- Marathon running causes a sharp increase in cardiac injury biomarkers post-race
- Temporary changes occur in heart structure, including ventricular size adjustments
- Small alterations in heart function are observed after completing a marathon race
Marathon running is known for its health and fitness benefits. Millions of people around the world participate in these long-distance races each year to improve endurance, challenge themselves, and maintain an active lifestyle. However, the high physical demand of running 42.2 kilometers puts extreme stress on the body, especially on the heart. A new study published in BMJ Open Sport & Exercise Medicine highlights how marathon running affects cardiac structure and certain biomarkers linked to heart injury. The findings suggest that these measurable changes happen immediately after a marathon, although the long-term relevance of these changes remains unclear.
Researchers conducted a systematic review and meta-analysis of 69 studies which involved healthy adult marathon runners. They combined data from multiple studies, they aimed to understand how the heart responds to the extreme physical effort required to complete a marathon. The study examined both blood biomarkers and imaging-based measurements of heart structure and function. While the results showed noticeable changes after races, the researchers emphasised that there is currently no strong evidence that these temporary changes lead to permanent heart damage in healthy athletes.
Rise In Cardiac Injury Biomarkers
One of the most important findings of the study was the sharp increase in cardiac biomarkers after marathon races. These biomarkers are substances released into the bloodstream when the heart experiences stress or injury.
The researchers found a significant increase in levels of troponin T, troponin I, and N-terminal pro-B-type natriuretic peptide (NT-proBNP) following marathon completion. Elevated levels of these markers are often linked to heart attacks, heart muscle injury, or heart failure. Also, many runners showed biomarker levels that exceeded standard medical thresholds used to spot heart problems.
Changes In Heart Structure
The study also revealed temporary changes in the structure of the heart after marathon races. Using echocardiography and other imaging techniques, researchers observed 3% increase in left ventricular dimensions and 3.5% reduction in right ventricular volume and diameter.
The left ventricle is responsible for pumping oxygen-rich blood throughout the body, while the right ventricle pumps blood to the lungs. During prolonged endurance exercise, these chambers work much harder than usual to meet the body's increased oxygen demands.
Although measurable changes were detected, the researchers described them as modest and not clinically significant. In other words, the alterations were noticeable in scientific measurements but were not considered signs of serious structural damage. Some imaging studies using MRI did not even confirm all of the structural changes observed through echocardiography. This suggests that further investigation is needed.
Effects On Heart Function
Beyond structural changes, the researchers also identified small changes in heart function. They found a slight increase in left ventricular fractional shortening, a measure of how effectively the heart contracts. At the same time, there was a modest reduction in right ventricular ejection fraction, which reflects how much blood the right side of the heart pumps with each heartbeat.
These changes were relatively small, amounting to only a few percentage points. Researchers believe they may reflect temporary adaptations to extreme physical exertion rather than harmful dysfunction. The findings highlight how marathon running places unique demands on the cardiovascular system.
What Do These Findings Mean
The study highlights that marathon running causes measurable short-term effects on the heart. Biomarkers associated with cardiac injury rise significantly, and small changes occur in heart structure and function immediately after a race. However, the available evidence does not show that these temporary responses translate into lasting heart damage for healthy runners.
Researchers stress that regular physical activity remains one of the best ways to boost cardiovascular health.
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