Reducing the energy cost of hemiparetic gait using center of mass feedback: a pilot study.

BACKGROUND: Hemiparetic gait following stroke requires substantial energy consumption, which would promote deconditioning and disability. Optimal modalities for decreasing this energy cost remain challenging. Excessive energy consumption, however, seems to be mainly due to extra positive muscle work to substantially lift the body's center of mass (CM) against gravity during the paretic limb swing.

OBJECTIVE: The authors tested a new rehabilitation strategy in a pilot study to specifically reduce the energy cost in hemiparetic gait.

METHODS: Six chronic hemiparetic patients underwent a 6-week gait training program on a treadmill with real-time feedback of their CM and were asked to reduce its increased vertical displacement. The authors assessed the walking energy cost, vertical CM displacement, kinematics, and electromyogram activity without feedback before and after treatment.

RESULTS: After treatment, the vertical CM displacement decreased by 10% (P = .005), particularly when the CM vaulted over the nonparetic limb in stance, and the energy cost decreased markedly by 30% (P = .009). The paretic knee flexion in swing increased concomitantly by 45% and muscle co-contraction decreased significantly in both thigh muscles by 15%.

CONCLUSIONS: The rehabilitation approach followed in this study seems remarkably effective in decreasing the walking energy cost. By treating the compensatory strategy (ie, the increased CM displacement), we also appear to treat primary deviations such as poststroke knee impairments, which is novel and complementary to current concepts in rehabilitation. This new approach is promising and merits further investigation.