Stepping onto raised, laterally compliant structures: A biomechanical study of age and gender effects in healthy adults

Objective: To investigate the effects of gender and age on the kinematics and kinetics associated with stepping onto, and balancing on, a raised structure with lateral compliance. Background: Falls from a stepladder tipping sideways are associated with considerable socioeconomic costs. Method: Ten young women (YF) and 10 young men (YM), aged 23 to 29 years, and 10 older men (OM) aged 66 to 75 years were asked to step up onto one of two raised structures with increasing lateral compliance (C₁ and C₂), presented in sets of six trials separated by up to 12 rigid (C₀) structure trials. Results: Structural compliance (C₁ or C₂) significantly affected step duration (p < .05) and lateral weight transfer velocity (p < .01). Significant age (p < .001) and gender (p < .05) differences were found in step duration and center of mass adjustments: With increasing structural compliance, participants required more time (YM: 15%; YF ranged from 33% to 45%; OM 35%-37%) to complete the step-up movement. Conclusion: Increasing age and structural compliance were both associated with larger and longer-lasting structural oscillations that increase the risk for a lateral fall. Application: Older adults, in particular, should not hurry their movements on raised structures. Actual or potential applications of this research include additional safety instructions for ladder users and considerations of structural compliance for designers and authors of national or international standards for raised structures.