Effect of exercise duration on pro-oxidants and pH in exhaled breath condensate in humans

Exercise promotes pulmonary oxidative imbalance. In this regard, some evidence has been obtained from the study of exhaled breath condensate (EBC) during urban races, in which the factors involved in the occurrence of this process are still not characterized. In this paper, under laboratory conditions, both the role of time of exercise on the generation of pro-oxidants (H₂O₂, NO₂ ⁻) and pH have been assessed in EBC of 16 under-trained subjects who completed three tests of cycloergometric exercise at low intensity (30 % of VO₂ max) with a duration of 10, 30, and 90 min. Samples were obtained as follows: immediately before and at 80 min post exertion in each test. In the 90-min test, an increase in H₂O₂, NO₂ ⁻ concentration in EBC at 80 min post exertion with no changes in the pH was observed. Total O₂ consumption and total ventilation weakly correlated with the changes in H₂O₂ and NO₂ ⁻. In conclusion, the concentration of pro-oxidants in the EBC depends on the duration of the exercise when it is performed at low intensity under laboratory conditions.