Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada.
Djavad Mowafaghian Centre for Brain Health, Aging, Mobility and Cognitive Neuroscience Laboratory, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
Exp Brain Res. 2019 Dec;237(12):3313-3319. doi: 10.1007/s00221-019-05673-1. Epub 2019 Nov 6.
Carrying an anterior load during obstacle negotiation increases attention demand, which may differ at various crossing stages. Less is known on the impact of lower visual field obstruction and the weight of the anterior load on obstacle negotiation and attention demand. The objectives of this study were to: (1) determine if carrying a weighted anterior load, lower visual field occlusion, or both, modify obstacle clearance and/or reaction time (RT); and (2) examine whether RT is modulated across obstacle crossing phases as measured by a probe RT protocol. Sixteen young adults crossed an obstacle while carrying no load, a clear 5 kg load, and an opaque 5 kg load, while performing a simple RT task. Auditory stimuli were presented at five locations: (1) two steps before the obstacle; (2) one step before the obstacle; (3) as the leading limb crossed the obstacle; (4) as the lead limb touched down after the obstacle; and (5) as the trail limb crossed the obstacle. The toe clearance height of the leading limb was greatest for the weighted opaque box load type followed by the weighted clear box type compared to the no box load type. Carrying an anterior load during obstacle crossing did not influence RT. RTs were longer at the pre-crossing and beginning of the crossing phases compared to after-crossing phases. Results suggest that carrying a weighted anterior load and lower visual field occlusion increase the risk for tripping. Attention demands differ across obstacle crossing phases during dual-tasking and should be considered in fall-risk assessments.
在障碍物跨越过程中携带前向负荷会增加注意力需求，而不同的跨越阶段可能会有所不同。对于下视野障碍物和前向负荷的重量对障碍物跨越和注意力需求的影响，人们了解较少。本研究的目的是：(1)确定携带负重前向负荷、下视野遮挡还是两者同时，是否会改变障碍物清除率和/或反应时间（RT）；(2)通过 RT 探测协议，检查 RT 是否跨障碍物跨越阶段而变化。16 名年轻人在不携带负荷、携带透明 5 公斤负荷和携带不透明 5 公斤负荷的情况下跨越障碍物，同时执行简单 RT 任务。听觉刺激在五个位置呈现：(1)在障碍物前两步；(2)在障碍物前一步；(3)在引导腿越过障碍物时；(4)在引导腿越过障碍物后触地时；(5)在跟随腿越过障碍物时。与不携带箱子的类型相比，负重不透明箱子的类型和负重透明箱子的类型的引导腿的足尖离地高度最大。在障碍物跨越过程中携带前向负荷不会影响 RT。与跨越后阶段相比，预跨越和跨越开始阶段的 RT 更长。结果表明，在障碍物跨越过程中携带负重前向负荷和下视野遮挡会增加绊倒的风险。在执行双重任务时，注意力需求在障碍物跨越阶段有所不同，应在跌倒风险评估中加以考虑。
