Abstract Background and aims: One of the most important potential problems of radiotherapy is the heart problem caused by this treatment. Therefore, this research aimed to investigate the effect of 8 weeks of moderate-intensity endurance training on the serum levels of troponin I (TNI) and brain (B-type) natriuretic peptide (BNP) in rats undergoing radiation therapy. Methods: In this experimental study, 32 male rats (4-6 months) were randomly divided into four groups of eight, including healthy control (C), aerobic training (AT), radiotherapy (RT), and AT+RT groups. First, rats were anesthetized with ketamine-xylazine solution (K: 60-90 kg/mg, Z: 6-10 kg/mg) and then located on a Plexiglas plate with a thickness of 1 cm. Photon beam RT was performed using X-rays with a dose of 11 Gy from an Elekta compact linear accelerator (Elekta Compact 6-MV China). AT program was performed for eight weeks, five days a week, and one session a day for 60 minutes (70-75% of maximal oxygen consumption). Finally, one-way ANOVA was run to examine the research variables. Results: The results showed that there was no significant difference between the groups in terms of the TNI level (P=0.23). However, a significant difference was found in the amount of BNP between the RT and C groups (P=0.009). In addition, no significant difference was reported in terms of BNP between AT+RT with AT (P=0.99), RT (P=0.32), and C (P=0.69) groups, as well as between AT with RT (P=0.1) and C (P=0.99) groups. Conclusion: Overall, radiation therapy caused a significant increase in BNP, but it had no significant effect on TNI. Aerobic training did not significantly affect TNI and BNP in healthy rats and those undergoing radiation therapy.
