Oxidative Stress And Antioxidant Response In Trained Men After Different Exercise Intensities

Physical activity has been related to benefits in the organism. However, some research has shown that exercise may generate oxidative stress by increasing reactive oxygen species (ROS) production with an insufficient antioxidant response. The intensity of exercise seems to be associated with this oxidative damage. PURPOSE: The aim of this study was to evaluate the effect of different exercise intensities on oxidative stress and antioxidant response in trained sportsmen. METHODS: Twenty trained cyclists participated in this study performing two protocol test exercises of different intensity on a cycloergometer. Maximal effort consisted in a progressive incremental ergometric protocol test until voluntary exhaustion. The submaximal protocol was a steady state test performed at 75% VO2 max during 30 minutes. Trials were performed in an exercise laboratory room where temperature varied between 23 and 25°C and humidity was between 45 and 55%. Venous blood samples were collected from the antecubital vein before and after the exercise. Plasmatic and erythrocyte malondialdehyde (MDA) were determined as oxidative stress markers. Plasma and erythrocyte vitamin C and E were determined as antioxidant response systems. Plasma data were corrected by haematocrit. Erythrocyte parameters were expressed as U/g of haemoglobin. The Wilcoxon test was performed for statistical analysis. A p value of <0.05 was used to determine statistical significance. RESULTS: In maximal trial, the data showed an increase in plasma and erythrocyte MDA after test (from 40.64 ± 18.96 to 45.41 ± 18.44 μM; and from 0.21 ± 0.1 to 0.23 ± 0.12 μmol/g Hb; p<0.05). Plasma vitamin C increased after tests while erythrocyte vitamin C decreased (from 3.80 ± 1.60 to 5.20 ± 2.16 μg/mL; and from 130.53 ± 34.66 to 83.38 ± 30.01 μg/g Hb; p<0.05). Both plasma and erythrocyte vitamin E decreased after maximal efforts although no significant differences were found. In submaximal exercise, significant differences did not appear either in MDA, vitamin C or vitamin E. CONCLUSION: In trained sportsmen, maximal exercise intensity may influence more than submaximal exercise intensity on reactive oxygen species production and causes different responses in antioxidant vitamins.