Effects of age, physical and self-perceived balance abilities on lateral stepping adjustments during competing lateral balance tasks.

backgroundDaily 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 (e.g. 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 capacity to execute appropriate lateral stepping adaptations. RESEARCH QUESTION: How do age, physical and self-perceived balance abilities interact to influence lateral stepping adaptations of older adults walking in complex environments with dynamic lateral path features?

methodsTwenty 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 laterally maneuver to an adjacent path (sub-task B). Recorded path characteristics were used to quantify spatial thresholds for stepping error onset and sub-task exchange.

resultsOlder 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 %. SIGNIFICANCE: 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.