Cardiac muscle relies highly on aerobic metabolism. Heart muscle has a high oxygen uptake at resting conditions, which increases many fold during exhaustive physical exercise. Such a high rate of oxidative metabolism is often associated with enhanced production of reactive oxygen metabolites. A single bout of strenuous exercise has been demonstrated to induce oxidative damage in heart. Such oxidant insult may lead to adaptive responses and strengthen antioxidant defenses in the heart tissue. Endurance exercise training has indeed been shown to upregulate heart tissue antioxidant defenses. Recently, we have observed that even predominantly anaerobic sprint training regimens may enhance cardiac antioxidant defenses. Regular physical exercise may beneficially influence cardiac antioxidant defenses and promote overall cardiac function.