Acute exercise is known to increase reactive oxygen species (ROS), contributing to oxidative stress. Although this relationship has been widely studied, most investigations rely on indirect biomarkers and endurance-based exercise models. Resistance-circuit training, however, remains underexplored in this context. This study aimed to evaluate the time-dependent effects of rest and a novel resistance-based high-intensity interval training (HIIT) protocol on ROS and Interleukin-6 (IL-6) levels in sedentary, healthy young women. Thirty participants completed a resistance-circuit HIIT protocol. Capillary blood samples were collected at four time points: Baseline (after overnight fasting), after a two-hour seated rest, immediately post-HIIT and 15-min post-HIIT. ROS levels were measured using electron paramagnetic resonance (EPR) spectroscopy, and IL-6 via high-sensitivity ELISA. A significant decline in ROS (-8.5 %, p < 0.001) and IL-6 (-12.3 %, p < 0.05) occurred during rest. Throughout HIIT, both markers increased significantly (ROS +12.3 %, p < 0.001; IL-6: +48.1 % p < 0.01), with partial reductions observed after 15 min (ROS: -6.9 %, p < 0.01; IL-6: -20.4 %, p < 0.01). These findings suggest that resistance-based HIIT can serve as a valid model for studying acute oxidative and inflammatory responses in exercise science, offering a complementary approach to traditional endurance-focused protocols.