Cardiac Troponin in Endurance Exercise—Fragments of the Imagination or Clinical Significance?

The levels of gold standard biomarkers of acute coronary syndrome (ACS),2 cardiac troponins T and I (cTnT and cTnI, respectively), are now known to be increased in many conditions without the presence of ACS. Although the vast majority of these elevations are associated with secondary cardiac pathologies and convey additional poor prognosis, 1 noticeable exception is subjects undertaking endurance exercise. The etiology of increased cTnT and cTnI levels in endurance exercise, either physiological or pathological, remains a central debate. Although regular exercise training conveys enhanced cardiovascular health (1), these data are based on relatively moderate duration and intensity of activity. What is the effect of prolonged high-intensity exercise? Is this detrimental to cardiovascular function? The notion of exercise-induced myocardial damage was first proposed in studies at the Boston Marathon, by using creatine kinase MB (muscle/brain) (2). Siegel and colleagues later confirmed the presence of plausible “cardiac damage” following prolonged exercise by use of cTnT (3). The early studies employed a cTnT assay that used a nonspecific detection antibody that cross …