Ankle Exoskeleton Resistance Training May Improve Older Adult Plantarflexor Strength and Mobility: A Pilot Evaluation

Older adults exhibit declining mobility with age, partly because ankle plantarflexor strength and function, which are crucial for propulsion, are diminished. Exoskeletons hold potential as task-specific resistance training tools that may lead to improved mobility by promoting functional neuromuscular control in addition to strength. Thus, this pilot study assessed the efficacy of an ankle exoskeleton resistance training paradigm on improving plantarflexor strength and mobility among older adults. Eight participants (age: 76 ± 5 years) completed twelve sessions of biofeedback-informed ankle exoskeleton resistance training over four weeks. Each session consisted of twenty minutes of treadmill walking with exoskeleton resistance and plantar pressure-based biofeedback. Prior to and following training, individuals completed plantarflexor strength testing, overground mobility assessments, and treadmill-based biomechanical assessments. Following resistance training, participants had increased plantarflexor muscle strength (+38%, p < 0.001), greater habitual (+13%, p < 0.001) and fastest (+9%, p = 0.005) overground walking speeds, and further six-minute walk test distances (+11%, p = 0.025). While walking on a treadmill at the same speed as their pre-assessment visit, individuals had increased peak ankle plantarflexion angles (+3.6°, p = 0.037) and hip range of motion (+1.6°, p = 0.005), but no differences in the cost of transport (-2%, p = 0.690), peak anterior ground reaction force (+5%, p = 0.285), peak ankle power (+2%, p = 0.757), and peak hip power (-7%, p = 0.348). A randomized trial investigating the full potential of this paradigm and the biomechanical mechanisms responsible for improved mobility warrants further exploration.