Cognitive performance during gait is worsened by overground but enhanced by treadmill walking

Purpose: Walking is an attention-demanding task that affects and is affected by cognitive performance. Since treadmill walking (TW) assists gait automaticity, we have hypothesized that TW affects cognitive performance to a smaller extent than overground walking (OW). Methods: Thirty young adults were recruited. Each subject walked overground over a 20-meter straight hallway at three different speeds (slow, normal and fast). Each task was repeated 3 times under Single Task (OW-ST) and Dual Task (OW-DT) condition, in a randomized sequence. DT was a serial subtraction by 7 starting from a different number (> 100) in each trial. Afterwards, each subject walked on the treadmill at the same three speeds as during OW-ST, while performing the dual task (TW-DT). The correct cognitive response (CCR), calculated from the number of correct responses and mistakes, was compared between rest, OW-DT and TW-DT. Dual-task cost (DTC) was calculated for speed and for CCR. Results: Backward counting diminished normal and fast OW-DT speed by about 15 %. Slow OW-DT speed was not significantly reduced. In turn, OW affected the cognitive performance. DTC for speed during OW-DT increased during normal and fast speed. CCR significantly decreased, more at slower OW-DT speed. Conversely, CCR was not worsened by TW-DT. CCR did not decline at slow TW-DT speed and improved significantly from slow and normal to fast speeds. DTC for CCR resulted smaller in TW-DT than OW-DT. Conclusions: Decline in the cognitive performance during OW-DT is more prominent at slow speed, in keeping with higher demand of attentional resources for this unusual locomotor behaviour. Conversely, motorized TW improves the cognitive performance likely because it reduces the attentional cost of walking. Gait training by TW might improve automaticity in patients with movement disorders.