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Walking requires frequent maneuvers to navigate changing environments with shifting goals. Humans accomplish maneuvers and simultaneously maintain balance primarily by modulating their foot placement, but a direct trade-off between these two objectives has been proposed. As older adults may rely more on foot placement to maintain lateral balance, they may be less able to adequately adapt stepping to perform lateral maneuvers. How do older adults adapt stepping to enact lateral lane-change maneuvers, and how do physical and perceived ability influence their task performance? Twenty young (21.7 ± 2.6 yrs) and 18 older (71.6 ± 6.0 yrs) adults walked on a motorized treadmill in a virtual environment. Following an audible and visual cue, participants switched between two parallel paths, centered 0.6 m apart, to continue walking on their new path. We quantified when participants initiated the maneuver following the cue, as well as their step width, lateral position, and stepping variability ellipses at each maneuver step. Young and older adults did not differ in when they initiated the maneuver, but participants with lower perceived ability took longer to do so. Young and older adults also did not exhibit differences in step width or lateral positions at any maneuver step, but participants with greater physical ability reached their new path faster. While only older adults exhibited stepping adaptations prior to initiating the maneuver, both groups traded off stability for maneuverability to enact the lateral maneuver. Physical and perceived balance ability, rather than age per se, differentially influenced maneuver task performance. Humans must make decisions related to the task of walking itself and do so based on both physical and perceived factors. Understanding and targeting these interactions may help improve walking performance among older adults. ● Walking requires frequent maneuvers to navigate changing environments. ● Healthy younger and older participants made repeated lateral lane-change maneuvers. ● Participants with lower perceived ability took longer to initiate these maneuvers. ● Older adults traded-off stability for maneuverability sooner to enact the lateral maneuvers. [ABSTRACT FROM AUTHOR]

Falls to the side are associated with significant morbidity, including increased risk of hip and radius fracture. Although step width variability, as measured by standard deviation, has been hypothesized to be associated with falls to the side, there is little supporting evidence. The extent to which such a relationship could be reliably established, however, is dependent on the accuracy with which step width, and thus step width variability, is measured. It has been reported that 400 consecutive steps are required to accurately estimate step width of young adults during treadmill walking. The degree to which this requirement generalizes to other populations has not been determined. Here, a secondary analysis of step width time series data from 19 middle-age women during treadmill walking revealed that 400 steps were insufficient to accurately estimate step width or step width variability for the majority of the women sampled. Patterns observed in the data suggest the potential influence of confounding factors including acclimatization to the task and fatigue during the protocol. The results suggest that the minimum number of steps previously reported as necessary to accurately assess step width and step width variability of young adults during treadmill walking is not valid for middle-age women. Furthermore, the results point to the potential value of reproducing and/or extending the original experiment that established 400 consecutive steps as necessary to accurately estimate step kinematics among young adults. [ABSTRACT FROM AUTHOR]