The attenuation of gastrointestinal symptoms in patients with IBS after aerobic training for 24 weeks may be due to the attenuation of the inflammatory process, with a reduction in plasma concentrations of cytokines (IL1β, IL-6, IL-8, IL-10 and TNF-α), reduction in oxidative stress markers, such as xanthine oxidase (XO), plasma malondialdehyde (MDA), and nitric oxide (NO), and increased antioxidant activity, such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) [119,120]. This evidence concerns the gene CAT and irritable bowel syndrome.