A new study has revealed that nearly half of recreational runners may be drinking too much fluid during races, while expert guidelines recommend runners to drink only when thirsty.
According to a survey of runners by Loyola University Health System researchers, 36.5 percent runners drink according to a fixed schedule or to maintain a certain body weight, whereas 8.9 percent drink as much as possible.
Almost one-third of runners - 29.6 percent, incorrectly believe they need to ingest extra salt while running, and more than half - 57.6 percent, say they drink sports drinks as the drinks have electrolytes that prevent low blood sodium.
Studies prove otherwise, suggesting that the main cause of low sodium in runners is drinking too much water or sports drinks.
"Many athletes hold unscientific views regarding the benefits of different hydration practices," the researchers said.
When runners drink in spite of not being thirsty, a potentially fatal condition - exercise-associated hyponatremia, is caused, which can dilute the sodium content of blood to abnormally low levels and the safest way experts suggest is to drink only when thirsty.
"It's the safest known way to hydrate during endurance exercise," Dr. James Winger, first author of the study, said.
Symptoms of hyponatremia include nausea, vomiting, headache, confusion, loss of energy, muscle weakness, spasms or cramps, with seizures, unconsciousness and coma in extreme cases.
Loyala's exercise physiologist Lara Dugas, a co-author of the study has said that there have been 12 documented and 8 suspected deaths of runners from hyponatremia in the recent years.
Researchers surveyed 197 runners who competed in the 2009 Westchester, II Veterans Day 10K and 5K runs along with two other runs on Chicago's lakefront.
The 91 male runners, on average, had been running for 13 years and had run an average of 1.9 10K races and 0.9 marathons. The 106 women, on average, had been running 8.3 years and had run an average of 1.3 10K races and 0.7 marathons.
In the survey, the runners generally said advertising by sports drink manufacturers had little or no influence on their beliefs, whereas their behaviours indicated otherwise.
"We have been trained to believe that dehydration is a complication of endurance exercise," Dugas said.
"But in fact, the normal physiological response to exercise is to lose a small amount of fluid. Runners should expect to lose several pounds during runs, and not be alarmed," Dugas added.
The study was published in the June, 2011, issue of the British Journal of Sports Medicine.