„To date at least seven fatalities and more than 250 cases of this condition have been described in the medical literature,“ said Timothy David Noakes, of the University of South Africa in Cape Town.

The death of a runner in the Boston Marathon last year from the little-known medical condition heightened awareness about the dangers of drinking too much while exercising.

Cynthia Lucero, 28, of Ecuador drank large amounts of a sports drink during the race, according to friends. In a commentary in The British Medical Journal, Noakes said that people in the military, hikers and athletes, particularly women marathon runners, are most likely to develop the condition.

But he said it is preventable and advised athletes to drink to quench their thirst. Most forms of recreational and competitive exercise would require between 400 and 800 ml (140 - 280 fl oz) of liquid per hour. Reuters