Effects of mountain ultra-marathon running on ROS production and oxidative damage by micro-invasive analytic techniques

Abstract

Purpose Aiming to gain a detailed insight into the physiological mechanisms involved under extreme conditions, a group of experienced ultra-marathon runners, performing the mountain Tor des Géants1ultra-marathon: 330 km trail-run in Valle d'Aosta, 24000 m of positive and negative elevation changes, was monitored. ROS production rate, antioxidant capacity, oxidative damage and inflammation markers were assessed, adopting micro-invasive analytic techniques. Methods Forty-six male athletes (45.04±8.75 yr, 72.6±8.4 kg, 1.76±0.05 m) were tested. Capillary blood and urine were collected before (Pre-), in the middle (Middle-) and immediately after (Post-) Race. Samples were analyzed for: Reactive Oxygen Species (ROS) production by Electron Paramagnetic Resonance; Antioxidant Capacity by Electrochemistry; oxidative damage (8-hydroxy-2-deoxy Guanosine: 8-OH-dG; 8-isoprostane: 8-isoPGF2α) and nitric oxide metabolites by enzymatic assays; inflammatory biomarkers (plasma and urine interleukin-6: IL-6-P and IL-6-U) by enzyme-linked immunosorbent assays (ELISA); Creatinine and Neopterin by HPLC, hematologic (lactate, glucose and hematocrit) and urine parameters by standard analyses. Results Twenty-five athletes finished the race, while twenty-one dropped out of it. A significant increase (Post-Race vs Pre) of the ROS production rate (2.20±0.27 vs 1.65±0.22 μmol.min-1), oxidative damage biomarkers (8-OH-dG: 6.32±2.38 vs 4.16±1.25 ng.mg-1 Creatinine and 8-isoPGF2α: 1404.0±518.30 vs 822.51±448.91 pg.mg-1Creatinine), inflammatory state (IL-6-P: 66.42±36.92 vs 1.29±0.54 pg.mL-1 and IL-6-U: 1.33±0.56 vs 0.71±0.17 pg.mL1) and lactate production (+190%), associated with a decrease of both antioxidant capacity (-7%) and renal function (i.e. Creatinine level +76%) was found. Conclusions The used micro-invasive analytic methods allowed us to perform most of them before, during and immediately after the race directly in the field, by passing the need of storing and transporting samples for further analysis. Considered altogether the investigated variables showed up that exhaustive and prolonged exercise not only promotes the generation of ROS but also induces oxidative stress, transient renal impairment and inflammation.