The initial report of the athlete’s heart dates back to the late 1890s. The concept that endurance-based exercise and strength-based exercise lead to distinctly different changes in left ventricular (LV) structure was proposed in the 1970s and has been confirmed by more recent studies. Advances in cardiac imaging, particularly echocardiography and cardiac magnetic resonance imaging, have allowed for more precise characterization of the structural changes that develop in the hearts of athletes engaged in different sporting disciplines. Despite our improved understanding of exercise-induced cardiac remodeling, the findings of: 1) increased LV chamber dimension, 2) increased LV wall thickness, and 3) increased right ventricular (RV) chamber dimension continue to be accompanied by significant diagnostic uncertainty in clinical practice. Determining whether these entities arise from exercise-induced cardiac remodeling or represent pathologic cardiomyopathy requires the integration of a number of diagnostic techniques, including evaluations with echocardiography and/or cardiac magnetic resonance imaging. Ambiguous cases require additional testing, such as cardiopulmonary exercise testing and assessing the response to a period of prescribed detraining. Novel imaging techniques coupled with physiologic provocation that assess regional LV and RV function may make the distinction between physiologic adaptation and pathology more clear in the future.