Leftward shift of the plantar flexion torque-ankle angle relationship during voluntary contractions at submaximal

Non-motorized ‘passive’ exoskeleton designs can reduce the metabolic cost of walking by reducing triceps surae activity. We evaluated the consequences of submaximal voluntary activation on the plantar flexion torque-ankle angle relationship. Our preliminary results indicate that this relationship is shifted towards shorter muscle-tendon unit (MTU) lengths as activity level is reduced. Future work will involve quantifying triceps surae fascicle behavior at the various activity levels.