A control system for controlled exercise controls a functional electrical stimulation (FES) system which applies electrical signals to muscle groups of a user such as a user having a disability; the user exercises on a motor driven exercise machine such that substantially isokinetic exercise during a movement is obtained as the user's body part moves with a motor driven displaceable element of the machine. This element provides resistance to applied displacement load from the user's stimulated muscles. A feedback control system receives signals indicative of the user's performance and a control arrangement controls electrical stimulation to the user's muscles to achieve a desired exercise regime.