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In immersive VR, a self-avatar that replicates the user’s movements and is viewed from a first-person perspective can substitute the real body. If the avatar’s movements are sufficiently synchronized with the user’s actual movements, the user can experience a sense of embodiment over the avatar. Recent studies have shown that discrepancies between the movements of the avatar and those of the user can be well tolerated while maintaining high levels of embodiment. The point at which a distortion is perceived (detection threshold) and its impact on the level of embodiment has not been studied in lower limb tasks such as gait. This study aimed to identify a detection threshold of gait asymmetry by unilaterally manipulating the step length of a self-avatar, and the effect of this detection on perceived embodiment. A real-time step length distortion model was developed, and a detection threshold between actual and avatar’s gait movement was assessed on thirty healthy participants. The step length was manipulated to introduce gait asymmetry (ascending condition) or start from a large asymmetry that was gradually decreased (descending). The results showed that, on average, the avatar’s step length could be increased by up to 12% before the participants detected the distortion. Furthermore, in the descending condition, they detected increases that were above 9%. The point of detection had no effect on the sense of embodiment as participants still reported being embodied in their avatars, even when they consciously detected the step length distortion. The sense of embodiment was closely correlated with the level of distortion; as distortion increased, embodiment decreased, and vice versa. For a given distortion level, embodiment was similar whether in the ascending or descending condition. This suggests that embodiment can be achieved even when the avatar’s spatial alignment initially differs from the participants’, provided that alignment is gradually restored. These results provide valuable insights into participants’ ability to tolerate movement discrepancies in embodied avatar experiences during gait in virtual environments, with potential applications in motor training and gait rehabilitation. [ABSTRACT FROM AUTHOR]

BACKGROUND: Physical activity as one of the major lifestyle-related health determinants is partially addressed by the Montreal Walking Exoskeleton Satisfaction and Perspectives-Questionnaire (MWESP-Q). OBJECTIVE: To document satisfaction of people with chronic spinal cord injury after the completion of a 10 to 16 weeks of the wearable robotic exoskeleton-assisted walking program, with the MWESP-Q updated to a context of health promotion. METHODS: Following a walking program (10–16 weeks), wheelchair users with chronic SCI completed the MWESP-Q online. Modification of the original questionnaire was conducted with 4 experts to ensure its content validity with a human framework to promote physical activity for health. RESULTS: Ten wheelchair users completed the questionnaire (men = 6; 45.8 ± 13.4 years, SCI duration: 10.1 ± 5.8 years). Participants strongly agreed to be satisfied with the overall program; agreed to be satisfied towards exoskeleton, motivation to engage in physical activity, learnability and program attributes; rated "medium effort" for physical and cognitive exertion during training; reported light improvements for health benefit domain, but light to moderate improvements for general endurance (mean 5.5 /7, SD 1.4) and psychological well-being (mean 5.7 /7, SD 1.3). CONCLUSIONS: The updated MWESP-Q is now better equipped to measure physical and cognitive efforts in physical activity and changes in body and organic systems and in capabilities (health promotion). The updated MWESP-Q has 54 statements (14 additional statements and 1 deleted) organized around seven domains. The original measure was replaced by three 7-point Likert scales, one regarding agreement level (40 statements), level of effort (12 statements), and level of change (2 statements). [ABSTRACT FROM AUTHOR]

Background: Living labs in the health and well-being domain have become increasingly common over the past decade but vary in available infrastructure, implemented study designs, and outcome measures. The Horizon 2020 Project Virtual Health and Wellbeing Living Lab Infrastructure aims to harmonize living lab procedures and open living lab infrastructures to facilitate and promote research activities in the health and well-being domain in Europe and beyond. This protocol will describe the design of a joint research activity, focusing on the use of innovative technology for both rehabilitation interventions and data collection in a rehabilitation context. Objective: With this joint research activity, this study primarily aims to gain insight into each living lab's infrastructure and procedures to harmonize health and well-being living lab procedures and infrastructures in Europe and beyond, particularly in the context of rehabilitation. Secondarily, this study aims to investigate the potential of innovative technologies for rehabilitation through living lab methodologies. Methods: This study has a mixed methods design comprising multiple phases. There are two main phases of data collection: cocreation (phase 1) and small-scale pilot studies (phase 2), which are preceded by a preliminary harmonization of procedures among the different international living labs. An intermediate phase further allows the implementation of minor adjustments to the intervention or protocol depending on the input that was obtained in the cocreation phase. A total of 6 small-scale pilot studies using innovative technologies for intervention or data collection will be performed across 4 countries. The target study sample comprises patients with stroke and older adults with mild cognitive impairment. The third and final phases involve Delphi procedures to reach a consensus on harmonized procedures and protocols. Results: Phase 1 data collection will begin in March 2022, and phase 2 data collection will begin in June 2022. Results will include the output of the cocreation sessions, small-scale pilot studies, and advice on harmonizing procedures and protocols for health and well-being living labs focusing on rehabilitation. Conclusions: The knowledge gained by the execution of this research will lead to harmonized procedures and protocols in a rehabilitation context for health and well-being living labs in Europe and beyond. In addition to the harmonized procedures and protocols in rehabilitation, we will also be able to provide new insights for improving the implementation of innovative technologies in rehabilitation. [ABSTRACT FROM AUTHOR]

The study aimed to (1) compare postural stability between sitting and standing in healthy individuals and (2) define center-of-pressure (COP) measures during sitting that could also explain standing stability. Fourteen healthy individuals randomly maintained (1) two short-sitting positions with eyes open or closed, with or without hand support, and (2) one standing position with eyes open with both upper limbs resting alongside the body. Thirty-six COP measures based on time and frequency series were computed. Greater COP displacement and velocity along with lower frequency measures were found for almost all directional components during standing compared with both sitting positions. The velocity, 95% confidence ellipse area, and centroidal frequency were found to be correlated between unsupported sitting and standing. Despite evidenced differences between sitting and standing, similarities in postural control were highlighted when sitting stability was the most challenging. These findings support further investigation between dynamic sitting and standing balance. [ABSTRACT FROM AUTHOR]

Aim: The main objectives of this study were to quantify clients' satisfaction and perception upon completion of a locomotor training program with an overground robotic exoskeleton. Methods: A group of 14 wheelchair users with a spinal cord injury, who finished a 6–8-week locomotor training program with the robotic exoskeleton (18 training sessions), were invited to complete a web-based electronic questionnaire. This questionnaire encompassed 41 statements organized around seven key domains: overall satisfaction related to the training program, satisfaction related to the overground robotic exoskeleton, satisfaction related to the program attributes, perceived learnability, perceived health benefits and risks and perceived motivation to engage in physical activity. Each statement was rated using a visual analogue scale ranging from "0 = totally disagree" to "100 = completely agree". Results: Overall, respondents unanimously considered themselves satisfied with the locomotor training program with the robotic exoskeleton (95.7 ± 0.7%) and provided positive feedback about the robotic exoskeleton itself (82.3 ± 6.9%), the attributes of the locomotor training program (84.5 ± 6.9%) and their ability to learn to perform sit–stand transfers and walk with the robotic exoskeleton (79.6 ± 17%). Respondents perceived some health benefits (67.9 ± 16.7%) and have reported no fear of developing secondary complications or of potential risk for themselves linked to the use of the robotic exoskeleton (16.7 ± 8.2%). At the end of the program, respondents felt motivated to engage in a regular physical activity program (91.3 ± 0.1%). Conclusion: This study provides new insights on satisfaction and perceptions of wheelchair users while also confirming the relevance to continue to improve such technologies, and informing the development of future clinical trials. All long-term manual wheelchair users with a spinal cord injury who participated in the study are unanimously satisfied upon completion of a 6–8-week locomotor training program with the robotic exoskeleton and would recommend the program to their peers. All long-term manual wheelchair users with a spinal cord injury who participated in the study offered positive feedback about the robotic exoskeleton itself and feel it is easy to learn to perform sit–stand transfers and walk with the robotic exoskeleton. All long-term manual wheelchair users with a spinal cord injury who participated in the study predominantly perceived improvements in their overall health status, upper limb strength and endurance as well as in their sleep and psychological well-being upon completion of a 6–8-week locomotor training program with the robotic exoskeleton. All long-term manual wheelchair users with a spinal cord injury who participated in the study unanimously felt motivated to engage in a regular physical activity program adapted to their condition and most of them do plan to continue to participate in moderate-to-strenuous physical exercise. Additional research on clients' perspectives, especially satisfaction with the overground exoskeleton and locomotor training program attributes, is needed. [ABSTRACT FROM AUTHOR]

Objective To quantify and compare the responsiveness and concurrent validity of 3 performance-based manual wheelchair propulsion tests among manual wheelchair users with subacute spinal cord injury (SCI) undergoing inpatient rehabilitation. Design Quasi-experimental repeated-measures design. Setting Publicly funded comprehensive inpatient SCI rehabilitation program. Participants Consenting adult manual wheelchair users with a subacute SCI admitted and discharged from inpatient rehabilitation (N=14). Intervention Participants performed 20-m propulsion at both self-selected natural and maximal speeds, the slalom, and the 6-minute propulsion tests at rehabilitation admission and discharge. Main Outcome Measures Time required to complete the performance-based wheelchair propulsion tests. Standardized response means (SRMs) were computed for each performance test and Pearson correlation coefficients (r) were calculated to explore the associations between performance tests. Results The slalom (SRM=1.24), 20-m propulsion at maximum speed (SRM=.99), and 6-minute propulsion tests (SRM=.84) were the most responsive. The slalom and 20-m propulsion at maximum speed were strongly correlated at both admission (r=.93) and discharge (r=.92). Conclusions The slalom and 6-minute propulsion tests best document wheelchair propulsion performance change over the course of inpatient rehabilitation. Adding the 20-m propulsion test performed at maximal speed provides a complementary description of performance change. [ABSTRACT FROM AUTHOR]

The purpose of this study was to characterize balance in individuals with and without an incomplete spinal cord injury (ISCI) during the single support phase of gait. Thirty-four individuals (17 with a ISCI, 17 able-bodied) walked at their self-selected walking speed. Among those, eighteen individuals (9 with ISCI, 9 able-bodied) with a similar walking speed were also analyzed. Stabilizing and destabilizing forces quantified balance during the single support phase of gait. The biomechanical factors included in the equation of the stabilizing and destabilizing forces served as explanatory factors. Individuals with ISCI had a lower stabilizing force and a higher destabilizing force compared to able-bodied individuals. The main explanatory factors of the forces extracted from the equations were the speed of the center of mass (maximal stabilizing force) and the distance between the center of pressure and the base of support (minimal destabilizing force). Only the minimal destabilizing force was significantly different among subgroups with a similar walking speed. The stabilizing and destabilizing forces suggest that individuals with ISCI were more stable than able-bodied, which was achieved by walking more slowly – which decrease the speed of the center of mass – and keeping the center of pressure away from the margin of the base of support in order to maintain balance within their range of physical ability. [ABSTRACT FROM AUTHOR]

Abstract: Background: Individuals with incomplete spinal cord injury need to be assessed in different environments. The objective of this study was to compare lower-limb power generation in subjects with spinal cord injury and healthy subjects while walking on an inclined pathway. Methods: Eleven subjects with spinal cord injury and eleven healthy subjects walked on an inclined pathway at their natural gait speed and at slow gait speed (healthy subjects only). Ground reaction forces were recorded by force plates embedded in the inclined pathway and a 3-D motion analysis system recorded lower-limb motions. Data analysis included gait cycle parameters and joint peak powers. Differences were identified by student t-tests. Findings: Gait cycle parameters were lower in spinal cord injury subjects compared to healthy subjects at natural speed but similar at slow gait speed. Subjects with spinal cord injury presented lower power at the ankle, knee and hip compared to healthy subjects at natural gait speed while only the power generation at push-off remained lower when the two groups performed at similar speed. Interpretation: The most important differences are associated with the fact that individuals with spinal cord injury walk at a slower speed, except for the ankle power generation. This study demonstrated that, even with a good motor recovery, distal deficits remain and may limit the ability to adapt to uphill and downhill walking. Inclined pathways are indicated to train patients with spinal cord injury. Clinicians should focus on the speed of uphill and downhill walking and on the use of plantar flexors. [Copyright &y& Elsevier]

Abstract: Background: Walking with a load at the ankle during gait training is a simple way to resist lower limb movements to induce functional muscle strengthening. This study investigated the effects of walking with different loads attached above the paretic ankle on biomechanical gait parameters during over ground walking in post-stroke participants. Methods: Ten participants with moderate chronic hemiparesis were evaluated while walking over ground with three different loads (0.5, 1.0, and 1.5kg) attached above the paretic ankle. Gait speed, cadence, step lengths as well as hip and knee angular displacements, joint moments and power of the paretic limb were compared while walking with and without loads. Findings: Walking with a load led to an increased in gait speed (+0.03–0.05m/s), and in step length of the paretic leg (+5.6 to 9.4% step length, effect size=0.49–0.63), but not of the non-paretic leg. The proportion of the stance and swing phases did not change. Maximal joint moments (+20 to 48%, effect size=0.26–0.55) and power (+20 to 114%, effect size=0.30–0.57) increases varied across participants but were mostly affected in early stance at the hip and during the late swing phase at the knee. Mean angular displacement changes were less than 4°. Interpretation: Post-stroke participants are able to increase hip and knee power bursts to meet the increased mechanical demand of added loads attached to the paretic ankle, while preserving the basic pattern of walking. Further study is needed before using loading to functionally strengthen paretic muscles. [Copyright &y& Elsevier]

Background Sensorimotor impairments secondary to a spinal cord injury affect standing postural balance. While quasi-static postural balance impairments have been documented, little information is known about dynamic postural balance in this population. The aim of this study was to quantify and characterize dynamic postural balance while standing among individuals with a spinal cord injury using the comfortable multidirectional limits of stability test and to explore its association with the quasi-static standing postural balance test. Methods Sixteen individuals with an incomplete spinal cord injury and sixteen able-bodied individuals participated in this study. For the comfortable multidirectional limits of stability test, participants were instructed to lean as far as possible in 8 directions, separated by 45° while standing with each foot on a forceplate and real-time COP visual feedback provided. Measures computed using the center of pressure (COP), such as the absolute maximal distance reached (COPmax) and the total length travelled by the COP to reach the maximal distance (COPlength), were used to characterize performance in each direction. Quasi-static standing postural balance with eyes open was evaluated using time-domain measures of the COP. The difference between the groups and the association between the dynamic and quasistatic test were analyzed. Results The COPlength of individuals with SCI was significantly greater (p ⩽ 0.001) than that of ablebodied individuals in all tested directions except in the anterior and posterior directions (p ⩽ 0.039), indicating an increased COP trajectory while progressing towards their maximal distance. The COPmax in the anterior direction was significantly smaller for individuals with SCI. Little association was found between the comfortable multidirectional limits of stability test and the quasi-static postural balance test (r ⩾ -0.658). Conclusion Standing dynamic postural balance performance in individuals with an incomplete spinal cord injury can be differentiated from that of able-bodied individuals with the comfortable limits of stability test. Performance among individuals with an incomplete spinal cord injury is characterized by lack of precision when reaching. The comfortable limits of stability test provides supplementary information and could serve as an adjunct to the quasi-static test when evaluating postural balance in an incomplete spinal cord injury population. [ABSTRACT FROM AUTHOR]

Abstract: Dynamic stability requirements have never been quantified when long-term manual wheelchair users transfer themselves in a seated position from an initial surface to a target surface, a functional task commonly referred to as sitting pivot transfers (SPTs). Ten individuals with spinal cord injury (SCI), who rely on a manual wheelchair for mobility, underwent a comprehensive biomechanical SPT assessment. SPTs performed toward a target seat of same height (even) and a seat 10cm higher than the initial seat (uneven), repeated three times for each task, were assessed. A dynamic equilibrium model, continuously measuring the theoretical forces required to move the center of pressure to the limit of the base of support (destabilizing force) and to neutralize the kinetic energy and stop the displacement of the center of mass at the limit of the base of support (stabilizing force) at each instance during the performance of SPTs, was used to identify the phases of greatest instability during the SPT tasks. The greatest levels of instability were reached around the time the buttocks lost contact with the initial seat and around the time the buttocks landed on the target seat (pre- and post-lift transition phases). These transition periods, characterized by the lowest destabilizing force (424.7–487.1N) and the greatest stabilizing force (24.2–33.2N), confirmed the greatest level of instability. The height of the target seat had no significant effect (p=0.278–0.739) on dynamic postural stability requirements during the SPTs. During SPTs towards even and uneven target seats, the greatest postural instability occurs during the transition phases in individuals with complete motor thoracic SCI. [Copyright &y& Elsevier]

AbstractPurposeMethodResultsConclusion\nIMPLICATIONS FOR REHABILITATIONTo examine the perspectives of wheelchair users with spinal cord injury (WUSCI) regarding their participation in a 16-week walking program using a wearable robotic exoskeleton (WRE); and explore concerns and expectations regarding potential use of this device and intervention in the context of a home or community-based adapted physical activity program.Semi-structured interviews were conducted using a narrative research, 3 weeks post-intervention. Thematic analysis resulted in 6 themes and 21 subthemes.Seven men and 4 women aged between 32 and 72 years were interviewed; 8 of them had a complete SCI. After the walking program, WUSCI reported positive psychological aspects (having fun and motivation) and experiencing improvements in physical aspects (strength, endurance, balance and flexibility, blood circulation and intestinal transit). The structural aspects of the WRE device were acceptable in a lab with research personnel (appearance, size, weight, and comfort). Participants had concerns about safety on uneven surfaces, and possibility of falling. They expressed the desire to use the WRE for more life habits than just walking.This is the first study in which WUSCI report that the WRE should be implemented in initial rehabilitation. Lack of availability for community use after rehabilitation remains a concern.Participation in a walking training program using a wearable robotic exoskeleton, 1-3 times weekly over several weeks, may be well tolerated and provide physical and psychological benefits for wheelchair users with spinal cord injuries.Using a robotic exoskeleton during initial rehabilitation may be well received and help with regaining strength, endurance, balance, and flexibility as well as promoting blood circulation and intestinal transit.The use of the wearable robotic exoskeleton always needs supervision of a clinician for walking and can’t be used independently by wheelchair users; there is no possibility for hands free for household tasks (e.g., washing floors, accessing cupboards or reaching shelves, using stairs), and for recreation (e.g., exercising, taking walks, cultural activities, concerts).Participation in a walking training program using a wearable robotic exoskeleton, 1-3 times weekly over several weeks, may be well tolerated and provide physical and psychological benefits for wheelchair users with spinal cord injuries.Using a robotic exoskeleton during initial rehabilitation may be well received and help with regaining strength, endurance, balance, and flexibility as well as promoting blood circulation and intestinal transit.The use of the wearable robotic exoskeleton always needs supervision of a clinician for walking and can’t be used independently by wheelchair users; there is no possibility for hands free for household tasks (e.g., washing floors, accessing cupboards or reaching shelves, using stairs), and for recreation (e.g., exercising, taking walks, cultural activities, concerts). [ABSTRACT FROM AUTHOR]

Abstract: Postural steadiness while standing is impaired in individuals with spinal cord injury (SCI) and could be potentially associated with increased reliance on visual inputs. The purpose of this study was to compare individuals with SCI and able-bodied participants on their use of visual inputs to maintain standing postural steadiness. Another aim was to quantify the association between visual contribution to achieve postural steadiness and a clinical balance scale. Individuals with SCI (n =15) and able-bodied controls (n =14) performed quasi-static stance, with eyes open or closed, on force plates for two 45s trials. Measurements of the centre of pressure (COP) included the mean value of the root mean square (RMS), mean COP velocity (MV) and COP sway area (SA). Individuals with SCI were also evaluated with the Mini-Balance Evaluation Systems Test (Mini BESTest), a clinical outcome measure of postural steadiness. Individuals with SCI were significantly less stable than able-bodied controls in both conditions. The Romberg ratios (eyes open/eyes closed) for COP MV and SA were significantly higher for individuals with SCI, indicating a higher contribution of visual inputs for postural steadiness in that population. Romberg ratios for RMS and SA were significantly associated with the Mini-BESTest. This study highlights the contribution of visual inputs in individuals with SCI when maintaining quasi-static standing posture. [Copyright &y& Elsevier]

The effects of lower limb (L/L) control options, developed for overground walking with a wearable robotic exoskeleton (WRE), on the neuromotor control of L/L muscles [i.e., muscle synergies (MSs)] during walking remain uncertain. To gain initial insights regarding the effects of different control options on the number of MSs at the L/L and on their muscle weighting within each MS when walking with a WRE. Twenty able-bodied adults walked overground without and with the WRE set at two control options with a predetermined foot pathway imposed by the WRE, and at three other control options with free L/L kinematics in the sagittal plane. Surface electromyography of eight right L/L muscles was recorded. MSs were extracted using a non-negative matrix factorisation algorithm. Cosine similarity and correlation coefficients characterised similarities between the MSs characteristics. Freely moving the L/L in the sagittal plane (i.e., non-trajectory controlled options) during WRE walking best duplicated typical MSs extracted when walking without WRE. Conversely, WRE walking while fully controlling the L/L trajectory presented the lowest correlations to all MSs extracted when walking without WRE, especially during early swing and L/L deceleration. Neuromotor control of L/L muscles is affected by the selected control option during WRE walking, particularly when a predetermined foot pathway is imposed. This exploratory study represents the first step in informing the decision-making process regarding the use of different L/L control options when using WRE and calls for further research among adults with sensorimotor impairments. [ABSTRACT FROM AUTHOR]

Background Many wheelchair users adopt a sedentary lifestyle, which results in progressive physical deconditioning with increased risk of musculoskeletal, cardiovascular and endocrine/metabolic morbidity and mortality. Engaging in a walking program with an overground robotic exoskeleton may be an effective strategy for mitigating these potential negative health consequences and optimizing fitness in this population. However, additional research is warranted to inform the development of adapted physical activity programs incorporating this technology. Objectives To determine cardiorespiratory demands during sitting, standing and overground walking with a robotic exoskeleton and to verify whether such overground walking results in at least moderate-intensity physical exercise. Methods We enrolled 13 long-term wheelchair users with complete motor spinal cord injury in a walking program with an overground robotic exoskeleton. Cardiorespiratory measures and rate of perceived exertion (RPE) were recorded by using a portable gas analyzer system during sitting, standing and four 10 m walking tasks with the robotic exoskeleton. Each participant also performed an arm crank ergometer test to determine maximal cardiorespiratory ability (i.e., peak heart rate and O 2 uptake [HR peak , VO 2peak ]). Results Cardiorespiratory measures increased by a range of 9%–35% from sitting to standing and further increased by 22%–52% from standing to walking with the robotic exoskeleton. During walking, median oxygen cost (O 2Walking ), relative HR (%HR peak ), relative O 2 consumption (%VO 2peak ) and respiratory exchange ratio (RER) reached 0.29 mL/kg/m, 82.9%, 41.8% and 0.9, respectively, whereas median RPE reached 3.2/10. O 2Walking was moderately influenced by total number of sessions and steps taken with the robotic exoskeleton since the start of the walking program. Conclusion Overground walking with the robotic exoskeleton over a short distance allowed wheelchair users to achieve a moderate-intensity level of exercise. Hence, an overground locomotor training program with a robotic exoskeleton may have cardiorespiratory health benefits in the population studied. [ABSTRACT FROM AUTHOR]

It is still unknown to what extent overground walking with a WRE is equivalent to natural overground walking without a WRE. Hence, the interpretability of the 10-m (10MWT) and six-minute (6MWT) walk tests during overground walking with a WRE against reference values collected during natural overground walking without a WRE is challenging. This study aimed to 1) compare walking performance across three different overground walking conditions: natural walking without a WRE, walking with a WRE providing minimal assistance (active walking), and walking with a WRE proving complete assistance (passive walking) and 2) assess the association and the agreement between the 10MWT and the 6MWT during passive and active walking with a WRE. Seventeen healthy individuals who underwent basic locomotor training with a WRE performed the 10MWT (preferred and maximal speeds) and the 6MWT under the three conditions. For the 10MWT, the speed progressively and significantly decreased from natural walking without a WRE (preferred: 1.40±0.18m/s; maximal: 2.16±0.19m/s), to active walking with a WRE (preferred: 0.48±0.10m/s; maximal: 0.61±0.14m/s), and to passive walking with a WRE (preferred: 0.38±0.09m/s; maximal: 0.42±0.10m/s). For the 6MWT, total distances decreased from walking without a WRE (609±53.9m), to active walking with a WRE (196.6±42.6m), and to passive walking with a WRE (144.3±33.3m). The 10MWT and 6MWT provide distinct information and can't be used interchangeably to document speed only during active walking with the WRE. Speed and distance drastically decrease during active and, even more so, passive walking with the WRE in comparison to walking without a WRE. Selection of walking tests should depend on the level of assistance provided by the WRE. [ABSTRACT FROM AUTHOR]

Changes in the number of muscles synergies (MSs) and in the weighting of muscles composing each MS are typically altered following an incomplete spinal cord injury (iSCI). To overcome this problem, locomotor training with a wearable robotic exoskeleton (WRE) represents a promising rehabilitation option though the effects of the various WRE control modes on MSs remain unknown. This case series aims to characterize how WRE control modes affect the number of MSs and the weighting of muscles composing each MSs in individuals with iSCI. Three participants with a chronic iSCI walked at a self-selected comfortable speed without and with a WRE set in different trajectory controlled (maximal assistance [MAX]; assistance-as-needed [ADAPT]) and non-trajectory controlled modes (high assistance [HASSIST], high resistance [HRESIST], and NEUTRAL). Recorded surface EMG of eight L/E muscles was used to extract the MSs using a non-negative matrix factorization algorithm. Cosine similarity and weighting relative differences characterized similarities between MSs of individuals with iSCI and against references obtained in a healthy control. The mode providing movement assistance within a self-selected L/E trajectory (HASSIST) best replicates MSs observed in healthy control during overground walking. The MSs extracted with the passive (MAX) and assistance-as-needed (ADAPT) modes differed to the greatest extent from MSs characteristics extracted from a healthy reference. Most of the control modes selected during overground walking with a WRE did not closely replicate the motor control required for the production of coordinated L/E movements during stereotypical overground walking. These first results may allow rehabilitation professionals to refine WRE locomotor training protocols. [ABSTRACT FROM AUTHOR]