Influence of exercise induced-oxidative stress on DNA damage/repair

Influence of exercise on DNA damage in lymphocytes was evaluated in extensively trained and untrained volunteers, who were performed a treadmill running at 85% VO2max for 30 min. The subjects had their peripheral blood taken before, immediately after and 30 min after the exercise for the analysis of antioxidants (vitamin E, vitamin C, β carotene, sulfhydryl groups) and lipid peroxide in plasma and DNA damage in lymphocytes, that was evaluated by micronucleus assay. The blood samples were also irradiated with X ray (1.5Gy) in vitro to examine the modification of exercise induced DNA damage by a secondarily induced oxidative stress. The trained subjects had a higher plasma creatine kinase (CK) activity even before the exercise, and a lower lactate concentration in blood during the exercise compared with those in the untrained subjects. Leukocyte counts in blood markedly increased immediately after exercise. Changes in the concentrations of antioxidants and lipid peroxides in plasma were well correlated with those in hematocrit. Spontaneous and X ray induced DNA damage in lymphocytes did not significantly increase at least until 30 min after the exercise both in the trained and untrained subjects. However, the ratio of X ray induced/spontaneous DNA damage tended to increase after the exercise. Interestingly, the spontaneous DNA damage in the trained subjects was significantly higher than that in untrained subjects. In addition, spontaneous DNA damage in lymphocytes showed a significant positive correlation with plasma CK activity in both trained and untrained subjects. These results suggest that exercise induced oxidative DNA damage in lymphocytes, which was occurred delay after one bout of exercise and could be related with muscle damage due to repeated bouts of exercise.