A wrist exerciser includes a casing comprised of upper and lower casing members mounted together to form a substantially spherical shape. A rotor has opposite shafts rotatably received in the holes defined in the casing for rotatably supporting the rotor in the casing. Illumination elements are mounted on an outside surface of the rotor. A power source is fixed in the rotor for powering the illumination elements. A control circuit is in electrical connection with the power source and the illumination elements for selectively lighting the illumination elements. A transmission device is mounted in the rotor and has an interface circuit connected to the control circuit and a socket connector in connection with the interface circuit. A transmission cable has opposite ends forming first and second connectors, wherein the first connector is mateable with the socket connector of the transmission device of the rotor and the second connector is engageable with for example a personal computer for transferring control programs from the external device to the control circuit.