Reducing Metabolic Cost of Walking by Exploiting Arm Swing to Drive Leg Swing
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Arm swing during human walking is primarily driven by passive pendulum dynamics, which requires little to no metabolic cost. We seek to exploit this energy saving mechanism by transferring energy from the swinging arms to the legs using a direct-linkage apparatus. The apparatus is made of a rope-pulley system that allows an individual to exert a pulling force with the arm, which can be used to initiate and propagate leg swing. We reason that exerting a pulling force with the arms will itself exact a metabolic cost, however, this would be outweighed by a reduction in the cost of initiating and propagating leg swing. Thus, we hypothesize that using the arms to drive the legs will reduce the metabolic cost of walking. We compared the metabolic cost during the following walking conditions: (1) connecting arms and legs but without tension (Normal), and (2) connecting arms and legs with tension (Arm-Driven). When compared with normal walking, we found an 11% reduction in the metabolic cost during the Arm-Driven trial (n = 1). In short, our pilot test results show a reduction in metabolic cost of human walking, aligning with our hypothesis. Future work will focus on optimizing the apparatus to achieve the lowest metabolic cost possible for individuals and to pursue a full study with at least twelve subjects. The apparatus shows promise in rehabilitation practices where reducing metabolic cost may be essential for gait re-training in individuals with lower-limb neuromuscular dysfunction.