Oxidative Stress Assessment in Response to Ultraendurance Exercise: Thiols Redox Status and ROS Production according to Duration of a Competitive Race.

Purpose. Response to an ultraendurance competitive race on thiols redox status, reactive oxygen species (ROS) production, and oxidative stress (OxS) was investigated according to duration. Methods. Twenty-four elite runners were examined: six completed 50km and eighteen 100km. Blood and urine samples were collected before and immediately after the race. Erythrocytes and plasma aminothiols by high-performance liquid chromatography, total antioxidant capacity (TAC), and OxS biomarkers (protein carbonyl (PC), thiobarbituric acid-reactive substances (TBARS), 8-isoprostane (8-iso-PGF2alpha), and 8-OH-2-deoxyguanosine (8-OH-dG)) by immunoenzymatic assays and ROS production by Electron Paramagnetic Resonance were assessed. Results. Significant increases (P between <0.05 and <0.0001) were recorded in plasma total and oxidized aminothiols concentration and TAC (P < 0.0001) only after 100km: plasmatic (ROS production (+12 versus +29%), PC (+54 versus +115%), and TBARS (+28 versus +55%)) and urinary (8-OH-dG.creatinine(-1) (+71 versus +158%) and 8-iso-PGF2alpha.creatinine(-1) (+43 versus +135%)) concentrations for 50 and 100km (duration 4h 3' versus 8h 42'), respectively. Conclusion. Very prolonged ultraendurance exercise causes an increase in ROS production and OxS depending on specific biomarker examined but always linearly and directly related to exercise duration. Redox status of erythrocytes was preserved. A relationship between running performance and both prerace ROS production and antioxidant-redox status was found in 100km race.