To improve postural stability in individuals with dystonic cerebral palsy, the concept of a dynamic seat has been suggested as a potential solution. An experimental set-up for the acquisition of movement during extensor thrusts while sitting on a seating system was defined and applied on a group of dystonic individuals, to compare a dynamic versus a rigid seat system, using quantitative movement analysis. The seating system in dynamic configuration is able to reduce the extensor thrust experienced by the consumers, as well as to increase range of motion in the anterior–posterior direction, limiting the sliding down of trunk and showing better upper limb smoothness during extensor thrusts. The procedures used in this study appear to provide a useful tool for better understanding how the concept of a dynamic back in a seat system may affect and influence position and stability of individuals with dystonia on the seat system.