Background
Age-related deficits in plantar flexor muscle function likely contribute to the decline in mobility that affects many older adults. Isolated strengthening of the plantar flexor muscles has failed to improve push-off power or walking economy in this population. New mobility aids and/or functional training interventions may help slow or prevent ambulatory decline in the elderly.
Lower-limb exoskeleton assistance targeting the ankle joint may hold potential for augmenting performance in high-intensity ambulatory activities in older adults by reducing metabolic energy cost. Conversely, resistive exoskeletons targeting ankle plantar flexor engagement could improve the effectiveness of functional gait training and help meet the demand to provide therapy to our aging population.
After demonstrating the success of ankle assistance and resistance in populations with neurological conditions. This feasibility study tested on six elderly participants ages 68-83.
Purpose
Explore the feasibility of using a dual-mode ankle exoskeleton for treating walking disability in the elderly; testing the device in assistance mode as a mobility aid to reduce energy consumption, and as a resistive gait training tool to facilitate functional recruitment of the plantar flexor muscles.
Findings
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Four of five participants exhibited a reduction (up to 19%) in metabolic power during walking with assistance relative to baseline, but there was no group group-level change. Participants who had greater baseline metabolic power exhibited a greater reduction during walking with assistance.
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Walking with resistance increased both soleus activity (18 – 186%) and ankle power (9 – 88%). Following 12-session ankle resistance gait training, the participant exhibited increased self-selected and fast walking speed, as well as plantar flexor strength.
Future directions
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Revise current device to allow for home-based training.
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Conduct longer term training on more participants.