Prospectively, we studied 42 patient to evaluate the usefulness of treadmill exercise to programme pacemaker DDD in relation to the functioning upper frequency (relation between block frequency of pacemaker and the upper rate frequency). We excluded patient who had no treadmill exercise test after implant pacemaker. During stress 7 (17%) patient presented AV conduction 1:1 (group I); 16 (38%) second degree AV block type Wenckebach (group II); 14 (33%) second degree AV block 2:1 (group III); and 5 (12%) showed inhibition of the pacemaker by intrinsic activity (group IV). Block frequency of the pacemaker in group I and II was superior in regard of the upper rate frequency, 156.85 +/- 22.16 vs 141.43 +/- 20.82 and 135.25 +/- 11.54 vs 121.25 +/- 5.9, respectively. In group III and IV, it was lower, 120.36 +/- 15.31 vs 138.57 +/- 13.29 and 121.0 +/- 7.38 vs 142.0 +/- 14.39. The comparative analysis of the block frequency of the pacemaker in relation with the upper rate frequency showed statistically significant differences (p < 0.05) between groups I and II, and between the group I and III. The appearance of second degree AV block 2:1 is nonphysiologic, is rather due to an abrupt falling in the cardiac output. This phenomenon is able to be predicted and corrected by programming with the use the telemetry with parameters as the AV delay, as well as upper rate frequency and post-ventricular refractory atrial period.