An energy generating system includes a first pair of elongate arms, having proximal and distal ends, configured for substantially symmetrically opposing reciprocal swinging motion in a substantially horizontal plane. Further embodiments comprise systems and software for implementing the above method and utilizing information obtained therefrom. In accordance with the invention, the rotatable handle is connected to the catch such that first a radially projecting locking member is inserted in a recess in axial direction and subsequently is brought into an axial locking position by a relative displacement so as to lock the handle in axial direction with the catch.