Changes in serum biochemical responses during cardiac rehabilitation

The objective of the study was to establish the difference in the exercise response profile of the enzymes lactate dehydrogenase (LDH), lactate dehydrogenase isoenzyme 1 (LDH-1), creatine kinase (CK), and creatine kinase polypeptide subunit MB (CK-MB) after a 12-wk cardiac rehabilitation exercise program.

Nineteen male nonblockade recent postmyocardial infarction patients (PMIP), aged 60.7 +/- 6.5 yr, performed a graded exercise test on a motorized treadmill until volitional cessation or reaching any of the American College of Sports Medicine criteria. After this, a 12-wk exercise-based cardiac rehabilitation program was adopted at a frequency of 3x wk-1. Each subject was then retested using the same protocol and intensity. Blood samples were collected by venipuncture from the antecubital vein into Vacutainer tubes preexercise, immediately, postexercise, and 24 h later. The blood samples were then centrifuged to obtain serum before being transported to the laboratory for enzymatic analysis by conventional methods.

a) a 12-wk cardiac rehabilitation exercise program had no influence on the serum activities of enzymes at rest; b) the same exercise reduced the enzyme activity level after training; and c) LDH and CK values returned to normal faster after the program.

These findings provide further evidence for the benefits of exercise-based cardiac rehabilitation and demonstrate that an exercise test provokes a temporary serum enzyme response, which does not reflect myocardial damage.