Background: Matrix metalloproteinase enzymes (MMPs) play a destructive role in atherosclerosis resulting in occurrence of cardiac ischemia. The aim of this study was to investigate the effect of concurrent training during cardiac rehabilitation on plasma levels of MMP-9 and tissue inhibitor of metalloproteinase-1 (TIMP-1) in patients with myocardial ischemia. Methods: Sixteen cardiac ischemic patients who were in the process of clinical cardiac rehabilitation were randomly assigned to experimental (n = 8) or control (n = 8) groups. The patients in experimental group performed concurrent exercise for eight weeks (one hour / three session per week) with the intensity of 40-60% of one repetition maximum and 60-80% maximum heart rate. Pre- and post-intervention blood samples were taken to assess plasma MMP-9 and TIMP-1 concentrations using ELISA method. Findings: Independent T-test showed the patients in experimental group had a significant decrease (t = 2.431; p = 0.029) in MMP-9 plasma concentration and a significant increase (t = 3.202; p = 0.006) in plasma levels of TIMP-1 compared to the control group. A significant within-group reduction in MMP-9 levels (t = 0.695; P = 0.008) and a significant within-group increase in TIMP-1 levels (t = 3.964; P = 0.005) were observed in the experimental group, while the pre- to post-value changes in MMP- 9 and TIMP-1 levels in the control group were not statistically significant. Conclusion: It seems that the favorable changes in MMP-9 and TIMP-1 following eight weeks of physical exercise prevent the progression of atherosclerosis and recurrence of cardiac ischemia during the process of cardiac rehabilitation

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