Effect of practice on stepping movements onto laterally compliant raised structures: Age differences in healthy males

Objective: The aim of this study was to examine effects of practice and age on step-up movements onto raised structures. Background: Falls from laterally compliant structures, such as stepladders, often cause injuries in elderly persons. Although age differences in step-up movements onto raised structures with unexpected structural compliance have been reported, practice effects of such movement control have not been investigated. Method: Movement behavior of 20 healthy adults (10 young and 10 older males) was measured while they stepped up onto a raised structure with no compliance (i.e., rigid) (C₀), a small amount of mediolateral compliance (C₁), or greater mediolateral compliance (C₂). The conditions C₀, C₁, and C₂ were presented in three sets of six fixed-order trials with step-up movements performed at a comfortable speed. Practice effects in step-up behavior were examined by comparing data within each trial block with the use of repeated-measures ANOVA. Results: Practice significantly reduced the stepping duration (Ts) needed to complete the step-up movement (p <.001). With practice, older males reduced their lateral oscillations 26% to 40% for C ₁ and C₂, whereas the corresponding results for young males lay between 8% and 17%, respectively. The age difference in Ts decreased across six consecutive trials but remained significant, especially on the structure with greater compliance. Conclusion: With practice, both young and elderly men adapted their stepping behavior to the presence of lateral structural compliance, but it is noteworthy from a fall-injury prevention perspective that the elderly men required more trials to do so. Application: Designers and users of raised structures, such as stepladders, should be aware of the age difference of people using such structures and should minimize the structure compliance when designing them.