MARATHON-MI is a prospective, observational study of twenty-five (25) participants with plans of completing the Detroit Free Press Marathon in Detroit, Michigan on October 19, 2008. All participants will undergo a rigorous pre-marathon screening process which will include: 1) blood testing, 2) complete cardiopulmonary exercise testing, 3) ECG testing, 4) Holter monitoring, 5) cardiac MRI. Blood work will be check after the marathon immediately after and one day after the event. Cardiac MRI will be repeated within 12 hours of finishing the marathon. Using the information derived from the blood work and radiological testing, we will attempt to determine if there is an association between marathon running and myocardial necrosis.