INTRODUCTION: The practice of physical exercise causes increase in production of oxygen reactive species (ORS), derived from the aerobic metabolism, creating a significant amount of heat due to the energy production resulting in organic overload. The associations between ORS and exercise, as well as exercise and air temperature variations have been studied; however there is a lack of information on the scientific literature concerning the association between the myocardium free radicals production and physical activity under high temperature. OBJECTIVE: The goal of this study was to compare the myocardium ORS production in rats submitted to low intensity training at different temperatures. METHODOLOGY: Twenty Wistar young male rats, with weight rage from 250 and 280 grams were used. They were divided in four groups: (G1 n = 5) exposed to training and heat (39 ± 1°C); (G2 n = 5) exposed to heat without training; (G3 n = 5) exposed to training and air temperature (22 ± 1°C); (G4 n = 5) exposed to air temperature without training. The training was performed on a treadmill in a controlled temperature room during 5 weeks, increasing 5 minutes every two sessions, reaching a total of 60 minutes under low intensity effort, 8 m/min. Room temperature was controlled between 39 ± 1° and 22 ± 1°, as well as between 40 to 60% of relative humidity. Lipoperoxidase was evaluated by Chemiluminescense (QL). Data analysis was accomplished using Two-Way ANOVA test. RESULTS: The QL analysis results revealed a light emission curve significantly lower for the animals exposed to room temperature exercise, compared to the sedentary ones kept under heat. TRAP analysis has showed a decrease in every experimental group in relation to G4. CONCLUSION: It can be concluded that there were lower levels of ORS production in the groups submitted either to heat only or exercise only.
Oxidative stress; Physical exercise; Heat
