A recent study delves into the science, but doctors say there’s more to it.

Running extreme distances may strain more than just muscles and joints. New research suggests ultramarathons can alter red blood cells in ways that make them less flexible and more prone to breakdown, ...

Ultramarathons might push red blood cells past their limits—accelerating their aging in the process.

Extreme endurance running damages red blood cells in ways that may affect their ability to function properly, according to a ...

For many years, scientists have been puzzled by individuals who live in high-elevation areas throughout the world. Surveys of high-altitude populations, from areas of the Andes to regions of the ...

Our blood consists of many cell types that develop through different stages from a precursor type -- the blood stem cell. An international research team has now investigated the developmental pathways ...

Extreme endurance training is often seen as a sign of strong physical fitness. However, new research indicates that very long-distance runs may have negative effects on the body.

Scientists have long known that people living at high altitudes, where oxygen levels are low, have lower rates of diabetes ...