Reducing postural sway by manipulating the difficulty levels of a cognitive task and a balance task.

Postural sway decreases when participants perform a balance task concurrently with a cognitive task. The present study examined whether this is based on the difficulty of the cognitive task, the difficulty of the balance task, or a combination of both. Participants completed easy and difficult Brooks' spatial and nonsense memory tasks in sitting and standing. Postural sway was measured while they performed one of three balance tasks concurrently with the Brooks' tasks and two control tasks. Performing the difficult cognitive task, yet not the easy cognitive task, was associated with a decrease in postural sway, F (3, 273)=3.53, MSE=0.007, p=0.015. The decrease was not influenced by the difficulty of the balance task. The difficulty level of the cognitive task was the critical factor that decreased sway in dual task conditions.