Preconditioning cardioprotection and exercise performance: a radical point of view

It is well known that regular exercise training can reduce the incidence of coronary events and increase survival chances after myocardial infarction. Myocardial beneficial effects are due to the reduction of several cardiovascular disease risk factors, such as high cholesterol, hypertension, metabolic syndrome, obesity, etc. Moreover, exercise can reproduce the so-called ‘‘preconditioning’’: the capacity of brief periods of ischemia to induce myocardial protection against ischemia/reperfusion injury. Pre- and postconditioning of the myocardium are two treatment strategies that considerably reduce post-ischemic contractile dysfunction and the amount of necrosis. Paradoxically, reactive oxygen and nitrogen species (ROS and RNS) have been identified as essential cardioprotective signaling molecules, in either pre- or postconditioning phenomena. Several clues demonstrate that preconditioning may be directly induced by exercise, thus leading to a protective phenotype at cardiac level without the necessity of causing ischemia. Also exercise appears to act as a physiological redox-sensitive stress that induces antioxidant beneficial myocardial adaptive responses at cellular level. The purpose of the present work is to review the role played by factors released during exercise in improving exercise performance and in triggering cardioprotection via a redox-sensitive mechanism.