A meta-analysis of 69 studies published in BMJ Open Sport & Exercise Medicine examined the relationship between marathon running and cardiac function. The analysis included 3,274 participants, of whom 73% were male, with an age range of 27 to 63 years.
Cardiac Biomarkers
Within one hour of completing a marathon, levels of cardiac troponin T (cTnT), cardiac troponin I (cTnI), and N-terminal proB-type natriuretic peptide (NT-proBNP) were consistently elevated. These levels frequently exceeded clinical thresholds typically associated with myocardial injury, ischemia, or heart failure.
Cardiac Imaging
- Echocardiography: Minor changes were observed in left ventricular ejection fraction and other chamber volumes and pumping dynamics. These alterations were not considered clinically meaningful.
- Cardiac MRI: No evidence of clinically relevant structural myocardial injury was detected.
Variability
The magnitude of biomarker changes and echocardiographic alterations varied among participants based on performance time, age, sex, and training level.
Limitations
The researchers noted that the majority of participants were male, which may limit the generalizability of the findings to female athletes. Training status was not consistently reported across the included studies, and many studies were assessed as having a high risk of bias.
The clinical relevance of post-marathon biomarker elevations and ventricular function changes remains unclear.
Conclusion
The authors stated that whether these changes represent normal physiological responses or early markers of pathological cardiac remodeling requires further investigation. They called for well-designed, long-term studies in diverse populations to address this question.