A cam system for an assistive device and related methods are disclosed. The cam system may comprise a cam profile and a cam follower. The cam profile has a curved outer edge comprising a concave portion. The cam follower is positioned within the concave portion when the assistive device is in an equilibrium position. The assistive device may further comprise a spring that deflects in response to a force applied by the cam system. The assistive device may have a sliding element to adjust the stiffness of the spring in deflection. The assistive device may take the form of a prosthesis or an orthosis.
