Musculoskeletal shoulder models have been used for many different applications. Up till now, these models have not been suited to operate in a real-time environment. This study uses the most cited and used musculoskeletal shoulder model in the field, Delft and Elbow and Shoulder Model (DESM), and changes the structure to make the model quicker. This is done with two approaches. First, the total model has been replaced by polynomials, which give the muscle forces as function of the input variables. Although this would reduce the calculation of the model significantly, results are unacceptable. The second approach was to replace a part of the model, within the kinematics module, by polynomials. This approach gave excellent results in accuracy and speed, although due to the limited amount of time of this project, a total model based on this principle has not yet been built.