A Methodology to Investigate the Relationship between Lower-Limb Dynamics and Shoe Stiffness Using Custom-Built Footwear

It has been demonstrated that, by varying the mechanical properties of footwear, the sprinting performance can be improved. It has been hypothesized that, for maximal performance, tuning the shoe stiffness to the requirements of the athlete is necessary. The aim of this study was to investigate the feasibility of using sprint shoes constructed with selective-laser-sintered Nylon 12 sole units for sprint-related jump tasks and to examine whether adaptations to the mechanical properties of the footwear were sufficient to elicit changes to lower-limb dynamics during athletic performance. An internationally competitive sprinter completed sprint-related jump metrics in various selective-laser-sintered shoes with bending stiffnesses of 9 N, 24.5 N, and 38 N in flexion and 7.4 N, 14.7 N, and 26.1 N in extension. The participant performed best in the medium-stiffness shoe for squat jumps and the maximum-stiffness shoe for bounce drop jumps. This investigation has demonstrated that selective laser sintering can produce high-integrity footwear with markedly different mechanical properties. Such footwear, coupled with an appropriate test method, has been shown to be suitable for investigating the relationship between lower-limb dynamics and shoe stiffness.