Characteristics of uneven surface walking in stroke patients: Modification in biomechanical parameters and muscle activity.

Background: Stroke patients have difficulty walking in outdoor environments, including uneven surfaces, reducing their opportunities for social participation. Changes in stroke patients' gait while walking on even surfaces have been reported; however, gait alterations on uneven surfaces remain unclear.

Research Question: To what extent do biomechanical parameters and muscle activity during even and uneven surface walking differ between stroke patients and healthy people?

Methods: Twenty stroke patients and 20 age-matched healthy people walked on a 6 m even and uneven surfaces. Data on gait speed, root mean square (RMS) of trunk acceleration as a measure of gait stability, maximum joint angle, average muscle activity, and muscle activity time were quantified using accelerometers attached to the trunk, video camera images, and electromyography of lower extremities. A two-factor mixed-model analysis of variance was used to test the effects of group, surface, and group × surface interactions.

Results: Gait speed decreased (p < 0.001) on the uneven surface in stroke patients and healthy people. RMS showed an interaction (p < 0.001), and the post-hoc test revealed an increase in stroke patients in the mediolateral direction during the swing phase on the uneven surface. The hip extension angle during the stance phase showed an interaction (p = 0.023), and the post-hoc test revealed a decrease in stroke patients on the uneven surface. The soleus muscle activity time showed an interaction during the swing phase (p = 0.041), and the post-hoc test revealed an increase in stroke patients compared to healthy people only on the uneven surface.

Significance: While walking on an uneven surface, stroke patients showed decreased gait stability, decreased hip extension angle during stance phase, and increased ankle plantar flexor activity time during swing phase. These changes may result from impaired motor control and compensatory strategies used by stroke patients on uneven surfaces.