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Purpose: Physical exercise has been shown to be protective against colon carcinogenesis. Physical exercise, however, covers a wide range of modalities, from which different effects on the human body have been reported. We sought to clarify whether aerobic and resistance trainings would differently affect the development of early carcinogenic events in the colon. Methods: Male BALB/c, C57/BL6, and interleukin 10 knockout (IL-10~ , on C57/BL6 background) mice were exposed to the carcinogen A-methyl-A'-nitro-A-nitrosoguanidine. BALB/c mice were subjected to either aerobic (swimming) or resistance trainings (climbing a ladder with load attached to the tail). C57/BL6 and IL-10- _ mice only swam. Results: In BALB/c carcinogen-exposed mice, aerobic and resistance trainings decreased serum creatine kinase levels (P< 0.001). Although aerobic and resistance trainings reduced the generation of lipid thiobarbituric reactive species (P< 0.01 and P< 0.001), only aerobic exercises enhanced serum glutathione levels aside from carcinogenic exposure (P < 0.05). Carcinogen-exposed and aerobic-trained mice developed 36% less colon preneoplastic lesions than its control group (P < 0.05). Aerobic training reduced colonic subepithelial cyclooxygenase-2 expression in carcinogen-exposed mice (P < 0.001). Interestingly, in this same group, colonic IL-10 expression was upregulated sevenfold (P < 0.001). Current findings were confirmed in C57/BL6 carcinogen-exposed mice, in which aerobic training promoted antipreneoplastic effects (P < 0.05). Knocking IL-10 out o f C57/BL6 mice abrogated antipreneoplastic effects of aerobic training on the colon tissue (.P > 0.05). Conclusions: IL-10 is a pivotal element for antipreneoplastic effects of aerobic training on the colon. [ABSTRACT FROM AUTHOR]