Ultramarathon Running Could Rapidly Age and Breakdown Red Blood Cells

discovermagazine.com · Feb 20, 2026 · Collected from GDELT

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Running can be a great way to keep the body moving and to stay in shape. But extreme endurance running, or ultramarathon running, can also have adverse effects on the body, including damage to red blood cells that can impair their function. A new study in Blood Red Cells & Iron joins a growing body of research that finds these ultra forms of exercise could be doing more harm than good to the body. “Based on these data, we don’t have guidance as to whether people should or should not participate in these types of events; what we can say is, when they do, that persistent stress is damaging the most abundant cell in the body,” said Travis Nemkov, the study’s lead author and associate professor in the department of biochemistry and molecular genetics at the University of Colorado Anschutz, in a press release. Read More: While Running a Marathon, the Brain Can Start to Eat ItselfUltramarathon Running and the Impact on Red Blood CellsPrevious studies, like the one published in Annals of Translational Medicine in 2019 examines how ultramarathon runners can experience red blood cell breakdown during a race, which may cause anemia. While that study noted the cell breakdown, the research team was unsure what actually caused it. Flash forward to 2026, and the Blood Red Cells & Iron study results show that runners competing in ultramarathons see their red blood cells become less flexible, which may reduce the cells' ability to efficiently carrynutrients, oxygen, and waste products throughout the body. “Participating in events like these can cause general inflammation in the body and damage red blood cells,” said Nemkov. The results also helped the research team create the most detailed and complex molecular map of how long-distance endurance races impact red blood cells. “Red blood cells are remarkably resilient, but they are also exquisitely sensitive to mechanical and oxidative stress,” said study co-author Angelo D’Alessandro, Ph.D, in a press release. Collecting Blood From Ultramarathon Racers For the study, the research team examined blood samples from 23 runners competing in either the Martigny-Combes à Chamonix race (25 miles) or the Ultra Trail de Mont Blanc race (106 miles). The team collected the runner’s blood right before and after the races and analyzed the samples for red blood cell health markers. The team then analyzed red blood cells and proteins, metabolites, and lipids. The results indicated consistent evidence of damage from physical and molecular drivers. According to the study, the physical damage to the cells was most likely caused by fluid pressures throughout the body induced by running, while the molecular damage was likely caused by inflammation or oxidative stress. The damage these cells experience — which accelerates their aging and causes them to break down — begins to take effect during the 25-mile race and is only amplified in the runners who participated in the 106-mile race, meaning the longer the run, the more damage the red blood cells experience. “At some point between marathon and ultra-marathon distances, the damage really starts to take hold,” said Nemkov in a press release. “We’ve observed this damage happening, but we don’t know how long it takes for the body to repair that damage, if that damage has a long-term impact, and whether that impact is good or bad.”Preserving Blood for the FutureWhile these forms of exercise can be harmful to red blood cells, the research team hopes these results could fuel further study to improve athletic performance or even reduce the impact of endurance exercise on red blood cells. These findings could even help improve storing blood in a blood bank, which is only viable for about 6 weeks. “This study shows that extreme endurance exercise pushes red blood cells toward accelerated aging through mechanisms that mirror what we observe during blood storage. Understanding these shared pathways gives us a unique opportunity to learn how to better protect blood cell function both in athletes and in transfusion medicine,” D’Alessandro concluded. The team noted that the study had a limited number of participants, lacked racial diversity, and collected blood samples at only two points in the race rather than multiple points. Future studies are planned to incorporate a more diverse group of athletes and more blood samples.This article is not offering medical advice and should be used for informational purposes only.Read More: This Ancient Practice May Lower Blood Pressure on Par With Some DrugsArticle SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:This article references information from a new study published in Blood Red Cells & Iron: Long-Distance Trail Running Induces Inflammatory-Associated Protein, Lipid, and Purine Oxidation in Red Blood CellsThis article references information from a study published in Nature Metabolism: Reversible reduction in brain myelin content upon marathon runningThis article references information from a study published in the Annals of Translational Medicine: Epidemiological, biological, and clinical update on exercise-induced hemolysis