ABSTRACT
BACKGROUND: High levels of oxidative stress promote degradation of the cell membrane impairing cellular function in fat oxidation. However, the influence of oxidative stress on exercise-induced weight-loss has not yet been investigated. Therefore, the aim of this study was to verify the influence of a lipidic peroxidation marker (malondialdehyde, MDA) and antioxidant status (total antioxidant capacity marker, TAC) on the magnitude of weight-loss by aerobic-induced exercise in previously sedentary overweight or obese individuals. METHODS: Seventy-five physically inactive adults were randomized into experimental (N.=58) and control (N.=17) groups, who engaged in a 12-week program of aerobic training walking and/or running (3 to 5 days/week) or stretching (1 day/week), respectively. Body composition (DXA), aerobic capacity (ergospirometric) and blood collections for oxidative stress analysis (MDA and TAC) were determined before and after the experimental protocol. Two-way ANOVA for repeated measures or Friedman's test were used to evaluate differences in time/group interaction. Pearson correlation was used to verify the relationship between the variables of oxidative stress and of body composition. RESULTS: Significant reduction was found in fat body mass of experimental when compared to control group (-1.3±1.9 kg versus -0.3±1.3, P=0.04). Experimental group also altered significantly the total body mass (-1.2±4.7 kg; effect size 0.44), body mass index - BMI (-0.3±1.1 effect size 0.37), fat percentage (1.3±1.6%; effect size 0.50) and lean body mass (0.6±1.5 kg; effect size 0.32).There was increase in MDA of 2.3 µmol/L to 2.7 µmol/L (P=0.00), without changes to TAC (25.6±13.9% to 28.0±10.4%). No correlation was found between these variations in body composition with either the initial values of MDA and TAC or delta variation of these indicators of oxidative stress in response to the training program. CONCLUSIONS: Indicators of oxidative stress (MDA and TAC) does not influence the magnitude of weight-loss induced by aerobic training.
