Running extreme distances may strain more than just muscles and joints. New research suggests ultramarathons can alter red ...

Extreme endurance running damages red blood cells in ways that may affect their ability to function properly, according to a study published in the American Society of Hematology's journal Blood Red ...

Red blood cells transport oxygen throughout your body, including to vital organs and tissues. They also help your body get rid of carbon dioxide. Too little or too many red blood cells may be ...