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A variety of robotic exoskeletons have been developed for patients with spinal cord injuries. However, the optimal training method and period for using a robotic exoskeleton have been uncertain until now.

The purpose of this study is to determine the minimum training period for using a robotic exoskeleton with minimal muscle activity by investigating the changes in muscle activity and muscle characteristics of healthy adults during robotic exoskeleton training.

A total of 16 people participated in the study. The robotic exoskeleton locomotion training consisted of three 50-min sessions a week for 7 weeks. The assessment consisted of sitting, standing, wide standing, sit-to-stand, and stand-to-sit where muscle activity and muscle characteristics were measured during each motion. All measurements were performed in the first session and every five sessions.

Participants showed decreased muscle activity up to 10 sessions of training in the standing position, and 15 sessions in sit-to-stand and stand-to-sit motions. Upper extremity muscles showed decreased muscle activity, tone, stiffness, and logarithmic decrement up to the 15th session.

The study results show that at least 15 training sessions are required to use the robotic exoskeleton with minimal load on the musculoskeletal system, and longer training is required for patients with spinal cord injury.

Keywords: exoskeleton device; robotics; physical functional performance; locomotion; orthosis

We trained healthy adults to conduct functional movements using the robotic exoskeleton 3 times a week for 50 min for 7 weeks and found that at least 15 training sessions were required for the subject to use the robot with minimal muscle activity. Therefore, we suggest that patients with SCI or other nervous system damage with lower physical functions compared to healthy people need at least 15 training sessions to minimize the burden on the musculoskeletal system when performing gait and functional movements using the robotic exoskeleton.