Reasonable agreement was obtained between the model and volunteer study in terms of bulk deformation of calf tissue for cuffs 3 and 4 using a plane strain assumption for the out-of-plane boundary condition (Fig. 4). In contrast, for cuffs 1 and 2, the agreement between the MR images and the model was not as close. The MR images showed that, for cuffs 1 and 2, the cross-sectional area of the calf under the cuff was clearly reduced suggesting either, that the material is compressible which is unlikely given typical behaviour of soft tissues [8], or that there is significant deformation in the out-of-plane direction. These observations led to the decision to implement a plane stress boundary condition