Exercise improves cardiovascular health and reduces risk factors for cardiovascular diseases. Controversially, studies involving vigorous endurance exercise demonstrate an increase in cardiac troponin, a biomarker for cardiac injury. The mechanism of exercise-induced troponin remains to be identified. Current models have major limitations that complicate the identification of this mechanism. In my project, the main goal is to mimic exercise in engineered heart tissue by electrical pacing. This “exercise-on-a-chip” model may help us to unravel the pathological or physiological effects of endurance exercise.