Lichy A, Hidler J, Cisper J, and Wall A; National Rehabilitation Hospital,Washington, DC. alisonlichy@hotmail.com.

PURPOSE: The goal of this study was to determine whether robotic-assisted walking alters natural muscle activation patterns, and to determine whether observed changes in EMGs are influenced by walking speed. BACKGROUND: Over the last ten years, there has been research showing patients with incomplete spinal cord injuries who receive body-weight supported treadmill therapy make significantly higher gains in motor function and walking ability than those who receive more traditional physiotherapy (Vistin and Barbeau,1989,1994, Wernig and Muller, 1992, 1999). A bi-lateral "robotic" orthosis called the Lokomat has been developed (Hocoma, inc., Zurich, Switzerland) to overcome the limitations associated with manual-assisted gait training. However, the necessary restrictions on gait patterns dictated by the robot may affect natural muscle activation patterns with normal gait function. METHODS: Seven, non-neurologically impaired individuals walked on a treadmill and within the Lokomat at four different walking speeds (1.5-2.7 km/hr), while muscle activity was collected from the gastrocnemius, tibialis anterior, rectus femoris, vastus lateralis, adductor longus, hamstrings, gluteus medius, and gluteus maximus. Electo-goniometers were used to track hip and knee angles while foot-switches were used to detect heel strike onset. ANALYSIS: A multi-factor ANOVA was used to compare muscle activation patterns exhibited during treadmill ambulation with those observed during Lokomat walking over the gait cycle RESULTS: Significant differences in muscle activation levels were found between Lokomat and treadmill ambulation throughout the gait cycle for various muscles (p < 0.05). This included both over-activity and under-activity during robotic-assisted gait training, depending on the muscle and phase of the gait cycle. For the range of speeds tested, there were no significant effects in muscle activity. CONCLUSION: Our findings suggest that robotic-assisted gait training does influence naturally occurring muscle activation patterns, however the extent of these differences various across the gait cycle and from muscle to muscle. Presumably these differences are due to restrictions in leg and trunk movement during gait. These restrictions by the robot are areas for further research to determine if alterations could provide more natural muscle activation patterns. FUNDING SOURCE: National Rehabilitation Hospital.

Copyright 2004 by the American Physical Therapy Association

Reprint Information
Requests for reprints should be directed to the corresponding author of the article. Students and other academic customers may receive permission to reprint copyrighted material from Physical Therapy by contacting the Copyright Clearance Center Inc, 222 Rosewood Dr, Danvers, MA 01923. Similar inquiries by all others should be made to the APTA Editorial Office, Attn: Physical Therapy.