Extreme exercise and oxidative DNA modification

Abstract

Extreme exercise increases oxygen uptake with a potential for increased formation of reactive oxygen species. Damage to biomolecules may occur if such an increase exceeds the protective capacity of antioxidant defence mechanisms. Vigorous exercise amounting to ∼ 10 h a day for 30 days increased the rate of oxidative DNA modification by 33% (95% confidence limits, 3–67%; P < 0.02) in 20 men owing to the urinary excretion of 8‐oxo‐7,8‐dihydro‐2'‐deoxyguanosine, an oxidatively modified deoxynucleoside originating from nuclear DNA repair, oxidation of the nucleotide pool from mitochondrial DNA and/or from cell turnover. Oxidative stress to DNA points to a risk for the development of cancer and premature ageing from extreme exercise.