Notably, although cMyC yields high diagnostic accuracy for acute myocardial infarction, cMyC concentrations postmarathon did not exceed the URL at any time point. This difference between cTn and cMyC concentrations following exercise may relate to the higher molecular mass of cMyC complexes (≈140 kDa) and fragments (≈40 kDa) compared with cTn complexes (cTnI ≈29 kDa, cTnT ≈37 kDa) and fragments (10–30 kDa), suggesting that cMyC may be less likely to leak from the cell into the circulation. Because postexercise cTn elevations can be challenging to interpret in the clinical setting because of concentrations exceeding the URL in the absence of signs of myocardial ischemia, a parallel assessment of cMyC might aid in discerning whether cTn elevations are physiological or pathological in endurance athletes.