Background: Cardiac rehabilitation in patients after myocardial infarction (MI) is a component of secondary prevention that has an established role in the current guidelines.

Aim: To determine the effect of physical training on exercise capacity parameters determined on the basis of cardiopulmonary exercise test (CPET) in patients after MI. We also evaluated the relationship between the number of training sessions and exercise capacity.

Methods: We prospectively evaluated 52 patients after MI who underwent percutaneous coronary intervention of the infarct-related artery. At the start of the training, patients had no symptoms of heart failure and coronary artery disease. Electrocardiographic exercise test was performed 4 to 6 weeks after MI, followed by CPET in patients with a negative stress test. After determination of the initial exercise capacity, patients underwent 12 training sessions on a cycle ergometer with a workload determined on the basis of anaerobic threshold or heart rate reserve. After 12 training sessions, CPET was performed, followed by another 12 training sessions and a follow-up CPET.

Results: All patients showed a significant increase in exercise capacity parameters: energy expenditure during CPET increased from 9.39 to 11.79 METs, peak oxygen uptake (VO₂peak) increased from 32.32 to 39.25 mL/kg/min (p < 0.001), and oxygen uptake at the anaerobic threshold increased from 18.34 to 24.65 mL/kg min (p < 0.001). The initial 12 training sessions resulted in a statistically significant increase in VO₂peak from 32.32 to 36.75 mL/kg/min (p = 0.003), while subsequent 12 training sessions were related with an insignificant increase in VO₂peak from 36.75 to 39.25 mL/kg/min (p = 0.065).

Conclusions: Regular physical activity improves exercise capacity as measured by CPET. A statistically significant improvement in exercise capacity was seen already after initial 12 training sessions, while another 12 training sessions were associated with smaller benefits.