Myocardial remodeling comprises changes in cardiac shape, mass, diameter, and function in response to changes in hemodynamic load, cardiac damage, or neurohumoral stimulation. Adaptive remodeling is a consequence of physiological stimuli such as physical activity. Maladaptive remodeling results from pathologic conditions such as myocardial ischemia and cardiac valve disease. Since regular vigorous endurance exercise can result in cardiac remodeling cardiologic screening is recommended for athletes to identify individuals with cardiomyopathies. Moderate physical activity is cornerstone of primary and secondary prevention of cardiovascular diseases. In secondary prevention, individual training recommendations need to be adapted to the underlying myocardial disease and individual risk factors. Experimental and clinical studies show that specific training interventions exert cardioprotective effects and reverse remodeling. However, clinical and basic science studies are needed to understand the mechanisms of adaptive and maladaptive remodeling and to better utilize this powerful therapeutic tool in the treatment of myocardial diseases.