The consequence of uneven walking transitory modulation strategies: A simulation-based approach

Area of Science:

• Biomechanics of human locomotion
• Robotics and human-machine systems
• Gerontology and fall prevention

Background:

• Navigating uneven terrain presents significant challenges to human gait control.
• While total step mechanical work is studied, other gait adjustment mechanisms are less explored.
• Center of mass (COM) work is crucial for understanding walking energetics.

Purpose of the Study:

• To analyze the mechanistic implications of transitory step adjustment strategies using an analytical model.
• To evaluate center of mass (COM) mechanical work and step frequency cost.
• To investigate gait control in older adults and their vulnerability to falls on uneven terrain.

Main Methods:

• Utilized an analytical model to examine COM mechanical work and step frequency cost.
• Simulated transient step length reduction and effective leg length adjustments.
• Evaluated anticipatory control strategies in older adults encountering terrain perturbations.

Main Results:

• Identified a threshold where the cost of overcoming a perturbation equals extending step length.
• Transient step length reduction with nominal push-off minimizes collisional dissipation and maintains momentum.
• Older adults exhibit a speed decrease before perturbations, increasing mechanical work demand and fall risk.

Conclusions:

• Step length adjustments and effective leg length control are complementary strategies for modulating push-off and preparing for perturbations.
• Transient step length reduction can compensate for lost momentum but is metabolically costlier than push-off regulation.
• Slower gait adjustments in older adults increase mechanical work, potentially contributing to falls.