Is Marathon Running Bad For You?

Running a marathon can be a grueling task — both mentally and physically. With the surge in popularity of organized races, the amount of non-elite runner participation has increased drastically posing important questions about what negative affects may be suffered by an average athlete. In fact, many post-race runners question whether they’ve caused permanent, unforeseen damage.

In 2019, over half a million individuals completed marathons across the country. There is no question about the health benefits associated with training for a marathon. Regular exercise decreases your risk of death from coronary heart disease and has “beneficial effects on blood pressure, lipid profile, insulin resistance, and overall risk of death.” (1)

is marathon running bad for you?

Racing a Marathon Has Important health Consequences

However, studies have shown that training for the race and running it are two different things. A 2006 study published in Circulation showed that running a marathon is correlated with biochemical and graphic evidence of cardiac dysfunction and injury. Findings further revealed than an increase in biomarkers for such injuries was correlated with the amount of training pre-race. Athletes who trained with an average of 35 running miles or less per week, compared with those who ran 45 or more, showed increased pulmonary pressures and right ventricular dysfunction. Regardless of training, echocardiograms showed runners suffered altered diastolic filling (i.e., ventricles cannot properly relax and become stiff causing the inability to fill properly), increased pulmonary pressures and decreased right ventricular systolic function. Researchers also found evidence of heart enzymes leaking through the heart membrane. (2)

No questions asked, we all know that our muscles are the most stressed by marathon running, but less obvious is that our heart is one of the muscles that is stressed the most. Blood measures of post-race runners showed the body experiencing an inflammatory storm with high levels of coagulation markers that are associated with heart attacks. Risk for a cardiac event is not only present throughout the race, but also for hours afterwards. This means that middle-aged men are at the highest risk for marathon-induced cardiac arrest. (3)

One thing these studies do not consider is whether running shorter races, such as a 5K or 8K “cold turkey”, without proper training is just as damaging as running a marathon after consistently running low-mileage, or no-mileage, weeks up to race day.

Moral of the story: training is important, but it cannot fully protect the human body from the great stress of running a marathon. There’s no need to quit all your marathon-running goals, and for those dedicated to running these lengths every year, an article about the health and heart risks is unlikely to derail goals. However, it’s important to keep in mind that unknown health risks can pose a risk for anyone — at any age. Training and building strength from the cyclical injury-and-repair process is one of the most critical factors in reducing injury and the inflammatory response associated with long-distance races.


(1) https://www.ahajournals.org/doi/pdf/10.1161/CIRCULATIONAHA.106.647461
(2) Id.
(3) https://www.menshealth.com/fitness/a19541152/the-severe-health-risks-of-marathon-running/