Distance-Induced Changes in Walking Speed After Stroke: Relationship to Community Walking Activity

Configuration variability of the six-minute walk test among licensed physical therapists working with neurologic conditions: a pilot survey

BACKGROUND

The six-minute walk test (6MWT) is considered reliable and valid for assessing walking capacity in people with neurologic conditions. However, the consistency in the test length and configuration used is unclear.

PURPOSE

To determine how the 6MWT was configured by licensed physical therapists working with patients with neurologic conditions in clinical practice, identify their knowledge of the American Thoracic Society (ATS) and Academy of Neurologic Physical Therapy (ANPT) guidelines for the 6MWT and assess relationships between therapist demographic characteristics and knowledge of the 6MWT guidelines.

METHODS

One hundred forty-six therapists completed a survey related to the configuration they used for the 6MWT.

RESULTS

Configuration of the 6MWT varied widely. Space limitation was the most frequently selected reason for reported configurations. Over half had available the standardized 100-feet straight walkway but fewer than one-third used this configuration of the ATS guidelines. Fewer than half knew of the ATS guidelines and nearly three-fourths knew of the ANPT guidelines. American Physical Therapy Association membership and having a higher percentage of neurologic patients were associated with knowledge of both guidelines.

CONCLUSION

The 6MWT must be completed within the constraints of the working environment, and this requirement is clinically relevant when comparing patient results to normative values and measurements across clinics. Our results suggest a need for updated norms that are more congruent with space constraints in current practice settings.

A Portable, Neurostimulation-Integrated, Force Measurement Platform for the Clinical Assessment of Plantarflexor Central Drive

Plantarflexor central drive is a promising biomarker of neuromotor impairment; however, routine clinical assessment is hindered by the unavailability of force measurement systems with integrated neurostimulation capabilities. In this study, we evaluate the accuracy of a portable, neurostimulation-integrated, plantarflexor force measurement system we developed to facilitate the assessment of plantarflexor neuromotor function in clinical settings. Two experiments were conducted with the Central Drive System (CEDRS). To evaluate accuracy, experiment #1 included 16 neurotypical adults and used intra-class correlation (ICC2,1) to test agreement of plantarflexor strength capacity measured with CEDRS versus a stationary dynamometer. To evaluate validity, experiment #2 added 26 individuals with post-stroke hemiparesis and used one-way ANOVAs to test for between-limb differences in CEDRS' measurements of plantarflexor neuromotor function, comparing neurotypical, non-paretic, and paretic limb measurements. The association between paretic plantarflexor neuromotor function and walking function outcomes derived from the six-minute walk test (6MWT) were also evaluated. CEDRS' measurements of plantarflexor neuromotor function showed high agreement with measurements made by the stationary dynamometer (ICC = 0.83, p < 0.001). CEDRS' measurements also showed the expected between-limb differences (p's < 0.001) in maximum voluntary strength (Neurotypical: 76.21 ± 13.84 ft-lbs., Non-paretic: 56.93 ± 17.75 ft-lbs., and Paretic: 31.51 ± 14.08 ft-lbs.), strength capacity (Neurotypical: 76.47 ± 13.59 ft-lbs., Non-paretic: 64.08 ± 14.50 ft-lbs., and Paretic: 44.55 ± 14.23 ft-lbs.), and central drive (Neurotypical: 88.73 ± 1.71%, Non-paretic: 73.66% ± 17.74%, and Paretic: 52.04% ± 20.22%). CEDRS-measured plantarflexor central drive was moderately correlated with 6MWT total distance (r = 0.69, p < 0.001) and distance-induced changes in speed (r = 0.61, p = 0.002). CEDRS is a clinician-operated, portable, neurostimulation-integrated force measurement platform that produces accurate measurements of plantarflexor neuromotor function that are associated with post-stroke walking ability.

Daily steps, walking tests, and functioning in chronic stroke; comparing independent walkers to device-users

BACKGROUND AND PURPOSE

Community mobility post-stroke is important for gaining independence in daily activities. Walking devices can facilitate mobility, but it remains unclear whether individuals who use a walking device walk as many daily steps as those who do not require a device. It is also unclear whether these groups differ in their independence in daily living. This study aimed (1) to compare daily steps, walking tests, and independence in basic and instrumental activities of daily living (IADL) six months post-stroke between individuals who walk independently and individuals who use a walking device, (2) within each group to assess correlations between daily steps and walking tests, independence in basic and IADL.

METHODS

Thirty-seven community-dwelling individuals with chronic stroke; 22 participants used a walking-device and 15 participants walked independently. Daily steps were calculated as a 3-day mean by hip accelerometers. Clinical walking tests included the 10-m-walk-test, Timed Up & Go and 'Walking While Talking'. Daily living was assessed using the Functional-Independence Measure and the IADL questionnaire.

RESULTS

Daily steps of the device-users were significantly lower than the independent-walkers (195-8068 versus 147-14010 steps/day) but independence in daily living was not significantly different. Different walking tests correlated with daily steps for device-users and independent-walkers.

CONCLUSIONS

This preliminary investigation in chronic stroke revealed that device-users walk significantly fewer daily steps but are as independent in daily living as independent-walkers. Clinicians should differentiate between individuals with and without a walking device and the use of different clinical walking tests to explain daily steps should be considered. Further research is needed to assess the impact of a walking device post-stroke.

An impairment-specific hip exoskeleton assistance for gait training in subjects with acquired brain injury: a feasibility study

This study was designed to investigate the feasibility and the potential effects on walking performance of a short gait training with a novel impairment-specific hip assistance (iHA) through a bilateral active pelvis orthosis (APO) in patients with acquired brain injury (ABI). Fourteen subjects capable of independent gait and exhibiting mild-to-moderate gait deficits, due to an ABI, were enrolled. Subjects presenting deficit in hip flexion and/or extension were included and divided into two groups based on the presence (group A, n = 6) or absence (group B, n = 8) of knee hyperextension during stance phase of walking. Two iHA-based profiles were developed for the groups. The protocol included two overground gait training sessions using APO, and two evaluation sessions, pre and post training. Primary outcomes were pre vs. post-training walking distance and steady-state speed in the 6-min walking test. Secondary outcomes were self-selected speed, joint kinematics and kinetics, gait symmetry and forward propulsion, assessed through 3D gait analysis. Following the training, study participants significantly increased the walked distance and average steady-state speed in the 6-min walking tests, both when walking with and without the APO. The increased walked distance surpassed the minimal clinically important difference for groups A and B, (respectively, 42 and 57 m > 34 m). In group A, five out of six subjects had decreased knee hyperextension at the post-training session (on average the peak of the knee extension angle was reduced by 36%). Knee flexion during swing phase increased, by 16% and 31%, for A and B groups respectively. Two-day gait training with APO providing iHA was effective and safe in improving walking performance and knee kinematics in ABI survivors. These preliminary findings suggest that this strategy may be viable for subject-specific post-ABI gait rehabilitation.

Gains in Daily Stepping Activity in People With Chronic Stroke After High-Intensity Gait Training in Variable Contexts

OBJECTIVE

Many physical therapist interventions provided to individuals with chronic stroke can lead to gains in gait speed or endurance (eg, 6-Minute Walk Test [6MWT]), although changes in objective measures of participation are not often observed. The goal of this study was to determine the influence of different walking interventions on daily stepping (steps per day) and the contributions of demographic, training, and clinical measures to these changes.

METHODS

In this secondary analysis of a randomized clinical trial, steps per day at baseline and changes in steps per day following 1 of 3 locomotor interventions were evaluated in individuals who were ambulatory and >6 months after stroke. Data were collected on 58 individuals who received ≤30 sessions of high-intensity training (HIT) in variable contexts (eg, tasks and environments; n = 19), HIT focused on forward walking (n = 19), or low-intensity variable training (n = 20). Primary outcomes were steps per day at baseline, at post-training, and at a 3-month follow-up, and secondary outcomes were gait speed, 6MWT, balance, and balance confidence. Correlation and regression analyses identified demographic and clinical variables associated with steps per day.

RESULTS

Gains in steps per day were observed across all groups combined, with no between-group differences; post hoc within-group analyses revealed significant gains only following HIT in variable contexts. Both HIT groups showed gains in endurance (6MWT), with increases in balance confidence only following HIT in variable contexts. Changes in steps per day were associated primarily with gains in 6MWT, with additional associations with baseline 6MWT, lower-extremity Fugl-Meyer scores, and changes in balance confidence.

CONCLUSION

HIT in variable contexts elicited gains in daily stepping, with changes primarily associated with gains in gait endurance.

IMPACT

Providing HIT in variable contexts appears to improve measures of participation (eg, daily stepping) that may be associated with clinical measures of function. Gains in multiple measures of mobility and participation with HIT in variable contexts may improve the efficiency and value of physical therapy services.

Gait parameters assessed with inertial measurement unit during 6-minute walk test in people after stroke

Gait impairments are among the main issues for stroke survivors as they are often linked with a lack of endurance capacity, balance impairments and functional limitations. These conditions can be carefully assessed by combining an endurance capacity test, the 6-minute walk test (6MWT), with the analysis of gait performed by an inertial measurement unit (IMU). We investigated the evolution of gait spatiotemporal and kinematic parameters during the 6MWT and compared it with age-matched healthy subjects. Moreover, gait parameters and 6MWT distance were associated with clinical outcome scales. In a postacute rehabilitation general hospital, we performed an observational study. Subjects with a single cortical stroke were recruited into the stroke group (SG). An age-matched healthy group (HG) was also recruited. All participants performed a 6MWT while wearing an IMU. The outcomes considered were 6MWT distance, gait spatiotemporal and kinematic parameters, and symmetry. Before the test at each subject, in the SG was administered Berg balance scale, Canadian neurological stroke scale and motricity index. 32 subjects were recruited into the SG, and 12 into the HG. Between the paretic and nonparetic limbs of the SG, there were differences in the stance phase and single support phase (P < 0.05). SG gait speed and stride length strongly correlated with balance, strength and disability scales. The SG walked fewer meters than the HG (Δ = -260.90 m; P < 0.001). Adopting an IMU during a 6mwt resulted valuable and effective in providing meaningful information regarding both the disability and functional capabilities of SG subjects.

Estimation of Walking Speed and Its Spatiotemporal Determinants Using a Single Inertial Sensor Worn on the Thigh: From Healthy to Hemiparetic Walking

We present the use of a single inertial measurement unit (IMU) worn on the thigh to produce stride-by-stride estimates of walking speed and its spatiotemporal determinants (i.e., stride time and stride length). Ten healthy and eight post-stroke individuals completed a 6-min walk test with an 18-camera motion capture system used for ground truth measurements. Subject-specific estimation models were trained to estimate walking speed using the polar radius extracted from phase portraits produced from the IMU-measured thigh angular position and velocity. Consecutive flexion peaks in the thigh angular position data were used to define each stride and compute stride times. Stride-by-stride estimates of walking speed and stride time were then used to compute stride length. In both the healthy and post-stroke cohorts, low error and high consistency were observed for the IMU estimates of walking speed (MAE < 0.035 m/s; ICC > 0.98), stride time (MAE < 30 ms; ICC > 0.97), and stride length (MAE < 0.037 m; ICC > 0.96). This study advances the use of a single wearable sensor to accurately estimate walking speed and its spatiotemporal determinants during both healthy and hemiparetic walking.

Depressive Symptoms Moderate the Relationship Among Physical Capacity, Balance Self-Efficacy, and Participation in People After Stroke

OBJECTIVE

It was previously found that balance self-efficacy mediated the relationship between physical capacity and participation after stroke. The effect of other factors that influence participation, such as depression, on this relationship has not been explored. This study examined the effect of symptoms of depression on the mediated relationship between physical capacity and participation by balance self-efficacy in individuals after stroke.

METHODS

In this cross-sectional study, 282 persons with chronic stroke (>6 months) were classified as having either low or high Geriatric Depression Scale scores. This study used a multiple group structural equation model to test moderated mediation by comparing a constrained model (indicating no effect of depression on the mediation) and an unconstrained model (indicating an effect of depression on the mediation). The models were compared using a chi-squared difference test.

RESULTS

The chi-squared difference test suggested that the unconstrained model was a better fit, indicating that depressive symptoms moderated the mediated relationship between physical capacity and participation (χ2(3, N = 282) = 9.0). In the Low Depression group, a significant indirect effect indicated that balance self-efficacy did mediate the relationship between physical capacity and participation. There was no significant indirect effect in the High Depression group.

CONCLUSION

The results suggest the relationship between physical capacity and participation appears to be mediated by balance self-efficacy in individuals after stroke with low reports of depressive symptoms, but in those with high reports of depressive symptoms, physical capacity and balance self-efficacy are unrelated to participation.

IMPACT

Targeting balance self-efficacy to improve post-stroke participation may be beneficial only for individuals with low reports of depression. In individuals after stroke with high reports of depression, treatment should include and emphasize the treatment of those depressive symptoms. Additional work further examining these complex relationships is warranted.

Beyond Physical Capacity: Factors Associated With Real-world Walking Activity After Stroke

OBJECTIVE

To identify homogeneous subsets of survivors of chronic stroke who share similar characteristics across several domains and test if these groups differ in real-world walking activity. We hypothesized that variables representing the domains of walking ability, psychosocial, environment, and cognition would be important contributors in differentiating real-world walking activity in survivors of chronic stroke.

DESIGN

Cross-sectional, secondary data analysis.

SETTING

University/laboratory.

PARTICIPANTS

A total of 283 individuals with chronic (≥6mo) stroke (N=238).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Thirteen variables representing 5 domains were included: (1) walking ability: 6-minute walk test (6MWT), self-selected speed (SSS) of gait; (2) psychosocial: Patient Health Questionnaire-9, Activities-specific Balance Confidence (ABC) scale; (3) physical health: low-density lipoprotein cholesterol, body mass index, Charlson Comorbidity Index (CCI); (4) cognition: Montreal Cognitive Assessment (MoCA); and (5) environment: living situation and marital status, work status, Area Deprivation Index (ADI), Walk Score. Mixture modeling was used to identify latent classes of survivors of stroke. After identifying the latent classes, walking activity, measured as steps per day (SPD), was included as a distal outcome to understand if classes were meaningfully different in their real-world walking RESULTS: A model with 3 latent classes was selected. The 6MWT, SSS, ABC scale, and Walk Score were significantly different among all 3 classes. Differences were also seen for the MoCA, ADI, and CCI between 2 of the 3 classes. Importantly, the distal outcome of SPD was significantly different in all classes, indicating that real-world walking activity differs among the groups identified by the mixture model.

CONCLUSIONS

Survivors of stroke with lower walking ability, lower self-efficacy, lower cognitive abilities, and greater area deprivation had lower SPD. These results demonstrate that the physical and social environment (including socioeconomic factors) and cognitive function should also be considered when developing interventions to improve real-world walking activity after stroke.

Central Drive to the Paretic Ankle Plantarflexors Affects the Relationship Between Propulsion and Walking Speed After Stroke

BACKGROUND AND PURPOSE

The ankle plantarflexor muscles are the primary generators of propulsion during walking. Impaired paretic plantarflexion is a key contributor to interlimb propulsion asymmetry after stroke. Poststroke muscle weakness may be the result of a reduced force-generating capacity, reduced central drive, or a combination of these impairments. This study sought to elucidate the relationship between the neuromuscular function of the paretic plantarflexor muscles and propulsion deficits across individuals with different walking speeds.

METHODS

For 40 individuals poststroke, we used instrumented gait analysis and dynamometry coupled with supramaximal electrostimulation to study the interplay between limb kinematics, the neuromuscular function of the paretic plantarflexors (ie, strength capacity and central drive), propulsion, and walking speed.

RESULTS

The strength capacity of the paretic plantarflexors was not independently related to paretic propulsion. Reduced central drive to the paretic plantarflexors independently contributed to paretic propulsion deficits. An interaction between walking speed and plantarflexor central drive was observed. Individuals with slower speeds and lower paretic plantarflexor central drive presented with the largest propulsion impairments. Some study participants with low paretic plantarflexor central drive presented with similarly fast speeds as those with near-normal central drive by leveraging a compensatory reliance on nonparetic propulsion. The final model accounted for 86% of the variance in paretic propulsion (R = 0.86, F = 33.10, P < 0.001).

DISCUSSION AND CONCLUSIONS

Individuals poststroke have latent paretic plantarflexion strength that they are not able to voluntarily access. The magnitude of central drive deficit is a strong indicator of propulsion impairment in both slow and fast walkers.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A298).

Physical Fitness, Exercise Self-Efficacy, and Quality of Life in Adulthood: A Systematic Review

Background: The aim of the present work is the elaboration of a systematic review of existing research on physical fitness, self-efficacy for physical exercise, and quality of life in adulthood. Method: Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines, and based on the findings in 493 articles, the final sample was composed of 37 articles, which were reviewed to show whether self-efficacy has previously been studied as a mediator in the relationship between physical fitness and quality of life in adulthood. Results: The results indicate that little research exists in relation to healthy, populations with the majority being people with pathology. Physical fitness should be considered as a fundamental aspect in determining the functional capacity of the person. Aerobic capacity was the most evaluated and the 6-min walk test was the most used. Only one article shows the joint relationship between the three variables. Conclusions: We discuss the need to investigate the mediation of self-efficacy in relation to the value of physical activity on quality of life and well-being in the healthy adult population in adult life.

Slip-Fall Predictors in Community-Dwelling, Ambulatory Stroke Survivors: A Cross-sectional Study

BACKGROUND AND PURPOSE

Considering the multifactorial nature and the often-grave consequences of falls in people with chronic stroke (PwCS), determining measurements that best predict fall risk is essential for identifying those who are at high risk. We aimed to determine measures from the domains of the International Classification of Functioning, Disability and Health (ICF) that can predict laboratory-induced slip-related fall risk among PwCS.

METHODS

Fifty-six PwCS participated in the experiment in which they were subjected to an unannounced slip of the paretic leg while walking on an overground walkway. Prior to the slip, they were given a battery of tests to assess fall risk factors. Balance was assessed using performance-based tests and instrumented measures. Other fall risk factors assessed were severity of sensorimotor impairment, muscle strength, physical activity level, and psychosocial factors. Logistic regression analysis was performed for all variables. The accuracy of each measure was examined based on its sensitivity and specificity for fall risk prediction.

RESULTS

Of the 56 participants, 24 (43%) fell upon slipping while 32 (57%) recovered their balance. The multivariate logistic regression analysis model identified dynamic gait stability, hip extensor strength, and the Timed Up and Go (TUG) score as significant laboratory-induced slip-fall predictors with a combined sensitivity of 75%, a specificity of 79.2%, and an overall accuracy of 77.3%.

DISCUSSION AND CONCLUSIONS

The results indicate that fall risk measures within the ICF domains-body, structure, and function (dynamic gait stability and hip extensor strength) and activity limitation (TUG)-could provide a sensitive laboratory-induced slip-fall prediction model in PwCS.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A323).

Walking faster and farther with a soft robotic exosuit: Implications for post-stroke gait assistance and rehabilitation

OBJECTIVE

Soft robotic exosuits can improve the mechanics and energetics of walking after stroke. Building on this prior work, we evaluated the effects of the first prototype of a portable soft robotic exosuit.

METHODS

Exosuit-induced changes in the overground walking speed, distance, and energy expenditure of individuals post-stroke were evaluated statistically with alpha set to 0.05 and compared to minimal clinically important difference scores.

RESULTS

Compared to baseline walking without the exosuit worn, the <5kg exosuit did not substantially modify walking speed, distance, or energy expenditure when worn unpowered. In contrast, when the exosuit was powered on to provide an average 22.87±0.58 %bodyweight of plantarflexor force assistance during the paretic limb's stance phase and assist the paretic dorsiflexors during swing phase to reduce drop-foot, study participants walked a median 0.14±0.06 m/s faster during the 10-meter walk test and traveled 32±8 m farther during the six minute walk test.

CONCLUSIONS

Individuals post-stroke can leverage the paretic plantarflexor and dorsiflexor assistance provided by soft robotic exosuits to achieve clinically-meaningful increases in speed and distance.