Background and objectiveLithium medication, given its significant role in the treatment or reduction of psychiatric disorders, may exert adverse effects on cardiac tissue. Therefore, this study aimed to investigate the effects of different exercise training intensities on the process of cardiac apoptosis and serum levels of cardiac troponin I (cTnI) resulting from lithium administration in male Wistar rats. MethodologyIn the present experimental study, 35 male Wistar rats were randomly divided into five groups (n=7); Control (CTL), Lithium (Li), High-Intensity training + lithium (HIT-Li), Moderate-Intensity training + lithium (MIT-Li), and Low-Intensity training + lithium (LIT-Li). Lithium drug (dose of 40mmol/kg dry food weight) and exercise training (5 days per week) were administered for eight weeks. Serum levels of cTnI, mRNA expression of Bcl-2, Bax, and Caspase-3, and histopatholigical changes were assessed by using the ELISA method, Real-Time PCR, and H&E staining, respectively. ResultsThe expression of the Bcl-2 gene was significantly increased in the LIT-Li group compared to the Li group (P = 0.003). Serum levels of cTnI were considereably higher in the Li group compared to the MIT-Li group (P = 0.0001). The expression of the Bax gene, in the LIT-Li, HIT-L, and Li groups, significantly increased compared to the MIT-Li group (P = 0.0001). Histopathological scores decreased in MIT-Li compared to Li group (P = 0.001). ConclusionIt seems that among different exercise intensities, the greatest protective effect against lithium consumption can be observed with moderate exercise intensity, which may potentially modulate factors influencing cardiac apoptosis and reduce lithium toxicity in the cardiac tissue of rats.