Greed, death and the “science of hydration”. The avoidable tragedy of exercise-induced hyponatremic encephalopathy (EAHE)

In 1981 we described the first recorded case of EAHE in a female South

African ultramarathon runner and concluded that EAHE is caused by

sustained voluntary over-drinking of water or sports drinks during

prolonged exercise. In 1991 we published the definitive study showing

that EAHE is caused by abnormal fluid retention in those who sustain

high rates of fluid ingestion (>1000ml/h) during exercise lasting more

than 4-6 hours. We presumed that this definitive evidence would

relegate EAHE to an historical oddity as athletes were henceforth

discouraged from overdrinking during prolonged exercise.

Instead in the 1990's new drinking guidelines were introduced by both

the US Military and the American College of Sports Medicine that

encouraged athletes to drink up to 1800ml/h during exercise or “as much

as tolerable”. As a consequence in the past 20 years at least 12 cases

of fatal EAHE and another 1000 cases of hospitalization from

exercise-associated hyponatremia (EAH) with or without significant

encephalopathy have occurred.

Since EAH and EAHE are preventable conditions that did not occur in the

more than 100 years of organized athletic competitions before 1981, the

question must be asked: What environmental factor(s) caused the sudden

appearance of this novel disease after 1980?

One likely suspect is the growth of the sports drink industry especially

in the USA. This industry promotes a “science of hydration” that

conflicts with the established evidence that humans do not need to drink

“as much as tolerable” to sustain their health and vigor during any form

of exercise.