Study Finds Marathon Cardiac Arrest Risk Stable, Survival Improving

A new analysis of nearly 30 million U.S. runners shows that the incidence of sudden cardiac arrest during long-distance races has remained stable over the past decade, but survival outcomes have improved significantly.

The RACER study, published in JAMA and presented at the American College of Cardiology’s 2025 Scientific Session, tracked marathon and half-marathon finishers between 2010 and 2023.

Researchers reported 176 cases of cardiac arrest—an overall rate of 0.60 per 100,000 participants. The risk was higher among men (1.12 per 100,000) compared to women (0.19 per 100,000), and in marathoners versus half-marathoners (1.04 vs. 0.47 per 100,000).

“Roughly one in 100,000 people who run a marathon are going to have a cardiac arrest,” said senior investigator Dr. Aaron Baggish. “What that means is that we’re still not doing any better at identifying people who are at risk.”

While incidence rates have not shifted since the early 2000s, survival has improved. Deaths declined from 71% in the 2000–2009 period to 34% in the latest analysis. Bystander CPR, rapid deployment of automated external defibrillators (AEDs), and stronger emergency action plans are believed to be key contributors.

“This is where I think you can convincingly use the term good news,” Baggish said. “We are doing a better job at resuscitating them.”

Lead investigator Dr. Jonathan Kim cautioned that even highly fit long-distance runners are not immune to cardiovascular disease.

“No patient that walks into their office is fit enough or runs enough to outrun the risk that comes with traditional risk factors,” he said.

Researchers concluded that while untargeted screening is not advised, careful evaluation of athletes with known risk factors is essential. Improved race preparedness has made survival more likely when emergencies occur. Read the full story here!