Interaction between age-related ankle torque deficits and exoskeleton assistance

Determine how age-related reductions in maximum ankle torque (plantar flexion and dorsiflexion) and maximum rate of torque development (MRTD) interact with ankle exoskeleton assistance during standing balance. Specifically, ascertain the combined effects of diminished ankle maximum torque and reduced MRTD with additional ankle torque provided by powered exoskeletons on stability outcomes for older adults.

Background

Standing balance in humans relies heavily on ankle torque, with aging associated with reduced maximum torque production and lower maximum rate of torque development (MRTD). These declines are linked to decreased stability and increased fall risk. Ankle exoskeletons, which apply assistive torque about the ankle in the sagittal plane, are proposed to mitigate these deficits and potentially enhance balance.

Existing balance studies with powered exoskeletons largely focus on young able-bodied users, leaving uncertainty about how exoskeleton assistance interacts with age-related joint-level changes. The paper highlights the need to understand the combined impact of reduced ankle MT and MRTD with exoskeleton torque assistance on stability in older adults, motivating a model-based analysis of this interaction.