Marathon runners who finish a race fastest, also lose the largest proportion of their body weight, according to a study. Conversely, those who actually gain weight during the race, performed the worst.
The runners were advised to drink 250 ml of either water or a sports drink every 20 minutes during the race, according to the Telegraph.
The research involved tracking 643 competitors who finished the 2009 Mont Saint Michel Marathon in France — a distance of 42km, the British Journal of Sports Medicine reports.
It was found that the fastest finishers, those who completed the course within three hours, lost three per cent or more of their body weight. Those finishing between three to four hours lost an average of 2.5 per cent of their body weight while those finishing in more than four hours lost two per cent weight. Almost one in 10 runners actually gained weight and finished the slowest.
Co-author Timothy David Noakes from the department of human biology at the University of Cape Town wrote: "Interestingly, 9.5 per cent of runners in this sample over-drank and gained body weight during the race."
{{/usCountry}}Co-author Timothy David Noakes from the department of human biology at the University of Cape Town wrote: "Interestingly, 9.5 per cent of runners in this sample over-drank and gained body weight during the race."
{{/usCountry}}Marathon runners have been persuaded to drink too much during a race by the drinks industry, said the researchers.
Athletes have been repeatedly told that even marginal dehydration can harm their performance, leading to a booming market for sports drinks.
British Soft Drinks Association spokesman said: "With the equipment or footwear you need, it makes sense to choose the right drink for your sporting activity."