More than 80% of marathon runners incur acute kidney disease, new research has shown.
A team of scientists led by Yale University medical school’s Chirag Parikh tested a small group of runners before and after the Hartford marathon in 2015, looking at markers such as creatinine serum levels and proteins in urine.
The results were startling: 82% of the runners tested showed symptoms of Stage 1 acute kidney injury (AKI) after the event.
AKI used to be known as sudden renal failure, and is primarily characterised by the inability of the kidneys to adequately remove waste material from the blood, and too little urine leaving the body.
In mild cases symptoms can include shortness of breath, fatigue, nausea and swollen legs. More serious cases result in chest pain, seizures, and coma. Although traditionally associated with the elderly, recent research has identified extended periods of heavy physical exercise – in particular, mine work and military training – with elevated AKI risk.
Parikh’s team is the first to test marathon runners for the condition, and the results throw into question the contention that for well-trained people running 42 kilometres (26 miles) non-stop is a healthy thing to do.
“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,” says Parikh.
Potential causes of AKI for marathon runners include high core body temperature, decreased blood flow to the kidneys, and dehydration. The symptoms recorded in the runners tested all resolved after 48 hours, but Parikh warns against complacency.
“We need to investigate this further,” he says. “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 is published in the American Journal of Kidney Diseases.
