Fast walking under cognitive-motor interference conditions in chronic stroke.

Gait in stroke patients is often characterised by slower speeds, which may be exacerbated by situations that combine gait with a cognitive task, leading to difficulties with everyday activities. Interaction between cognitive task performance and gait speed may differ according to walking intensity. This study examines the effects of two cognitive tasks on gait at preferred walking pace, and at a faster pace, using dual-task methodology. 21 chronic stroke patients and 10 age-matched control subjects performed 2 single motor tasks (walking at preferred and at fast pace around a walkway), and two cognitive tasks (serial subtractions of 3s and a visual-spatial decision task) under single- and dual-task conditions (cognitive-motor interference) in a randomised order. Cognitive task score and gait speed were measured. The healthy control group showed no effects of CMI. The stroke group decreased their walking speed whilst concurrently performing serial 3s during both preferred and fast walking trials and made more mistakes in the visuo-spatial task during fast walking. There was no effect of walking on the serial 3 performance. The findings show that in stroke patients, during walking whilst concurrently counting backwards in 3s the cognitive task appeared to take priority over maintenance of walking speed. During fast walking whilst concurrently performing a visuo-spatial imagery task, they appeared to favour walking. This may indicate that people spontaneously favour one activity over the other, which has implications for gait rehabilitation.