Background: Apoptosis or programmed cell death plays an important role in the development of cardiovascular diseases, particularly heart failure. Current evidence suggests that exercise training may alter apoptosis-related signaling in sensitive somatic tissues such as the myocardium.

Objectives: The aim of this study was to assess the effect of exercise training on Bcl-2 and Bax genes expression as key molecules involved in intrinsic pathway of apoptosis in the rat heart.

Materials and Methods: This study was conducted with a two-group experimental design (animal model) and sixteen three-month-old male rats were selected and randomly divided to two groups of exercise training (n = 8) and control (n = 8). Rats in the trained group participated in an exercise training program for 12 weeks (10 – 60 m min^-1, 24 – 33 min d^-1, 15%). The rat hearts were removed forty-eight hours after the last training session. RNA extraction and synthesis of cDNA was done, and Bax and Bcl2 genes expression was analyzed through the Real Time-Polymerase Chain Reaction (RT-PCR). Kolmogorov-Smirnov and independent t-test were applied for statistical analysis of the data (P < 0.05).

Results: The results showed that Bax gene expression and Bax/Bcl2 ratio of the trained group were significantly lower than the control group, 81% and 89%, respectively (P < 0.05). Moreover, there was no significant difference between the two groups in Bcl2 (P > 0.05). However, Bcl2 expression was higher in the trained group compared to the control group (11%).

Conclusions: In general, it seems that three-month exercise training was effective in reducing cardiac mitochondrial pro-apoptotic protein. However, considering the results of the Bcl2 gene expression, more researches are needed to identify effects of exercise trainings on indices of myocardial apoptosis.