In this book, a subject specific three dimensional finite element foot model has been developed based on computer tomography images and validated with subject specific biomechanical tests. The model was successfully used to study deformation of the foot during normal/inversion landing and to develop a new concept of using under calcaneus area plug in the midsole for heel pressure relief. The FE model incorporated realistic component structures and material properties of the soft tissues, which was validated by subject specific in vivo indentation tests. The plantar pressure was assessed in controlled balance standing tests and the data were used to validate the FE model and establish the optimum loading conditions and meshing scheme through mesh sensitivity tests. The validated model, combined with specially designed biomechanical test, was then used to simulate the foot deformation in landing and to predict the effects of UCA plugs of different materials and sizes on the heel pressure distribution.