Reduced cognitive resources induces risky stepping strategies in older adults

Falls frequently occur during situations that require a transfer or shift of bodyweight (e.g., stepping around an obstacle or turning). One contributor to falls in this scenario is a risky stepping strategy known as 'cross-stepping', whereby the feet cross over during the step. However, contributors to this potentially dangerous stepping strategy are not understood. This study examined whether reduced cognitive resources are a contributor to 'cross-stepping'.

Fifty-one older adults without neurological, musculoskeletal, or major cognitive impairment participated. Participants completed a modified multitarget stepping task while traversing a GAITRite walkway containing stepping targets forming paths of various colors. Participants walked designated color paths under single-task (normal walking) and a dual-task (serial subtraction) condition designed to reduce cognitive resources available for walking. The number of cross-steps and stepping errors were assessed. Cognitive performance, gait velocity, and double-limb support (% of gait cycle) were also collected.

During single-task conditions, measures of executive function (set-shifting)/attention (Trail Making Test-Part B) independently predicted greater cross-steps (B=0.01, p = .025). Walking under dual-task conditions significantly increased cross-steps (p = .001). Gait velocity also significantly decreased when compared to single-task, whilst global stepping errors and percentage of the gait cycle spent in double-limb support significantly increased.

These findings suggest that cross-steps can result from reduced cognitive resources being allocated to movement planning and execution. Future research should seek to explore if the relationship between cognition and cross-stepping is causally linked to increased fall risk.