Acute and Long-Term Effects of Spinning-Based High-Intensity Interval Training on Inducible Nitric Oxide Synthase: A Randomized Controlled Trial

Uysal, A and Soslu, R. Acute and long-term effects of spinning-based high-intensity interval training on inducible nitric oxide synthase: a randomized controlled trial. J Strength Cond Res XX(X): 000-000, 2026-This study investigated the acute and long-term effects of a 6-week high-intensity interval training (HIIT) spinning program on oxidative stress and inflammatory biomarkers, including inducible nitric oxide synthase (iNOS), in physically active male university students. Subjects were randomly assigned to an experimental group (n = 10), which completed the supervised HIIT intervention, and a control group (n = 10), which maintained their habitual physical activity. Acute physiological stress was elicited using the 30-15 Intermittent Fitness Test (30-15 IFT), and venous blood samples were collected immediately before and after the 30-15 IFT, both before and after the intervention. Analyses included total antioxidant capacity, total oxidant capacity, oxidative stress index, paraoxonase 1, arylesterase, and iNOS. The acute exercise (30-15 IFT) performed did not lead to significant changes in biochemical parameters in either group. Long-term spinning-based HIIT resulted in significant increases in resting pretest values in the experimental group, with total antioxidant capacity significantly increased (p < 0.001), suggesting enhanced endogenous antioxidant defense. This was accompanied by a significant increase in total oxidant capacity (p < 0.007) and oxidative stress index (p < 0.032), indicating elevated oxidative load and systemic redox imbalance. A marked increase in paraoxonase 1 activity (p < 0.001) further reflected adaptive upregulation of antioxidant enzyme systems. However, no significant changes were detected in arylesterase activity or iNOS levels. In conclusion, the findings indicate that spinning-based HIIT elicits selective biochemical responses, particularly enhancing antioxidant status, while inflammatory and enzymatic responses may require higher exercise volume or prolonged exposure to manifest.