Uneven Walking is Challenging: step-ups or extended steps that is the question

Uneven terrain presents significant challenges for walkers, resulting in increased energy expenditures. Given that Center of Mass (COM) work reflects this energy demand, it's reasonable to assume that individuals also seek strategies to minimize mechanical work. One such strategy involves deciding between extending step length to avoid terrain irregularities or simply traversing over them. Each approach carries its own mechanical cost, leading to the adoption of the less costly option. To investigate this, we conducted a simulation focusing on COM mechanical work under the assumption that gait energy is entirely provided through pre-emptive push-off. We examined the COM work required for step length extension, ranging from nominal to twice its magnitude, and compared it with the mechanical work needed for step-ups from zero to 0.05 m. The simulation revealed a critical threshold for a given walking velocity and perturbation amplitude: below it, extending step length was more favorable, while beyond it, landing atop perturbations became the preferred choice. As perturbation amplitude rose, the magnitude of the threshold also increased.