Brown L A, Shumway-Cook A, Woollacott M H
Department of Kinesiology and Physical Education, University of Lethbridge, Alberta, Canada.
J Gerontol A Biol Sci Med Sci. 1999 Apr;54(4):M165-71. doi: 10.1093/gerona/54.4.m165.
Cognitive demands associated with balance and locomotion may contribute to the incidence of falling among older adults. This study addressed issues related to the effects of aging on the attentional demands of recovering from an external disturbance to balance. This research also investigated whether performing a secondary cognitive task differentially affects postural recovery in young versus older adults.
Fifteen young and 10 healthy older adults were exposed to a series of balance disturbances. Attentional demands were assessed using a dual task paradigm where postural recovery served as the primary task, and counting backwards served as a concurrent secondary cognitive task. The effect of the counting task was assessed by comparing kinematic variables related to feet-in-place and stepping recovery strategies.
Recovering upright stance was found to be attentionally demanding in both age groups. The type of recovery strategy did not influence attentional demands in young adults; however, a hierarchy of increasing attentional demands between the ankle strategy and compensatory stepping was apparent among older adults. In addition, stepping appears to be more attentionally demanding for older adults than for younger adults. Counting backwards did not affect the type of strategy used; however, it did affect the kinematics of stepping. For both age groups, steps occurred when the center of mass was located in a more central location within the base of support when the secondary task was added.
The ability to recover a stable posture following an external perturbation is more attentionally demanding for older adults than for younger adults. This would suggest that for some older adults, an increased risk for loss of balance and falls may result if sufficient attentional resources are not allocated to the task of postural recovery.
与平衡和移动相关的认知需求可能会导致老年人跌倒。本研究探讨了衰老对从外部干扰中恢复平衡时注意力需求的影响。本研究还调查了执行次要认知任务是否会对年轻人和老年人的姿势恢复产生不同影响。
15名年轻人和10名健康老年人经历了一系列平衡干扰。注意力需求通过双任务范式进行评估，其中姿势恢复作为主要任务，倒数作为同时进行的次要认知任务。通过比较与原地双脚和跨步恢复策略相关的运动学变量来评估计数任务的效果。
在两个年龄组中，恢复直立姿势都需要注意力。恢复策略的类型对年轻人的注意力需求没有影响；然而，在老年人中，踝关节策略和代偿性跨步之间的注意力需求增加层次是明显的。此外，跨步对老年人来说似乎比年轻人更需要注意力。倒数并没有影响所使用策略的类型；然而，它确实影响了跨步的运动学。对于两个年龄组，当添加次要任务时，当质心位于支撑面内更中心的位置时会出现跨步。
对于老年人来说，在外部扰动后恢复稳定姿势的能力比年轻人更需要注意力。这表明，对于一些老年人来说，如果没有将足够的注意力资源分配到姿势恢复任务中，可能会导致平衡丧失和跌倒的风险增加。
