Effects of Low-Intensity Aaerobic Training on Cardiac Dysfunction and Myocardial Fibrosis Induced by Doxorubicin in Wistar Rats.

Doxorubicin-induced cardiotoxicity is a major limitation in cancer therapy. Physical exercise has been proposed as a non-pharmacological strategy capable of mitigating these effects through cardiovascular adaptations. This study evaluated whether low-intensity aerobic training attenuates cardiac dysfunction induced by doxorubicin. Twenty-five adult male Wistar rats (450 and 500 g) were allocated and divided into four groups: Control (C), Doxorubicin (D), Doxorubicin and Trained (DT), and Trained (T). The D and DT groups received weekly intraperitoneal injections of doxorubicin over a four-week period, totaling a cumulative dose of 8 mg/kg. The DT and T groups underwent low-intensity aerobic training for 25 weeks, three times a week, with sessions lasting 10 to 20 min at 50 and 60% of maximum aerobic speed. Statistical analysis was performed using GraphPad Prism software (version 8.0). The D group showed a significant increase in myocardial collagen deposition and a reduction in S wave values (parietal and septal) on echocardiography, compared to the control group. The values observed were 0.040 for group D and 0.065 for group C in the parietal S wave (overall p = 0.0248), and 0.040 for group D and 0.070 for group C in the septal S wave (overall p = 0.0389). Regarding exercise tolerance, group D showed the greatest reduction in performance from Test 0 to Test 5 (65.06%; p < 0.0001), followed by group C (23.60%; p = 0.0103). Group DT showed a smaller numerical reduction in performance (23.07%), but this change did not reach statistical significance (p = 0.1256), while group T showed a non-significant numerical improvement (10.99%; p = 0.2020). The results suggest that low-intensity aerobic training may attenuate cardiac fibrosis and partially preserve functional capacity in rats with doxorubicin-induced cardiotoxicity.