The invention relates to cardiac rhythm management systems, and more particularly, to rate adaptive cardiac pacing systems and methods. In an embodiment, the invention includes a method for providing rate-adaptive cardiac pacing therapy from an implantable medical device, the method including sensing a pulmonary function of a patient； determining a rate of change in the pulmonary function； sensing a cardiac function of the patient； determining a rate of change in the cardiac function； and calculating a target pacing rate based on an existing pacing rate, the rate of change in the pulmonary function, and the rate of change in the cardiac function.
