Interaction of running shoe midsole hardness and bending stiffness on the lower-limb joints mechanics

Abstract

Recent racing shoes, represented by the NIKE Vaporfly, have similar characteristics, such as lighter and softer midsole materials, a curved carbon plate inside the midsole, and thicker midsoles with rocker construction. Carbon plates seem to play a role in maintaining rocker construction (Nigg et al., 2020) because softer midsole materials would lead to a more deformable shoe shape. Although a previous study reported that a softer midsole enhanced running economy (Worobets et al., 2014), Nigg et al. claimed that shoe construction was more effective in improving running performance (Nigg et al., 2020). Other studies have indicated that the combination of these features could enhance running economy; however, there is no biomechanical evidence yet (Patoz et al., 2022).