High fluid intake could prove fatal: study

Long distance athletes might endanger their lives if they drink too much water or other fluids, a study by researchers from the Harvard School of Medicine has said.

According to the study, researchers tested the blood samples of 488 runners participating in the 2002 Boston Marathon, before and after the conclusion of the race. The blood samples of 13 per cent of the runners showed high level of salt dilution. This kind of dilution, known as hyponatremia, might induce coma and might even prove fatal in some cases.

A 28-year-old athlete who died during the 2002 race was reported to have major salt dilution in her bloodstream.

According to the researchers, slow runners were more susceptible to this condition since they took more frequent fluid breaks. Such runners were found to drink an average of three litres of water or sports drink.

“Hyponatremia and, particularly, severe hyponatremia may be a greater problem than previously recognized,” said Dr Christopher Almond, the lead author of the study. But he did not indicate how much fluid athletes should ingest since every athlete’s physical makeup and perspiration rate was different.

Dr Almond, however, said that athletes could judge their levels of hydration by checking their weight before and after training laps. A weight gain indicates high levels of liquid intake. “The strongest single predictor of hyponatremia was considerable weight gain during the race,” the study concluded.

Dr Marvin Adner, medical director, Boston Marathon, said, “Before this study we suspected there was a problem. But this proves it.”

According to hyponatremia expert Dr Tim Noakes, both doctors as well as sports drink manufacturers push dehydration as a ‘medical illness that was to be feared’. “Everyone becomes dehydrated when they race. But I have not found one death in an athlete from dehydration in a competitive race in the whole history of running. Not one. Not even a case of illness,” he said.

The study has been published in The New England Journal of Medicine.