Background: Intense physical activity increases the production of reactive oxygen species in vital tissues such as the liver and causes oxidative stress. Aim: This study investigates the effect of high-intensity interval training and intense endurance training on oxidative stress of liver tissue in immature male rats during puberty. Materials and Methods: A total of 24 male Wistar rats (aged= 22 days, weight= 60±0.63 g), after one week of acclimatization, were divided randomly into three groups: control, IET, and HIIT. Rats were subjected to a four-week training on an animal treadmill. The effects of training treatment in rat liver were investigated by assaying oxidative stress biomarkers. Results: Comparing to control group, in both training groups significantly lower Malondialdehyde (MDA) was seen (( P (IET)= 0.016/ P (HIIT)= 0.020). However, there were no statistical differences in Glutathione Peroxidase (GPX) ( P = 0.463) and total antioxidant capacity (TAC) activity levels ( P = 0.194) among groups. HIIT training significantly increased superoxide dismutase (SOD) ( P = 0.040) and catalase enzyme (CAT) levels ( P = 0.007). IET and HIIT had significantly increased endurance performance (both: P = 0.001). Conclusion: Both training intensities did not lead to an increase in oxidative stress and can be used during puberty.
