Marathon running does not cause lasting heart damage in most runners: Study

A decade-long study has brought reassuring news for marathon runners, easing long-standing concerns about whether running 42 kilometres places lasting strain on the heart. According to new research published in JAMA Cardiology, marathon running does not cause permanent heart damage in most recreational runners.

The study followed 152 recreational marathon runners over ten years. Researchers examined their heart function before and after races and monitored their cardiovascular health during the follow-up period. While temporary changes were observed immediately after marathons, no long-term deterioration in heart structure or function was found.

Scientists noted that the heart’s right ventricle, which pumps blood to the lungs, showed a short-term reduction in pumping ability immediately after races. However, this change was consistently resolved within days. Over the full decade, heart size and performance remained within normal limits.

The findings are significant because earlier studies had raised alarms after detecting elevated levels of troponin in runners’ blood following endurance events. Troponin is a protein released when heart muscle cells are stressed and is commonly used to diagnose heart attacks. Its rise after marathons had prompted fears of hidden heart injury.

Experts now stress that context is critical. Post-race troponin elevations in healthy runners usually reflect temporary stress on heart cells rather than permanent damage. Heart scans such as ultrasounds and MRIs typically show no signs of blocked arteries or lasting injury in these cases.

Deaths during marathons remain extremely rare, estimated at about one per 100,000 participants, and are usually linked to undiagnosed heart conditions rather than running itself. However, doctors warn that chest pain, breathlessness or collapse during or after exercise should never be ignored, even in fit individuals.

The debate continues around very high-level endurance athletes. Some studies have found small areas of heart scarring in athletes who train intensely for many years, which may increase the risk of abnormal heart rhythms. Still, serious complications remain uncommon and vary widely between individuals.

Overall, researchers conclude that for most recreational runners, marathon training strengthens the heart rather than harming it. Temporary post-race changes are part of the body’s normal response to extreme exertion. While fitness offers strong protection, experts emphasise that runners should remain alert to symptoms and seek medical care when needed.