The increasing use of robotic devices in clinical settings for rehabilitation and assistance underscores the need to understand their effects on muscle activation patterns. Prior studies have suggested that excessive assistance from robotic devices reduces voluntary control, leading to potential negative consequences on rehabilitation outcomes. However, the observation of muscle activation during exoskeleton-assisted walking in unimpaired individuals suggests the absence of adaptive responses to short-term exposure at high levels of assistance. The objective of this study is to determine whether prolonged exposure to maximum exoskeleton assistance induces adaptive changes in muscle activity and to analyze if distinct muscle activation profiles emerged during assisted versus unassisted walking. To achieve this, we performed the electromyographic analysis of eight bilateral lower limb muscles in ten participants during a one-hour training session. The results revealed a decrease in muscle activity over time. Furthermore, assisted walking exhibited distinct muscle patterns compared to unassisted walking, demonstrating that the level of assistance, along with the exoskeleton’s structure, significantly influences muscle activity. These findings hold significance for optimizing assistance regulation in exoskeleton-assisted walking, in terms of levels and timing of assistance changes, to enhance rehabilitative outcomes. Understanding how exoskeletons influence muscle activation can lead to improved rehabilitation strategies, maximizing the benefits of this technology for enhancing walking ability in people with neurological conditions or injuries.

Spinal cord injury (SCI) profoundly affects motor–sensory functions, reducing mobility and quality of life. Robotic exoskeletons offer a promising solution to support gait training, improve mobility, and prevent secondary complications. Existing research predominantly focuses on complete SCI, with limited exploration of long-term effects and tailored training for incomplete SCI. This study investigates device-based outcomes of personalized exoskeleton gait training in 33 individuals with incomplete SCI, with different lesion levels: cervical, thoracic, and lumbar. Participants underwent up to 39 sessions of gait training with a commercially available lower limb exoskeleton. Session parameters, including duration, intensity, and modality, were tailored to each individual’s clinical needs as determined by a medical team. Analysis focused on endurance, performance on the device, and patient-reported outcomes related to walking fluidity, safety, and satisfaction. Results showed overall improvement in endurance and performance, with the most significant gains observed in participants with thoracic-level injuries. All participants reported increased perceived safety, walking fluidity, and high satisfaction with the training. These findings support the potential of personalized exoskeleton training to enhance outcomes and experiences for individuals with incomplete SCI. The difference in improvement between lesion levels highlights the need for customized approaches to address the diverse clinical conditions within this population.

Objective. Body-machine interfaces (BoMIs) translate human body movements into commands for controlling external devices, such as computer cursors. This process allows researchers to study the development and refinement of inverse models, which generate motor commands necessary for achieving desired movements. Traditionally, motor learning has focused on solo practice, but recent research has shifted towards exploring dyadic tasks, where two individuals practice together. Within dyadic tasks, synergic practice—where partners collaborate toward a shared goal—has shown promise in enhancing performance and reducing stress. However, the impact of contributions of each partner within synergic practice on individual and collective learning remains underexplored. This study aims to (i) investigate how different levels of contribution during synergic practice affect both individual and collective motor learning, and (ii) assess the impact of these contribution levels on individual performance when returning to solo practice. Approach. Forty naïve participants underwent individual practice, dyadic synergic practice, and a final round of individual practice using a BoMI to control a cursor. Participants were classified as high or low contributors based on their participation in the cursor trajectory during dyadic practice. We analyzed how these contribution levels influenced performance, motor strategies, and internal models during and after the dyadic phase. Main results. During dyadic practice, high contributors maintained motor strategies similar to their initial solo performance, while low contributors showed significant deviations. After returning to solo practice, high contributors retained better task performance, whereas low contributors initially regressed but quickly improved with additional practice, eventually matching high contributors’ performance levels. Significance. This understanding holds practical implications for optimizing dyadic practice. Our study sheds light on the influence of synergic practice on subsequent individual motor performance, contributing to a clearer understanding of its advantages and limitations for optimal implementation.

Cervical spinal cord injury (cSCI) often results in bilateral impairment of the arms, leading to difficulties in performing daily activities. However, little is known about the neuromotor alterations that affect the ability of individuals with cSCI to perform coordinated movements with both arms. To address this issue, we developed and tested a functional assessment that integrates clinical, kinematic, and muscle activity measures, including the evaluation of bilateral arm movements. Twelve subjects with a C5-C7 spinal lesion and six unimpaired subjects underwent an evaluation that included three tests: the Manual Muscle Test, Range Of Motion test and Arm stabilisation test, a subsection of the 'Van Lieshout arm/hand function test'. During the latter, we recorded kinematic and muscle activity data from the upper-body during the execution of a set of movements that required participants to stabilize both arms against gravity at different configurations. Analytical methods, including muscle synergies, spinal maps, and Principal Component Analysis, were used to analyse the data. Clinical tests detected limitations in shoulder abduction-flexion of cSCI participants and alterations in elbows-wrists motor function. The instrumented assessment provided insight into how these limitations impacted the ability of cSCI participants to perform bilateral movements. They exhibited severe difficulty in performing movements involving over-the-shoulder motion and shoulder internal rotation due to altered patterns of activity of the scapular stabilizer muscles, latissimus dorsi, pectoralis, and triceps. Our findings shed light on the bilateral neuromotor changes that occur post-cSCI addressing not only motor deficits, but also the underlying abnormal, weak, or silent muscle activations.

Background and objective: Independent living and transportation are crucial aspects for people living with a disability. After an injury, it is important to assess driving ability, in terms of physical and psychological conditions, and to test the effects of prescribed drugs. Within this framework, driving simulators are suitable tools for training driving skills; however, available tools are expensive or lack appropriate sets of behavioral measures to fully characterize the drivers’ ability. Methods: This work presents the first step toward the development of ADRIS, a new open-source, accessible, realistic virtual reality simulator for training and testing driving skills of people with sensory-motor disability. This includes a prototype based on an open-source simulator for autonomous driving research (CARLA), with the addition of customized features such as adaptable driving controllers, a virtual reality headset, and the possibility to collect behavioral and physiological data. Also, the new system allows to set different environmental conditions, to include and control the timing of potentially dangerous situations, and to set scenarios with various difficulty levels. Results: Tests on 17 healthy participants demonstrated that the simulator is well tolerated in terms of discomfort, physical fatigue, and mental effort. Also, the system is easy to use and is capable of providing a realistic driving experience, allowing the extraction of reliable behavioral parameters. Conclusions: ADRIS combines a high-fidelity virtual world, with customizable features specifically designed for the training and testing of people living with a disability, thus making it usable in many contexts such as home training, rehabilitation, education, and research.

Several exoskeletons have been developed and increasingly used in clinical settings for training and assisting locomotion. These devices allow people with severe motor deficits to regain mobility and sustain intense and repetitive gait training. However, three factors might affect normal muscle activations during walking: the assistive forces that are provided during walking, the crutches or walker that are always used in combination with the device, and the mechanical structure of the device itself. To investigate these effects, we evaluated eight healthy volunteers walking with the Ekso, which is a battery-powered, wearable exoskeleton. They walked supported by either crutches or a walker under five different assistance modalities: bilateral maximum assistance, no assistance, bilateral adaptive assistance, and unilateral adaptive assistance on each leg. Participants also walked overground without the exoskeleton. Surface electromyography was recorded bilaterally, and the statistical parametric mapping approach and muscle synergies analysis were used to investigate differences in muscular activity across different walking conditions. The lower limb muscle activations while walking with the Ekso were not influenced by the use of crutches or walker aids. Compared to normal walking without robotic assistance, the Ekso reduced the amplitude of activation for the distal lower limb muscles while changing the timing for the others. This depended mainly on the structure of the device, and not on the type or level of assistance. In fact, the presence of assistance did not change the timing of the muscle activations, but instead mainly had the effect of increasing the level of activation of the proximal lower limb muscles. Surprisingly, we found no significant changes in the adaptive control with respect to a maximal fixed assistance that did not account for subjects' performance. These are important effects to take into careful considerations in clinics where these devices are used for gait rehabilitation in people with neurological diseases.