Increasing cognitive load with increasing balance challenge: recipe for catastrophe.

Area of Science:

• Neuroscience
• Human Motor Control
• Cognitive Psychology

Background:

• Previous studies on cognitive tasks and postural balance yield inconsistent results.
• Heterogeneity in task difficulty and lack of comparability contribute to varied outcomes.
• Falls have rarely been incorporated as an experimental variable in balance research.

Purpose of the Study:

• To investigate the spectrum of interactions between graded cognitive tasks and postural challenges.
• To compare the effects of verbal versus spatial cognitive tasks on balance.
• To examine the role of falls as an experimental variable in multi-tasking balance studies.

Main Methods:

• Two studies were conducted: a between-groups design with varying beam widths and cognitive tasks, followed by a within-group design on the most challenging beam.
• Participants performed verbal or spatial Stroop tasks while balancing on beams of graded difficulty.
• Measurements included center of pressure, sway velocity, head displacement, task errors, and fall rates.

Main Results:

• No correlation was found between sway magnitude and fall frequency within subjects.
• Spatial task errors increased with balance challenge, while verbal task performance remained stable.
• The spatial task significantly increased fall incidence by 50% compared to no task, whereas the verbal task had no significant effect.

Conclusions:

• Sway magnitude is an inadequate indicator of multi-tasking load.
• Multi-tasking, particularly with spatial cognitive demands, can elevate the risk of falling.
• The 'posture first' principle can be overridden during cognitive loading, especially when individuals perceive they can manage risks.