Exercise-induced oxidative stress.

The role of exercise in free radical processes is not clear; however, recent evidence suggests that elevated oxygen consumption may increase free radical activity. Direct measurement of free radical signals can be made by electron spin resonance and indirect measures include mitochondrial membrane damage, conjugated dienes, hydroperoxides, thiobarbituric acid reactive substances, short chain hydrocarbons, and oxidized nucleosides. Although exact levels are not known, the type, duration, and intensity of exercise affect biomarkers of free radical activity, as does one's training status. Oxidative stress associated with exercise-induced free radical activity seems to be better tolerated by trained subjects exercising at moderate intensity.