Distance-related changes in gait parameters during uneven-surface walking in people with stroke versus healthy...

People with Stroke (PwS) struggle with walking outdoors, especially on uneven surfaces, which limits their social participation. Distance-related changes on uneven surfaces remain unclear. We compared these changes between PwS and healthy controls (HC).

Nineteen PwS and 19 HC walked four laps on a 10-m uneven surface. Gait speed, root mean square of trunk acceleration (stability), maximum joint angles, electromyography (EMG) amplitude, and instantaneous mean frequency (IMNF) were measured. Linear mixed models were used to compare gait-parameter changes across laps.

No group × lap interaction was detected for gait speed, stability, stance-phase hip extension, or swing-phase knee flexion. An interaction was observed for ankle dorsiflexion during initial contact (p = 0.036; decreased across laps in PwS). For EMG amplitude, tibialis anterior during initial contact showed an interaction (p = 0.036; increased only in HC). Regarding IMNF, gluteus medius showed a group main effect during mid-stance (p < 0.001; higher in PwS) and an interaction during terminal stance (p = 0.036; decreased only in PwS); during mid-swing, group main effects were observed for rectus femoris (p = 0.044), biceps femoris (p = 0.011), and gluteus medius (p = 0.023), with higher IMNF in PwS.

PwS maintained gait speed and stability, increasing distances on uneven surfaces, showing adaptations comparable to HC. PwS did not sufficiently augment tibialis anterior amplitude, accompanied by reduced ankle dorsiflexion and limited shock absorption. Elevated IMNF indicates greater motor-unit recruitment contributing to the maintenance of joint angles, whereas gluteus medius IMNF declined during terminal stance, suggesting fatigue. Overall, adaptation was present but limited, with a risk of fatigue.