Too much water can be deadly, athletes warned
14/04/2005 - 15:33:24Drinking too much water during intense exercise can severely damage your health, US doctors have warned.
A study of participants in the Boston marathon found that 13% drank so much during the race they developed hyponatremia, or abnormally low blood sodium levels.
Three runners had levels so low that they were in danger of dying, according to the study, published in the New England Journal of Medicine.
Those athletes also tended to be slower, taking more than four hours to finish the course. And they drank so much water – an average of three litres – they actually put on weight during the race.
One female runner died of hyponatremia.
The research involved 488 runners in the 2002 marathon. The athletes gave blood samples before and after the race which were tested for salt content.
The study, led by Dr Christopher Almond at Boston Children’s Hospital, warns that endurance athletes are severely diluting their blood by drinking such large quantities of water and energy drinks.
Dr Almond said the problem may be more serious then previously thought.
He does not make specific recommendations about how much fluid runners should consume but says the best level of hydration can be found by weighing yourself before and after training runs.
If athletes have gained weight by the end, they have probably taken in too much fluid, researchers said.
“The strongest single predictor of hyponatremia was considerable weight gain during the race,” the study concludes.
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