The effects of cognitive tasks on the frequency of non-MTC gait cycle during walking in healthy older and young adults.

[Purpose] To investigate the effects of cognitive tasks on the non-minimum toe clearance gait cycles (nMTC) frequency during walking in healthy older and young adults. [Participants and Methods] This study included 20 healthy older and 20 young adults. The participants performed 3 min preferred-speed walking under a single-task and three dual-tasks (DTs) consisting of verbal, subtraction, and recall tasks. We determined the nMTC, which could not detect a trough in the toe trajectory during the swing phase. We evaluated the nMTC frequency (the cases of nMTC / total gait cycles) and compared them among the tasks and between groups. [Results] The results of the two-way analysis of variance revealed that there were no differences among the tasks, while the nMTC frequency in the older group was higher than that in the young group. The DT cost (DTc), which was used as an indicator of cognitive-motor interference (CMI), was higher in the subtraction and recall tasks in the older group than those in the young group. [Conclusion] This study showed that adding a cognitive task while walking increased in the nMTC frequency in older adults. These results suggest that the nMTC frequency under DT would reflect the increased CMI in healthy older adults.