Exercising device for developing, strengthening and/or rehabilitating the muscles or joints of the body

A portable exercising device for developing, strengthening and/or rehabilitating muscles or joints of a body by working against a counterforce, comprising:

• a rotating body configured to retract a rope, a cord, a webbing or a cable wound around an exterior surface of the rotating body and having an end configured for being pulled by a user to exert a force;
• a transmission means connected to the rotating body;
• an electric motor directly connected to the transmission means and configured to drive or retard rotation of the transmission means, wherein the rotating body is located coaxially aligned to and around the electric motor, wherein:
• when the end is pulled, the electric motor and the transmission means retard rotation,
• when the end returns to the rotating body, the electric motor and the transmission means drive rotation of the rotating body rewinding the end, and
• the transmission means rotates at about a same angular velocity of the rotating body;
• a control unit connected to the electric motor and configured to command the electric motor during exercise of a specific motion based on an input value;
• means for supplying electrical current to the electric motor;
• and
• an attachment mechanism of the exercising device for fixing the exercising device on different training equipment or supports.