The effects of attentional focus and cognitive tasks on postural sway may be the result of automaticity

Research reveals improvements in postural control when focus is placed on movement effects rather than movement production, and further improvements during the performance of a concurrent cognitive task. It has yet to be determined if these changes are due to the use of an ankle stiffening strategy or to the use of more automatic postural control processes. The objectives of the present study were to replicate the effect of attentional focus and cognitive tasks on postural control and to test that no change occurs in lower leg muscle activity in these conditions. Twenty five healthy young adults (20.7 ± 2.76 years, 10 male) were asked to stand still while performing various tasks: baseline standing, internally focusing on minimizing movement of the ankles, externally focusing on minimizing movement of an apparatus placed on their ankle joint, and two cognitive tasks consisting of counting and simultaneously summing one or two single digits in a series of three-digit numbers. Compared to baseline and internal focus, sway decreased in external focus conditions and decreased further in cognitive task conditions. Furthermore, sway velocity increased in cognitive task conditions and sway frequency increased in the medial-lateral direction in the more difficult cognitive task. Finally, no effect of condition was found on muscle activity around the ankle joint. Collectively, the findings lend support to the hypothesis that changes in postural control were the result of an automatic type of postural control rather than due to stiffening occurring at the ankle joint.