Biomechanical Effects of Variable Stiffness Shoes in Normal Walking After 60-minute Adaptation

The use of variable stiffness shoes (VSS) has been found to be conducive to reducing external knee adduction moment (EKAM). However, it is still unknown whether the claimed biomechanical effects of VSS remain after the subjects have adapted to the footwear. The objective of the study is to examine the effects of VSS immediately upon usage, as well as its effects after 60 min of adaptation. It is hypothesized that the lowering of EKAM is not just the short term biomechanical response due to the immediate use of VSS. Twenty subjects were instructed to walk in three shod conditions which are walking in control shoes, walking in VSS, and walking in VSS after 60-min of adaptation. All of the dynamic exercises were recorded simultaneously by VICON Motion Systems (Oxford Metric, UK). The results showed that EKAM was significantly reduced with the immediate use of VSS (8.43%, p < 0.05), as compared to the control shoes. The reduction remained significant, even after the given 60-min adaptation time. The effect of VSS on the reduction of EKAM is found to be consistent, even after familiarization. The use of VSS is postulated to be helpful in alleviating the loading across the medial compartment of the knee joint.