Effects of Age, Physical and Self-Perceived Balance Abilities on Lateral Stepping Adjustments During Competing Lateral Balance Tasks
Meghan Kazanski a,*, Jonathan B. Dingwell a
a Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802 USA
Daily walking paths exhibit varying environment features and require continuous adjustments to locomotor trajectories. Humans maintain lateral balance while navigating paths by modifying stepping in accordance with changing side-to-side path limitations (i.e. path width, lateral location). These processes are influenced by one’s actual physical ability to maintain balance, as well as their self-perceived balance ability. Older adults experience decreases in each of these abilities, which may alter their capacities to execute appropriate lateral stepping adaptations. Here, we examined age, physical and self-perceived balance abilities as interacting factors which influence lateral stepping adaptations of older adults walking in complex environments with dynamic lateral path features. Twenty young (age mean±SD: 21.7±2.6) and 18 older adults (age mean±SD: 71.6±6.0) walked on an instrumented treadmill in a virtual-reality system. Participants adjusted lateral stepping during two competing lateral balance sub-tasks that manipulated either path width or location. Participants began walking on a gradually-narrowing path (sub-task A), then decided when/ how to exchange sub-tasks by laterally maneuvering to an adjacent path (sub-task B). Recorded path characteristics were used to quantify spatial thresholds for stepping error onset and sub-task exchange. Older adults made sub-task A stepping errors on wider paths and exchanged sub-tasks earlier. These differences were not directly attributed to age. Statistical path analyses revealed that physical balance ability mediated age effects on stepping error onset, while self-perceived balance ability mediated age effects on sub-task exchange. Both age groups exchanged sub-tasks when stepping accuracy likelihoods were similar and high, ~90%. This work demonstrates important mechanisms for how age, via degradation of physical and self-perceived balance abilities, indirectly and differentially influences navigation of competing lateral balance tasks. Mediating physical and perceptual factors are potential targets for improving older adults’ navigation of complex environments.
Figure: (A): Young and older healthy adults navigated series of two parallel walking paths with dynamic spatial constraints. Participants adapted stepping to remain on a path of constantly-decreasing width while minimizing stepping errors outside of the path boundaries. (B): Participants decided when and how to laterally maneuver from the narrowing path to an adjacent, wider path. (C): We extracted narrowing path widths at instants of first stepping error (werror1) and path switching (wswitch) to evaluate whether older adults were differentially sensitive to the spatial limitations of the complex paths.
Figure: (A): Older healthy adults (OH) made initial stepping errors sooner, at wider path widths (werror1). These age effects on werror1 were indirect, mediated by age-related physical balance abilities. (B): Older healthy adults (OH) executed path switches sooner, at wider path widths (wswitch). These age effects on wswitch were indirect, mediated by age-related self-perceptions of balance abilities.
Highlights
Spatial limitations of environment-defined walking paths impose proactive balance challenges.
Humans often navigate complex paths by adjusting lateral steps to concurrent, competing balance challenges (e.g., dynamic path width and path location).
During concurrent balance challenges imposed by complex paths, older adults make stepping errors and exchange tasks sooner.
Healthy aging preserves stepping accuracy thresholds but alters how adults interact w/ paths.
Physical & self-perceived balance deficits mediate age effects on lateral stepping adjustments on complex paths.