An apparatus to generate pressure support ventilation and a method to control pressure support ventilation. The apparatus comprises: at least one sensor adapted to measure at least one respiratory parameter; a flow generator adapted for coupling with a patient respiratory interface; and a controller, coupled to the at least one sensor and the flow generator. The flow generator is configured to provide a flow of breathable gas for pressure support ventilation to the patient respiratory interface. The controller is configured to control the pressure support ventilation with the flow generator. The controller is further configured with a rest mode and an exercise mode. The rest mode comprises a first value set of control parameters for the pressure support ventilation and the exercise mode comprises a second value set of control parameters for the pressure support ventilation.