Trunk muscle activation patterns during walking with robotic exoskeletons in people with high thoracic motor-complete spinal cord injury

• Main Author: Alamro, Raid
• Language: English
• Published: University of British Columbia 2017
• Online Access: http://hdl.handle.net/2429/61270

Background: Maintaining postural stability during sitting or standing depends critically on motor function in the trunk muscles. Trunk muscle function is typically assumed to be poor or absent in people with a complete spinal cord injury (SCI) at or above the thoracic level. However, recent studies have revealed sparing of trunk muscle function in people with high-thoracic motor-complete SCI, opening up the possibility for training techniques to improve their function. The Lokomat and Ekso are used in gait rehabilitation for people with SCI, but it remains unknown how much they engage those trunk muscles that are normally activated during walking. These devices provide gait training in different methods. In Lokomat, the trunk is rigidly and passively supported by a body weight support harness, which could imply lesser recruitment of postural muscles. In contrast, the Ekso requires continuous weight shifting from one limb to the other to trigger steps, which could lead to better postural muscle activation. Objective: To compare trunk muscle activation patterns during Ekso- vs Lokomat-assisted walking in people with high-thoracic motor-complete SCI. Methods: 8 individual with C7-T4 chronic motor-complete SCI were recruited. Subjects performed 3 walking conditions (at matched speeds): Lokomat-assisted walking (Loko-TM), Ekso-assisted walking on treadmill (Ekso-TM), and Ekso-assisted walking overground (Ekso-OG). Surface electromyography (EMG) signals were recorded bilaterally from rectus abdominis (RA), external oblique (EO), and erector spinae (ES) and normalized to (attempted) maximum voluntary contraction (MVC). EMG amplitudes were compared during baseline (lying supine) (BAS) and across the 3 walking conditions. EMG onset and total activity times were compared across the 3 walking conditions. Results: Trunk EMG amplitudes were significantly higher in Ekso-TM compared to both Loko-TM and BAS. RA and ES amplitudes were not different during Loko-TM walking compared to BAS. When Ekso-OG was compared to Ekso-TM, only ES amplitude was significantly different. Onset and total activity times were not significantly different across the walking conditions Conclusion: Ekso-assisted walking was better in activating trunk muscles than the Lokomat-assisted walking. These results suggest that Ekso could possibly be used to train trunk strength and improve sitting postural control in people with high-thoracic motor-complete SCI. === Education, Faculty of === Kinesiology, School of === Graduate