According to certain aspects, the invention includes a limb-exercising system for coupling (i.e., attaching, retrofitting) to or manufacturing with the swivel chair. The limb-exercising system includes a rigid framework, at least one limb-exercising unit, a force resistor and a cable. The rigid framework includes at least one chair coupler that couples the rigid framework with the swivel chair (e.g., so that the limb-exercising apparatus is disposed underneath the chair leg base), such that the relative movement between the rigid framework and the swivel chair is minimal. The rigid framework is coupled with the limb-exercising unit and with the force resistor, which in turn is coupled with the limb-exercising unit via the cable. The limb-exercising unit is operative to provide movement exercise for at least one muscle group of the body of a user.