Benefit effects of exercise training are well known and validated after a cardiac event, but some patients fail to ameliorate their functional capacity. This retrospective study determined which parameters in the initial cardio pulmonary exercise test could predict an improvement of functional capacity after training in cardiac patients. 292 cardiac patients with a complete training intervention were divided in two groups at the end of their rehabilitation : one group with a gain equal or more than 1 MET (148 patients) and one group with a gain less than 1 MET (144 patients) when the initial and final cardio pulmonary exercise tests were compared. The cardiac event (coronary revascularization 38%, aortic valvular surgery 23%, coronary stenting 18%) was similar in both group. The initial peak VO2 was not different (100 watts vs 110 watts, 15.6ml/kg/min vs 16.1ml/kg/min) neither the ventilator threshold nor the training intervention (19.3 sessions vs 17.9). At the end of the exercise training intervention, the gain of peak VO2 was 4.1ml/kg/min (+28%) in the global population and 6.8 ml/kg/min (+46%) in the group ≥1 METS vs 1.29ml/kg/min (9.3%) in the group < 1 MET. Clinical predictor factors for a gain ≥1 MET were: age (58.3 years vs 62 * * p < 0,05 ), sex male (92% vs 83% * ), ejection fraction (LVEF 52,5% vs 49,9% ** ** p < 0,001 ). The initial discriminated exercise parameters were the energetic cost per watt (VO2/watt) 11,4 vs 12,2 ** the ventilatory cost (VE/watt) 0.62 vs 0.67 * , the intensity per body kilogram (watts/kg) 1.43 vs 1.31 * and the cardiac frequency per 1 liter of VO2 was lower 102 vs 110 * . The benefit on functional capacity after exercise training intervention depended more of the initial physical condition than of the cardiac pathology in patients discharged in our cardiac rehabilitation centers. The exercise training should be more directed by the initial excise test.