Bernard-Demanze L, Dumitrescu M, Jimeno P, Borel L, Lacour M
Laboratoire de Modélisation des Activités Sportives, Domaine Universitaire de Savoie-Technolac - 73376 Le Bourget du Lac Cedex, France.
Curr Aging Sci. 2009 Jul;2(2):139-49.
The simple postural task of quiet standing, which requires minimal attentional resources, is generally paired with cognitive activity. Competition for attentional resources is a consequence of simultaneously performing balance tasks and cognitive tasks, and impairment of attentional resource allocation with aging leads to increased risks of fall. We investigated age-related changes in posture control during dual task performance, using a paradigm that crossed a static (quiet standing) and a dynamic (keeping balance on a translational force plate) postural task and cognitive tasks of low demand (mental arithmetic) and high demand (spatial memory). Postural performance was analyzed through center-of-pressure displacements using both statistical (body sway area/sway velocity) and nonlinear (wavelet transform) methods in three age groups (younger, middle-aged, and older healthy participants). Results showed that 1) the nonlinear analysis method was more sensitive than the traditional approach in distinguishing performance between age groups, a result that explains discrepancies in the dual-task literature; 2) dual-tasking costs were dependent on both postural task difficulty and cognitive task complexity, corroborating previous investigations; 3) younger adults improved their postural performance during dual-tasking, but older adults lowered their performance; 4) balance recovery strategies in the dynamic postural task appeared to differ in younger versus older adults. Together, our findings on dual-tasking can be interpreted within the conceptual frame of task prioritization: shifting attention away from postural task automates posture control in the younger adults, whereas prioritization of postural task and selection of compensatory strategy are the main characteristics of posture control in the older population.
安静站立这一简单的姿势任务，所需注意力资源极少，却通常与认知活动同时进行。注意力资源的竞争是同时执行平衡任务和认知任务的结果，而随着年龄增长注意力资源分配受损会导致跌倒风险增加。我们使用一种范式来研究双任务执行期间姿势控制的年龄相关变化，该范式将静态（安静站立）和动态（在平移力板上保持平衡）姿势任务与低需求（心算）和高需求（空间记忆）的认知任务交叉组合。通过使用统计方法（身体摆动面积/摆动速度）和非线性方法（小波变换）对压力中心位移进行分析，研究了三个年龄组（年轻、中年和老年健康参与者）的姿势表现。结果表明：1）在区分年龄组之间的表现时，非线性分析方法比传统方法更敏感，这一结果解释了双任务文献中的差异；2）双任务成本取决于姿势任务难度和认知任务复杂性，这与之前的研究结果一致；3）年轻人在双任务执行期间提高了他们的姿势表现，但老年人则降低了表现；4）动态姿势任务中的平衡恢复策略在年轻人和老年人中似乎有所不同。总之，我们关于双任务的研究结果可以在任务优先级的概念框架内进行解释：年轻人将注意力从姿势任务上转移开，从而使姿势控制自动化，而姿势任务优先级和补偿策略的选择是老年人群体姿势控制的主要特征。
