Myocardial ischaemia-reperfusion (I-R) injury is the major contributor to the morbidity and mortality associated with coronary artery disease. Although several factors contribute to I-R-mediated myocardial injury, strong evidence indicates that production of radicals and other reactive oxygen species are important mediators of this type of cardiac damage. It follows that increasing myocardial levels of antioxidants could provide cardioprotection against an I-R insult. This tutorial lecture will discuss recent experiments examining the effects of exercise training in providing cardiac protection against I-R injury. In this regard, new evidence suggests that both short term (days) and long-term (weeks) endurance exercise training reduces I-R-induced myocardial injury. Recent experiments investigating the role of exercise-induced increases in cardiac manganese superoxide activity and glutathione levels in this exercise-mediated cardioprotection will be discussed.