Motor Adaptation to Weight Shifting Assistance Transfers to Overground Walking in People with Spinal Cord Injury

BACKGROUND: Locomotor training has been used to improve walking function in people with incomplete spinal cord injury (iSCI), but functional gains are relatively small for some patients, which may be due to the lack of weight shifting training. OBJECTIVE: To determine whether applying a pelvis assistance force in the coronal plane during walking would improve weight shifting and stepping in people with iSCI. DESIGN: Repeated measures study. SETTING: Rehabilitation hospital. PARTICIPANTS: Seventeen people with iSCI. INTERVENTIONS: A controlled assistance force was bilaterally applied to the pelvis in the medial-lateral direction to facilitate weight shifting, which gradually increased during the course of treadmill walking. MAIN OUTCOME MEASURES: Weight shifting, step length, margin of stability, and muscle activities of the weaker leg were used to quantify gait performance. The spatial-temporal gait parameters during overground walking were collected pre, post, and 10 minutes after treadmill training. RESULTS: During treadmill walking, participants significantly improved weight shifting (ie, center of mass [CoM] lateral distance reduced from 0.16 ± 0.06 m to 0.12 ± 0.07 m, P = .012), and increased step length (from 0.35 ± 0.08 m to 0.37 ± 0.09 m, P = .037) on the stronger side when the force was applied, which were partially retained (ie, CoM distance was 0.14 ± 0.06, P = .019, and step length was 0.37 ± 0.09 m, P = .005) during the late postadaptation period when the force was removed. In addition, weight shifting and step length on the weaker side during overground walking also improved (support base reduced from 0.13 ± 0.06 m to 0.12 ± 0.06 m, P = .042, and step length increased from 0.48 ± 0.12 m to 0.51 ± 0.09 m, P = .045) after treadmill training. CONCLUSIONS: Applying pelvis assistance during treadmill walking may facilitate weight shifting and improve step length in people with SCI, which may partially transfer to overground walking. LEVEL OF EVIDENCE: III.