A rate responsive cardiac pacemaker for providing an optimized pacing rate of stimulation pulses as a function of at least one selected rate control parameter. Each rate control parameter has a value which varies as a function of changes in a patient's physiologic demand and includes a sensor system for sensing the rate control parameter value and for providing a sensor output representative thereof. The cardiac pacemaker also includes control circuitry which includes a rate response defining means for deriving desired pacing rates as a function of the sensor output and an achievement monitoring means that has a predetermined achievement criterion, for monitoring the relationship between the derived pacing rates and the achievement criterion over an optimization period. An output circuitry provides optimized pacing rates as a function of the desired pacing rates, such optimization being accomplished by adjusting the rate response function for each sensor as a function of of the monitored achievement relationship. Another optimization function is provided by adjusting a sensor weighting value which weights or regulates the relative contribution each sensor's derived desired pacing rates will contribute toward the pacemaker-derived optimized pacing rates, such sensor weighting value being adjusted as a function of the monitored achievement relationshp, or as a function of the sensor gain optimization activity, as desired.