Age Does Not Reduce Oneʼs Ability to Adapt and Resist Backward Falling Following Repeated Slip Exposure.

This is the authors' abstract. We don't add key points for this paper.

Purpose/Hypothesis: A previous study found that with repeated exposure to slipping during a sit-to-stand task, fall incidence decreased at a similar exponential rate in young and older adults. This study investigated whether such adaptations adopted by the Central Nervous System (CNS) were task specific. Subjects: Forty young (18–35 yrs) and 30 older (>65 years) subjects participated in the study. Materials/Methods: Slips were induced during walking using low-friction platforms, in both the young and older adults, after they were secured in a safety-harness. Subjects underwent a block of 8 slips, a block of 3 non-slip trials, another block of 8 slips, second block of 3 nonslip trials, and a block of mixed trials. The outcome of a slip was classified as recovery, loss of balance, or fall. Dynamic stability was obtained as the shortest distance between the measured center of mass state (position and velocity) and the model-predicted threshold for backward loss of balance at liftoff of the recovery step. The older adults' results were contrasted to those of young during walking and to the existing data on older adults' slip-related adaptive behavior during the task of sit-to-stand (N=40, >65 yrs). Results: In the first 5 repeated slips, the older adults adjusted the COM state to increase their stability at the recovery step liftoff (p<.001), contributing to a decrease in loss of balance (from 100% to <5%) and falls (from 50% to 0%) incidence (p<.001). On the first re-slip after the non-slip block the older adults had a balance loss incidence of only 20% and fall incidence of < 5%. Such rapid changes in both the behavioral outcome as well as the control of dynamic stability were similar to those of the young adults and similar to older adults' adaptation to slips during sit-to-stand (p>0.05). Conclusions: The adaptive ability of the CNS for control of COM state stability, to prevent backward falling, appears to generalize across age and tasks. Clinical Relevance: The behavioral benefit from such adaptation, of being able to avoid slip-related falls, in both young and older adults, could have a broad application across different activities of daily living.