The issue of whether exercise training improves exercise hyperpnea in patients after coronary arterial bypass graft (CABG) surgery has not been fully explored. Effects of short-term physical training on ventilatory response and cardiac output during exercise in patients following coronary arterial bypass grafting surgery is studied. Thirty-four patients underwent exercise training for 2 weeks after the second postoperative week (Ex group); 23 stayed sedentary (Sed group). Ventilatory and cardiac output response during the cardiopulmonary exercise test was measured before and after the training period. The minute ventilation-carbon dioxide output (VE-VCO2) slope decreased from 38.9+/-8.1 to 35.1+/-6.7 (p<0.05) in the Ex group, but failed to decrease in the Sed group (39.7+/-11.1 to 41.5+/-11.4). Cardiac output during exercise at 20W and at peak exercise, and peak oxygen pulse (VO2/HR) increased significantly only in the Ex group after training. There was a correlation between improvement of the VE-VCO2 slope and peak cardiac output during the training interval (r=-0.47) in the Ex group. Short-term physical training after CABG improves ventilatory response to exercise and increases cardiac output during exercise. Improvement of cardiac output is correlated with a decreased value of the VE-VCO2 slope.