"Wearing sub-optimally fitted lower limb prosthesis cause disorders of the stump that strongly lessens the well-being and the performance of an amputee. As experimental measurements are currently not capable of providing enough insights in the dynamic behaviour of the stump, simulations need to be employed to achieve the necessary knowledge gain to significantly improve the socket design and, hence, to increase the amputee’s well-being and performance. The overall goal of this proposal is to provide the enabling technology in form of novel computational and experimental methodologies to assist the design process of next-generation prosthetic devices. The focus hereby is to gain a better understanding of the dynamics of the musculoskeletal system of a lower extremity amputee, here, the stump of an above-knee amputee. To achieve this, LEAD pursues two aims. The first and main aim focuses on substantially changing existing modelling philosophies and methodologies of forward dynamics approaches such that they are capable of representing muscles, bone, and skin as 3D continuum-mechanical objects. To counteract the increase of computational cost by switching from 1D lumped-parameter models to 3D models, novel, elegant, and efficient algorithms, e.g. nested iteration techniques tuned for efficiency through model-based coupling strategies and optimised solvers, need to be developed. The second aim is to experimentally measure physical quantities that provide the necessary input to drive the forward dynamics model, e.g. EMG, and to provide means of validation, e.g. with respect to pressure measurements, ultrasound recordings, and motion capture. Given the non-existing field of forward dynamics appealing to continuum-mechanical skeletal muscle models, LEAD creates a new field of research."