Effect of Different Volumes of High-intensity Interval Trainingon Serum Troponin I and Creatine KinaseMB Levels in Patients After Myocardial Infarction

Introduction: Serum levels of cardiac troponin (CTnI) and creatine kinase (CK-MB) are two indicators of cardiac cell damage. The present study aimedto investigate the effect of different volumes of a high-intensity interval training (HIIT) course on serum CTnI and CK-MB levels in cardiac patients after myocardial infarction (MI). Materials and Methods: In this semi-experimental study with pretest–posttest design, thirty patients (50.03±4.32 years) with documented MI were selected voluntarily. Regarding the researchcriteria, all participants were randomly assigned into three groups (n=10 per group): Acontrol group and two high-volume HIIT training (HV-HIIT) and low-volume HIIT training (LV-HIIT)groups.The HV-HIIT group did exercisesthree days a week for 40 minutes, and the LV-HIIT group didexercises three days a week for 20 minutes.Blood samples were taken before and after the 12-week intervention. Statistical analysis of the variables was performedusingpaired t-tests, one-way analysis of variance, and Tukey's post hoc test. Results: At the end of the intervention, CTnI in the LV-HIIT and HV-HIIT groups decreased significantly (70% and 50%, respectively); however, no significant change was observed in the control group. CK-MB levels showed a significant decrease (26%)only in the LV-HIIT group. In the serum levels of CTnI, a significant difference was observed amongthe three groups (p=0.035), and the results of Tukey's post hoc test showed a significant difference between the control and LV-HIIT groupsin terms ofdecreasedCTnI levels(p=0.012). Conclusion: LV-HIIT training as an exercise strategy for cardiac rehabilitation programs after MI can improve cardiac injury indices more effectively than HV-HIIT and is associated with less cardiac damage and fatigue.