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Summary Background 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. Objective 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. Methods 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. Results 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. Conclusion Neuromotor control of L/L muscles is affected by the selected control option during WRE walking, particularly when a predetermined foot pathway is imposed. Significance 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.

Introduction Safe and efficient use of a manual wheelchair (MWC) requires appropriate training. New MWC users should learn how to maneuver in different environments (restricted spaces, uneven surfaces, etc.). Learning of appropriate balance skills is also crucial, to avoid falls when handling forward or side slopes. Moreover, long-term MWC use can lead to repetitive shoulder strain injuries, which can be avoided through adequate propulsion technique (increasing push amplitude, while decreasing cadence). We have developed a virtual reality MWC simulator for the training of MWC skills. The velocities of the rear wheels control a virtual MWC in a 3D scene presented on a computer screen in front of the participant, while force feedback simulates the effects of gravity and inertia. Our objective was to improve the realism of our existing wheelchair simulator, through the addition of upper body motion tracking that will provide feedback on trunk posture and propulsion movement. Material and methods Ten MWC users participated in the study. They propelled the virtual MWC while their trunk and arm movements were simultaneously recorded by three systems: – five inertial sensors placed on the trunk, arms and forearms; – a markerless, 3D depth camera system; – a high-precision motion capture system (gold standard). Upper body position as measured by the two low-cost approaches (inertial system and depth camera) was compared to the motion capture system. Results and conclusion Findings from this interdisciplinary study will optimize mobility of MWC users, through better MWC skills (balance and propulsion techniques), while possibly decreasing the incidence of falls and shoulder injuries.

Introduction Les modeles actuels de propulsion en fauteuil roulant manuel (FRM) considerent exclusivement les forces appliquees sur les mains courantes. Or, il est possible de diriger le FRM uniquement avec les mouvements du tronc et des membres superieurs (MS). Afin de comprendre l’effet de ces mouvements, les profils d’angle de ces articulations ont ete mesures lors d’une manœuvre d’evitement au basket-ball en fauteuil roulant (BFR). Materiel et methodes Neuf athletes de BFR, âges de 30 ± 5 ans, se dirigeaient a vitesse maximale vers un cone a 6 m et l’evitaient par la droite sans toucher aux mains courantes du FRM. Quatorze cameras optoelectroniques ont mesure la position de l’athlete et son FRM, permettant de calculer les valeurs d’angles du tronc et des MSs. Resultats Les participants ont modifie leur posture a une distance de 1,10 m ± 0,47 et a un temps de 0,47 s ± 0,20 avant l’obstacle. Une variation des angles articulaires decrite par une inclinaison laterale droite de 18,63° ± 8,41 et une torsion antihoraire de 43,79° ± 14,41 ont ete observees par anticipation a l’evitement, ainsi qu’une elevation a l’epaule droite de 56,96° ± 17,38. Aucune inclinaison sagittale du tronc n’a ete observee (−0,86° ± 3,20). Discussion/Conclusion Le mouvement du tronc et des MSs modifient le comportement de la propulsion en FRM en induisant une rotation du FRM et une augmentation du moment d’inertie, soulignant l’importance du controle de ces articulations pour modifier la trajectoire du FRM. De meilleures connaissances des interactions entre l’athlete et son fauteuil aideront a mieux adapter l’enseignement des techniques de propulsion.

Study design Case series. Background Changes in the number of muscle synergies (MSs) and in the weighting of muscles composing each MS are typically altered following an incomplete spinal cord injury (iSCI). Wearable robotic exoskeletons (WRE) represent a promising rehabilitation option, though the effects of various WRE control modes on MSs still remain unknown. Objective This case series characterizes how WRE control modes affect the number of MSs and the weighting of muscles composing each MS in individuals with iSCI. Setting Pathokinesioly laboratory of a rehabilitation research center. Methods Three participants with a chronic iSCI walked at a self-selected comfortable speed without and with a WRE set in two trajectory-controlled (Total Assistance, TOT; Assistance-as-Needed, ADAPT) and three non-trajectory controlled modes (High Assistance, HASSIST; High Resistance, HRESIST; NEUTRAL). Surface EMG of eight lower extremity (L/E) muscles was recorded and used to extract MSs using a nonnegative matrix factorization algorithm. Cosine similarity and weighting relative differences characterized similarities in MSs between individuals with iSCI and able-bodied controls. Results The mode providing movement assistance within a self-selected L/E trajectory (HASSIST) best replicated MSs in able-bodied controls during overground walking. MSs extracted with the trajectory-controlled modes differed to the greatest extent from able-bodied group MSs. Conclusions Most WRE control modes did not replicate the motor control required for typical L/E muscle coordination during stereotypical overground walking. These results highlight the need to gain a better understanding of the effects of various control modes on L/E motor control for rehabilitation professionals to incorporate research evidence when selecting WRE control mode(s) during WRE locomotor interventions.

La majorite des personnes touchee par un accident vasculaire cerebral ou une lesion de la moelle epiniere doit composer avec des deficiences sensorimotrices qui, malgre la readaptation fonctionnelle intensive, perturbent leur capacite locomotrice. D’une part, certaines personnes ne retrouveront aucune capacite de marche et utiliseront un fauteuil roulant manuel ou motorise a long terme comme principal mode de mobilite. D’autre part, certaines personnes recupereront une capacite de marche restreinte avec un patron de marche atypique et asymetrique, une vitesse de marche restreinte ou une endurance diminuee. Pour ces raisons, un des objectifs de readaptation les plus formules par ces personnes est de recuperer la capacite de marche. Parmi les approches therapeutiques disponibles pour cibler cet objectif, les exosquelettes robotises de marche (EXROM) sont des technologies actuellement en emergence en readaptation et en activite physique adaptee. Les EXORM produisent generalement une assistance motorisee aux membres inferieurs (MI) afin de generer des mouvements de marche. Lors de la marche, les membres superieurs (MS), en contact avec le sol via l’utilisation d’un aide technique, doivent concilier deux roles : – supporter et transferer le poids du corps et de l’EXORM vers le MI demeurant en appui au sol ; – controler l’equilibre debout afin d’eviter les chutes, particulierement lors du debut de la prise du pas avec l’autre MI. L’execution simultanee de ces tâches engendre aussi une concurrence pour les ressources attentionnelles. Somme toute, la marche reciproque et continue avec un EXORM repose grandement sur les systemes musculosquelettiques, postural et cognitif. Etonnamment, ces systemes fondamentaux et leurs interactions lors de la marche avec un EXORM n’ont pratiquement pas ete etudies. Ainsi, nous restons avec une comprehension fragmentee des determinants et predicateurs qui influencent les performances lors de l’utilisation de cette technologie. Nous demeurons egalement avec une meconnaissance des facteurs a considerer pour le developpement de programmes d’entrainement locomoteur avec l’EXORM fonde sur des preuves. Cette conference resumera des travaux de recherche elabores par notre equipe qui vise a : – quantifier les exigences musculaires, posturales, et cognitives lors des transferts assis-debout, du maintien de la position debout et de la marche au sol avec l’utilisation d’un EXORM ; – developper et tester des programmes d’entrainement locomoteur innovants concus pour optimiser la capacite locomotrice et minimiser les effets nefastes de la sedentarite.