The Influence of Cognitive Task Difficulty on Automatic Postural Control During Quiet Stance

Engaging in a cognitive dual-task while standing relies on the allocation of available cognitive resources. Automatic postural control is engaged while distracted; however, the use of automatic mechanisms and modulation of this automaticity based on the level of cognitive load has not been thoroughly explored. This study aims to determine whether the level of cognitive task difficulty influences automatic postural control and the magnitude of postural sway during quiet stance. Twenty-six healthy young adults (22.2 ± 2.2 years) completed twelve upright stance trials consisting of quiet standing without distraction and five arithmetic cognitive task conditions (add by 3 and subtract by 3, 7, 3.3, 7.7) while standing upright with eyes open or closed. Automaticity was assessed using sample entropy of center of pressure (COP). Magnitude and variability of COP excursions were quantified using 95% confidence ellipse area and root mean square, respectively. In general, engaging in a cognitive dual-task led to an increase in sample entropy and reduced COP variability, but these did not change as a function of cognitive task difficulty. Manipulating the availability of visual input had a variable effect across outcome measures. Young healthy adults use automatic control mechanisms to remain stable regardless of the level of cognitive load.