Sports Science Laboratory, Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo.
Department of Humanities and Social Sciences, Institute of Liberal Arts, Kyushu Institute of Technology.
Percept Mot Skills. 2020 Aug;127(4):639-650. doi: 10.1177/0031512520919543. Epub 2020 Apr 27.
The execution of cognitive tasks is known to alter postural sway during standing, but the underlying mechanisms are still debated. This study investigated how performing a mental task modified balance control during standing. We required 15 healthy adult males to maintain an upright stance under conditions of simply relaxing and maintaining normal quiet standing (control condition) or while performing a secondary cognitive task (mental arithmetic). Under each condition, we measured the participants' center of pressure and used kinematic measurements for a quantitative evaluation of postural control modulation. We calculated the standard deviation of the joint angles (ankle, knee, and hip) and the estimated joint stiffness to measure joint mobility changes in postural control. To estimate the kinematic pattern of covariation among these joints, we used uncontrolled manifold analysis, an assessment of the strength of multijoint coordination. Compared to normal standing, executing the cognitive task while standing led to reduced movements of the ankle and hip joints. There were no significant differences in ankle stiffness or uncontrolled manifold ratios between the conditions. Our results suggest that when performing a secondary cognitive task during standing, neither changes in the modification of stiffness nor the strength of multijoint coordination (both of which preserve the center of mass position) explains changes in postural sway.
执行认知任务已知会改变站立时的姿势摆动，但背后的机制仍存在争议。本研究旨在探究执行一项心理任务如何改变站立时的平衡控制。我们要求 15 名健康成年男性在放松和正常安静站立（对照条件）或执行次要认知任务（心算）的情况下保持直立姿势。在每种情况下，我们测量参与者的压力中心，并使用运动学测量来定量评估姿势控制调制。我们计算了关节角度（脚踝、膝盖和臀部）的标准偏差和估计的关节刚度，以测量姿势控制中关节灵活性的变化。为了估计这些关节之间运动变化的协变模式，我们使用了无控制流形分析，这是一种评估多关节协调强度的方法。与正常站立相比，站立时执行认知任务会导致脚踝和髋关节的运动减少。在条件之间，踝关节刚度或无控制流形比没有显著差异。我们的结果表明，当在站立时执行次要认知任务时，无论是刚度的调节变化还是多关节协调的强度（两者都能保持质心位置）都不会解释姿势摆动的变化。
