WASHINGTON - A health and performance rule cherished by 30 million American runners, and legions of other exercise enthusiasts, is dangerous, has no basis in scientific fact, and should be trashed.
That's the message going out to doctors today about the idea that athletes should “stay ahead of your thirst,” drinking as much water as possible during strenuous exercise even if they don't feel thirsty.
The new advice: “Listen to your thirst,” and consume only as much water or sports drink to quench it.
It finally is trickling out to a broader audience, months after growing acceptance by a sports community long uncertain about the actual amount of fluid athletes should drink for good health and peak performance.
“Exercisers must be warned that the over consumption of fluid (either water or sports drinks) before, during, or after exercise is unnecessary and can have a potentially fatal outcome,” the British Medical Journal said in today's edition.
“Perhaps the best advice is that drinking according to the personal dictates of thirst seems to be safe and effective.”
It was written by Dr. Timothy D. Noakes, an internationally known sports medicine expert at the University of Cape Town in South Africa. He has been influential in getting organizations to revise their hydration guidelines.
USA Track & Field, for instance, cited Dr. Noakes's research in May when it adopted new fluid-replacement guidelines for long-distance runners and athletes in general.
“Simply put, runners should be sensitive to the onset of thirst as the signal to drink, rather than staying ahead of thirst,” said the group, which is the national governing body for track and field, long-distance running, and race walking.
The International Marathon Medical Directors Association did the same in 2002 when it issued a similar hydration advisory.
Another major organization, the American College of Sports Medicine (ACSM), reportedly is reviewing its hydration guidelines. An ACSM spokesperson did not respond to a request for comment.
The ACSM guidelines advise athletes to tank up on fluid before exercise. During exercise, athletes should try to replace all water lost through sweating “or consume the maximal amount that can be tolerated,” the guidelines, issued in 1996, state.
Dr. Noakes described a curious origin for the conventional wisdom that people should tank up on fluids before, during, and after exercise.
From antiquity until the late 1960s, athletes were told never to drink during exercise because fluids hampered performance. Then in 1969, the headline writer for a scientific journal goofed, and titled an article “The Danger of an Inadequate Water Intake During Marathon Running.”
The article actually involved a study that didn't report any dangers, or even involve a marathon. Nevertheless, the title alone triggered a flurry of other studies, some sponsored by the then-fledgling sports drink industry.
None of the studies produced sound scientific evidence that athletes need to be told how much to drink. Nevertheless, organizations like US Track & Field and ACSM issued guidelines for athletes promoting the “drink-as-much-as-you can” idea. It also became gospel for people engaged in more casual exercise.
Doctors now know that overconsumption of fluids, either during exercise or at rest, can cause a potentially fatal condition called exertional hyponatraemia (EH). Dr. Noakes said the first cases appeared after the guidelines were issued.