Go test results. The secondary outcome measures were the ankle passive range of motion and ankle joint proprioception. The t test, mixed model univariate analysis of variance, and Spearman rank correlation were used for statistical analysis.

RESULTS

Data collection and statistical analysis are complete. The interpretation of results is underway. We expect the results to be published in winter 2020.

CONCLUSIONS

We believe that patients with high ankle plantar flexor spasticity after stroke will demonstrate greater balance dysfunction, which will worsen with impaired proprioception, passive range of motion, and eyes closed.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR1-10.2196/16045.

Attentional concentration during physiotherapeutic intervention improves gait and trunk control in patients with stroke

The restoration of motor function is important in daily life in patients with brain damage. Although attentional concentration can affect motor function, most physical therapists focus only on therapeutic exercise. Therefore, we investigated changes in motor function in patients with high attentional concentration during our intervention. A total of 21 subjects diagnosed with stroke participated in the study. They were divided into the high attentional concentration group and low attentional concentration group based on the self-programmed attention index. The subjects underwent trunk strengthening and gait training for 30 min per session, twice a day, 5 days a week, for a total of 4 weeks. All patients wore electroencephalogram (EEG) devices during the treatment to enable EEG examinations. Diagnostic ultrasound was used to measure muscles of the abdomen: external oblique abdominal, internal oblique abdominal, transversus abdominis, and rectus abdominal muscles. A trunk impairment scale was used to evaluate trunk control. We used Gaitrite to measure the spatial and temporal components during gait. The group with high attentional concentration showed significant differences in abdominal muscle strength and trunk control. In gait, there was a significant difference in swing cycle, stance cycle, single cycle, double support cycle, stance time, and double support time. Therefore, attentional concentration should be considered to improve motor function as a part of therapeutic exercises for stroke patients.

Walking characteristics including mild motor paralysis and slow walking speed in post-stroke patients

Walking speed is strongly influenced by the severity of motor paralysis in post-stroke patients. Nevertheless, some patients with mild motor paralysis still walk slowly. Factors associated with this difference in walking speed have not been elucidated. To confirm walking characteristics of patients with mild motor paralysis and slow walking speed, this study identified patient subgroups based on the association between the severity of motor paralysis and walking speed. Fugl-Meyer assessment synergy score (FMS) and the walking speed were measured (n = 42), and cluster analysis was performed based on the association between FMS and walking speed to identify the subgroups. FMS and walking speed were associated (ρ = 0.50); however, some patients walked slowly despite only mild motor paralysis. Cluster analysis using FMS and walking speed as the main variables classified patients into subgroups. Patients with mild motor paralysis (FMS: 18.4 ± 2.09 points) and slow walking speed (0.28 ± 0.14 m/s) exhibited poorer trunk stability, increased co-contraction of the shank muscle, and increased intramuscular coherence in walking compared to other clusters. This group was identified by their inability to fully utilize the residual potential of motor function. In walking training, intervention in instability and excessive cortical control may be effective.

Treadmill-Based Locomotor Training With Robotic Pelvic Assist and Visual Feedback: A Feasibility Study

BACKGROUND AND PURPOSE

Gait asymmetries are common after stroke, and often persist despite conventional rehabilitation. Robots provide training at a greater practice frequency than conventional approaches. However, prior studies of have found the transfer of learned skills outside of the device to be inadequate. The tethered pelvic assist device (TPAD) promotes weight shifting, yet allows users to independently navigate spatiotemporal aspects of gait. The purpose of this study was to evaluate feasibility and preliminary efficacy of a 5-day intervention combining TPAD training with visual feedback and task-specific overground training to promote improved force and stance symmetry in individuals after stroke.

METHODS

After baseline assessments, 11 participants chronically after stroke received 1 hour of practice for 5 consecutive days. Training sessions included visual feedback during TPAD treadmill training followed by overground gait training. Safety, perceived exertion, and adherence were recorded as measures of feasibility. Load and stance symmetry were reassessed after the intervention (posttraining) and again 1 week later.

RESULTS

No adverse events were reported. Mean (SD) perceived exertion (3.61 (0.23)) was low and did not significantly change throughout the intervention. Overall adherence was 96.4%. Load asymmetry was not significantly reduced on the treadmill from baseline to posttraining (P = 0.075). Overground stance symmetry significantly improved on posttraining (F = 8.498, P = 0.002), but was not sustained at follow-up. (See the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A311, which summarizes the study background, methods, and results.) DISCUSSION AND CONCLUSIONS:: Results demonstrate this combined interventional approach was feasible and improved stance symmetry overground, yet further work should consider increasing training intensity and/or duration to induce gains lasting through follow-up.