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Is Running Bad for You? Marathons Temporarily Damage Kidneys in Runners' Bodies, Study Finds

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Runners are seen at the start of the Tokyo Marathon on Feb. 26, 2017. Toru Hanai/Reuters

Running a marathon has long been dangerous undertaking. As legend has it, Pheidippides—the Athenian considered to be the first-ever marathoner—collapsed and died after running from Marathon to Athens, roughly 25 miles, to announce at the Acropolis a Greek victory in battle.

So it stands to reason that completing a modern marathon, or 26.2 miles, could damage a runner's body. A new study from Yale University published Tuesday by the American Journal of Kidney Disease found that running a marathon could cause temporary damage to the participant's kidneys.

The researchers collected and analyzed blood and urine samples from runners in the 2015 Hartford Marathon. Eight-two percent of the participants displayed Stage 1 Acute Kidney Injury or AKI. That means kidneys aren't properly filtering waste from blood. It can, in turn, affect other organs like the brain, heart and lung, according to the National Kidney Foundation.

"The kidney responds to the physical stress of marathon running as if it's injured, in a way that's similar to what happens in hospitalized patients when the kidney is affected by medical and surgical complications," Dr. Chirag Parikh, the study's lead researcher, said in a Yale news release

The study found the kidney injury subsided within two days after the marathon, but the researchers stressed that further studies are needed to determine how damaging running such races can be. 

"We need to investigate this further," Parikh said in the release. "Research has shown there are also changes in heart function associated with marathon running. Our study adds to the story—even the kidney responds to marathon-related stress."

Most people would expect marathoners to suffer typical injuries that come with participating in sports. Runners World noted runner's knee, Achilles tendonitis and shinsplints were some of the most common "body breakdowns" for marathoners.

But a 2012 study published in the the American Journal of Sports Medicine noted that 28 people died in the 24 hours directly after completing a marathon in the ten-year period from 2000 through 2009. The study also pointed out, however, that while the number of participants rose sharply during that decade the death rate was unchanged. 

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