RESUMEN
Doxorubicin is associated with cardiotoxicity, and physical exercise seeks to minimize the toxic effects of doxorubicin through physiological cardiac remodeling, as well as the reduction of oxidative stress, evidenced by previous studies. This study aimed to analyze whether running training before treatment with doxorubicin influences tolerance to physical exertion and cardiotoxicity. Thirty-nine male Wistar rats, aged 90 days and weighing between 250 and 300 g, were divided into 4 groups: Control (C), Doxorubicin (D), Trained (T), and Trained + Doxorubicin (TD). Animals in groups T and DT were submitted to treadmill running for 3 weeks, 5 times a week at 18 m/min for 20-30 min before treatment with doxorubicin. Animals in groups D and DT received intraperitoneal injections of doxorubicin hydrochloride three times a week for two weeks, reaching a total cumulative dose of 7.50 mg/kg. Our results show an increase in total collagen fibers in the D group (p = 0.01), but no increase in the TD group, in addition to the attenuation of the number of cardiac mast cells in the animals in the TD group (p = 0.05). The animals in the TD group showed maintenance of tolerance to exertion compared to group D. Therefore, running training attenuated the cardiac damage caused by the treatment with doxorubicin, in addition to maintaining the tolerance to exertion in the rats.