Department of Mechanical Science and Bioengineering, Osaka University, Osaka, 5608531, Japan.
Department of Statistics, North Carolina State University, Raleigh, NC, 27695-8203, USA.
Sci Rep. 2024 Jul 16;14(1):16410. doi: 10.1038/s41598-024-66727-1.
Gait cycle variability during steady walking, described by the stride interval time series, has been used as a gait-stability-related measure. In particular, the positive persistency in the stride intervals with 1/f-like fluctuation and reduction of the persistency are the well-documented metrics that can characterize gait patterns of healthy young adults and elderly including patients with neurological diseases, respectively. Here, we examined effects of a dual task on gait cycle variability in healthy young adults, based on the mean and standard deviation statistics as well as the positive persistency of the stride intervals during steady walking on a treadmill. Specifically, three gait conditions were examined: control condition, non-cognitive task with holding a smartphone in front of the chest using their dominant hand and looking fixedly at a blank screen of the smartphone, and cognitive motor task with holding a smartphone as in the non-cognitive task and playing a puzzle game displayed on the smartphone by one-thumb operation. We showed that only the positive persistency, not the mean and standard deviation statistics, was affected by the cognitive and motor load of smartphone usage in the cognitive condition. More specifically, the positive persistency exhibited in the control and the non-cognitive conditions was significantly reduced in the cognitive condition. Our results suggest that the decrease in the positive persistency during the cognitive task, which might represent the deterioration of healthy gait pattern, is caused endogenously by the cognitive and motor load, not necessarily by the reduction of visual field as often hypothesized.
在稳定行走期间，步幅间隔时间序列描述的步态循环可变性已被用作与步态稳定性相关的测量指标。特别是，步幅间隔具有 1/f 样波动的正持续性和持续性降低，是分别能够描述健康年轻成年人和老年人（包括患有神经疾病的患者）步态模式的有据可查的指标。在这里，我们根据在跑步机上稳定行走时的平均和标准差统计以及步幅间隔的正持续性，检查了双重任务对健康年轻成年人步态循环可变性的影响。具体来说，检查了三种步态条件：对照条件、使用惯用手将智能手机放在胸前并固定注视智能手机空白屏幕的非认知任务以及使用智能手机的认知运动任务与非认知任务相同，并通过单手操作在智能手机上玩拼图游戏。我们发现，只有正持续性，而不是平均和标准差统计，受到认知任务中使用智能手机的认知和运动负荷的影响。更具体地说，在控制和非认知条件下表现出的正持续性在认知条件下显著降低。我们的结果表明，认知任务期间正持续性的降低，可能代表健康步态模式的恶化，是由认知和运动负荷引起的，而不一定像通常假设的那样是由于视野缩小引起的。
