Evaluation of the effects of the Arm Light Exoskeleton on movement execution and muscle activities: a pilot study on healthy subjects

Abstract

BackgroundExoskeletons for lower and upper extremities have been introduced in neurorehabilitation because they can guide the patient’s limb following its anatomy, covering many degrees of freedom and most of its natural workspace, and allowing the control of the articular joints. The aims of this study were to evaluate the possible use of a novel exoskeleton, the Arm Light Exoskeleton (ALEx), for robot-aided neurorehabilitation and to investigate the effects of some rehabilitative strategies adopted in robot-assisted training.MethodsWe studied movement execution and muscle activities of 16 upper limb muscles in six healthy subjects, focusing on end-effector and joint kinematics, muscle synergies, and spinal maps. The subjects performed three dimensional point-to-point reaching movements, without and with the exoskeleton in different assistive modalities and control strategies.ResultsThe results showed that ALEx supported the upper limb in all modalities and control strategies: it reduced the muscular activity of the shoulder’s abductors and it increased the activity of the elbow flexors. The different assistive modalities favored kinematics and muscle coordination similar to natural movements, but the muscle activity during the movements assisted by the exoskeleton was reduced with respect to the movements actively performed by the subjects. Moreover, natural trajectories recorded from the movements actively performed by the subjects seemed to promote an activity of muscles and spinal circuitries more similar to the natural one.ConclusionsThe preliminary analysis on healthy subjects supported the use of ALEx for post-stroke upper limb robotic assisted rehabilitation, and it provided clues on the effects of different rehabilitative strategies on movement and muscle coordination.

Spatiotemporal Maps of Proprioceptive Inputs to the Cervical Spinal Cord During Three-Dimensional Reaching and Grasping

“…Finally, rostral segments are again activated but with a lower amplitude during the pulling phase. These results are in agreement with experimental findings in human subjects performing a similar task [44].…”

Model-based variables for the kinematic assessment of upper-extremity impairments in post-stroke patients

“…Indeed, patients with more severe functional damages most often require robot assistance to accomplish the task [39]. Future works are recommended to address this issue, and to extend the model to other volitional arm movements and assistive devices, such as exoskeletons [40–43]. Indeed, exoskeletons offer several advantages over planar manipulandum because they enlarge the task space to three dimensions following the arm in its natural workspace with no restrictions [44].…”

Motor improvement estimation and task adaptation for personalized robot-aided therapy: a feasibility study

“…We first experimentally validated our model in a group of 17 healthy participants. Using the robotic upper limb exoskeleton ALEx [39, 40], we designed a three-dimensional point-to-point reaching task (Fig. 1a-b), a training exercise commonly used in robotic rehabilitation therapy [41–43].…”

“…Using the robotic upper limb exoskeleton ALEx [39, 40], we designed a three-dimensional point-to-point reaching task, a training exercise commonly used in robotic rehabilitation therapy [41–43]. The movement amplitude was selected to allow the exploration of a functional workspace, while movement directions were chosen to elicit independent and synergistic motion of shoulder and elbow, capitalizing on the advantages provided by robotic exoskeleton devices [51].…”

“…We implemented the motor improvement model and the personalization routine in the robotic upper-limb exoskeleton ALEx [39, 40]. During the experiments, the patient and the healthy participants were instructed to perform point-to-point reaching movements at their comfortable speed (Fig.…”