Systems, devices, and methods are disclosed for limiting the duration of elevated pacing rates in an implantable medical device. An illustrative device may include a housing, a plurality of electrodes connected to the housing, and a controller within the housing and connected to the electrodes. The controller may deliver pacing pulses to the electrodes at a base pacing rate, detect a measure of elevated metabolic demand which may vary over time, deliver pacing pulses at an elevated pacing rate based on the measure of elevated metabolic demand. The controller may change a heart stress tracking value (HSTV) when the pacing rate is elevated and may be changed faster during times of relatively higher elevated pacing rates than times of relatively lower elevated pacing rates. The elevated pacing rate may be reduced back toward the base pacing rate after the HSTV crossed a predetermined heart stress threshold.