Analysis of Torsional Mechanical Behavior of Adjustable Air Cushion Sole Structures: Impact Simulation on Cutting Maneuvers

Shoe design features and mechanical properties are crucial to human locomotion. This study investigated the effects of adjustable shoe sole configuration on the stiffness behavior of shoes under cyclic torsional loading to mimic real-world cutting effects.

Three shoe conditions were examined: (i) control shoes (CS) featuring adjustable air cushion shoe soles, (ii) midpart-altered shoes (MAS), and (iii) forepart-altered shoes (FAS), both modified the CS using adjustable elastomeric spacers in sole constructions. Shoes were secured in a specially designed fixture in a material testing machine and subjected to repeated torsional loading–unloading with angular displacements of 0–30° for inversion and eversion motion at an angular velocity of 1°/s.

A reliability test validated the experimental method for inversion TS, revealing good intra-session reliability (ICC (3, 1) = 0.71) and excellent inter-session reliability (ICC (3, k) = 0.87). Inversion TS showed a 35.38% increase for the MAS and a 6.15% increase for the FAS compared to the CS. Likewise, eversion TS increased by 29.82% for the MAS and 14.04% for the FAS compared to the CS. These results indicate that altering sole construction with adjustable spacers improved TS and might have the potential to lower the risk of ankle injuries during cutting. It can be inferred that shoes with greater TS may require less mechanical energy to stabilize the foot–ankle structure and that MAS might be a suitable option for sports. The MAS exhibited the highest TS, with values of 0.088 Nm/° during inversion and 0.074 Nm/° during eversion movements, compared to the CS and FAS. This suggests that components of the midpart sole region have a greater impact on TS, and changes in midpart sole construction could have a greater effect on TS characteristics. The findings underscore the importance of the midpart sole region over the forepart.

The adjustment of midpart sole configurations had a higher effect on the shoe’s torsional stiffness behavior, which might be important for enhancing performance during cutting movements in sports.