The aim of this study was to assess the effectiveness of an early predischarge exercise therapy, started 2 weeks following acute myocardial infarction (AMI), to working functional capacity. Seventeen AMI patients (10 males, 7 females, mean age 62 +/- 11 years) were examined in this study. Six, serious clinical symptoms and complications, were excluded, while the remaining 11 patients completed, the whole exercise therapy protocol (2 weeks). Patients performed exercise performed for 20-30 min twice daily at a target heart rate (90% level of heart rate at AT) on the basis of anaerobic threshold (AT) determined using treadmill ramp exercise with our protocol. Heart rates (HR) at rest, warming-up and AT point decreased significantly (p less than 0.05) after exercise therapy, although peak HR remained unchanged. O2 pulse at the AT point and endpoint, after exercise therapy, improved significantly (p less than 0.05), when compared to that before therapy. Moreover, AT and peak VO2 improved remarkably (p less than 0.05), as did exercise time to the AT point and endpoint after exercise therapy (p less than 0.05), when compared to that before therapy. These results indicate that the predischarge early exercise therapy begun 2 weeks after AMI will be effective and beneficial in improving working capacity with improvement of physical deconditioning. Additionally, it is necessary that patients with severe clinical symptoms and complications be excluded.