주행 효율 증대를 위한 운동화의 최적 굽힘 강성 선정

Abstract

Previous researches suggested that shoe with high bending stiffness help runner reduce metabolic cost. However, there have not been clear explanations for underlying mechanisms. As the metatarsophalangeal (MTP) joint could be modeled as a bending stiffness, we hypothesized that additional bending stiffness via stiff shoe could assist MTP work but excessively stiff shoe than natural MTP stiffness could restrict natural MTP flexion. So an optimal shoe stiffness could be estimated by maximizing reutilization of elastic energy stored and also minimizing decrease in natural MTP flexion, and such an optimal stiffness would be near natural MTP stiffness. Kinetic, kinematic, and metabolic data were collected when nine healthy young subjects wearing shoes with carbon insoles ran with velocity under their anaerobic thresholds. As hypothesized, with bending stiffness near natural MTP stiffness, MTP flexion did not decrease but reutilization of elastic energy was maximized. However, with higher stiffness than natural MTP stiffness, MTP flexion was decreased so ankle torque lever arm was increased which caused decrease in propulsion force and increase in muscle activation duration. Lowest metabolic cost was also found with suggested optimal shoe stiffness. Suggested optimal shoe stiffness could be applied to running shoe design to get better running economy.