Physics-based deformation models are applied to in vivo imaged organ data to reconstruct both shape and motion. Specific instances where such models can be applied are crash simulations, virtual surgery, blunt or penetrating trauma assessment, shape and motion recovery from CT, MRI and/or SPAMM data, recovery of human motion from video or range data. The SPAMM technique imprints a magnetic grid into tissue so that the motion of the grid intercepts can be detected and tracked even in the absence of observable anatomical features. Such information provides a means for assessing an athlete's fitness, for modeling and describing heart motion for disease diagnosis, and for estimating and simulating blood flow. Jinah Park has been able to model and quantify the shape and motion of the left ventricle using deformable models with a small number of ``intuitive'' parameters such as elongation and twisting. Based on the Lagrange equations of motion, these deformable meshes are fit to sequences of time-varying SPAMM data [31].