Chapman G J, Hollands M A
Human Movement Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
Gait Posture. 2007 Jun;26(1):59-67. doi: 10.1016/j.gaitpost.2006.07.010. Epub 2006 Aug 30.
Previous research has highlighted differences between older adults determined to be at a low-risk of falling (low-risk) and older adults prone to falling (high-risk) in both where and when they look at stepping targets and the precision with which they subsequently step. On the basis of these findings, we proposed that high-risk older adults prioritise the planning of future stepping actions over the accurate execution of ongoing movements and that adoption of this strategy contributes to increased likelihood of falls. The present experiment was designed to test this hypothesis by manipulating the complexity of the required walking conditions and comparing gaze and stepping performance between young, high-risk and low-risk older adults. Participants walked at a self-selected pace along a 7-m pathway and encountered one of three obstacle conditions: (1) a single stepping target, (2) two stepping targets, (3) two stepping targets separated by a raised obstacle. On average, when there was a single target (Target 1) in the travel path, all groups fixated the target until after heel contact. However, when challenged with additional impending stepping constraints, high-risk older adults transferred their gaze significantly sooner from Target 1 prior to heel contact. On average, low-risk older adults and younger adults maintained gaze on Target 1 until after heel contact, irrespective of future constraints. Premature gaze transfer was associated with decline in stepping accuracy and precision. Our findings suggest that high-risk older adults choose a potentially hazardous gaze strategy when challenged with multiple obstacles. Putative mechanisms underlying this behaviour are discussed.
先前的研究突出了被确定为低跌倒风险（低风险）的老年人与易跌倒的老年人（高风险）在注视步阶目标的位置和时间以及随后步阶的精准度方面存在差异。基于这些发现，我们提出，高风险的老年人将未来步阶动作的规划置于当前动作的准确执行之上，而采用这种策略会增加跌倒的可能性。本实验旨在通过操纵所需行走条件的复杂性，并比较年轻、高风险和低风险老年人的注视和步阶表现来检验这一假设。参与者以自选的速度沿着一条7米长的路径行走，并遇到三种障碍条件之一：（1）单个步阶目标；（2）两个步阶目标；（3）由一个凸起障碍物隔开的两个步阶目标。平均而言，当行进路径上有单个目标（目标1）时，所有组都会注视该目标直到脚跟触地之后。然而，当面临额外的即将到来的步阶限制时，高风险的老年人在脚跟触地之前会更早地将目光从目标1移开。平均而言，低风险的老年人和年轻人会一直注视目标1直到脚跟触地，而不管未来的限制如何。过早的目光转移与步阶准确性和精准度的下降有关。我们的研究结果表明，高风险的老年人在面临多个障碍物时会选择一种潜在危险的注视策略。本文讨论了这种行为背后的潜在机制。
