Sports drinks consumption under scrutiny in journal editorial
sports drinks, during exercise, writes a sports medicine expert in
this week's BMJ, prompting swift reaction from sports drink
maker Gatorade.
Athletes should be warned against drinking too much water, or other sports drinks, during and after exercise as it can have a potentially fatal outcome, according to a sports medicine expert writing in this week's British Medical Journal.
The warning follows reports of several deaths from a severe lack of salt in the blood due to excessive drinking (hyponatremic encephalopathy). But the article has prompted reaction from makers of sports drink Gatorade which said the advice does not take into account the dangers associated with the more common condition of dehydration.
Until the late 1960s, athletes were advised not to drink during exercise since it was believed that fluid ingestion impaired athletic performance, said Timothy Noakes of the Sports Science Institute of South Africa. The publication in 1969 of an incorrectly titled article, 'The danger of an inadequate water intake during marathon running' provided the impetus for change, and led to guidelines for ingestion of fluids during exercise.
These guidelines make several assumptions that are not backed up by evidence. Nor were trials undertaken to ensure that these guidelines are always safe, wrote the author. The first reports of hyponatraemic encephalopathy in athletes, military personnel, and hikers appeared shortly after the new guidelines, and since then at least seven fatalities and more than 250 cases of the condition have been described in medical literature, says Noakes.
Drinking according to the personal dictates of thirst seems to be the safest and best advice, said Noakes. Such fluid intake typically ranges between 400 ml and 800 ml per hour in most forms of recreational and competitive exercise.
PepsiCo-owned Gatorade said in a release however that the editorial is "not representative of the comprehensive research that is available on the topic of hydration during exercise".
"There is solid scientific evidence that dehydration increases the risk of heat illness and impairs performance. Research also clearly shows that relying on thirst will cause athletes to underestimate fluid needs, leading to dehydration during exercise," said the company.
"Several leading sports health associations that are charged with the care and well-being of athletes have issued position statements and guidelines on fluid replacement that continue to reflect the importance of hydration before, during and after exercise," it added, referring to recent guidelines issued by the Inter-Association Task Force on Exertional Heat Illnesses (comprised of 18 health and sports-medicine groups).
The company added that is agreed with the dangers for both athletes and non-athletes to drink excessively, but that while hyponatremia is a rare but dangerous condition that affects a very, very small subset of the population, "dehydration and heat illness occur far more frequently and represent the greater threat to anyone who is physically active in a warm environment".
