Ultra-marathon running can reduce red blood cell flexibility, a study finds

Ultra-marathon running may make red blood cells less flexible, potentially hindering oxygen delivery and waste removal. A new study found this inflexibility and other damage were more pronounced in ultra-marathon runners compared to those completing shorter races. Researchers are investigating if this stress exceeds the body's repair capabilities. The findings are based on a small group of elite runners and do not recommend against participation. The damage observed is similar to that seen in stored blood, offering potential insights for transfusion medicine.