Cardiac response of trained and untrained males to a repeated psychological stressor.

The authors examined cardiac response to repeated exposure to a psychological stressor of aerobically conditioned (n = 15) and unconditioned subjects (n = 15). Heart rate and electrocardiographic T-wave amplitude responses of 10 trials of the Stroop Test were monitored during and after performance. Both groups' adaptation patterns were similar, with a plateauing of heart rate response after the third trial. Compared with the unconditioned group, however, the aerobically conditioned subjects recorded lower absolute heart rate responses during and after the stressor for every trial. Relative heart rate responses during the stressor and recovery were similar for both groups. There was also no difference between groups in T-wave response during or after the stressor. These data suggest that absolute heart rate response during and after repeated exposure to a psychological stressor is lower for aerobically trained individuals.