Running Marathons Could Be Bad for Your Kidneys

A small study including 22 people who took part in the Hartford, Connecticut Marathon suggested that the long test of endurance takes a toll on the kidneys.

Researchers believe that this may be a result of sustained high core body temperature, dehydration or decreased blood flow to the kidneys. While running, blood is pumped to the skin and muscles—and as a result, the kidneys may not get as much blood as they typically would. Regardless of the cause, 82 percent of the participants showed kidneys that failed to filter waste from the blood.

In order to draw the conclusions above, the team of researchers looked at blood and urine samples collected before and after the marathon, recording creatinine (a waste product excreted by the kidneys) levels in the runners’ blood and proteins their in urine. Kidney cells were also observed under a microscope.

Dr. Chirag Parikh, professor of medicine at Yale University, oversaw the study. He found symptoms of this kidney failure to present themselves the day of the marathon—although they cleared up soon after.

“On day 2, they are all fine,” Parikh said.

The bigger question is whether or not repeated bouts of this injury in marathon runners can lead to chronic kidney disease years later. According to Dr. Parikh, further research and analysis is necessary before those assumptions can be made. However, it has been suggested that marathoners who want to reduce their risk of kidney injury should avoid using anti-inflammatory drugs before a race.

Photo: Derek Hatfield, CC-BY