Exhaustive Physical Exercise Effects on Nitric Oxide, Uric Acid, Antioxidant Activity and Oxidative Stress in Saliva of Elite Triathlete

Abstract

Physical exercise can increase organism antioxidant defenses. However, it is not clear if the increase of antioxidant defenses is enough to avoid oxidative stress during long-duration physical exercise. PURPOSE: To determine the effects of exhaustive physical exercise on nitric oxide (NO) and uric acid (UA) production, oxidative stress (OS), and total antioxidant activity (TAA) in human saliva. METHODS: Twelve elite triathletes (men, n=7 and women, n=5; mean age; 21 + 1 yr) were studied during the Falcon-state 2006 triathlon. Saliva samples were withdrawn at three time points; 24 and 1 h before the race, and immediately after competition (IAC). Subsequent to rinsing the mouth with water, samples of stimulated whole saliva were placed in assay tubes and frozen at −5°C. Before analysis, saliva samples were centrifuged at 3,000 rpm for 10 min. The production of NO was determined by the Griess reaction, OS was determined by the FOX method, UA by enzymatic method, and the TAA by ABTS method. One-way ANO VA with repeated measures was used to examine effects of exhaustive physical exercise on dependent variables. The alpha level (p=0.05) was set a-priori and corrected by the Bonferroni technique for multiple comparisons. RESULTS: In human saliva, exhaustive physical exercise (participants average time in the race: 131 + 10 min) caused an increase in UA in comparison to 24 h (IAC: 3.53 ± 1.58 mg/dl vs. 24 h: 1.35 ± 0.68 mg/dl vs.; p< 0.05) and 1 h (1.96 ± 0.93 mg/dl; p< 0.05) prior to competition. In contrast, TAA decreased at 1 h before the race in comparison to 24 h prior to competition (1 h:1.02 ± 0.28 mMvs. 24 h: 1.42 ± 0.25 mM; p< 0.05), but TAA was higher at IAC in comparison to 24 h and 1h prior to competition (1.91 ± 0.42 mM; p< 0.05). Oxidative stress was reduced at 1 h before the race in comparison to 24 h prior to competition (1 h: 85.2 ± 13.9 μMvs. 24 h: 90.8 ± 9.4 μM; p< 0.05), and further decreased following exercise (69.8 ±11.8 μM; p< 0.05). On the other hand, NO derivative products were unchanged by this type of exercise in these athletes. CONCLUSIONS: Exhaustive physical exercise induced an increase in both saliva UA and TAA, and these results could explain the reduction of oxidative stress observed after the competition. In addition, these results might also demonstrate an anticipatory metabolic response before exercise.