Watch out, too much intense exercise may cause “Myocardial Fibrosis”

Did you know that too much intense exercise increases your risk of myocardial fibrosis? Overuse of intense exercise can increase your risk of myocardial fibrosis, according to a study in the journal Medicine and Science in Sports and Exercise. 

Myocardial fibrosis is known to be a common heart failure characteristic with is associated with frequent ventricular premature beats as well as ventricular tachycardia. This condition leads to the progression of the deterioration of the cardiac muscle as well as left ventricular dilatation which results in the failure of pump function (Liu et.al., 2017).

The study found that people who exercised at a high intensity (defined as intensity that causes muscle damage) more than three times per week had a greater risk of developing fibrosis, compared with those who exercised less intensely. The study participants were asked about their exercise habits and whether they had developed fibrosis over the previous five years. Fibrosis is a condition in which the muscles become stiff and thickened, and it can lead to heart problems. Long-term intense exercise induces several changes in the heart to adapt to the rise in oxygen demand of the body. These changes according to the researchers increase the mass of the whole heart resulting in increased contractility, high cardiac output, as well as a rise in left and right ventricular end-diastolic volume (EDV) (Rajanayagam et.al., 2021). 

The process that results in myocardial fibrosis is a chronic inflammatory response from cardiac remodeling. The increase in the heart’s contractility, cardiac output, and left & right ventricular volumes as Rajanayagam said, all lead to an increased number of free radicals, which are basically unstable molecules. Free radicals can damage cells, which can then lead to myocardial fibrosis. Cardia remodeling is detected based on morphological changes such as the size, geometry, and mass of the heart after an injury (Azevedo et. al., 2016). The sequence of events that takes place to result in myocardial fibrosis often starts with injuries such as pressure or cardiac volume overload or inflammation which may be caused by long-term intense exercises. This first event initiates cardiac remodeling which can be in the form of structural changes, molecular changes, biochemical changes, and cellular changes. Lastly, there is ventricular dysfunction following cardiac remodeling which results in symptomatic or asymptomatic heart failure (Azevedo et. al., 2016).

The researchers noted that people who develop fibrosis often have symptoms such as chest pain, shortness of breath, and fatigue. They suggest that people who are planning to start exercising at a high intensity should talk to their doctor first to make sure they are safe.

CITATION:

Rajanayagam, J., & Alsabri, M. (2021). Intense Endurance Exercise: A Potential Risk Factor in the Development of Heart Disease. Cureus, 13(1), e12608. https://doi.org/10.7759/cureus.12608

Azevedo, P. S., Polegato, B. F., Minicucci, M. F., Paiva, S. A., & Zornoff, L. A. (2016). Cardiac Remodeling: Concepts, Clinical Impact, Pathophysiological Mechanisms and Pharmacologic Treatment. Arquivos brasileiros de cardiologia, 106(1), 62–69. https://doi.org/10.5935/abc.20160005

Liu, T., Song, D., Dong, J., Zhu, P., Liu, J., Liu, W., Ma, X., Zhao, L., & Ling, S. (2017). Current Understanding of the Pathophysiology of Myocardial Fibrosis and Its Quantitative Assessment in Heart Failure. Frontiers in physiology, 8, 238. https://doi.org/10.3389/fphys.2017.00238