A method of developing a respiration pacing signal includes detecting respiration and movement activity in an implanted patient and developing corresponding respiration and movement signals. A respiration pacing signal is synchronized with the detected respiration activity and delivered to respiration neural tissue of the implanted patient to promote breathing of the implanted patient. A plurality of respiration sensing modes are used that reflect activity of the movement signal over time to optimize system power consumption over time, including: i. an active respiration mode when the movement signal is either actively changing or remains unchanged for a brief period less than some reduced activity period, wherein the respiration signal is measured continuously, and ii. a plurality of reduced activity respiration modes when the movement signal has remained unchanged for the reduced activity period, wherein the respiration signal is measured only during a limited respiration sampling period.
