Cardiac troponins after a downhill marathon

In the present study we searched for biochemical evidence of myocardial damage following eccentric endurance exercise and tested the hypothesis that exercise-induced increases in cardiac troponins may result from the increase of myocardial wall stress. Cardiac troponin I (cTnI), cardiac troponin T (cTnT), and N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured after a downhill marathon (eccentric endurance exercise). CTnI exceeded 0.04 μg/L in 69%, and cTnT exceeded 0.01 μg/L in 46% of all athletes. Moreover, we found a ∼ 3-fold increase in NT-proBNP in male athletes. The percentages of positive troponin levels are similar after the downhill marathon as compared to previously published data obtained after running a flat course marathon (74% cTnI, and 42% cTnT). Moreover, myocardial wall stress seems to be considerably lower during a downhill marathon (∼3-fold increase in NT-proBNP concentrations) compared to a flat course marathon (∼5-fold increase in NT-proBNP concentrations). Therefore, we conclude that the increase in myocardial wall stress during exercise may not be responsible for the elevated markers of myocardial damage (cTnI and cTnT). Since provocation of an autoimmune response to cTnI induces inflammation in the myocardium followed by fibrosis and heart failure, our data suggest that eccentric training can not be recommended as a safe approach to perform muscular exercise training with minimal cardiovascular stress.