The present invention relates to devices and methods for exercising the lower limbs, in particular for exercising lower limbs. The devices are suitable for training the lower limbs of persons suffering from paraplegia or hemiplegia or musculoskeletal disorders in general. In some aspects, the present invention relates to powered articulated systems (ASs) and to the rehabilitation by aid of said ASs. The parallel or hybrid ASs of the invention are based on a parallel or hybrid, lambda-type framework and are controlled by a data processing unit. The ASs are preferably controlled by a closed-loop, real time control system.