Smaller stepping thresholds in older adults might be related to reduced ability to suppress conflicting sensory information

Aging leads to alterations in the sensorimotor system and balance control but it is not well understood how changes in sensorimotor function affect how people respond to postural disturbances. Elucidating the relationships between balance control and sensorimotor function is crucial for developing effective rehabilitations. Here, we compared the kinematic responses to platform translations and rotations during standing in 10 young and 30 older adults and explored relationships between sensorimotor function and balance responses. We found that older adults were less able to withstand perturbations without stepping, not because their non-stepping strategies were less effective but because they chose to step at smaller deviations of the extrapolated center of mass. Older adults performed worse than young adults on measures of sensory and motor function but lower stepping thresholds were associated with susceptibility to unreliable visual information and not with reduced sensory acuity or reduced strength. Poor sensory reweighting may contribute to and combine with age-related cognitive rigidity, leading to a higher priority on safer strategies. Older adults may resort to stepping, even if a step is not necessary, rather than rely on potentially inaccurate sensory signals to inform a corrective response. Our results provide initial evidence that sensory reweighting could be a potential target for fall prevention methods.