Practical aspects: Physical exercise is a basic component of the rehabilitation program for patients recuperating from myocardial infarction or bypass surgery. The aim of exercise is to enhance physical performance by improving coordination, flexibility, strength, speed and endurance. The training concept is matched to the individual capability, which is determined by an exercise test at the beginning of the rehabilitation program. On the basis of this test, an "exercise heart rate" is calculated with the aim of protecting the patient from overstrenuous activity. Depending on their physical fitness, the patients are divided into two groups: those with a capability of less, and those with a capability of more than 1 watt/kg. Most elderly patients are no longer active participants in sports, so that guidance through flexibility and coordination exercise is offered. Usually, patients perform a daily program of 15 minutes of physical activity in their individual groups, and spend 45 minutes walking and relaxing. In addition, they have opportunities for swimming, jogging and cycling. Decreased left-ventricular function: The effects of a four-week training program in myocardial infarction (MI) patients with moderate-to-severe left-ventricular dysfunction were investigated in two distinct studies. In neither study was a deterioration in the ejection fraction at rest or during exercise observed. In the second study, an additional parameter was provided by the Swan-Ganz catheter. Neither pulmonary wedge pressure (PWP) nor cardiac output indicated any deterioration in response to dosed training. However, in this second study, four patients in the training group with a resting ejection fraction (EF) less than 30% developed complications. All these patients had a pathological PWP at rest. Nevertheless, five patients with an EF less than 30% but with a normal PWP at rest completed the training program without complications. The long-term prognosis for training post-MI patients with severe left-ventricular dysfunction would appear to be no worse than for controls. Results of the first study: During the four-week training program, no complications occurred. No major changes in the EF at rest and during training were seen. In the training group the EF at rest increased slightly to 40 +/- 10%. The EF during exercise improved to 39 +/- 10%. Delta EF showed a decrease of 3 +/- 8%. After the four-week training period the decrease was 1 +/- 9%. In the control group, a major increase in the EF at rest to 41 +/- 10% was seen. The EF during exercise, however, showed only a small increase to 43 +/- 15%.(ABSTRACT TRUNCATED AT 400 WORDS)