Motor inhibition during voluntary gait initiation in young and older adults.

Based on a novel approach, this study explores feasibility and relevance of an inhibition task for studying age-related differences in motor inhibition during gait initiation. When presented with a go-signal, young adults (YA, n = 24) and older adults (OA, n = 55) were required to promptly initiate gait. Participants completed 3 blocks of 12 gait trials. Each block contained 3 stop trials in which the go-signal was followed by a stop-signal that required the person to block gait initiation and remain standing. Stop-signals were presented randomly and with different delays. Data analyses focused on changes in the centre of pressure (COP) and success of motor inhibition. Compared to go-trials, stop trials resulted in a marked decrease of timing and amplitude of COP displacement. Overall success rate of motor inhibition was low (29% in YA vs. 19% in OA) and decreased with increasing COP displacement. Inhibitory success was associated with two strategies: a pro-active cautious COP displacement; and the inhibition of further COP displacement after a stop-signal. Results demonstrate age-related differences in adaptive behavior as well as boundaries beyond which neither old nor young persons were successful. This study yields important insights into motor inhibition during gait and essential input nto further studies.