Comparison of dual task performance.

As individuals age, they may experience a decline in gait automaticity, which requires increased attentional resources for the control of gait. This age-related decline in gait automaticity has been shown to contribute to higher prefrontal cortex (PFC) activation and lower dual-task performance during dual-task walking in older adults. This study is to investigate the effect of treadmill walking on PFC activation and dual-task performance in older adults. A total of 20 older adults (mean age, 64.35 ± 2.74 years) and 20 younger adults (mean age, 30.00 ± 3.15 years) performed single- and dual-task walking in overground and treadmill conditions. A wearable functional near-infrared spectroscopy and gait analyzer were used to analyze PFC activation and dual-task performance, respectively. To determine the dual-task (gait and cognitive) performance, the dual-task cost (DTC) was calculated using the following formula: (single-task − dual-task)/single-task × 100. In both groups, dual-task treadmill walking led to reduced PFC activation and reduced DTC compared to dual-task overground walking. Furthermore, despite a higher DTC in gait variability, correct response, total response, response index and a higher error score in older adults than in younger adults during overground walking, there was no difference in treadmill walking. The difference in PFC activation between single- and dual-tasks was also observed only in overground walking. Performing dual-task walking on a treadmill compared to overground walking results in different levels of dual-task performance and PFC activity. Specifically, older adults are able to maintain similar levels of dual-task performance as younger adults while walking on a treadmill, with reduced PFC activation due to the automaticity induced by the treadmill. Therefore, older adults who exhibit low dual-task performance during overground walking may be able to improve their performance while walking on a treadmill with fewer attentional resources.

随着个体年龄增长，步态自动化程度可出现衰退，使得步态控制需要投入更多的注意资源。已有研究证实，这种年龄相关的步态自动化衰退，会导致老年人在双任务行走时前额叶皮层（prefrontal cortex, PFC）激活水平升高，同时双任务表现下降。本研究旨在探究跑步机行走对老年人前额叶皮层激活与双任务表现的影响。本研究共纳入20名老年人（平均年龄64.35±2.74岁）与20名青年人（平均年龄30.00±3.15岁），所有受试者均在平地与跑步机两种环境下完成单任务行走与双任务行走实验。研究分别采用可穿戴功能性近红外光谱设备（functional near-infrared spectroscopy）与步态分析仪，分析前额叶皮层激活数据与双任务表现数据。为评估步态与认知双任务表现，本研究通过下述公式计算双任务代价（dual-task cost, DTC）：(单任务成绩−双任务成绩)/单任务成绩 × 100。与平地双任务行走相比，两组受试者在跑步机上进行双任务行走时，其前额叶皮层激活程度与双任务代价均显著更低。此外，在平地行走时，老年人在步态变异性、正确反应数、总反应数、反应指数相关的双任务代价均高于青年人，且错误得分也更高；但在跑步机行走时，两组间上述指标均无显著差异。仅在平地行走时，才可观察到单任务与双任务状态下前额叶皮层激活程度的差异。与平地双任务行走相比，在跑步机上开展双任务行走时，受试者的双任务表现与前额叶皮层活动水平存在显著差异。具体而言，老年人在跑步机上行走时，可维持与青年人相当的双任务表现水平，且由于跑步机诱导的步态自动化效应，其前额叶皮层激活程度有所降低。因此，那些在平地行走时双任务表现欠佳的老年人，在跑步机上行走时，仅需投入更少的注意资源即可改善自身表现。