Carey L. Holleran

Importance of specificity, amount, and intensity of locomotor training to improve ambulatory function in patients poststroke.

Abstract The majority of individuals poststroke recover the ability to walk overground, although residual impairments contribute to reduced walking speed, spatiotemporal asymmetries, inefficient gait, and limited walking activity in the home and community. A substantial number of studies have investigated the effects of various interventions on locomotor function in individuals poststroke; these studies vary widely in types of tasks practiced, the amount of practiced activities, and the intensity or workload during the intervention. In contrast, basic and applied studies have identified specific parameters of training that could be applied towards treatment of patients poststroke. More directly, the specificity, amount, and intensity of walking practice are thought to be critical variables of rehabilitation interventions that can facilitate plasticity of neuromuscular and cardiopulmonary systems and result in improved locomotor function. In the present commentary, we delineate the evidence and physiological rationale for providing large amounts of high-intensity locomotor training to improve ambulatory function in individuals poststroke. Additional evidence is presented to indicate that improvements in non-walking tasks, such as static balance and performance of transfers, may also occur following locomotor training. We further evaluate previous and more recent studies in the context of these parameters and provide suggestions for providing locomotor training for patients with stroke in the clinical setting.

Feasibility and Potential Efficacy of High-Intensity Stepping Training in Variable Contexts in Subacute and Chronic Stroke

Background. Previous data suggest that the amount and aerobic intensity of stepping training may improve walking poststroke. Recent animal and human studies suggest that training in challenging and variable contexts can also improve locomotor function. Such practice may elicit substantial stepping errors, although alterations in locomotor strategies to correct these errors could lead to improved walking ability. Objective. This unblinded pilot study was designed to evaluate the feasibility and preliminary efficacy of providing stepping practice in variable, challenging contexts (tasks and environments) at high aerobic intensities in participants >6 months and 1-6 months post-stroke. Methods. A total of 25 participants (gait speeds <0.9 m/s with no more than moderate assistance) participated in ≤40 training sessions (duration of 1 hour) within 10 weeks. Stepping training in variable, challenging contexts was performed at 70% to 80% heart rate reserve, with feasibility measures of total steps/session, ability to achieve targeted intensities, patient tolerance, dropouts, and adverse events. Gait speed, symmetry, and 6-minute walk were measured every 4 to 5 weeks or 20 sessions, with a 3-month follow-up (F/U). Results. In all, 22 participants completed ≥4 training weeks, averaging 2887 ± 780 steps/session over 36 ± 5.8 sessions. Self-selected (0.38 ± 0.27 to 0.66 ± 0.35 m/s) and fastest speed (0.51 ± 0.40 to 0.99 ± 0.58 m/s), paretic single-limb stance (20% ± 5.9% to 25% ± 6.4%), and 6-minute walk (141 ± 99 to 260 ± 146 m) improved significantly at posttraining. Conclusions. This preliminary study suggests that stepping training at high aerobic intensities in variable contexts was tolerated by participants poststroke, with significant locomotor improvements. Future studies should delineate the relative contributions of amount, intensity, and variability of stepping training to maximize outcomes.

Kinematic, Muscular, and Metabolic Responses During Exoskeletal-, Elliptical-, or Therapist-Assisted Stepping in People With Incomplete Spinal Cord Injury

Background Robotic-assisted locomotor training has demonstrated some efficacy in individuals with neurological injury and is slowly gaining clinical acceptance. Both exoskeletal devices, which control individual joint movements, and elliptical devices, which control endpoint trajectories, have been utilized with specific patient populations and are available commercially. No studies have directly compared training efficacy or patient performance during stepping between devices. Objective The purpose of this study was to evaluate kinematic, electromyographic (EMG), and metabolic responses during elliptical- and exoskeletal-assisted stepping in individuals with incomplete spinal cord injury (SCI) compared with therapist-assisted stepping. Design A prospective, cross-sectional, repeated-measures design was used. Methods Participants with incomplete SCI (n=11) performed 3 separate bouts of exoskeletal-, elliptical-, or therapist-assisted stepping. Unilateral hip and knee sagittal-plane kinematics, lower-limb EMG recordings, and oxygen consumption were compared across stepping conditions and with control participants (n=10) during treadmill stepping. Results Exoskeletal stepping kinematics closely approximated normal gait patterns, whereas significantly greater hip and knee flexion postures were observed during elliptical-assisted stepping. Measures of kinematic variability indicated consistent patterns in control participants and during exoskeletal-assisted stepping, whereas therapist- and elliptical-assisted stepping kinematics were more variable. Despite specific differences, EMG patterns generally were similar across stepping conditions in the participants with SCI. In contrast, oxygen consumption was consistently greater during therapist-assisted stepping. Limitations Limitations included a small sample size, lack of ability to evaluate kinetics during stepping, unilateral EMG recordings, and sagittal-plane kinematics. Conclusions Despite specific differences in kinematics and EMG activity, metabolic activity was similar during stepping in each robotic device. Understanding potential differences and similarities in stepping performance with robotic assistance may be important in delivery of repeated locomotor training using robotic or therapist assistance and for consumers of robotic devices.

Variable Intensive Early Walking Poststroke (VIEWS): A Randomized Controlled Trial

Background. Converging evidence suggests that the amount of stepping practice is an important training parameter that influences locomotor recovery poststroke. More recent data suggest that stepping intensity and variability are also important, although such strategies are often discouraged early poststroke. Objective. The present study examined the efficacy of high-intensity, variable stepping training on walking and nonwalking outcomes in individuals 1 to 6 months poststroke as compared with conventional interventions. Methods. Individuals with unilateral stroke (mean duration = 101 days) were randomized to receive ≤40, 1-hour experimental or control training sessions over 10 weeks. Experimental interventions consisted only of stepping practice at high cardiovascular intensity (70%-80% heart rate reserve) in variable contexts (tasks or environments). Control interventions were determined by clinical physical therapists and supplemented using standardized conventional strategies. Blinded assessments were obtained at baseline, midtraining, and posttraining with a 2-month follow-up. Results. A total of 32 individuals (15 experimental) received different training paradigms that varied in the amount, intensity, and types of tasks performed. Primary outcomes of walking speed (experimental, 0.27 ± 0.22 m/s vs control, 0.09 ± 0.09 m/s) and distances (119 ± 113 m vs 30 ± 32 m) were different between groups, with stepping amount and intensity related to these differences. Gains in temporal gait symmetry and self-reported participation scores were greater following experimental training, without differences in balance or sit-to-stand performance. Conclusion. Variable intensive stepping training resulted in greater improvements in walking ability than conventional interventions early poststroke. Future studies should evaluate the relative contributions of these training parameters.

Effects of Dynamic Stepping Training on Nonlocomotor Tasks in Individuals Poststroke

Background During the physical rehabilitation of individuals poststroke, therapists are challenged to provide sufficient amounts of task-specific practice in order to maximize outcomes of multiple functional skills within limited visits. Basic and applied studies have suggested that training of one motor task may affect performance of biomechanically separate tasks that utilize overlapping neural circuits. However, few studies have explicitly investigated the impact of training one functional task on separate, nonpracticed tasks. Objective The purpose of this preliminary study was to investigate the potential gains in specific nonlocomotor assessments in individuals poststroke following only stepping training of variable, challenging tasks at high aerobic intensities. Methods Individuals with locomotor deficits following subacute and chronic stroke (n=22) completed a locomotor training paradigm using a repeated-measures design. Practice of multiple stepping tasks was provided in variable environments or contexts at high aerobic intensities for ≥40 sessions over 10 weeks. The primary outcome was timed Five-Times Sit-to-Stand Test (5XSTS) performance, with secondary measures of sit-to-stand kinematics and kinetics, clinical assessment of balance, and isometric lower limb strength. Results Participants improved their timed 5XSTS performance following stepping training, with changes in selected biomechanical measures. Statistical and clinically meaningful improvements in balance were observed, with more modest changes in paretic leg strength. Conclusions The present data suggest that significant gains in selected nonlocomotor tasks can be achieved with high-intensity, variable stepping training. Improvements in nonpracticed tasks may minimize the need to practice multiple tasks within and across treatment sessions.

Effects of Locomotor Exercise Intensity on Gait Performance in Individuals With Incomplete Spinal Cord Injury

Background High-intensity stepping practice may be a critical component to improve gait following motor incomplete spinal cord injury (iSCI). However, such practice is discouraged by traditional theories of rehabilitation that suggest high-intensity locomotor exercise degrades gait performance. Accordingly, such training is thought to reinforce abnormal movement patterns, although evidence to support this notion is limited. Objective The purposes of this study were: (1) to evaluate the effects of short-term manipulations in locomotor intensity on gait performance in people with iSCI and (2) to evaluate potential detrimental effects of high-intensity locomotor training on walking performance. Design A single-day, repeated-measures, pretraining-posttraining study design was used. Methods Nineteen individuals with chronic iSCI performed a graded-intensity locomotor exercise task with simultaneous collection of lower extremity kinematic and electromyographic data. Measures of interest were compared across intensity levels of 33%, 67%, and 100% of peak gait speed. A subset of 9 individuals participated in 12 weeks of high-intensity locomotor training. Similar measurements were collected and compared between pretraining and posttraining evaluations. Results The results indicate that short-term increases in intensity led to significant improvements in muscle activity, spatiotemporal metrics, and joint excursions, with selected improvements in measures of locomotor coordination. High-intensity locomotor training led to significant increases in peak gait speed (0.64–0.80 m/s), and spatiotemporal and kinematic metrics indicate a trend for improved coordination. Limitations Measures of gait performance were assessed during treadmill ambulation and not compared with a control group. Generalizability of these results to overground ambulation is unknown. Conclusions High-intensity locomotor exercise and training does not degrade, but rather improves, locomotor function and quality in individuals with iSCI, which contrasts with traditional theories of motor dysfunction following neurologic injury.

Alterations in Aerobic Exercise Performance and Gait Economy Following High-Intensity Dynamic Stepping Training in Persons With Subacute Stroke.

Background and Purpose: Impairments in metabolic capacity and economy (O2cost) are hallmark characteristics of locomotor dysfunction following stroke. High-intensity (aerobic) training has been shown to improve peak oxygen consumption in this population, with fewer reports of changes in O2cost. However, particularly in persons with subacute stroke, inconsistent gains in walking function are observed with minimal associations with gains in metabolic parameters. The purpose of this study was to evaluate changes in aerobic exercise performance in participants with subacute stroke following high-intensity variable stepping training as compared with conventional therapy. Methods: A secondary analysis was performed on data from a randomized controlled trial comparing high-intensity training with conventional interventions, and from the pilot study that formed the basis for the randomized controlled trial. Participants 1 to 6 months poststroke received 40 or fewer sessions of high-intensity variable stepping training (n = 21) or conventional interventions (n = 12). Assessments were performed at baseline (BSL), posttraining, and 2- to 3-month follow-up and included changes in submaximal O2 ( O2submax) and O2cost at fastest possible treadmill speeds and peak speeds at BSL testing. Results: Significant improvements were observed in O2submax with less consistent improvements in O2cost, although individual responses varied substantially. Combined changes in both O2submax and O2 at matched peak BSL speeds revealed stronger correlations to improvements in walking function as compared with either measure alone. Discussion and Conclusions: High-intensity stepping training may elicit significant improvements in O2submax, whereas changes in both peak capacity and economy better reflect gains in walking function. Providing high-intensity training to improve locomotor and aerobic exercise performance may increase the efficiency of rehabilitation sessions. Video Abstract available for more insights from the authors (see Supplemental Digital Content, http://links.lww.com/JNPT/A142).

Feasibility of Focused Stepping Practice During Inpatient Rehabilitation Poststroke and Potential Contributions to Mobility Outcomes

Background. Optimal physical therapy strategies to maximize locomotor function in patients early poststroke are not well established. Emerging data indicate that substantial amounts of task-specific stepping practice may improve locomotor function, although stepping practice provided during inpatient rehabilitation is limited (<300 steps/session). Objective. The purpose of this investigation was to determine the feasibility of providing focused stepping training to patients early poststroke and its potential association with walking and other mobility outcomes. Methods. Daily stepping was recorded on 201 patients <6 months poststroke (80% < 1 month) during inpatient rehabilitation following implementation of a focused training program to maximize stepping practice during clinical physical therapy sessions. Primary outcomes included distance and physical assistance required during a 6-minute walk test (6MWT) and balance using the Berg Balance Scale (BBS). Retrospective data analysis included multiple regression techniques to evaluate the contributions of demographics, training activities, and baseline motor function to primary outcomes at discharge. Results. Median stepping activity recorded from patients was 1516 steps/d, which is 5 to 6 times greater than that typically observed. The number of steps per day was positively correlated with both discharge 6MWT and BBS and improvements from baseline (changes; r = 0.40-0.87), independently contributing 10% to 31% of the total variance. Stepping activity also predicted level of assistance at discharge and discharge location (home vs other facility). Conclusion. Providing focused, repeated stepping training was feasible early poststroke during inpatient rehabilitation and was related to mobility outcomes. Further research is required to evaluate the effectiveness of these training strategies on short- or long-term mobility outcomes as compared with conventional interventions.

Altered Sagittal- and Frontal-Plane Kinematics Following High-Intensity Stepping Training Versus Conventional Interventions in Subacute Stroke

Background Common locomotor deficits observed in people poststroke include decreased speeds and abnormal kinematics, characterized by altered symmetry, reduced sagittal-plane joint excursions, and use of compensatory frontal-plane behaviors during the swing phase of gait. Conventional interventions utilized to mitigate these deficits often incorporate low-intensity, impairment-based or functional exercises focused on normalizing kinematics, although the efficacy of these strategies is unclear. Conversely, higher-intensity training protocols that provide only stepping practice and do not focus on kinematics have demonstrated gains in walking function, although minimal attention toward gait quality may be concerning and has not been assessed. Objective The present study evaluated changes in spatiotemporal and joint kinematics following experimental, high-intensity stepping training compared with conventional interventions. Design Kinematic data were combined from a randomized controlled trial comparing experimental and conventional training and from a pilot experimental training study. Methods Individuals with gait deficits 1 to 6 months poststroke received up to 40 sessions of either high-intensity stepping training in variable contexts or conventional lower-intensity interventions. Analyses focused on kinematic changes during graded treadmill testing before and following training. Results Significant improvements in speed, symmetry, and selected sagittal-plane kinematics favored experimental training over conventional training, although increases in compensatory strategies also were observed. Changes in many kinematic patterns were correlated with speed changes, and increased compensatory behaviors were associated with both stride length gains and baseline impairments. Limitations Limitations include a small sample size and use of multiple statistical comparisons. Conclusions Improved speeds and selected kinematics were observed following high-intensity training, although such training also resulted in increased use of compensatory strategies. Future studies should explore the consequences of utilizing these compensatory strategies despite the observed functional gains.

Intensive Goal-Directed Treatments in Enriched Environments Augments Patient Outcomes

Main Outcome Measures: MAS or AS ankle score, MAS/AS responder analyses, Physician Global Assessment of Response (PGA), and Goal Attainment Scale (GAS). Results or Clinical Course: Greater AS ankle score improvements and higher response rates for patients receiving onabotulinumtoxinA versus placebo were reported in all 3 studies. In Study 1, reductions in MAS ankle score were greater with onabotulinumtoxinA versus placebo, with significant differences at weeks 4, 6, and 8 (p<.001). Proportion of responders ( 1 point reduction from baseline muscle tone ankle score) was greater with onabotulinumtoxinA than placebo at weeks 4, 6, and 8 (p<.001). Study 2 demonstrated a significant difference between onabotulinumtoxinA 300U and placebo in AS at week 8 (p1⁄4.011); the 200U dose did not differentiate from placebo. PGA improved with onabotulinumtoxinA versus placebo, with significant differences at weeks 4, 6, and 8 (p<.05) in Study 1 (results similar in studies 2 and 3). Study 3 demonstrated clinically and statistically significant improvements with onabotulinumtoxinA relative to placebo in functioning measured by GAS. In all 3 studies, significant correlations between measures of muscle tone and study-specific global measure by physician were observed at relevant time-points (p .008). OnabotulinumtoxinA was well-tolerated in all 3 studies. Most frequently-reported AEs were myalgia, injection site pain, fall and urinary tract infection, with no differences in frequency of AEs between onabotulinumtoxinA and placebo. Conclusions: OnabotulinumtoxinA (300U) significantly decreased ankle flexor tone in adults with PS lower limb spasticity. Decrease in muscle tone was considered clinically meaningful, as shown by significant correlations with study-specific investigator global assessments.