Standardized measurement of balance and mobility post-stroke: Consensus-based core recommendations from the third Stroke Recovery and Rehabilitation Roundtable.

BACKGROUND: Mobility is a key priority for stroke survivors. Worldwide consensus of standardized outcome instruments for measuring mobility recovery after stroke is an essential milestone to optimize the quality of stroke rehabilitation and recovery studies and to enable data synthesis across trials. METHODS: Using a standardized methodology, which involved convening of 13 worldwide experts in the field of mobility rehabilitation, consensus was established through an a priori defined survey-based approach followed by group discussions. The group agreed on balance- and mobility-related definitions and recommended a core set of outcome measure instruments for lower extremity motor function, balance and mobility, biomechanical metrics, and technologies for measuring quality of movement. RESULTS: Selected measures included the Fugl-Meyer Motor Assessment lower extremity subscale for motor function, the Trunk Impairment Scale for sitting balance, and the Mini Balance Evaluation System Test (Mini-BESTest) and Berg Balance Scale (BBS) for standing balance. The group recommended the Functional Ambulation Category (FAC, 0-5) for walking independence, the 10-meter Walk Test (10 mWT) for walking speed, the 6-Minute Walk Test (6 MWT) for walking endurance, and the Dynamic Gait Index (DGI) for complex walking. An FAC score of less than three should be used to determine the need for an additional standing test (FAC < 3, add BBS to Mini-BESTest) or the feasibility to assess walking (FAC < 3, 10 mWT, 6 MWT, and DGI are "not testable"). In addition, recommendations are given for prioritized kinetic and kinematic metrics to be investigated that measure recovery of movement quality of standing balance and walking, as well as for assessment protocols and preferred equipment to be used. CONCLUSIONS: The present recommendations of measures, metrics, technology, and protocols build on previous consensus meetings of the International Stroke Recovery and Rehabilitation Alliance to guide the research community to improve the validity and comparability between stroke recovery and rehabilitation studies as a prerequisite for building high-quality, standardized "big data" sets. Ultimately, these recommendations could lead to high-quality, participant-specific data sets to aid the progress toward precision medicine in stroke rehabilitation.

Standardized measurement of balance and mobility post-stroke: Consensus-based core recommendations from the third Stroke Recovery and Rehabilitation Roundtable.

BACKGROUND: Mobility is a key priority for stroke survivors. Worldwide consensus of standardized outcome instruments for measuring mobility recovery after stroke is an essential milestone to optimize the quality of stroke rehabilitation and recovery studies and to enable data synthesis across trials. METHODS: Using a standardized methodology, which involved convening of 13 worldwide experts in the field of mobility rehabilitation, consensus was established through an a priori defined survey-based approach followed by group discussions. The group agreed on balance- and mobility-related definitions and recommended a core set of outcome measure instruments for lower extremity motor function, balance and mobility, biomechanical metrics, and technologies for measuring quality of movement. RESULTS: Selected measures included the Fugl-Meyer Motor Assessment lower extremity subscale for motor function, the Trunk Impairment Scale for sitting balance, and the Mini Balance Evaluation System Test (Mini-BESTest) and Berg Balance Scale (BBS) for standing balance. The group recommended the Functional Ambulation Category (FAC, 0-5) for walking independence, the 10-meter Walk Test (10 mWT) for walking speed, the 6-Minute Walk Test (6 MWT) for walking endurance, and the Dynamic Gait Index (DGI) for complex walking. An FAC score of less than three should be used to determine the need for an additional standing test (FAC < 3, add BBS to Mini-BESTest) or the feasibility to assess walking (FAC < 3, 10 mWT, 6 MWT, and DGI are "not testable"). In addition, recommendations are given for prioritized kinetic and kinematic metrics to be investigated that measure recovery of movement quality of standing balance and walking, as well as for assessment protocols and preferred equipment to be used. CONCLUSIONS: The present recommendations of measures, metrics, technology, and protocols build on previous consensus meetings of the International Stroke Recovery and Rehabilitation Alliance to guide the research community to improve the validity and comparability between stroke recovery and rehabilitation studies as a prerequisite for building high-quality, standardized "big data" sets. Ultimately, these recommendations could lead to high-quality, participant-specific data sets to aid the progress toward precision medicine in stroke rehabilitation.

The effect of sex, stature, and limb length on the preferred walk-to-run transition speed.

BACKGROUND: The preferred walk-to-run transition speed (PTS) for healthy adults is approximately 2 m∙s-1, however, PTS is influenced by anthropometric factors. Yet despite known sex differences in anthropometrics, studies have reported no sex differences in PTS. RESEARCH QUESTION: Do stature and limb length affect PTS in the same way for both male and female healthy adults? METHODS: Thirty-seven (19 female) non-injured adults volunteered for this study. Participants completed a walk-to-run transition protocol, where the treadmill speed was increased from 1.2 m∙s-1 to 2.2 m∙s-1, in increments of 0.1 m∙s-1 every two minutes. An independent t-test compared PTS between sexes. Multiple regression analysis determined the effect of sex and stature and sex and limb length on PTS. RESULTS: Female participants transitioned at a lower PTS than male participants (1.8 (0.2) m∙s-1 versus 1.9 (0.1) m∙s-1; p ≤ 0.026). Sex and stature explained 19% of the variance in PTS, while sex and limb length explained 21% of the variance. Including interactions increased the variance explained by 23% and 2% for sex and stature and sex and limb length, respectively. The significant interaction between sex and stature showed PTS was inversely proportional to stature for male participants but directly proportional for female participants. SIGNIFICANCE: These findings suggest that the extent to which stature and limb length influence the preferred transition speed may differ between sexes.

Stroke survivors' perceptions of participating in a high repetition arm training trial early after stroke.

PURPOSE: The study explored the acceptability of high repetition arm training as part of a randomised controlled trial, early after stroke, when fatigue levels and emotional strain are often high. MATERIALS AND METHODS: 36 sub-acute stroke survivors (61 years+/-15) attended for assessment sessions at 3, 6, and 12 weeks after stroke. Individuals were randomised to receive 6 high repetition arm training sessions between 3 and 6 weeks (intervention) or the control group. Semi-structured interviews were conducted at trial completion. Interview transcripts were analysed through framework analysis conducted independently by 2 researchers. RESULTS: Stroke survivors participated despite high levels of fatigue because they hoped for personal benefit or to potentially benefit future patients. Benefits reported from participation included physical improvements, psychological benefit, improved understanding of their condition as well as a feeling of hope and distraction. The arm training at three weeks after stroke, aiming for 420 movement repetitions was not considered to be too intensive or too early, and most individuals felt lucky to have been, or would have preferred to be in the early training group. CONCLUSION: High repetition arm training early after stroke was acceptable to participants. Study participation was generally viewed as a positive experience, suggesting that early intervention may not only be physically beneficial but also psychologically.Implications for rehabilitationStroke survivors report that high repetition arm training early after stroke is acceptable.Participation in rehabilitation research early after stroke provides stroke survivors with hope and meaning despite the high prevalence of fatigue.Complex information needs to be repeated and provided in a number of formats early after stroke.

Immediate effect of voluntary-induced stepping response training on protective stepping in persons with chronic stroke: a randomized controlled trial.

PURPOSE: To compare the immediate effects of voluntary-induced stepping response training (VSR) and DynSTABLE perturbation training (DST) on protective stepping in patients with stroke. METHODS: A randomized controlled trial (registration number: TCTR20170827001) was conducted in 34 patients with chronic stroke who were randomly allocated to the VSR (n = 17) or DST (n = 17) group. The VSR group was instructed to lean forward to induce protective stepping, while the DST group experienced support surface translation. All participants received one session of training (3 set, 10 min for each set with 10-minute rest in between). Step length, step width, number of steps and center of mass (CoM) position during protective stepping were assessed using a computer-assisted rehabilitation environment (CAREN) system prior to and immediately after training. Two-way ANOVA was used to compare between groups and times. RESULTS: Both types of training resulted in an increase in step width, but step length increased and there was a more positive COM position exhibited following DST (p < .05) than following VSR. Single-step incidence increased, whereas multiple-step incidence decreased significantly in both groups. Only participants in the VSR group generated protective stepping with the affected leg in a larger percentage of trials (27%) after training than before training. CONCLUSION: Both DST and VSR led to changes in protective stepping parameters after a single session of training. VSR may be a feasible alternative to equipment-based training but requires further study.Implication for RehabilitationVSR and DST trainings improved protective stepping in stroke.Step length and CoM control at foot touchdown increased after DST training.VSR training for 50 minutes led to increase affected stepping and reduce grasping.Step width, affected step length, and single step increased after both trainings.Without instrument, VSR increased steps execution and performance similar to DST.

Postural control during quiet standing and voluntary stepping response tasks in individuals post-stroke: a case-control study.

BACKGROUND: Postural control impairments following a stroke have an impact on mobility, reduce independence, and increase the risk of falls. Assessing these impairments during tasks representative of real-life situations, such as quiet standing (QS) and voluntary stepping response (VSR), will enhance our understanding of how the postural control system is impaired in individuals post-stroke (IPS). It will also inform the development of a more targeted and effective rehabilitation to prevent falls in IPS. OBJECTIVES: Identify the postural control impairments encountered by IPS during QS and VSR. METHODS: Twenty IPS and 16 healthy controls were recruited to perform QS and VSR tasks, while ground reaction forces and whole-body motion were measured. Displacement and speed variation of the COM, center of pressure (COP) displacement and spatiotemporal data were calculated and compared between groups. RESULTS: During QS, IPS exhibited greater maximal COP displacement in mediolateral direction, COM displacement in vertical direction and COM speed excursions compared to controls. During VSR, IPS exhibited smaller step length, braking force, posterior foot placement in relation to the pelvis and COM anteroposterior excursion compared to controls. IPS presented less static and dynamic postural stability compared to controls. CONCLUSIONS: Greater postural sway during QS, smaller anteroposterior COM displacement before losing balance and altered voluntary recovering steps during VSR could place IPS at more risk of falling when they face a postural challenge in the community. These novel results will improve the current knowledge base and should be considered in IPS rehabilitation.

The Strength of the Corticospinal Tract Not the Reticulospinal Tract Determines Upper-Limb Impairment Level and Capacity for Skill-Acquisition in the Sub-Acute Post-Stroke Period.

Background. Upper-limb impairment in patients with chronic stroke appears to be partly attributable to an upregulated reticulospinal tract (RST). Here, we assessed whether the impact of corticospinal (CST) and RST connectivity on motor impairment and skill-acquisition differs in sub-acute stroke, using transcranial magnetic stimulation (TMS)-based proxy measures. Methods. Thirty-eight stroke survivors were randomized to either reach training 3-6 weeks post-stroke (plus usual care) or usual care only. At 3, 6 and 12 weeks post-stroke, we measured ipsilesional and contralesional cortical connectivity (surrogates for CST and RST connectivity, respectively) to weak pre-activated triceps and deltoid muscles with single pulse TMS, accuracy of planar reaching movements, muscle strength (Motricity Index) and synergies (Fugl-Meyer upper-limb score). Results. Strength and presence of synergies were associated with ipsilesional (CST) connectivity to the paretic upper-limb at 3 and 12 weeks. Training led to planar reaching skill beyond that expected from spontaneous recovery and occurred for both weak and strong ipsilesional tract integrity. Reaching ability, presence of synergies, skill-acquisition and strength were not affected by either the presence or absence of contralesional (RST) connectivity. Conclusion. The degree of ipsilesional CST connectivity is the main determinant of proximal dexterity, upper-limb strength and synergy expression in sub-acute stroke. In contrast, there is no evidence for enhanced contralesional RST connectivity contributing to any of these components of impairment. In the sub-acute post-stroke period, the balance of activity between CST and RST may matter more for the paretic phenotype than RST upregulation per se.

Comfortably numb? Experiences of people with stroke and lower limb sensation deficits: impact and solutions.

PURPOSE: To explore personal experiences of loss of foot sensation following stroke in order to inform the focus of clinical assessments and development of a vibrotactile insole. METHODS: Qualitative design with an interpretive phenomenological approach to data collection and analysis. Eight community dwelling adults with stroke (>6 months) and sensory impairment in the feet participated. Data was collected via conversational style interviews which were transcribed and analyzed using a thematic framework. Themes were verified with co-researchers and a lay advisory group. RESULTS: Data formed four themes: Sensory deficits are prevalent and constant, but individual and variable; Sensory deficits have a direct impact on balance, gait, mobility and falls; Sensory deficits have consequences for peoples' lives; Footwear is the link between function, the environment and identity. They embraced the concept of discrete vibrotactile insoles, their potential benefits and demonstrated a willingness to try it. CONCLUSIONS: Sensory deficit contributes to effects upon physical function, mobility and activity. Clinical outcome measures need to capture the emotional, psychological and social impacts of sensory deficit. Participants demonstrated a resilience and resourcefulness through adaption in daily living and self-management of footwear. The participants focus on footwear provides the opportunity to develop discrete and non-burdensome vibrotactile insoles for this patient group.IMPLICATIONS FOR REHABILITATIONSensory deficits are wide ranging and varied and are not distinct from motor deficits though contribute to the overall effect on physical function, mobility and activity.The physical effects impact on participants' lives emotionally, psychologically and socially. Measurement of outcomes need to capture specific activities that are valued by patients.The participants have revealed resilience and resourcefulness to create a "new normal" for their lives through adaption and self-management with a focus being on footwear as a solution.The participants have revealed the need for insole interventions to be discreet and non-burdensome, welcoming insole technology and contributing to the design and features of such insoles.

Characteristics of Voluntary-induced Stepping Response in Persons with Stroke compared with those of healthy Young and Older Adults.

BACKGROUND: Impairment of protective steps to recover balance from external perturbation is evident after stroke. Voluntary-induced stepping response (VSR) can be used to practice protective steps by instructing an individual to voluntarily lean their whole body forward until they perceive a loss of balance and automatically induce a step. However, to improve protective stepping performance, detailed characteristics of VSR in healthy persons are required. RESEARCH QUESTION: What is the difference in VSR between healthy and persons with stroke? METHODS: An observational study was conducted in 30 participants, (10 young, 10 older, and 10 persons with stroke). All participants performed VSR for 10 trials. Step length, step width, step duration, CoM position, CoM velocity, trunk-hip displacement, and strategies of response were recorded using a motion capture system and analysed using Matlab software. Statistical analysis was performed using One-way ANOVA and Chi-square. RESULTS: On average, participants with stroke had shorter step lengths and step durations than young and older adults. Step width of older adults and participants with stroke was wider than that of young adults (p < 0.05). While multiple steps and losing balance were reported more frequently in participants with stroke than the others, the percentage of trials in which participants grasped the handrails was not significantly different between older adults and participants with stroke. CoM position, CoM velocity, and trunk-hip displacement at foot liftoff were significantly smaller in older adults and participants with stroke than young adults (p < 0.05). Participants with stroke tended to use trunk bending rather than trunk leaning strategies to generate VSR in contrast to healthy participant. The prevalence of the trunk bending strategy was also greater in older adults than young adults. SIGNIFICANCE: Values obtained from healthy groups can be used as guidelines to set realistic goals during VSR training to improve protective steps in patients with stroke.

Foot-placement accuracy during planned and reactive target stepping during walking in stroke survivors and healthy adults.

BACKGROUND: The high prevalence of falls due to trips and slips following stroke may signify difficulty adjusting foot-placement in response to the environment. However, little is known about under what circumstances foot-placement adjustment becomes difficult for stroke survivors (SS), making the design of targeted rehabilitation interventions to improve independent community mobility difficult. RESEARCH QUESTION: To investigate the effect of planned and reactive target-stepping on foot-placement accuracy in stroke survivors and young and older healthy adults? METHODS: Young (N = 11, 30 ± 6 years) and older (N = 10, 64 ± 8 years) healthy adults and SS (N = 11, 67 ± 9 years) walked, at preferred pace, on a force instrumented treadmill. Each participant walked to illuminated targets, visible two steps in advance (planned) or appearing at contralateral midstance (reactive). Foot-placement error (magnitude and bias) and number of missed targets were compared. RESULTS: All participants missed more reactive than planned targets (p = 0.05), and SS missed more targets than young (p < 0.001) and older (p = 0.001) adults. But no interaction showing SS missed more reactive targets than other groups was found. For all groups: reactive adaptations to steps in the antero-posterior plane resulted in lower error than planned adaptations (p = 0.027). Lengthening steps where undershot more than shortening (p < 0.001) by all groups. Reactive medio-lateral adaptations over all induced larger error (p = 0.029) than planned and changed the direction of bias (p = 0.018). SIGNIFICANCE: SS experience difficulty making all adjustments, they showed increased error in all conditions but less pronounced difference between planned and reactive stepping. SS may use a reactive control strategy for all adjustments, in contrast to healthy young adults who may plan foot-placement in advance. The likelihood of stroke survivors misplacing a step is large, with 9.8% targets missed; possibly leading to falls. Further investigation is needed to understand foot-placement control strategies used by SS and the role of planning in gait adaptability.

SPARC Metrics Provide Mobility Smoothness Assessment in Oldest-Old With and Without a History of Falls: A Case Control Study.

Aging-related neuromuscular and neurocognitive decline induces unsmooth movements in daily functional mobility. Here, we used a robust analysis of linear and angular spectral arc length (SPARC) in the single and dual task instrumented timed up-and-go (iTUG) test to compare functional mobility smoothness in fallers and non-fallers aged 85 and older. 64 participants aged 85 and older took part in this case control study. The case group (fallers, n = 32) had experienced falls to the ground in the 6 months prior to the assessment. SPARC analyses were conducted in all phases of the single and dual task iTUGs. We also performed correlation mapping to test the relation of socio-demographic and clinical features on SPARC metrics. The magnitude of between-group differences was calculated using D-Cohen effect size (ES). SPARC was able to distinguish fallers during the single iTUG (ES ≈ 4.18). Turning while walking in the iTUG induced pronounced unsmooth movements in the fallers (SPARC ≈ -13; ES = 3.52) and was associated with the ability to maintain balance in the functional reach task. This information is of importance in the study of functional mobility in the oldest-old and to assess the efficacy of fall-prevention programs.

Evaluation of the Effects of Prescribing Gait Complexity Using Several Fluctuating Timing Imperatives.

Variability in the temporal structure of gait patterns, measured by "Fractal Index" (FI), is thought to represent abundancy of movement patterns facilitating adaptive control of walking. However we do not know how FI changes according to different walking rhythms or if this is repeatable, as needed to exploit the paradigm for rehabilitation. Fourteen healthy young adults synchronised heel contact to an auditory metronome twice each in four conditions (uncued, white noise, pink noise, and red noise) and three sessions. FI differed based on the walking condition while no effect of session was revealed. The results of this study suggest gait fractality changes systematically with different stimuli and can be consistently prescribed in a desired direction within a group of healthy young individuals.

How accuracy of foot-placement is affected by the size of the base of support and crutch support in stroke survivors and healthy adults.

BACKGROUND: The high prevalence of falls due to trips and slips following stroke may signify difficulty controlling balance and adjusting foot-placement in response to the environment. We know very little about how controlling foot-placement is affected by balance requirements and the effects of stroke. Therefore, in this study the research question is how foot-placement control is affected by balance support from crutches and reducing or enlarging the base of support. By understanding how foot-placement control and balance deficits following stroke interact, rehabilitation efforts can be more effectively targeted towards the cause of poor mobility. METHODS: Young (N=13, 30±6 years) and older (N=10, 64±8 years) healthy adults and stroke survivors (N=11, 67±9 years) walked to targets on an instrumented treadmill with or without crutch support for balance. Targets were randomized to either reduce or increase the base of support in the antero-posterior (AP) or medio-lateral (ML) direction. Mean and absolute foot-placement error were measured using motion analysis. These outcomes were compared using repeated measures ANCOVA with walking speed as a covariate. RESULTS: Overall, stroke survivors missed more targets (9.1±2.3%, p=0.001) than young (1.0±2.5%) and older (0.2±2.1%) healthy adults (p=0.001). However, there were no significant differences between groups in foot-placement error. Crutch support reduced both AP and ML foot-placement error (p=<0.001, AP 5.2±0.5cm unsupported, 4.1±0.4cm supported, ML 2.3±0.2cm unsupported, 1.9±0.2cm supported) for all participants. Interaction effects indicate crutch support reduced foot-placement error more when narrowing (unsupported 2.8±0.2cm, supported 1.8±0.2cm) than widening (unsupported 2.6±0.4cm, supported 2.4±0.4cm) steps (p<0.001), SIGNIFICANCE: Stroke survivors have greater difficulty accurately adjusting steps in response to the environment. Crutch support reduces foot-placement error for all steps, but particularly when narrowing foot-placement. These results provide support for the implication of walking aids, which support balance to improve ability to adjust footplacement in response to the environment.

Quantifying sit-to-stand and stand-to-sit transitions in free-living environments using the activPAL thigh-worn activity monitor.

PURPOSE: Standing up, sitting down and walking require considerable effort and coordination, which are crucial indicators to rehabilitation (e.g. stroke), and in older populations may indicate the onset of frailty and physical and cognitive decline. Currently, there are few reports robustly quantifying sit-to-stand and stand-to-sit transitions in free-living environments. The aim of this study was to identify and quantify these transitions using the peak velocity of sit-to-stand and stand-to-sit transitions to determine if these velocities were different in a healthy cohort and a mobility-impaired population. METHODS: Free-living sit-to-stand and stand-to-sit acceleration data were recorded from 21 healthy volunteers and 34 stroke survivors using activPAL3™ monitors over a one-week period. Thigh inclination velocity was calculated from these accelerometer data. Maximum velocities were compared between populations. RESULTS: A total of 10,299 and 11,392 sit-to-stand and stand-to-sit transitions were recorded in healthy volunteers and stroke survivors, respectively. Healthy volunteers had significantly higher overall mean peak velocities for both transitions compared with stroke survivors [70.7°/s ± 52.2 versus 44.2°/s ± 28.0 for sit-to-stand, P < 0.001 and 74.7°/s ± 51.8 versus 46.0°/s ± 31.9 for stand-to-sit; P < 0.001]. Mean peak velocity of transition was associated with increased variation in peak velocity across both groups. CONCLUSION: There were significant differences in the mean peak velocity of sit-to-stand and stand-to-sit transitions between the groups. Variation in an individual's mean peak velocity may be associated with the ability to perform these transitions. This method could be used to evaluate the effectiveness of interventions following injury such as stroke, as well as monitor decline in functional ability.

Gait adaptability.

Our activities of daily living inherently involve interacting with the physical environment. This interaction involves both reactive (feedback) and proactive (feedforward) gait adaptations. Reactive adaptations involve responses to mechanical perturbations and occur, for instance, when we stumble over a doorstep or slip on an icy spot on the pavement. Examples of proactive adaptations in response to visual stimuli include stepping over an obstacle, targeting precise foot placements when walking on rough terrain, stepping up to the pavement, or making a turn for going around a corner. These adaptations have to be implemented in our steady-state gait pattern, thus posing a challenge to center-of-mass control and maintenance of forward progression. Yet, despite the apparent complexity of adaptive bipedal walking, we commonly do this with remarkable ease. This chapter will provide a comprehensive overview of the behavioral strategies and control mechanisms that we apply for executing these common, yet complex, gait adaptations. In addition, how we use visual information for guiding proactive gait adaptations and path selection will be discussed. Finally, cognitive involvement during gait adaptations will also be addressed.

Validation of gait event detection by centre of pressure during target stepping in healthy and paretic gait.

BACKGROUND: Target-stepping paradigms are increasingly used to assess and train gait adaptability. Accurate gait-event detection (GED) is key to locating targets relative to the ongoing step cycle as well as measuring foot-placement error. In the current literature GED is either based on kinematics or centre of pressure (CoP), and both have been previously validated with young healthy individuals. However, CoP based GED has not been validated for stroke survivors who demonstrate altered CoP pattern. METHODS: Young healthy adults and individuals affected by stroke stepped to targets on a treadmill, while gait events were measured using three detection methods; verticies of CoP cyclograms, and two kinematic criteria, (1) vertical velocity and position and of the heel marker, (2) anterior velocity and position of the heel and toe marker, were used. The percentage of unmatched gait events was used to determine the success of the GED method. The difference between CoP and kinematic GED methods were tested with two one sample (two-tailed) t-tests against a reference value of zero. Differences between group and paretic and non-paretic leg were tested with a repeated measures ANOVA. RESULTS: The kinematic method based on vertical velocity only detected about 80% of foot contact events on the paretic side in stroke survivors while the method on anterior velocity was more successful in both young healthy adults as stroke survivors (3% young healthy and 7% stroke survivors unmatched). Both kinematic methods detected gait events significantly earlier than CoP GED (p < 0.001) except for foot contact in stroke survivors based on the vertical velocity. CONCLUSIONS: CoP GED may be more appropriate for gait analyses of SS than kinematic methods; even when walking and varying steps.

Estimation of muscle activation during different walking speeds with two mathematical approaches compared to surface EMG.

BACKGROUND: Muscle force estimation could improve clinical gait analysis by enhancing insight into causes of impairments and informing targeted treatments. However, it is not currently standard practice to use muscle force models to augment clinical gait analysis, partly, because robust validations of estimated muscle activations, underpinning force modelling processes, against recorded electromyography (EMG) are lacking. RESEARCH QUESTION: Therefore, in order to facilitate future clinical use, this study sought to validate estimated lower limb muscle activation using two mathematical models (static optimisation SO, computed muscle control CMC) against recorded muscle activations of ten healthy participants. METHODS: Participants walked at five speeds. Visual agreement in activation onset and offset as well as linear correlation (r) and mean absolute error (MAE) between models and EMG were evaluated. RESULTS: MAE between measured and recorded activations were variable across speeds (SO vs EMG 15-68%, CMC vs EMG 13-69%). Slower speeds resulted in smaller deviations (mean MAE < 30%) than faster speeds. Correlation was high (r > 0.5) for only 11/40 (CMC) and 6/40 (SO) conditions (muscles X speeds) compared to EMG. SIGNIFICANCE: Modelling approaches do not yet show sufficient consistency of agreement between estimated and recorded muscle activation to support recommending immediate clinical adoption of muscle force modelling. This may be because assumptions underlying muscle activation estimations (e.g. muscles' anatomy and maximum voluntary contraction) are not yet sufficiently individualizable. Future research needs to find timely and cost efficient ways to scale musculoskeletal models for better individualisation to facilitate future clinical implementation.

A systematic review of approaches to modelling lower limb muscle forces during gait: Applicability to clinical gait analyses.

Computational methods to estimate muscle forces during walking are becoming more common in biomechanical research but not yet in clinical gait analysis. This systematic review aims to identify the current state-of-the-art, examine the differences between approaches, and consider applicability of the current approaches in clinical gait analysis. A systematic database search identified studies including estimated muscle force profiles of the lower limb during healthy walking. These were rated for quality and the muscle force profiles digitised for comparison. From 13.449 identified studies, 22 were finally included which used four modelling approaches: static optimisation, enhanced static optimisation, forward dynamics and EMG-driven. These used a range of different musculoskeletal models, muscle-tendon characteristics and cost functions. There is visually broad agreement between and within approaches about when muscles are active throughout the gait cycle. There remain, considerable differences (CV 7%-151%, range of timing of peak forces in gait cycle 1%-31%) in patterns and magnitudes of force between and within modelling approaches. The main source of this variability is not clear. Different musculoskeletal models, experimental protocols, and modelling approaches will clearly have an effect as will the variability of joint kinetics between healthy individuals. Limited validation of modelling approaches, particularly at the level of individual participants, makes it difficult to conclude if any of the approaches give consistently better estimates than others. While muscle force modelling has clear potential to enhance clinical gait analyses future research is needed to improve validation, accuracy and feasibility of implementation in clinical practice.

Functional electrical stimulation and ankle foot orthoses provide equivalent therapeutic effects on foot drop: A meta-analysis providing direction for future research.

OBJECTIVE: To compare the randomized controlled trial evidence for therapeutic effects on walking of functional electrical stimulation and ankle foot orthoses for foot drop caused by central nervous system conditions. DATA SOURCES: MEDLINE, CINAHL, Cochrane Central Register of Controlled Trials, REHABDATA, PEDro, NIHR Centre for Reviews and Dissemination, Scopus and clinicaltrials.gov. STUDY SELECTION: One reviewer screened titles/abstracts. Two independent reviewers then screened the full articles. DATA EXTRACTION: One reviewer extracted data, another screened for accuracy. Risk of bias was assessed by 2 independent reviewers using the Cochrane Risk of Bias Tool. DATA SYNTHESIS: Eight papers were eligible; 7 involving participants with stroke and 1 involving participants with cerebral palsy. Two papes reporting different measures from the same trial were grouped, resulting in 7 synthesized randomized controlled trials (n= 464). Meta-analysis of walking speed at final assessment (p = 0.46), for stroke participants (p = 0.54) and after 4-6 weeks' use (p = 0.49) showed equal improvement for both devices. CONCLUSION: Functional electrical stimulation and ankle foot orthoses have an equally positive therapeutic effect on walking speed in non-progressive central nervous system diagnoses. The current randomized controlled trial evidence base does not show whether this improvement translates into the user's own environment or reveal the mechanisms that achieve that change. Future studies should focus on measuring activity, muscle activity and gait kinematics. They should also report specific device details, capture sustained therapeutic effects and involve a variety of central nervous system diagnoses.

Can an aversive, extinction-resistant memory trigger impairments in walking adaptability? An experimental study using adult rats.

Cognitive demands can influence the adaptation of walking, a crucial skill to maintain body stability and prevent falls. Whilst previous research has shown emotional load tunes goal-directed movements, little attention has been given to this finding. This study sought to assess the effects of suffering an extinction-resistant memory on skilled walking performance in adult rats, as an indicator of walking adaptability. Thus, 36 Wistar rats were divided in a two-part experiment. In the first part (n=16), the aversive, extinction-resistance memory paradigm was established using a fear-conditioning chamber. In the second, rats (n=20) were assessed in a neutral room using the ladder rung walking test before and tree days after inducing an extinction-resistance memory. In addition, the elevated plus-maze test was used to control the influence of the anxiety-like status on gait adaptability. Our results revealed the shock group exhibited worse walking adaptability (lower skilled walking score), when compared to the sham group. Moreover, the immobility time in the ladder rung walking test was similar to the controls, suggesting that gait adaptability performance was not a consequence of the fear generalization. No anxiety-like behavior was observed in the plus maze test. Finally, correlation coefficients also showed the skilled walking performance score was positively correlated with the number of gait cycles and trial time in the ladder rung walking test and the total crossings in the plus maze. Overall, these preliminary findings provide evidence to hypothesize an aversive, extinction-resistant experience might change the emotional load, affecting the ability to adapt walking.