Apparatus and methods for rehabilitating a muscle are provided including one or more electrodes configured to be positioned in or adjacent to tissue, one or more sensors configured to sense muscle contraction and to generate a sensor signal based on the muscle contraction, and a pulse generator operatively coupled to the one or more electrodes, e.g., via a lead, and having a controller configured to receive the sensor signal and to adjust the stimulation frequency based on the sensor signal to cause the muscle to contract where muscle contraction is smooth and continuous.
