Oxidative stress and antioxidants in exercise

Increased aerobic metabolism during exercise is a potential source of oxida tive stress. In muscle, mitochondria are one important source of reactive i ntermediates that include superoxide (O-2*(-)) hydrogen peroxide (H2O2), an d possibly hydroxyl radical (HO*). The recent discovery that mitochondria m ay generate nitric oxide (NO*) also has implications for oxidant production and mitochondrial function. In this review, we critically examine the conc ept that production of reactive intermediates increases during exercise. Be cause the health benefits of regular exercise are well-documented, we also examine adaptations to exercise that may decrease oxidative stress. These i nclude increased antioxidant defenses, reduced basal production of oxidants , and reduction of radical leak during oxidative phosphorylation.