Circulation publication for exercise physiologists

13 August 2019

An increased concentration of cardiac troponin (a regulatory protein) in the blood after prolonged walking is associated with an increased risk of cardiovascular disease and premature death. This was the conclusion of a study involving 725 participants in a long-distance walking event (Nijmegen Four Days Marches) that was published in the journal Circulation.

Regular exercise is healthy and reduces the risk of cardiovascular disease. Nevertheless, it appears that prolonged and/or intensive exercise can lead to an increase in cardiac biomarkers in the blood, such as the regulatory protein troponin. Troponin is a protein that is present in every heart muscle cell. In the event of damage to the heart, these proteins leak into the blood vessels. An increased troponin concentration in the blood is therefore used to diagnose a heart attack, among other purposes. But the implications of increased troponin levels after exercise had not been systematically investigated until now.
 
Research involving participants in a long-distance walking event
To investigate the relevance of this increased troponin concentration after exercise, researchers of the Radboud University Medical Center (Nijmegen, the Netherlands), Hartford Hospital (Connecticut, United States) and John Moores University (Liverpool, United Kingdom) took blood samples from 725 walkers before and after a bout of prolonged walking exercise and determined the troponin concentration. Subsequently, the research team contacted the walkers annually to determine their cardiovascular health and survival status.
 
Higher risk
“After ten years of research we can finally answer this important question,” says researcher Thijs Eijsvogels. “Of the participants who had a high troponin concentration after walking, 27% developed severe cardiovascular disease or died during follow-up, while this was the case for only 7% in the group of participants with a low troponin concentration after walking. This study shows for the first time that an exercise-related increase in troponin is clinically relevant.”
 
Stress test for the heart
PhD student Vincent Aengevaeren emphasizes that these findings are not necessarily bad news for people who exercise regularly: “You can consider exercise as a stress test for the heart, and walkers with a high troponin concentration may be suffering from sub-clinical cardiovascular disease that has not yet been diagnosed. Therefore, our findings may contribute to early identification of susceptible individuals in the future, so that appropriate treatment can be started.” Eijsvogels also warns against misinterpreting the results: “It is simply not the case that exercise is harmful to your heart. People who exercise regularly live 3 to 6 years longer than those who do not, so getting enough exercise remains important for everyone.”

This research was conducted within the theme Vascular damage.
 
Publication 
Exercise-Induced Cardiac Troponin I Increase and Incident Mortality and Cardiovascular Events
Vincent L. Aengevaeren, Maria T.E. Hopman, Paul D. Thompson, Esmée A. Bakker, Keith P. George, Dick H.J. Thijssen, and Thijs M.H. Eijsvogels.