Amplify Gait to Improve Locomotor Engagement in Spinal Cord Injury (AGILE SCI Trial)

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Background: Among ambulatory individuals with incomplete spinal cord injury (iSCI), residual balance deficits are common and are a primary factor limiting participation in walking activities. There is broad recognition that effective evidence-based interventions are needed to enhance dynamic balance following iSCI. However, improving dynamic balance after iSCI has proven to be very challenging. Experimental interventions that amplify self-generated movements (e.g. error augmentation) may accelerate motor learning by intensifying sensory- motor feedback and facilitating exploration of alternative motor control strategies. These features may be beneficial for retraining dynamic balance after iSCI. We have developed a cable-driven robot to create a movement amplification environment during treadmill walking by applying a continuous viscous force field to the pelvis that is proportional in magnitude to a participant’s real-time COM velocity. Our purpose is to investigate if locomotor training performed in a movement amplification environment can effectively improve dynamic balance and increase participation in walking activities of individuals with iSCI. Specific Aims: Aim 1: To evaluate if locomotor training performed in a movement amplification environment is effective for improving dynamic balance of individuals with iSCI. Our pilot data found that following locomotor training performed in a movement amplification environment three individuals with iSCI each improved dynamic balance by more than 30%. These improvements were accompanied by faster over ground walking speeds and improved reactive balance. Thus, we hypothesize that improvements in dynamic balance during walking will be greater when locomotor training is performed in a movement amplification environment when compared to locomotor training performed in a traditional treadmill environment. Aim 2: To evaluate the impact of locomotor training performed in either a movement amplification environment or in a traditional treadmill environment on participation in walking activities. Based on evidence identifying a strong relationship between balance and steps per day in ambulatory individuals with iSCI, we hypothesize that training in the movement amplification environment will positively impact dynamic balance, and in turn increase participating in walking activities. Approach: We will conduct a two-arm parallel-assignment intervention. We will enroll 36 ambulatory participants with chronic motor incomplete spinal cord injury. Participants will be randomized into either a Control group receiving locomotor training or an Experimental group receiving locomotor training performed in a movement amplification environment. All participants will receive 20 training sessions. We will assess changes in dynamic balance using measures that span the International Classification of Functioning, Disability and Health (ICF) framework including; 1) clinical outcome measures of gait, balance, and quality of life, 2) biomechanical assessments of the capacity to control COM motion during walking, and 3) data collected from activity monitors to quantify changes in participation in walking activities as evaluated by number of steps taken per day. Impact: Training dynamic balance of individuals with iSCI by amplifying their own self-generated center of mass motion during walking is a radical departure from current practice and may create effective new clinical strategies for addressing balance impairments of individuals with iSCI. Successful outcomes from the proposed trial would motivate development of clinically-feasible tools to first replicate and then to evaluate the movement amplification environment within the VA’s clinical care settings. Knowledge gained from this study will expand our understanding of how individuals with iSCI learn dynamic balance and how targeted dynamic balance training impacts participation in walking activities.