Does an Externally Focused Dual-task Mitigate Real-time Conscious Postural Control in Older Adults?

Objectives: This study first examined whether real-time conscious postural control (reinvestment) and postural sway increase with different postural difficulties on a compliant surface among older adults. The second objective was to investigate the effect of an externally focused dual-task on real-time reinvestment and postural sway under a relatively challenging standing position. Method: Thirty-two community-dwelling older adults (mean age = 72.09, SD = 4.18 years) were recruited. Participants performed balance tasks in four standing positions in a randomized order on a balance foam pad. The four positions included wide-based standing on foam (WBF), narrow-based standing on foam (NBF), tandem-based standing on foam (TBF) and tandem-based standing on foam with an externally focused dual-task (TBFE). Throughout all the balance tasks, participants' real-time reinvestment and body sway were indicated by the Alpha2 T3-Fz Electroencephalogram (EEG) coherence and the total sway length (TSL), respectively. Results and Discussion: Our results revealed no significant difference in real-time reinvestment among different standing positions while postural sway increased from WBF to NBF and reduced from NBF to TBF. We also demonstrated that when performing a relatively challenging standing task on a compliant surface, an externally focused dual-task (TBFE), compared to a baseline single task (TBF), can neither mitigate real-time reinvestment nor improve balance performance in community-dwelling older adults with good balance capability. Potential explanations and implications are discussed.