Does practice modify the relationship between postural control and the execution of a secondary task in young and older individuals?
BACKGROUND
Numerous daily activities require performing more than one task simultaneously, such as standing while engaging in a conversation. Recent studies have shown that postural control may be degraded when individuals are asked to perform a secondary task and that this effect seems to be more pronounced in older adults. Since various types of secondary tasks have been used in postural control studies, the novelty of the tasks may partly explain why dual-task interference occurs. It is known that novel tasks require greater attentional resources and thus may interfere to a greater extent with the performance of another task. Therefore, by practicing this dual-task situation, interference could perhaps be diminished. Since the dual-tasking efficiency is reduced with aging, practice could be very beneficial to older adults.


OBJECTIVE
The main goal of this study was to examine whether practice could modify the changes seen in postural sway when individuals are asked to perform a secondary task while maintaining upright stance and whether older individuals could benefit to a greater extent from practice than would young individuals. The second goal was to examine the dual-task performance in young versus older adults and to determine whether older individuals benefit equally or to a greater extent from practice as compared with young individuals.


METHODS
Young and older individuals were asked to stand on a force platform while performing a secondary task or no task. The secondary task condition was repeated six times to examine the effects of practice.


RESULTS
Practice did not modify the performance of postural sway, but did lead to an increase in speed of execution of the secondary task for both groups equally. In young participants, the amplitude of sway was decreased, and the frequency of sway was increased, indicating an increased stiffness when performing the cognitive task. Older participants showed increased amplitude of sway and increased frequency of sway in the mediolateral direction only.


CONCLUSIONS
Since the dual-task condition was only repeated six times, it could be hypothesized that the effect of practice would be greater, if more trials were added or if more practice sessions were included. More research is needed to verify this hypothesis.
Dault
Mylène C
MC
Canadian Institutes of Health Research, Ottawa, Ont., Canada. mdault@irsc-cihr.gc.ca
Frank
James S
JS
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology* / Q000523:psychology*; D001288:Attention; D006801:Humans; D011187:Posture / Q000502:physiology*; D018794:Problem-Based Learning; D013647:Task Performance and Analysis