OXIDATIVE STRESS AFTER THREE DIFFERENT INTENSITIES OF RUNNING

Abstract

The exercise induces oxidative stress (OS). However, it is not clear at which intensity it occurs, and if different fitness can influence OS levels. Many researchers studied the influence of different percent of oxygen uptake (VO2) on the mechanisms that underlie OS. However, ventilatory threshold is a better determinant of relative exercise intensity. PURPOSE To study the influence of three different exercise intensities on OS parameters in trained (T) and untrained (UT) subjects. METHODS Seventeen healthy, volunteered male subjects were assigned into a 2X3X2 factorial design according to training level [T (n=8)], exercise intensity (low, moderate and high intensity) and blood collect (before and after exercise). The subjects were evaluated through a maximal aerobic power test in a treadmill. The maximal oxygen uptake (VO2max) and ventilatory thresholds (VT1 and VT2) were obtained. Three exercise tests were performed in random order at a VO2 of 10% bellow VT1 (low intensity), 10% bellow VT2 (moderate intensity) and between VT2 and VO2max (high intensity). Chemiluminescence (CL), total antioxidant capacity (TRAP), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were measured in the blood. RESULTS Exercise effect was observed on TRAP, which increased after exercise (p < 0.05); and fitness effect on GPx, which was greater in T group (p < 0.05). In plasma, CL decreased (3589±193 to 3274±223 cps.mg Hb−1, P < 0.05), and TRAP was increased (304±45 to 384±57 μM trolox, P < 0.05) after high intensity exercise in T group. SOD increased after low (8.35±0.85 to 9.23±1.03 U SOD.mg protein−1) and moderate (8.89±0.98 to 10.44±86 U SOD.mg protein−1) exercise intensity in UT (p < 0.05). CAT did not changed. CONCLUSIONS Our results indicate that exercise in this model did not increase LPO, despite alterations in some antioxidants. Probably the reactive oxygen species involved were scavengered by GPx and TRAP. Supported by CNPq, CAPES and SNE-MET-Brazil