An implantable medical device, IMD, implantable within a patient's heart, the IMD comprising: two or more sensors including a motion sensor; a controller operatively coupled to the two or more sensors, the controller configured to: identify (502; 802) a plurality of heart beats using one or more of the sensors, each of the plurality of heart beats having a systole phase and diastole phase; identify (504; 804) each of two or more of the plurality of heart beats as an intrinsically initiated heart beat or a pace initiated heart beat; identify a calibration time window, and during the calibration time window: identify a baseline intrinsic motion level by identifying a motion level of the IMD using the motion sensor during N intrinsically initiated heart beats, where N is greater than two; identify a baseline pace motion level by identifying a motion level of the IMD using the motion sensor during N pace initiated heart beats, where N is greater than two; determine an offset based at least in part on the baseline intrinsic motion level and the baseline pace motion level; after the calibration time window: for an intrinsically initiated heart beat that immediately follows a pace initiated heart beat, identify (506; 808) a motion level of the IMD using the motion sensor and apply the offset, and compare (508; 810) the identified motion level of the IMD with the applied offset to a motion level of the IMD identified for the immediately preceding pace initiated heart beat, and identify (510; 812) a motion level of the patient based at least in part on the comparison; and set (518; 822) a pacing rate parameter based at least in part on the identified motion level of the patient. two or more sensors including a motion sensor; a controller operatively coupled to the two or more sensors, the controller configured to: identify (502; 802) a plurality of heart beats using one or more of the sensors, each of the plurality of heart beats having a systole phase and diastole phase; identify (504; 804) each of two or more of the plurality of heart beats as an intrinsically initiated heart beat or a pace initiated heart beat; identify a calibration time window, and during the calibration time window: identify a baseline intrinsic motion level by identifying a motion level of the IMD using the motion sensor during N intrinsically initiated heart beats, where N is greater than two; identify a baseline pace motion level by identifying a motion level of the IMD using the motion sensor during N pace initiated heart beats, where N is greater than two; determine an offset based at least in part on the baseline intrinsic motion level and the baseline pace motion level; after the calibration time window: for an intrinsically initiated heart beat that immediately follows a pace initiated heart beat, identify (506; 808) a motion level of the IMD using the motion sensor and apply the offset, and compare (508; 810) the identified motion level of the IMD with the applied offset to a motion level of the IMD identified for the immediately preceding pace initiated heart beat, and identify (510; 812) a motion level of the patient based at least in part on the comparison; and set (518; 822) a pacing rate parameter based at least in part on the identified motion level of the patient. identify (502; 802) a plurality of heart beats using one or more of the sensors, each of the plurality of heart beats having a systole phase and diastole phase; identify (504; 804) each of two or more of the plurality of heart beats as an intrinsically initiated heart beat or a pace initiated heart beat; identify a calibration time window, and during the calibration time window: identify a baseline intrinsic motion level by identifying a motion level of the IMD using the motion sensor during N intrinsically initiated heart beats, where N is greater than two; identify a baseline pace motion level by identifying a motion level of the IMD using the motion sensor during N pace initiated heart beats, where N is greater than two; identify a baseline intrinsic motion level by identifying a motion level of the IMD using the motion sensor during N intrinsically initiated heart beats, where N is greater than two; identify a baseline pace motion level by identifying a motion level of the IMD using the motion sensor during N pace initiated heart beats, where N is greater than two; determine an offset based at least in part on the baseline intrinsic motion level and the baseline pace motion level; after the calibration time window: for an intrinsically initiated heart beat that immediately follows a pace initiated heart beat, identify (506; 808) a motion level of the IMD using the motion sensor and apply the offset, and compare (508; 810) the identified motion level of the IMD with the applied offset to a motion level of the IMD identified for the immediately preceding pace initiated heart beat, and identify (510; 812) a motion level of the patient based at least in part on the comparison; and set (518; 822) a pacing rate parameter based at least in part on the identified motion level of the patient.