Scientists from Yale University have found the physical stress of running a marathon can cause short-term kidney injury.
They analysed the blood and urine of a small group of participants in the 2015 Hartford Marathon before and after the 26.2-mile event. In particular they examined a variety of markers of kidney injury, including serum creatinine levels, kidney cells on microscopy, and proteins in urine.
The researchers found that 82% of the runners that were studied showed Stage 1 Acute Kidney Injury (AKI) soon after the race. AKI is a condition in which the kidneys fail to filter waste from the blood.
“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 hospitalised patients when the kidney is affected by medical and surgical complications,” said lead author, Professor of Medicine Chirag Parikh, M.D.
The researchers stated that potential causes of the marathon-related kidney damage could be the sustained rise in core body temperature, dehydration, or decreased blood flow to the kidneys that occur during a marathon.
While the measured kidney injury resolved within two days post-marathon, the study still raises questions about the effects of repeated strenuous activity over time, especially in warm climates.
“We need to investigate this further,” said Parikh. “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.”
The study was published by the American Journal of Kidney Diseases.