Can telling older adults where to look reduce falls? Evidence for a causal link between inappropriate visual sampling and suboptimal stepping performance.

摘要

Older adults at high risk of falling look away prematurely from targets they are stepping on in order to fixate future constraints in their walking path. This gaze behaviour is associated with decreased stepping accuracy and precision. The aims of the present study were to determine whether this apparently maladaptive gaze behaviour can be altered through intervention and to measure any corresponding improvements in stepping performance. Sixteen older adults, randomly placed into a control or intervention group, walked a 10-m path placing their feet into targets while their gaze direction and lower limb kinematics were measured. On average, both groups looked away from a stepping target around 100 ms prior to foot contact and the extent of early gaze transfer correlated with stepping errors. The participants returned on a separate day and repeated the experiment; however, the intervention group was instructed to maintain gaze on each target until heel contact. Following intervention, on average participants delayed gaze transfer from the first target until after heel contact and this change in behaviour resulted in a significant reduction in stepping errors. We propose that suboptimal visual sampling strategies contribute to the incidence of falls in the elderly.